A. Messineo

The RD48 (ROSE) collaboration has succeeded to develop radiation hard silicon detectors, capable to withstand the harsh hadron fluences in the tracking areas of LHC experiments. In order to reach this objective, a defect engineering technique was employed resulting in the development of Oxygen enriched FZ silicon (DOFZ), ensuring the necessary O-enrichment of about 2×1017 O/cm3 in the normal detector processing. Systematic investigations have been carried out on various standard and oxygenated silicon diodes with neutron, proton and pion irradiation up to a fluence of 5×1014 cm−2 (1 MeV neutron equivalent). Major focus is on the changes of the effective doping concentration (depletion voltage). Other aspects (reverse current, charge collection) are covered too and the appreciable benefits obtained with DOFZ silicon in radiation tolerance for charged hadrons are outlined. The results are reliably described by the “Hamburg model”: its application to LHC experimental conditions is shown, demonstrating the superiority of the defect engineered silicon. Microscopic aspects of damage effects are also discussed, including differences due to charged and neutral hadron irradiation.

Extended results on the cosmic-ray electron + positron spectrum from 11 GeV to 4.8 TeV are presented based on observations with the Calorimetric Electron Telescope (CALET) on the International Space Station utilizing the data up to November 2017. The analysis uses the full detector acceptance at high energies, approximately doubling the statistics compared to the previous result. CALET is an all-calorimetric instrument with a total thickness of 30 $X_0$ at normal incidence and fine imaging capability, designed to achieve large proton rejection and excellent energy resolution well into the TeV energy region. The observed energy spectrum in the region below 1 TeV shows good agreement with Alpha Magnetic Spectrometer (AMS-02) data. In the energy region below $\sim$300 GeV, CALET's spectral index is found to be consistent with the AMS-02, Fermi Large Area Telescope (Fermi-LAT) and Dark Matter Particle Explorer (DAMPE), while from 300 to 600 GeV the spectrum is significantly softer than the spectra from the latter two experiments. The absolute flux of CALET is consistent with other experiments at around a few tens of GeV. However, it is lower than those of DAMPE and Fermi-LAT with the difference increasing up to several hundred GeV. The observed energy spectrum above $\sim$1 TeV suggests a flux suppression consistent within the errors with the results of DAMPE, while CALET does not observe any significant evidence for a narrow spectral feature in the energy region around 1.4 TeV. Our measured all-electron flux, including statistical errors and a detailed breakdown of the systematic errors, is tabulated in the Supplemental Material in order to allow more refined spectral analyses based on our data.

In this paper, we present the analysis and results of a direct measurement of the cosmic-ray proton spectrum with the CALET instrument onboard the International Space Station, including the detailed assessment of systematic uncertainties. The observation period used in this analysis is from October 13, 2015 to August 31, 2018 (1054 days). We have achieved the very wide energy range necessary to carry out measurements of the spectrum from 50 GeV to 10 TeV covering, for the first time in space, with a single instrument the whole energy interval previously investigated in most cases in separate subranges by magnetic spectrometers (BESS-TeV, PAMELA, and AMS-02) and calorimetric instruments (ATIC, CREAM, and NUCLEON). The observed spectrum is consistent with AMS-02 but extends to nearly an order of magnitude higher energy, showing a very smooth transition of the power-law spectral index from -2.81±0.03 (50-500 GeV) neglecting solar modulation effects (or -2.87±0.06 including solar modulation effects in the lower energy region) to -2.56±0.04 (1-10 TeV), thereby confirming the existence of spectral hardening and providing evidence of a deviation from a single power law by more than 3σ.

First results of a cosmic-ray electron + positron spectrum, from 10 GeV to 3 TeV, is presented based upon observations with the CALET instrument on the ISS starting in October, 2015.Nearly a half million electron + positron events are included in the analysis.CALET is an all-calorimetric instrument with total vertical thickness of 30 X0 and a fine imaging capability designed to achieve a large proton rejection and excellent energy resolution well into the TeV energy region.The observed energy spectrum over 30 GeV can be fit with a single power law with a spectral index of -3.152±0.016(stat.+syst.).Possible structure observed above 100 GeV requires further investigation with increased statistics and refined data analysis.

A precise measurement of the cosmic-ray proton spectrum with the Calorimetric Electron Telescope (CALET) is presented in the energy interval from 50 GeV to 60 TeV, and the observation of a softening of the spectrum above 10 TeV is reported. The analysis is based on the data collected during ∼6.2 years of smooth operations aboard the International Space Station and covers a broader energy range with respect to the previous proton flux measurement by CALET, with an increase of the available statistics by a factor of ∼2.2. Above a few hundred GeV we confirm our previous observation of a progressive spectral hardening with a higher significance (more than 20 sigma). In the multi-TeV region we observe a second spectral feature with a softening around 10 TeV and a spectral index change from -2.6 to -2.9 consistently, within the errors, with the shape of the spectrum reported by DAMPE. We apply a simultaneous fit of the proton differential spectrum which well reproduces the gradual change of the spectral index encompassing the lower energy power-law regime and the two spectral features observed at higher energies.

We present the results of a direct measurement of the cosmic-ray helium spectrum with the CALET instrument in operation on the International Space Station since 2015. The observation period covered by this analysis spans from October 13, 2015 to April 30, 2022 (2392 days). The very wide dynamic range of CALET allowed to collect helium data over a large energy interval, from ~40 GeV to ~250 TeV, for the first time with a single instrument in Low Earth Orbit. The measured spectrum shows evidence of a deviation of the flux from a single power-law by more than 8$\sigma$ with a progressive spectral hardening from a few hundred GeV to a few tens of TeV. This result is consistent with the data reported by space instruments including PAMELA, AMS-02, DAMPE and balloon instruments including CREAM. At higher energy we report the onset of a softening of the helium spectrum around 30 TeV (total kinetic energy). Though affected by large uncertainties in the highest energy bins, the observation of a flux reduction turns out to be consistent with the most recent results of DAMPE. A Double Broken Power Law (DBPL) is found to fit simultaneously both spectral features: the hardening (at lower energy) and the softening (at higher energy). A measurement of the proton to helium flux ratio in the energy range from 60 GeV/n to about 60 TeV/n is also presented, using the CALET proton flux recently updated with higher statistics.

In this paper, we present the measurement of the energy spectra of carbon and oxygen in cosmic rays based on observations with the Calorimetric Electron Telescope (CALET) on the International Space Station from October 2015 to October 2019. Analysis, including the detailed assessment of systematic uncertainties, and results are reported. The energy spectra are measured in kinetic energy per nucleon from 10 GeV$/n$ to 2.2 TeV$/n$ with an all-calorimetric instrument with a total thickness corresponding to 1.3 nuclear interaction length. The observed carbon and oxygen fluxes show a spectral index change of $\sim$0.15 around 200 GeV$/n$ established with a significance $>3\sigma$. They have the same energy dependence with a constant C/O flux ratio $0.911\pm 0.006$ above 25 GeV$/n$. The spectral hardening is consistent with that measured by AMS-02, but the absolute normalization of the flux is about 27% lower, though in agreement with observations from previous experiments including the PAMELA spectrometer and the calorimetric balloon-borne experiment CREAM.

The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray iron over a wide energy interval. In this Letter a measurement of the iron spectrum is presented in the range of kinetic energy per nucleon from 10 GeV$/n$ to 2.0 TeV$/n$ allowing the inclusion of iron in the list of elements studied with unprecedented precision by space-borne instruments. The measurement is based on observations carried out from January 2016 to May 2020. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number $Z$ = 40). The energy is measured by a homogeneous calorimeter with a total equivalent thickness of 1.2 proton interaction lengths preceded by a thin (3 radiation lengths) imaging section providing tracking and energy sampling. The analysis of the data and the detailed assessment of systematic uncertainties are described and results are compared with the findings of previous experiments. The observed differential spectrum is consistent within the errors with previous experiments. In the region from 50 GeV$/n$ to 2 TeV$/n$ our present data are compatible with a single power law with spectral index -2.60 $\pm$ 0.03.

This report summarises the final results obtained by the RD48 collaboration. The emphasis is on the more practical aspects directly relevant for LHC applications. The report is based on the comprehensive survey given in the 1999 status report (RD48 3rd Status Report, CERN/LHCC 2000-009, December 1999), a recent conference report (Lindström et al. (RD48), and some latest experimental results. Additional data have been reported in the last ROSE workshop (5th ROSE workshop, CERN, CERN/LEB 2000-005). A compilation of all RD48 internal reports and a full publication list can be found on the RD48 homepage (http://cern.ch/RD48/). The success of the oxygen enrichment of FZ-silicon as a highly powerful defect engineering technique and its optimisation with various commercial manufacturers are reported. The focus is on the changes of the effective doping concentration (depletion voltage). The RD48 model for the dependence of radiation effects on fluence, temperature and operational time is verified; projections to operational scenarios for main LHC experiments demonstrate vital benefits. Progress in the microscopic understanding of damage effects as well as the application of defect kinetics models and device modelling for the prediction of the macroscopic behaviour has also been achieved but will not be covered in detail.

This paper covers the main technological and design aspects relevant to the development of a new generation of thin 3D pixel sensors with small pixel size aimed at the High-Luminosity LHC upgrades.

In August 2015, the CALorimetric Electron Telescope (CALET), designed for long exposure observations of high energy cosmic rays, docked with the International Space Station (ISS) and shortly thereafter began tocollect data. CALET will measure the cosmic ray electron spectrum over the energy range of 1 GeV to 20 TeV with a very high resolution of 2% above 100 GeV, based on a dedicated instrument incorporating an exceptionally thick 30 radiation-length calorimeter with both total absorption and imaging (TASC and IMC) units. Each TASC readout channel must be carefully calibrated over the extremely wide dynamic range of CALET that spans six orders of magnitude in order to obtain a degree of calibration accuracy matching the resolution of energy measurements. These calibrations consist of calculating the conversion factors between ADC units and energy deposits, ensuring linearity over each gain range, and providing a seamless transition between neighboring gain ranges. This paper describes these calibration methods in detail, along with the resulting data and associated accuracies. The results presented in this paper show that a sufficient accuracy was achieved for the calibrations of each channel in order to obtain a suitable resolution over the entire dynamic range of the electron spectrum measurement.

We present the measurement of the energy dependence of the boron flux in cosmic rays and its ratio to the carbon flux in an energy interval from 8.4 GeV/n to 3.8 TeV/n based on the data collected by the Calorimetric Electron Telescope (CALET) during ∼6.4 yr of operation on the International Space Station. An update of the energy spectrum of carbon is also presented with an increase in statistics over our previous measurement. The observed boron flux shows a spectral hardening at the same transition energy E0∼200 GeV/n of the C spectrum, though B and C fluxes have different energy dependences. The spectral index of the B spectrum is found to be γ=−3.047±0.024 in the interval 25<E<200 GeV/n. The B spectrum hardens by ΔγB=0.25±0.12, while the best fit value for the spectral variation of C is ΔγC=0.19±0.03. The B/C flux ratio is compatible with a hardening of 0.09±0.05, though a single power-law energy dependence cannot be ruled out given the current statistical uncertainties. A break in the B/C ratio energy dependence would support the recent AMS-02 observations that secondary cosmic rays exhibit a stronger hardening than primary ones. We also perform a fit to the B/C ratio with a leaky-box model of the cosmic-ray propagation in the Galaxy in order to probe a possible residual value λ0 of the mean escape path length λ at high energy. We find that our B/C data are compatible with a nonzero value of λ0, which can be interpreted as the column density of matter that cosmic rays cross within the acceleration region.Received 7 October 2022Revised 7 November 2022Accepted 22 November 2022DOI:https://doi.org/10.1103/PhysRevLett.129.251103Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Cosmic rays & astroparticlesResearch AreasCosmic rays & astroparticlesResearch AreasCosmic ray & astroparticle detectorsCosmic ray accelerationCosmic ray composition & spectraCosmic ray propagationCosmic ray sourcesCosmic rays & astroparticlesGravitation, Cosmology & Astrophysics

The CALorimetric Electron Telescope (CALET), launched for installation on the International Space Station (ISS) in August, 2015, has been accumulating scientific data since October, 2015. CALET is intended to perform long-duration observations of high-energy cosmic rays onboard the ISS. CALET directly measures the cosmic-ray electron spectrum in the energy range of 1 GeV to 20 TeV with a 2% energy resolution above 30 GeV. In addition, the instrument can measure the spectrum of gamma rays well into the TeV range, and the spectra of protons and nuclei up to a PeV. In order to operate the CALET onboard ISS, JAXA Ground Support Equipment (JAXA-GSE) and the Waseda CALET Operations Center (WCOC) have been established at JAXA and Waseda University, respectively. Scientific operations using CALET are planned at WCOC, taking into account orbital variations of geomagnetic rigidity cutoff. Scheduled command sequences are used to control the CALET observation modes on orbit. Calibration data acquisition by, for example, recording pedestal and penetrating particle events, a low-energy electron trigger mode operating at high geomagnetic latitude, a low-energy gamma-ray trigger mode operating at low geomagnetic latitude, and an ultra heavy trigger mode, are scheduled around the ISS orbit while maintaining maximum exposure to high-energy electrons and other high-energy shower events by always having the high-energy trigger mode active. The WCOC also prepares and distributes CALET flight data to collaborators in Italy and the United States. As of August 31, 2017, the total observation time is 689 days with a live time fraction of the total time of ∼ 84%. Nearly 450 million events are collected with a high-energy (E > 10 GeV) trigger. In addition, calibration data acquisition and low-energy trigger modes, as well as an ultra-heavy trigger mode, are consistently scheduled around the ISS orbit. By combining all operation modes with the excellent-quality on-orbit data collected thus far, it is expected that a five-year observation period will provide a wealth of new and interesting results.

The relative abundance of cosmic ray nickel nuclei with respect to iron is by far larger than for all other transiron elements; therefore it provides a favorable opportunity for a low background measurement of its spectrum. Since nickel, as well as iron, is one of the most stable nuclei, the nickel energy spectrum and its relative abundance with respect to iron provide important information to estimate the abundances at the cosmic ray source and to model the Galactic propagation of heavy nuclei. However, only a few direct measurements of cosmic-ray nickel at energy larger than ∼3 GeV/n are available at present in the literature, and they are affected by strong limitations in both energy reach and statistics. In this Letter, we present a measurement of the differential energy spectrum of nickel in the energy range from 8.8 to 240 GeV/n, carried out with unprecedented precision by the Calorimetric Electron Telescope (CALET) in operation on the International Space Station since 2015. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z=40). The particle's energy is measured by a homogeneous calorimeter (1.2 proton interaction lengths, 27 radiation lengths) preceded by a thin imaging section (3 radiation lengths) providing tracking and energy sampling. This Letter follows our previous measurement of the iron spectrum [1O. Adriani et al. (CALET Collaboration), Phys. Rev. Lett. 126, 241101 (2021).PRLTAO0031-900710.1103/PhysRevLett.126.241101], and it extends our investigation on the energy dependence of the spectral index of heavy elements. It reports the analysis of nickel data collected from November 2015 to May 2021 and a detailed assessment of the systematic uncertainties. In the region from 20 to 240 GeV/n our present data are compatible within the errors with a single power law with spectral index -2.51±0.07.

We present upper limits in the hard X-ray and gamma-ray bands at the time of the LIGO gravitational-wave event GW 151226 derived from the CALorimetric Electron Telescope (CALET) observation. The main instrument of CALET, CALorimeter (CAL), observes gamma-rays from ~1 GeV up to 10 TeV with a field of view of ~2 sr. The CALET gamma-ray burst monitor (CGBM) views ~3 sr and ~2pi sr of the sky in the 7 keV - 1 MeV and the 40 keV - 20 MeV bands, respectively, by using two different scintillator-based instruments. The CGBM covered 32.5% and 49.1% of the GW 151226 sky localization probability in the 7 keV - 1 MeV and 40 keV - 20 MeV bands respectively. We place a 90% upper limit of 2 x 10^{-7} erg cm-2 s-1 in the 1 - 100 GeV band where CAL reaches 15% of the integrated LIGO probability (~1.1 sr). The CGBM 7 sigma upper limits are 1.0 x 10^{-6} erg cm-2 s-1 (7-500 keV) and 1.8 x 10^{-6} erg cm-2 s-1 (50-1000 keV) for one second exposure. Those upper limits correspond to the luminosity of 3-5 x 10^{49} erg s-1 which is significantly lower than typical short GRBs.

We present a comparative study of the performance of elemental and compound solid state crystals of possible use in X-raY digital radiography. The general purpose EGS4 code was used to simulate photon-electron transport in the energy range 20 to 60 keV. The efficiency and the energy resolution, as a function of X-ray energy, are calculated and correlated to the different physical characteristics of the crystals considered.

The Compact Muon Solenoid (CMS) is one of the experiments at the Large Hadron Collider (LHC) under construction at CERN. Its inner tracking system consist of the world largest Silicon Strip Tracker (SST). In total it implements 24,244 silicon sensors covering an area of 206m2. To construct a large system of this size and ensure its functionality for the full lifetime of 10 years under LHC condition, the CMS collaboration developed an elaborate design and a detailed quality assurance program. This paper describes the strategy and shows first results on sensor qualification.

The purpose of this work is to study layout solutions aimed at increasing the breakdown voltage in silicon micro-strip detectors. Several structures with multiple floating guards in different configurations have been designed and produced on high-resistivity silicon wafers. The main electrical characteristics of these devices have been measured before and after irradiation. Both radiation-induced surface and bulk damage effects were considered as well. The highest breakdown voltage was found on devices featuring p/sup +/ guards without field plates. A simulation study has been carried out on simplified structures to evaluate the distribution of the breakdown field as a function of the guard layout. The aim was design optimization.

Abstract The CALorimetric Electron Telescope primary detector (CALET-CAL) is a 30 radiation-length-deep hybrid calorimeter designed for the accurate measurement of high-energy cosmic rays. It is capable of triggering on and giving near complete containment of electromagnetic showers from primary electrons and gamma rays from 1 GeV to over 10 TeV. The first 24 months of on-orbit scientific data (2015 November 01–2017 October 31) provide valuable characterization of the performance of the calorimeter based on analyses of the gamma-ray data set in general and bright point sources in particular. We describe the gamma-ray analysis, the expected performance of the calorimeter based on Monte Carlo simulations, the agreement of the flight data with the simulated results, and the outlook for long-term gamma-ray observations with the CAL.

We report on the 3-year INFN ATLAS–CMS joint research activity in collaboration with FBK, started in 2014, and aimed at the development of new thin pixel detectors for the High Luminosity LHC Phase-2 upgrades. The program is concerned with both 3D and planar active-edge pixel sensors to be made on 6" p-type wafers. The technology and the design will be optimized and qualified for extreme radiation hardness (2×1016 neq cm−2). Pixel layouts compatible with present (for testing) and future (RD53 65 nm) front-end chips of ATLAS and CMS are considered. The paper covers the main aspects of the research program, from the sensor design and fabrication technology, to the results of initial tests performed on the first prototypes.

Iron and nickel cosmic ray nuclei play a key role in the understanding of the acceleration and propagation mechanisms of charged particles in our Galaxy. In fact, iron and nickel are the most abundant nuclei among the heavy elements and provide favorable conditions for a low background measurement thanks to the negligible contamination from spallation of higher mass elements. CALET, operating on the ISS since 2015, has excellent capabilities of charge discrimination up to nickel and can measure the energy of cosmic ray nuclei thanks to a lead tungstate calorimeter providing a direct and precise measurement of heavy charged nuclei spectra. In this contribution, a direct measurement of iron and nickel nuclei spectra in the energy range from 10 GeV/n to 2 TeV/n and from 8.8 GeV/n to 240 GeV/n, respectively is presented. More than five years of data collected by CALET were used. A detailed study of systematic uncertainties is also illustrated. The measured spectra are compared with the ones measured by other experiments and are compatible with a single power law fit in the energy region from 50 GeV/n to 2 TeV/n and from 20 GeV/n to 240 GeV/n for iron and nickel respectively. Also, the ratio between nickel and iron spectra is reported.

The Calorimetric Electron Telescope, CALET, is an astroparticle physics mission installed on the International Space Station, ISS. The primary objective of the mission is studying the details of galactic cosmic-ray acceleration and propagation, and searching for the possible nearby sources of high-energy electrons and dark matter signatures. The CALET experiment measure the flux of cosmic-ray electrons (including positrons) to 20 TeV, gamma-rays to 10 TeV and nuclei to 1000 TeV. The detector is an all-calorimetric instrument with a total vertical thickness of 30 radiation lengths and fine imaging capability, optimized for the measurement of the electron and positron (all-electron) spectrum well into the TeV energy region. It consists of a charge detector (CHD) with two layers of segmented plastic scintillators for the identification of cosmic-rays via a measurement of their charge over the range Z=1∼40, a 3 radiation length thick tungsten-scintillating fiber imaging calorimeter (IMC) and a 27 radiation length thick lead-tungstate calorimeter (TASC). The instrument was launched on August 19, 2015 to the ISS and installed on the Japanese Experiment Module-Exposed Facility. Since the start of operation in October, 2015, CALET has been collecting scientific data without any major interruption for more than eight years. The number of triggered events over 10 GeV is nearly 1.97 billion events as of November 30, 2023. In this paper, we present the results of the CALET mission so far, including the all-electron energy spectrum, the spectra of protons and other nuclei, gamma-ray observations, as well as the characterization of on-orbit performance. Some results on the electromagnetic counterpart search for LIGO/Virgo gravitational wave events and the observations of solar modulation and gamma-ray bursts are also included.

We report on the design, manufacturing and first characterisation of pad diodes, test structures and microstrip detectors processed with high resistivity magnetic Czochralski (MCz) p- and n-type Si. The pre-irradiation study on newly processed microstrip detectors and test structures show a good overall quality of the processed wafers. After irradiation with 24 GeV/c protons up to 4×1014 cm-2 the characterisation of n-on-p and p-on-n MCz Si sensors with the C–V method show a decrease of the full depletion voltage and no space charge sign inversion. Microscopic characterisation has been performed to study the role of thermal donors in Czochralski Si. No evidence of thermal donor activation was observed in n-type MCz Si detectors if contact sintering was performed at a temperature lower than 380 °C and the final passivation oxide was omitted.

Results of an extensive R&D program aiming at radiation hard, small pitch, 3D pixel sensors are reported. The CMS experiment is supporting this R&D in the scope of the Inner Tracker upgrade for the High Luminosity phase of the CERN Large Hadron Collider (HL-LHC). In the HL-LHC the Inner Tracker will have to withstand an integrated fluence up to 2.3×1016neq/cm2. A small number of 3D sensors were interconnected with the RD53A readout chip, which is the first prototype of 65 nm CMOS pixel readout chip designed for the HL-LHC pixel trackers. In this paper results obtained in beam tests before and after irradiation are reported. The irradiation of a single chip module was performed up to a maximum equivalent fluence of about 1×1016neq/cm2. The analysis of the collected data shows excellent performance: the spatial resolution in not irradiated sensors can reach about 3 to 5 μm, for inclined tracks, depending on the pixel pitch. The measured hit detection efficiencies are close to 99% measured both before and after the above mentioned irradiation fluence.

Interstrip and backplane capacitances on silicon microstrip detectors with p+ strip on n substrate of 320μm thickness were measured for pitches between 60 and 240μm and width over pitch ratios between 0.13 and 0.5. Parametrisations of capacitance w.r.t. pitch and width were compared with data. The detectors were measured before and after being irradiated to a fluence of 4×1014protons/cm2 of 24GeV/c momentum. The effect of the crystal orientation of the silicon has been found to have a relevant influence on the surface radiation damage, favouring the choice of a 〈100〉 substrate. Working at high bias (up to 500 V in CMS) might be critical for the stability of detector, for a small width over pitch ratio. The influence of having a metal strip larger than the p+ implant has been studied and found to enhance the stability.

Abstract We present the results of searches for gamma-ray counterparts of the LIGO/Virgo gravitational wave events using CALorimetric Electron Telescope ( CALET ) observations. The main instrument of CALET , CALorimeter (CAL), observes gamma-rays from ∼1 GeV up to 10 TeV with a field of view (FOV) of nearly 2 sr. In addition, the CALET gamma-ray burst monitor views ∼3 sr and ∼2 π sr of the sky in the 7 keV–1 MeV and the 40 keV–20 MeV bands, respectively, by using two different crystal scintillators. The CALET observations on the International Space Station started in 2015 October, and here we report analyses of events associated with the following gravitational wave events: GW151226, GW170104, GW170608, GW170814, and GW170817. Although only upper limits on gamma-ray emission are obtained, they correspond to a luminosity of 10 49 ∼ 10 53 erg s −1 in the GeV energy band depending on the distance and the assumed time duration of each event, which is approximately on the order of luminosity of typical short gamma-ray bursts. This implies that there will be a favorable opportunity to detect high-energy gamma-ray emission in further observations if additional gravitational wave events with favorable geometry will occur within our FOV. We also show the sensitivity of CALET for gamma-ray transient events, which is on the order of 10 −7 erg cm −2 s −1 for an observation of 100 s in duration.

3D type of pixel sensors is a promising option for the innermost pixel layer at the High-Luminosity LHC. However, the required very high hit-rate capabilities, finer pixel granularity, extreme radiation hardness and reduced material budget call for a downscale of the pixel size as compared to existing 3D sensors, involving smaller pitch (e.g. 50 × 50 or 25×100μm2), shorter inter-electrode spacing (∼30μm), narrower electrodes (∼6μm diameter), and reduced active thickness (∼100–150μm). Within a joint R&D effort with INFN, FBK has produced a new generation of 3D pixel sensors with these challenging features. In this talk preliminary results from the electrical and functional characterisation of the first prototypes are reported, included their behaviour after large radiation fluence, close to the ones expected in the High Luminosity LHC environment. Prospects for the next prototypes are also presented.

Test beam results obtained with 3D pixel sensors bump-bonded to the RD53A prototype readout ASIC are reported. Sensors from FBK Italy and IMB-CNM (Spain) have been tested before and after proton-irradiation to an equivalent fluence of about 1 × 1016 ≠cm-2 (1 MeV equivalent neutrons). This is the first time that one single collecting electrode fine pitch 3D sensors are irradiated up to such fluence bump-bonded to a fine pitch ASIC. The preliminary analysis of the collected data shows no degradation on the hit detection efficiencies of the tested sensors after high energy proton irradiation, demonstrating the excellent radiation tolerance of the 3D pixel sensors. Thus, they will be excellent candidates for the extreme radiation environment at the innermost layers of the HL-LHC experiments.

The CALorimetric Electron Telescope (CALET) on the International Space Station (ISS) consists of a high-energy cosmic ray CALorimeter (CAL) and a lower-energy CALET Gamma ray Burst Monitor (CGBM). CAL is sensitive to electrons up to 20 TeV, cosmic ray nuclei from Z = 1 through Z $\sim$ 40, and gamma rays over the range 1 GeV - 10 TeV. CGBM observes gamma rays from 7 keV to 20 MeV. The combined CAL-CGBM instrument has conducted a search for gamma ray bursts (GRBs) since Oct. 2015. We report here on the results of a search for X-ray/gamma ray counterparts to gravitational wave events reported during the LIGO/Virgo observing run O3. No events have been detected that pass all acceptance criteria. We describe the components, performance, and triggering algorithms of the CGBM - the two Hard X-ray Monitors (HXM) consisting of LaBr$_{3}$(Ce) scintillators sensitive to 7 keV to 1 MeV gamma rays and a Soft Gamma ray Monitor (SGM) BGO scintillator sensitive to 40 keV to 20 MeV - and the high-energy CAL consisting of a CHarge-Detection module (CHD), IMaging Calorimeter (IMC), and fully active Total Absorption Calorimeter (TASC). The analysis procedure is described and upper limits to the time-averaged fluxes are presented.

We present the observation of a charge-sign dependent solar modulation of galactic cosmic rays (GCRs) with the Calorimetric Electron Telescope onboard the International Space Station over 6 yr, corresponding to the positive polarity of the solar magnetic field. The observed variation of proton count rate is consistent with the neutron monitor count rate, validating our methods for determining the proton count rate. It is observed by the Calorimetric Electron Telescope that both GCR electron and proton count rates at the same average rigidity vary in anticorrelation with the tilt angle of the heliospheric current sheet, while the amplitude of the variation is significantly larger in the electron count rate than in the proton count rate. We show that this observed charge-sign dependence is reproduced by a numerical ``drift model'' of the GCR transport in the heliosphere. This is a clear signature of the drift effect on the long-term solar modulation observed with a single detector.

The CALorimetric Electron Telescope (CALET) is a space-based calorimetric instrument, designed to carry out precision measurements of high energy cosmic rays.Installed on the Japanese Experiment Module -Exposed Facility on the ISS, it is collecting data with excellent performance and no significant interruptions since October 2015.We present the results of a direct measurement of the energy spectrum of cosmic-ray helium, based on about 6.5 years of collected data.It shows significant deviations from a single power law with a progressive hardening around a few hundred GeV followed by a softening in the multi-TeV region.A measurement of the proton to helium flux ratio is also presented.Thanks to the recent update of the CALET proton flux with higher statistics, the p/He ratio is measured with high precision, extending the energy reach of previous measurements with magnetic spectrometers by more than one order of magnitude.

The CALorimetric Electron Telescope (CALET) cosmic ray detector on the International Space Station (ISS) has been in operation since its launch in 2015. The main instrument, the CALorimeter (CAL), is optimized to observe high-energy electrons up to TeV energies, but its three-storied, composite and thick detector enable us to discriminate gamma rays from overwhelming background of charged cosmic rays. Thus, it is monitoring the gamma ray sky from 1 GeV up to 10 TeV with a field of view of about 2 sr, but the exposure is somewhat non-uniform because of the limitation imposed by the inclination angle (51.6 degree) of the ISS orbit. In this paper we report results from gamma ray observations obtained during its mission for more than seven years with increased statistics compared with previous reports. They include properties of the Galactic diffuse gamma rays, spectra of bright Galactic point sources, and light curves of extragalactic active galactic nuclei, which show good consistencies with Fermi-LAT observations of which energy range overlaps with CALET.

We present the solar modulation of electrons and protons observed by the CALorimetric Electron Telescope onboard the International Space Station for about 7 years since October 2015, during the transition phase from the descending phase of the 24th solar cycle to the ascending phase of the 25th solar cycle.The observed variations of electron and proton count rates at an identical average rigidity of 3.8 GV show a clear charge-sign dependence of the solar modulation of galactic cosmic rays (GCRs), which is reproduced by a numerical drift model of the GCR transport in the heliosphere.It is also found that the ratio of 3.8 GV proton count rate to the neutron monitor count rate in the ascending phase of the 25th solar cycle is clearly different from that in the descending phase of the 24th solar cycle.Correlations between the electron (proton) count rate and the heliospheric environmental parameters, such as the current sheet tilt angle, obtained in this study would be useful for developing an appropriate numerical model of solar modulation for reproducing the observation.

The CALorimetric Electron Telescope (CALET) has been collecting data on the International Space Station for more than seven years since October 2015.CALET is an all-calorimetric instrument with a total vertical thickness of 30 radiation lengths and fine imaging capability, optimized for the measurement of the electron and positron (all-electron) spectrum well into the TeV energy region.The observed event statistics have increased more than three times since its last publication about the all-electron spectrum to 4.8 TeV in 2018.Based on Monte Carlo simulations, the data analysis effectively rejects background protons, resulting in less than 10% contamination up to the TeV region.The expected systematic errors are investigated.The significance of the cutoff at the TeV region in the energy spectrum, which is expected as a result of radiation loss during propagation, has increased to over 6σ.By observing the detailed structure in the TeV region of the energy spectrum, we will investigate on the presence of possible nearby cosmic-ray sources.In this paper, we will present the updated all-electron spectrum, and briefly discuss its interpretations.

We present the measurement of the energy spectrum of the boron flux in cosmic rays based on the data collected by the CALorimetric Electron Telescope (CALET) during 7.25 years of operation on the International Space Station.The energy spectrum is measured from 8.4 GeV/n to 3.8 TeV/n with an all calorimetric instrument with a total thickness corresponding to 1.3 nuclear interaction length and equipped with charge detectors capable of single element resolution.The observed boron flux shows a spectral hardening at the same transition energy E 0 ∼ 200 GeV/n of the carbon and oxygen spectra, though B flux has a different energy dependence with respect to C and O. Within the limitations of our data's present statistical significance, the boron spectral index change is found to be slightly larger than that of carbon and oxygen, which are similar.A corresponding break in the energy dependence of the B/C and B/O flux ratios also supports the idea that the secondary cosmic rays exhibit a stronger hardening than primary ones.Moreover, interpreting our data with a Leaky Box model, we argue that the trend of the energy dependence of the B/C and B/O ratios in the TeV/n region could suggest a possible presence of a residual propagation path length, compatible with the hypothesis that a fraction of secondary B nuclei can be produced near the cosmic-ray source.

The study of the spectral behavior of heavy cosmic-ray elements may shed light on the details of propagation and acceleration phenomena in our Galaxy.The CALorimetric Electron Telescope (CALET) is measuring the spectra of heavy nuclei up to the highest directly observed energies on the International Space Station.In this contribution, based on the data collected during 7 years of operation, the measurement of the energy dependence of iron and nickel fluxes is presented.With respect to our previous published measurements, the analysis has been extended to a data sample enriched with more than 2.5 (1.5) extra years for iron (nickel).The results of the new analysis are reported together with a detailed assessment of systematic uncertainties.In the energy range explored so far, both spectra show a similar shape and energy dependence, suggesting that iron and nickel may follow almost identical acceleration and propagation mechanisms.

The Calorimetric Electron Telescope (CALET), launched to the ISS in August 2015 and in continuous operation since, measures cosmic-ray (CR) electrons, nuclei, and gamma rays.CALET, with its 27 radiation length deep Total Absorption Calorimeter (TASC), measures particle energy, allowing for the determination of spectra and secondary to primary ratios of the more abundant CR nuclei through 28 Ni, while the main charge detector (CHD) can measure Ultra-Heavy (UH) CR nuclei through 40 Zr.Previous CALET UHCR analyses used a special high duty cycle (∼90%) UH trigger that does not require passage through the TASC and used time-and position-dependent detector response corrections based on 14 Si and 26 Fe and an angle-dependent geomagnetic cutoff rigidity selection to show abundances of even nuclei in agreement with SuperTIGER and ACE-CRIS.The work shown here further improves upon those results by restricting UH events to those that pass through both the TASC and CHD.While this constraint does reduce the number of events to ∼1/6 of the original UH trigger analysis, the loss of statistics is compensated by improvements in event selection from an energy-binned charge determination and minimum deposited energy that substitutes for the previous minimum geomagnetic rigidity selection.The results shown here represent 7 years of observation for the abundances of elements from Z=10 to Z=40 relative to 26 Fe and are compared to previous measurements from ACE-CRIS, SuperTIGER, and HEAO-3.

The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spectrum of electron+positron cosmic rays up to 20 TeV.Supernova remnants (SNR) are the most likely astrophysical sources to provide the majority of the electron flux, out of which a few nearby young SNR like Vela are expected to dominate in the TeV-region with potentially detectable spectral signatures.Another expected contribution to the spectrum is from pulsars as a primary positron-electron pair source for explanation of the positron excess.Complementary to the CALET all-electron spectrum, the positron-only spectrum measured by the magnet spectrometer AMS-02 below the TeV range provides detailed information on this component.An interpretation of the CALET and AMS-02 data by overlapping spectra from individual pulsar and SNR point sources is presented, combining sources known from electromagnetic wave observations with further randomly generated ones spread throughout the galaxy.Based on the study of a large number of samples with randomized source locations and emission spectra parameters, best fitting ranges and constraints for these parameters, as well as predictions for the spectrum beyond the so far measured energy range have been derived.

A precise measurement of the cosmic-ray proton spectrum is carried out with the Calorimetric Electron Telescope (CALET) and a sharp softening of the energy spectrum above 10 TeV is observed.CALET, located on the International Space Station, has started data taking in October 2015 and has accumulated data for more than seven years without any serious troubles.CALET is pursuing the direct measurement of the main components of high energy cosmic rays up to ~1 PeV in order to understand the cosmic ray acceleration and propagation.Thanks to the thick calorimeter that corresponds to 30 radiation lengths and to ∼1.3 proton interaction lengths, the proton analysis presented in this paper spans a broad energy range from 50 GeV to 60 TeV.Proton energy resolution is 30-40%, and the residual background is less than 10% in the < 10 TeV region.In the multi-TeV region, we observed a spectral softening with a spectral index change from -2.6 to -2.9 in addition to the spectral hardening we had previously confirmed with a high significance above a few hundred GeV.The transition to the softer regime is much sharper than the smooth onset of hardening observed at lower energy.

The latest LIGO/Virgo/KAGRA observing run (O4) started on May 24 in 2023. Many ground and space instruments have participated in follow-up observation and search for electromagnetic counterparts of gravitational waves. Calorimetric Electron Telescope (CALET) on the Interna- tional Space Station has also searched for electromagnetic counterparts since the observation started in October 2015. Although CALET is a payload for direct measurement of high-energy cosmic rays, CALET has the capability to observe high-energy gamma-rays above 1 GeV with the Calorimeter (CAL) and X-rays / gamma rays in the energy range from 7 keV to 20 MeV with the CALET Gamma-ray Burst Monitor (CGBM). We searched for electromagnetic counterparts of gravitational wave events in the last LIGO/Virgo observing run (O3). Although no candidate was found in CALET data in O3, CAL and CGBM estimated upper limits of gamma-ray / X-ray flux for the gravitational waves in O3. We have been searching for electromagnetic counterparts of gravitational waves in O4 with improved and automated analysis pipelines to deal with many events with high event rates. As of the end of June 2023, the LIGO/Virgo/KAGRA collaboration reported 169 events via the GCN/LVC NOTICE, and 15 of 169 events were reported to GCN Circulars as significant events. Although CGBM and CAL searched for signals associated with the significant events, no candidates were found around the event time of the significant events. We obtained CAL upper limits for eight significant events of which localization high probability region overlapped with the CAL field of view.

Detailed measurements of the spectral structure of cosmic-ray electrons and positrons from 10.6 GeV to 7.5 TeV are presented from over 7 years of observations with the CALorimetric Electron Telescope (CALET) on the International Space Station. The instrument, consisting of a charge detector, an imaging calorimeter, and a total absorption calorimeter with a total depth of 30 radiation lengths at normal incidence and a fine shower imaging capability, is optimized to measure the all-electron spectrum well into the TeV region. Because of the excellent energy resolution (a few percent above 10 GeV) and the outstanding e/p separation (10^{5}), CALET provides optimal performance for a detailed search of structures in the energy spectrum. The analysis uses data up to the end of 2022, and the statistics of observed electron candidates has increased more than 3 times since the last publication in 2018. By adopting an updated boosted decision tree analysis, a sufficient proton rejection power up to 7.5 TeV is achieved, with a residual proton contamination less than 10%. The observed energy spectrum becomes gradually harder in the lower energy region from around 30 GeV, consistently with AMS-02, but from 300 to 600 GeV it is considerably softer than the spectra measured by DAMPE and Fermi-LAT. At high energies, the spectrum presents a sharp break around 1 TeV, with a spectral index change from -3.15 to -3.91, and a broken power law fitting the data in the energy range from 30 GeV to 4.8 TeV better than a single power law with 6.9 sigma significance, which is compatible with the DAMPE results. The break is consistent with the expected effects of radiation loss during the propagation from distant sources (except the highest energy bin). We have fitted the spectrum with a model consistent with the positron flux measured by AMS-02 below 1 TeV and interpreted the electron+positron spectrum with possible contributions from pulsars and nearby sources. Above 4.8 TeV, a possible contribution from known nearby supernova remnants, including Vela, is addressed by an event-by-event analysis providing a higher proton-rejection power than a purely statistical analysis.

Within the R&D Program for the luminosity upgrade proposed for the Large Hadron Collider (LHC), silicon strip detectors (SSD) and test structures (TS) were manufactured on several high-resistivity substrates: p-type Magnetic Czochralski (MCz) and Float Zone (FZ), and n-type FZ. To test total dose (TID) effects they were irradiated with 60Co gammas and the impact of surface radiation damage on the detector properties was studied. Selected results from the pre-rad and post-rad characterization of detectors and TS are presented, in particular interstrip capacitance and resistance, break-down voltage, flatband voltage and oxide charge. Surface damage effects show saturation after 150 krad and breakdown performance improves considerably after 210 krad. Annealing was performed both at room temperature and at 60 °C, and large effects on the surface parameters observed.

We designed, realized, and tested a 2.5-Gb/s optical wireless communication (OWC) system prototype, that should be employed in high energy physics (HEP) experiments, such as the compact muon solenoid (CMS). The system consists of off-the-shelf components, mainly a vertical cavity surface emitting laser (VCSEL) and a PIN photodiode with a proper ball lens. Since it should be used to transmit data among particle sensors in neighboring rings of the CMS, its target distance is 10 cm. Its most attractive feature is that it does not require a (complex) active tracking system because its measured tolerance to misalignment is around <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 1 mm (at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$10^{-12}$</tex-math></inline-formula> bit error rate). We also report the X-rays irradiation tests of all components (Quartz lens, VCSEL, and PIN photodiode): None of them showed any degradation up till 238-Mrad (Si) dose. These results indicate that the designed OWC can be a viable solution for future HEP experiments.

The CALorimetric Electron Telescope (CALET) is a high-energy astroparticle physics space experiment installed on the International Space Station (ISS), developed and operated by Japan in collaboration with Italy and the United States. The CALET mission goals include the investigation of possible nearby sources of high-energy electrons, of the details of galactic particle acceleration and propagation, and of potential signatures of dark matter. CALET measures the cosmic-ray electron + positron flux up to 20 TeV, gamma-rays up to 10 TeV, and nuclei with Z=1 to 40 up to 1,000 TeV for the more abundant elements during a long-term observation aboard the ISS. Starting science operation in mid-October 2015, CALET performed continuous observation without major interruption with close to 20 million triggered events over 10 GeV per month. Based on the data taken during the first two-years, we present an overview of CALET observations: uses w/o major interruption 1) Electron + positron energy spectrum, 2) Nuclei analysis, 3) Gamma-ray observation including a characterization of on-orbit performance. Results of the electromagnetic counterpart search for LIGO/Virgo gravitational wave events are discussed as well.

Results obtained with 3D columnar pixel sensors bump-bonded to the RD53A prototype readout chip are reported. The interconnected modules have been tested in a hadron beam before and after irradiation to a fluence of about 1×1016 neq cm−2 (1 MeV equivalent neutrons). All presented results are part of the CMS R&D activities in view of the pixel detector upgrade for the High Luminosity phase of the LHC at CERN (HL-LHC) . A preliminary analysis of the collected data shows hit detection efficiencies around 97% measured after proton irradiation.

We report on the ATLAS and CMS joint research activity, which is aiming at the development of new, thin silicon pixel detectors for the Large Hadron Collider Phase-2 detector upgrades. This R&D is performed under special agreement between Istituto Nazionale di Fisica Nucleare and FBK foundation (Trento, Italy). New generations of 3D and planar pixel sensors with active edges are being developed in the R&D project, and will be fabricated at FBK. A first planar pixel batch, which was produced by the end of year 2014, will be described in this paper. First clean room measurement results on planar sensors obtained before and after neutron irradiation will be presented.

To obtain full charge collection the CMS silicon detectors should be able to operate at high bias voltage. We observed that multiguard structures enhance the breakdown performance of the devices on several tens of baby detectors designed for CMS. The beneficial effects of the multiguard structures still remains after the strong neutron irradiation performed to simulate the operation at the LHC.

The luminosity upgrade of the CERN Large Hadron Collider (SLHC) imposes severe requirements on the radiation hardness of the tracking systems. The CERN RD50 collaboration as well as the Italian INFN SMART project (fifth commission) are focused on the study of new radiation hard materials and devices in view of this upgrade. Preliminary studies on irradiated high resistivity n- and p-type magnetic Czochralski silicon are described in this paper. Electrical characterization and microscopic defect studies were performed on a wide set of diodes made with both n- and p-type float zone and magnetic Czochralski silicon irradiated up to a nominal fluence of 3×1015 cm−2 1 MeV equivalent neutrons. The annealing behavior was studied in detail and a first evaluation of the damage-related parameters is shown.

The charge collected from p-type silicon strip sensors irradiated to SuperLHC fluences has been determined with a beta source using fast front-end electronics. The bias voltage dependence of the collected charge and the hit detection efficiency have been measured before and after accelerated annealing. Predictions of the performance at the SuperLHC are derived.

Due to the large expected instantaneous luminosity, the future HL-LHC upgrade sets strong requirements on the radiation hardness of the CMS detector Inner Tracker. Sensors based on 3D pixel technology, with its superior radiation tolerance, comply with these extreme conditions. A full study and characterization of pixelated 3D sensors fabricated by FBK is presented here. The sensors were bump-bonded to RD53A readout chips and measured at several CERN SPS test beams. Results on charge collection and efficiency, for both non-irradiated and irradiated up to 1016 neq/cm2 samples, are presented. Two main studies are described: in the first the behaviour of the sensor is qualified as a function of irradiation, while kept under identical conditions; in the second the response is measured under typical operating conditions.

We report the results of two beam tests performed in July and September 1995 at CERN using silicon microstrip detectors of various types: single sided, double sided with small angle stereo strips, double sided with orthogonal strips, double sided with pads. For the read-out electronics use was made of Preshape32, Premux128 and VA1 chips. The signal to noise ratio and the resolution of the detectors was studied for different incident angles of the incoming particles and for different values of the detector bias voltage. The goal of these tests was to check and improve the performances of the prototypes for the CMS Central Detector.

The results of the pre- and post-irradiation characterization of n- and p-type magnetic Czochralski silicon micro-strip sensors are reported. This work has been carried out within the INFN funded SMART project aimed at the development of radiation-hard semiconductor detectors for the luminosity upgrade of the large Hadron collider (LHC). The detectors have been fabricated at ITC-IRST (Trento, Italy) on 4 in wafers and the layout contains 10 mini-sensors. The devices have been irradiated with 24 GeV/c and 26 MeV protons in two different irradiation campaigns up to an equivalent fluence of 3.4×1015 1-MeV n/cm2. The post-irradiation results show an improved radiation hardness of the magnetic Czochralski mini-sensors with respect to the reference float-zone sample.

The CALorimetric Electron Telescope (CALET) mission is proposed for a long exposure observation of high energy cosmic rays and gamma radiation, taking advantage of the JEM-EF facility on the International Space Station. The instrument is optimized for the search of nearby sources of acceleration of cosmic ray electrons in the TeV energy range. Its large collection power also allows for precision studies of the elemental composition of VHE nuclei and of their spectral features. The charge identification of the incoming particle is performed by a double-layered array of pixelated silicon sensors, covering a seamless sensitive area of the order of 1 m 2 . The conceptual design of the array and its front-end electronics are presented.

During the scheduled high luminosity upgrade of LHC, the world's largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face more intense radiation environment than the present system was designed for. To upgrade the tracker to required performance level, extensive measurements and simulations studies have already been carried out. A defect model of Synopsys Sentaurus TCAD simulation package for the bulk properties of proton irradiated devices has been producing simulations closely matching with measurements of silicon strip detectors. However, the model does not provide expected behavior due to the fluence increased surface damage. The solution requires an approach that does not affect the accurate bulk properties produced by the proton model, but only adds to it the required radiation induced properties close to the surface. These include the observed position dependency of the strip detector's charge collection efficiency (CCE). In this paper a procedure to find a defect model that reproduces the correct CCE loss, along with other surface properties of a strip detector up to a fluence $1.5\times10^{15}$ 1 MeV n$_{\textrm{eq}}$ cm$^{-2}$, will be presented. When applied with CCE loss measurements at different fluences, this method may provide means for the parametrization of the accumulation of oxide charge at the SiO2/Si interface as a function of dose.

The High Luminosity upgrade of the CERN Large Hadron Collider (HL-LHC) calls for new high radiation-tolerant solid-state pixel sensors, capable of surviving irradiation fluences up to a few 1016 neq/cm2 at ∼3 cm from the interaction point. The INFN ATLAS-CMS joint research activity, in collaboration with Fondazione Bruno Kessler, is aiming at the development of thin n+ on p type pixel sensors to be operated at the HL-LHC. The R&D covers both planar and 3D pixel devices made on substrates obtained by the Direct Wafer Bonding technique. The active thickness of the planar sensors studied in this paper is 100μm or 130μm, that of 3D sensors 130μm. First prototypes of hybrid modules, bump-bonded to the present CMS readout chips (PSI46 digital), have been characterized in beam tests. First results on their performance before and after irradiation up to a maximum fluence of ∼5×1015 neq/cm2 are reported in this article.

We report on the processing and characterization of microstrip sensors and pad detectors produced on n- and p-type Magnetic Czochralski (MCz), Epitaxial (EPI) and Float Zone (FZ) silicon within the SMART project to develop radiation-hard silicon position sensitive detectors for future colliders. Each wafer contains 10 microstrip sensors with different geometries, several diodes and test structures. The isolation in the strip detectors produced on p-type material has been achieved by means of a uniform p-spray implantation, with doping of 3×1012 cm−2 (low-dose p-spray) and 5×1012 cm−2 (high-dose p-spray). The samples have undergone irradiations with 26 MeV protons and reactor neutrons up to ∼1016 cm−2 1 MeV equivalent neutrons (neq/cm2), and have been completely characterized before and after irradiation in terms of leakage current, depletion voltage and breakdown voltage. The current damage parameter α has been determined for all substrates. MCz diodes show less pronounced dependence of effective doping concentration Neff on the fluence when compared to standard FZ silicon, giving results comparable to diffusion oxygenated FZ devices for all irradiation sources. The observed increase of Neff with fluence can be interpreted in EPI material as a net donor introduction process, overcompensating the usual acceptor introduction process. This effect is stronger for 26 MeV proton irradiation than for neutron irradiation.

The depletion depth of irradiated n-type silicon microstrip detectors can be inferred from both the reciprocal capacitance and from the amount of collected charge. Capacitance voltage (C–V) measurements at different frequencies and temperatures are being compared with the bias voltage dependence of the charge collection on an irradiated n-type magnetic Czochralski silicon detector. Good agreement between the reciprocal capacitance and the median collected charge is found when the frequency of the C–V measurement is selected such that it scales with the temperature dependence of the leakage current. Measuring C–V characteristics at prescribed combinations of temperature and frequency allows then a realistic estimate of the depletion characteristics of irradiated silicon strip detectors based on C–V data alone.

One of the proposed solutions for a transverse momentum (pT) based trigger at SLHC for the CMS experiment is based on the concept known as the "cluster width" approach, in which clusters produced by low pT tracks are rejected based on the width of the cluster shape, made either on a single strip sensor or a doublet of strip sensors by a suitable electronics logic at the level of the front-end. This information can then be used in many ways to provide first level trigger primitives. These kinds of modules are inexpensive, and coupled high-speed opto-electronic components this concept provides the simplest solution to the first level trigger for SLHC trackers. We will present the simulation studies aimed to optimize the concept, as well as the basic building blocks of the module and their connectivity. Finally we will provide the experimental validation of it by using data collected by the CMS Tracker during the Cosmic runs in 2008 and 2009 as well as the first collision data from the LHC.

The general-purpose EGS4 code has been used to evaluate the efficiency, the energy and the spatial resolution of a silicon crystal with double-side microstrips readout to detect X-rays in the diagnostic energy range (10–100 keV). A single crystal configuration, a sandwich arrangement with a high-Z converter foil in between two crystals and a multicrystal configuration have been investigated. The simulation with a low energy spectrum X-ray beam and a breast phantom has shown that this type of detector would be of valuable use in mammography applications: breast calcification with a diameter smaller than 500 μm can be easily identified.

Magnetic Czochralski (MCz) silicon is currently being considered as a promising material for the development of radiation tolerant detectors for future high luminosity HEP experiments. Silicon wafers grown by the MCz method have been processed by ITC-IRST (Trento, Italy) with a layout designed by the SMART collaboration. The diodes produced with n-type MCz material have undergone various irradiation campaigns, using 24 GeV/c (SPS-CERN) protons, 26MeV (FZK-Karlsruhe) protons and reactor neutrons (JSI-Ljubljana), with fluences up to 1016 1 MeV equivalent neutrons (neq)cm-2. This paper investigates space charge sign inversion effects after these irradiation levels. Samples have been characterized by reverse current and capacitance measurements before and after irradiation, and by Transient Current Technique (TCT) after irradiation. Results of the study of depletion voltage as a function of fluence and of TCT signal shapes show that Space Charge Sign Inversion has already occurred in the devices at a fluence of 4.2×1014neqcm-2 after 26 MeV proton irradiation, and at 5×1014neqcm-2 after neutron irradiation.

The paper describes the role of the n+ edge implants in the breakdown process of p+ on n-bulk silicon diodes. Laboratory measurements and simulation studies are presented on a series of test structures aimed at an optimization of the design in the edge region. The dependence of the breakdown voltage on the geometrical parameters of the devices is discussed in detail. Design rules are extracted for the use of n+-layers along the scribe line to avoid surface conduction of current generated by the exposed edges. The effect of neutron irradiation has been studied up to a fluence of 1.8×1015 cm−2.

The aim of this work is the development of radiation hard detectors for very high luminosity colliders. A growing interest has been recently focused on Czochralski silicon as a potentially radiation-hard material. We report on the processing and characterization of micro-strip sensors and pad detectors produced by ITC-IRST on n- and p-type magnetic Czochralski and float zone silicon. Part of the samples has been irradiated using 24 GeV/c protons (CERN-Geneva), while another part has been irradiated with 26 MeV protons (FZK-Karlsruhe) up to a fluence of 5×1015 1 MeV-neutron-equivalent/cm2. All the samples have been completely characterized before and after irradiation. Their radiation hardness as a function of the irradiation fluence has been established in terms of breakdown voltage, leakage current and evaluating the more relevant mini-sensor parameter variation. Moreover, the time evolution of depletion voltage, leakage current and inter-strip capacitance has been monitored in order to study their annealing behavior and space charge sign inversion effects.

The charge collected from p-type silicon strip sensors irradiated to SuperLHC fluences has been determined in a beta source using fast front-end electronics. The bias voltage dependence of the collected charge and the efficiency have been measured before and after accelerated annealing. Predictions of the performance at the LHC are derived.

We are developing the CALorimetric Electron Telescope, CALET, mission for the Japanese Experiment Module Exposed Facility, JEM-EF, of the International Space Station. Major scientific objectives are to search for the nearby cosmic ray sources and dark matter by carrying out a precise measurement of the electrons in 1 GeV - 20 TeV and gamma rays in 20 MeV - several 10 TeV. CALET has a unique capability to observe electrons and gamma rays over 1 TeV since the hadron rejection power can be larger than 10⁵ and the energy resolution better than a few % over 100 GeV. The detector consists of an imaging calorimeter with scintillating fibers and tungsten plates and a total absorption calorimeter with BGO scintillators. CALET has also a capability to measure cosmic ray H, He and heavy ionsi up to 1000 TeV. It also will have a function to monitor solar activity and gamma ray transients. The phase A study has started on a schedule of launch in 2013 by H-II Transfer Vehicle (HTV) for 5 year observation.

We present results obtained with full-size wedge silicon microstrip detectors bonded to APV6 (Raymond et al., Proceedings of the 3rd Workshop on Electronics for LHC Experiments, CERN/LHCC/97-60) readout chips. We used two identical modules, each consisting of two crystals bonded together. One module was irradiated with 1.7×1014neutrons/cm2. The detectors have been characterized both in the laboratory and by exposing them to a beam of minimum ionizing particles. The results obtained are a good starting point for the evaluation of the performance of the “ensemble” detector plus readout chip in a version very similar to the final production one. We detected the signal from minimum ionizing particles with a signal-to-noise ratio ranging from 9.3 for the irradiated detector up to 20.5 for the non-irradiated detector, provided the parameters of the readout chips are carefully tuned.

3D sensors are a promising option for the innermost pixel layers at the High Luminosity LHC.However, the required very high hit-rate capabilities, increased pixel granularity, extreme radiation hardness, and reduced material budget call for a device downscale as compared to existing 3D sensors, involving smaller pitch (e.g., 50×50 or 25×100 µm 2 ), shorter inter-electrode spacing (~30 µm), narrower electrodes (~5 µm), and reduced active thickness (~100 µm).The development of a new generation of 3D pixel sensors with these challenging features is under way by many research groups, in collaboration with processing facilities like FBK, CNM, and SINTEF.This paper talk will review the lessons learned from existing 3D detectors, and will address the main design and technological issues for small pitch 3D devices.Preliminary results from the electrical and functional characterization of the first prototypes will be reported and compared to TCAD simulations.

Abstract The CALET (CALorimetric Electron Telescope) space experiment, which is currently conducting direct cosmic-ray observations onboard the International Space Station (ISS), is an all-calorimetric instrument optimized for cosmic-ray electron measurements with capability to measure hadrons and gamma-rays. Since the start of observation in October 2015, smooth and continuous operations have taken place. In this paper, we will give a brief summary of the CALET observations ranging from charged cosmic rays, gamma-rays, to space weather, while focusing on the energy spectra of electrons and protons.

The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spec- trum of electron+positron cosmic rays up to 20 TeV. Cosmic-ray electrons of TeV region energy are limited by energy loss to a propagation range of about 1 kpc, therefore the expected sources are a few nearby supernova remnants (SNR), with the Vela SNR dominating the spectrum. The latest spectrum measured by CALET in combination with the positron-only flux published by AMS-02 is fitted with a comprehensive model including nearby pulsars as the source of the positron excess. This model is extended to the TeV region by addition of the flux from the Vela SNR as calculated with DRAGON, with the integrated energy emitted in electron cosmic rays by the SNR as a variable scale factor. Exploring various scenarios for the time and energy dependence of the cosmic-ray release from Vela, under varied propagation conditions, best-fitting interpretations of the spectrum and upper limits on the emission of cosmic-ray electrons by Vela have been derived.

Abstract Optical Wireless Communication (OWC) system for particles detector can be a viable solution for reducing the complexity of the optical fibre network used to extract the data from the detector. In this work we present the initial study of the tolerance to misalignment for the OWC system under investigation. We observed that using collimators of beam waist from 0.35 mm to 3.5 mm we can obtain tolerance in range from ± 0.25 mm to ± 0.8 mm . We also observed using ray trace simulation that both transmitting power and tolerance can be improved by using optimized lens at the receiver having VCSEL as transmitting source.

High speed optical fiber or copper wire communication systems are frequently deployed for readout data links used in particle physics detectors. Future detector upgrades will need more bandwidth for data transfer, but routing requirements for new cables or optical fiber will be challenging due to space limitations. Optical wireless communication (OWC) can provide high bandwidth connectivity with an advantage of reduced material budget and complexity of cable installation and management. In a collaborative effort, Scuola Superiore Sant'Anna and INFN Pisa are pursuing the development of a free-space optical link that could be installed in a future particle physics detector or upgrade. We describe initial studies of an OWC link using the inner tracker of the Compact Muon Solenoid (CMS) detector as a reference architecture. The results of two experiments are described: the first to verify that the laser source transmission wavelength of 1550 nm will not introduce fake signals in silicon strip sensors while the second was to study the source beam diameter and its tolerance to misalignment. For data rates of 2.5 Gb/s and 10 Gb/s over a 10 cm working distance it was observed that a tolerance limit of ±0.25 mm to ±0.8 mm can be obtained for misaligned systems with source beam diameters of 0.38 mm to 3.5 mm, respectively.

Abstract We present the results of the detailed simulation of the response of a HgI 2 crystal in terms of efficiency, energy and space resolutions versus photon energy in the diagnostic energy range 20–100 keV. Some configurations of CdTe crystals for positron emission tomography are also evaluated.

A proposal for a pixel-based Level 1 trigger for the Super-LHC is presented. The trigger is based on fast track reconstruction using the full pixel granularity exploiting a readout which connects different layers in specific trigger towers. The trigger will implement the current CMS high level trigger functionality in a novel concept of intelligent detector. A possible layout is discussed and implications on data links are evaluated.

The CALET Calorimeter on the International Space Station(ISS) has previously measured the flux and spectrum of iron cosmic-ray nuclei above 10 GeV/n.In order to extend the measurement to the region below 10 GeV/n, we carry out an analysis to utilize the geomagnetic effect.Cutoff rigidities of cosmic-ray nuclei are calculated for all directions for each observation point in the ISS orbit.The integral spectrum of observed rigidities is then obtained by counting the number of iron nuclei in each bin of cutoff rigidity.The absolute flux and differential spectrum are then calculated by taking the detection efficiencies into account.Here we present the details of the analysis procedure and the iron spectrum below 10 GeV/n.

The Calorimetric Electron Telescope (CALET), launched to the International Space Station in 2015, provides more than 7 years of continuous observation of the radiation environment at low earth orbit.Using this dataset, we present a method for the detection and categorization of MeV relativistic electron precipitation (REP) events.From this catalog we identify a subset of a few hundred REP events observed at times where CALET is in magnetic conjunction with the Van Allen probes.These conjugate measurements enable studies of associated plasma wave data from RBSPA/B and potential drivers for MeV electron precipitation.We show that roughly 10 percent of the observed REP events are associated with enhanced electromagnetic ion cyclotron wave activity, suggesting that waves can play a significant role in driving MeV electron precipitation.

The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spectrum of electron+positron cosmic rays up to 20 TeV.Annihilation or decay of dark matter (DM) could produce signatures in the positron and electron cosmic-ray spectra, thus the parameter space of DM candidate models can be probed by studying these messengers.The TeV-region extension of the spectrum provided by CALET is especially important for heavy DM search, since the signature's location in energy is closely correlated with the DM mass.The magnet spectrometer AMS-02 on the other hand provides an exclusive positron-only spectrum below the TeV range.The combined analysis of both data-sets allows for DM search with a sophisticated modeling of the astrophysical background, comprising pulsars as the primary positron source and supernova remnant (SNR) sources providing the majority of the electron flux, in addition to a secondary component.As a refinement over a phenomenological power-law parametrization of the background, overlapping individual point source spectra are used as background for deriving limits on DM annihilation and decay from the CALET all-electron and the AMS-02 positron-only data.The used SNR and pulsar samples combine known nearby sources dominating the spectrum at high energies with randomly generated ones throughout the galaxy.By analyzing a large number of samples with also randomized emission spectra parameters, the expected variability of the background is taken into account, improving the reliability of the obtained limits on DM annihilation cross-section and lifetime.

The CALorimetric Electron Telescope (CALET) has successfully been carrying out cosmic-ray observations on the International Space Station since October, 2015.CALET directly measures the cosmic-ray electron spectrum in the energy range of 1 GeV to 20 TeV with a 2 % energy resolution above 30 GeV.In addition, the instrument can measure the spectrum of gamma rays well into the TeV range, and the spectra of protons and nuclei up to a PeV.The scientific operations are implemented by taking into account orbital variations of geomagnetic rigidity cutoff.Scheduled command sequences are used to control the CALET observation modes on orbit.The high-energy (>10 GeV) trigger mode is always active for maintaining maximum exposure to high-energy electrons and other high-energy shower events.Also, around the ISS orbit, calibration data acquisition by, for example, recording pedestal and penetrating particle events, a low-energy electron trigger mode operating at high geomagnetic latitude, a low-energy gamma-ray trigger mode operating at low geomagnetic latitude, and an ultra-heavy trigger mode, are scheduled.As of June 30, 2023, the total observation time is 2818 days with a live time fraction of the total time around 86 %.Nearly 1.86 billion events are collected with the high-energy trigger.

The Calorimetric Electron Telescope (CALET) is a deep electromagnetic calorimeter designed for the measurement of cosmic-ray electrons on the International Space Station. Deployed on the Exposed Facility of the Japanese Experiment Module since August 2015, it observes cosmic-ray electrons with energies up to above 10 TeV and hadrons up to PeV total energies. Above a few TeV, the decrease in the electron flux and increased contamination by protons in the boosted decision tree (BDT) selection introduce challenges to determination of the flux at the highest energies and the search for signatures of nearby accelerators. To address the proton contamination, we apply a dedicated event-by-event analysis to evaluate the likelihood of each candidate event being a real electron or a contaminating proton. In this work, we detail the implementation of the likelihood analysis based on physically motivated shower parameters in the CALET calorimeter. Large simulated electron and proton datasets tailored to the parameters of the observed candidate events are generated and studied to produce a likelihood parameter for the improved rejection of protons. The results are tied to the BDT selection in the flight data analysis and summarized for the currently identified candidate events. Finally, we discuss an expansion of this work presently under development to use BDTs trained specifically for each candidate to provide an additional figure of merit.

The International Space Station (ISS) provides an orbital platform for astrophysical missions with lower resource requirements than free-flying satellites.The many uses of the ISS, how7 keVever, can produce unique challenges to the accurate analysis of the data acquired by these instruments.In this work, we present effects observed by the Calorimetric Electron Telescope (CALET), an astroparticle physics mission installed on the Japanese Experiment Module Exposed Facility of the ISS.The CALET calorimeter is sensitive to cosmic-ray electrons and gamma rays from 1 GeV up to above 10 TeV, and to cosmic-ray hadrons up to PeV total energies.The CALET Gamma-ray Burst Monitor (CGBM) is sensitive to X-rays and low-energy gamma rays from 7 keV to 20 MeV.Furthermore, ultra-heavy galactic cosmic-ray (UHGCRs) abundances are measured by CALET using a much more open geometry than is possible for events which shower in the instrument.In this work, we discuss ISS-related issues that affect the observations by CALET.Here we detail the ways these effects are accounted for in the production of scientific results.Finally, the possible impact on future missions such as TIGERISS (Trans-Iron Galactic Element Recorder for the International Space Station; planned for deployment to the ISS in 2026) and mitigation strategies are discussed.

In this work, we present a feasibility study aiming at an enhanced statistical precision of CR helium flux with CALET data.It is based on a wider acceptance with respect to the present fiducial one while ensuring a correct identification of charged particles crossing the detector within much wider geometrical configurations.The expected statistical enhancement for the all-acceptance configuration is nearly 2× with respect to the previous analysis, over the entire energy range (from tens of GeV, up to hundreds of TeV).Preliminary assessment of efficiencies and background sources has been carried out based on energy-dependent charge selections.

The study of flux ratios of cosmic-ray primary elements is of particular interest not only to assess the relative abundance of each element, but also to gain a deeper understanding of their propagation in the galaxy.High energy cosmic ray data are the best candidate for this purpose as convection, nuclear decay, and energy degradation can be neglected during their propagation.CALET on the International Space Station has been measuring the flux of several primary elements from proton to nickel for 7 years to date.In this contribution, the flux ratios of heavy primary elements to lighter primaries will be shown, extending the energy range already investigated by previous measurements.

CALET, the Calorimetric Electron Telescope, launched to the International Space Station in August 2015 and in continuous operation since, has gathered over seven years of data so far.CALET is able to measure cosmic-ray (CR) electrons, nuclei, and gamma rays and with its 27 radiation length deep Total Absorption Calorimeter (TASC), measures particle energy, allowing for the determination of spectra and secondary to primary ratios of the more abundant CR nuclei through 28 Ni, while the main charge detector (CHD) can measure Ultra-Heavy (UH) CR nuclei through 40 Zr.CALET UHCR analyses use a special high duty cycle UH trigger with an expanded geometry that does not require passage through the TASC.To effectively analyze UHCR trigger events, a number of screens and corrections have been developed for the analysis.From time-and position-dependent detector response corrections based on 14 Si and 26 Fe, to an angle-dependent geomagnetic cutoff rigidity selections and minimum deposited energy screens, a number of methods have been explored to optimize UH statistics to varying effect.In this work, we aim to show how these event selection screens and corrections have been developed, how the rigidity screens shown previously by Rauch et al compare to the newer TASC methodology shown in our other ICRC paper, and how TASC selections may be used to influence analysis on the full UH-trigger dataset.

The Calorimetric Electron Telescope (CALET) is a cosmic-ray observatory operating since October 2015 onboard the International Space Station (ISS). The data processed since the beginning of the mission has made it possible to measure with high precision the inclusive flux of cosmic electrons and positrons (all-electron) in the multi-TeV region. The appearance of any structures in this energy region can potentially be connected to the presence of nearby astrophysical sources or dark matter. The CALET detector, consisting of a charge detector, an imaging calorimeter and a total absorption calorimeter has a total vertical thickness of about 30 radiation lengths. The construction characteristics of the instrument allow to obtain an energy resolution better than 2% for electrons and a proton rejection power of about $10^5$. However, the exploration of the multi-TeV region involves dealing with a limited statistical sample and a large proton background. As a consequence, a complex multivariate analysis based on variables connected to the shower development has been adopted. In this contribution, we summarize the results of a study conducted on different multivariate analysis techniques in order to optimize the proton rejection at high energies in the all-electron flux measurement. In particular, we discuss the features of the different methods, the tuning of their parameters and the overall strategy to increase the separation between electrons and protons, avoiding the phenomenon of overfitting.

Received 21 August 2023DOI:https://doi.org/10.1103/PhysRevLett.131.109902Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCosmic ray composition & spectraCosmic ray propagationCosmic ray sourcesCosmic rays & astroparticlesGravitation, Cosmology & Astrophysics

The CALorimetric Electron Telescope, CALET, has been measuring high-energy cosmic rays on the International Space Station since October 13, 2015. The scientific objectives addressed by the mission are to search for possible nearby sources of high-energy electrons and potential signatures of dark matter, and to investigate the details of galactic cosmic-ray acceleration and propagation. The calorimetric instrument, which is 30 radiation lengths or 1.3 proton interaction lengths thick with fine imaging capability, is optimized to measure cosmic-ray electrons by achieving large proton rejection and excellent energy resolution well into the TeV region. In addition, very wide dynamic range of energy measurement and individual charge identification capability enable us to measure proton and nuclei spectra from a few tens GeV to a PeV scale. Nearly 20 million cosmic-ray shower events over 10 GeV per month are triggered and the continuous observation has been kept without any major interruption since the start of operation. Using the data obtained over 6.5 years of operation, we will present a brief summary of the CALET observation including electron spectrum, and proton and nuclei spectra as well as the performance study on orbit with MC simulations.

This paper describes the main achievements in the development of radiation resistant silicon detectors to be used in the CMS tracker. After a general description of the basic requirements for the operation of large semiconductor systems in the LHC environment, the issue of radiation resistance is discussed in detail. Advantages and disadvantages of the different technological options are presented for comparison. Laboratory measurements and test beam data are used to check the performance of several series of prototypes fabricated by different companies. The expected performance of the final detector modules are presented together with preliminary test beam results on system prototypes.

The response to pions of an ALEPH electromagnetic calorimeter petal combined with the ALEPH hadron calorimeter prototype has been studied in the energy range between 2 and 30 GeV. The resolution of the combined calorimeters was found to be lower than that for the hadron calorimeter alone at low energies and approached this value at higher energies.

The paper describes a study of the radiation hardness of micro-strip devices, processed on different silicon substrates, designed to explore the feasibility of a tracker system for the experiments upgrade at the Super-LHC (S-LHC) collider. The radiation tolerance of the devices has been established comparing the Charge Collection Efficiency (CCE) measured on irradiated and not irradiated sensors of the same type. The CCE has been measured with minimum ionizing events and the read-out electronics and data acquisition system are the same designed for the CMS experiment at LHC. The performances of different silicon substrates (MCz, Fz, Epi)1 and different bulk doping types (p, n) have been investigated. The radiation hardness has been studied up to a fluence of 3.5×1015neqcm-2, value expected at a radial distance of about 9 cm from the interaction point at S-LHC. Preliminary results of radiation hard candidate material are shown. This work is part of the research activities of INFN SMART and RD50 CERN collaborations.

To cope with the harsh environment foreseen at the high luminosity conditions of HL- LHC, the ATLAS pixel detector has to be upgraded to be fully efficient with a good granularity, a maximized geometrical acceptance and an high read out rate. LPNHE, FBK and INFN are involved in the development of thin and edgeless planar pixel sensors in which the insensitive area at the border of the sensor is minimized thanks to the active edge technology. In this paper we report on two productions, a first one consisting of 200 {\mu}m thick n-on-p sensors with active edge, a second one composed of 100 and 130 {\mu}m thick n-on-p sensors. Those sensors have been tested on beam, both at CERN-SPS and at DESY and their performance before and after irradiation will be presented.

The tracking detector of ATLAS, one of the experiments at the Large Hadron Collider (LHC), will be upgraded in 2024–2026 to cope with the challenging environment conditions of the High Luminosity LHC (HL-LHC). The LPNHE, in collaboration with FBK and INFN, has produced 130μm thick n−on−p silicon pixel sensors which can withstand the expected large particle fluences at HL-LHC, while delivering data at high rate with excellent hit efficiency. Such sensors were tested in beam before and after irradiation both at CERN-SPS and at DESY, and their performance are presented in this paper. Beam test data indicate that these detectors are suited for all the layers where planar sensors are foreseen in the future ATLAS tracker: hit-efficiency is greater than 97% for fluences of Φ≲7×1015neq∕cm2 and module power consumption is within the specified limits. Moreover, at a fluence of Φ=1.3×1016neq∕cm2, hit-efficiency is still as high as 88% and charge collection efficiency is about 30%.

In order to address the problems caused by the harsh radiation environment during the high luminosity phase of the LHC (HL-LHC), all silicon tracking detectors (pixels and strips) in the CMS experiment will undergo an upgrade. And so to develop radiation hard pixel sensors, simulations have been performed using the 2D TCAD device simulator, SILVACO, to obtain design parameters. The effect of various design parameters like pixel size, pixel depth, implant width, metal overhang, p-stop concentration, p-stop depth and bulk doping density on the leakage current and critical electric field are studied for both non-irradiated as well as irradiated pixel sensors. These 2D simulation results of planar pixels are useful for providing insight into the behaviour of non-irradiated and irradiated silicon pixel sensors and further work on 3D simulation is underway.

The High Luminosity upgrade of the CERN Large Hadron Collider (HL–LHC) calls for an upgrade of the CMS tracker detector to cope with the increased radiation levels while maintaining the excellent performance of the existing detector. Specifically, new high-radiation tolerant solid-state pixel sensors, capable of surviving irradiation fluences up to 1.9×1016neq/cm2 at 3 cm from the interaction point, need to be developed. For this purpose an R&D program involving different vendors have been pursued, aiming at the development of thin n-in-p type pixel sensors. The R&D covers both planar (manufactured by Fondazione Bruno Kessler, FBK; Hamamatsu Photonics, HPK and LFoundry) and single-sided 3D columnar (manufactured by FBK and Centro Nacional de Microelectronica, CNM) pixel devices. The target active thickness is 150μm while two different pixel cell dimensions are currently investigated (25 × 100 and 50×50μm2). Sensors presented in this article have been bump-bonded to the RD53A readout chip (ROC), the first prototype towards the development of a ROC to be employed during HL–LHC operation. Test beam studies, both of thin planar and 3D devices, have been performed by the CMS collaboration at the CERN, DESY and Fermilab test beam facilities. Results of modules performance before and after irradiation (up to 2.4×1016neq/cm2) are presented in this article.

The relative abundance of cosmic ray nickel nuclei with respect to iron is by far larger than for all other transiron elements; therefore it provides a favorable opportunity for a low background measurement of its spectrum. Since nickel, as well as iron, is one of the most stable nuclei, the nickel energy spectrum and its relative abundance with respect to iron provide important information to estimate the abundances at the cosmic ray source and to model the Galactic propagation of heavy nuclei. However, only a few direct measurements of cosmic-ray nickel at energy larger than ∼3 GeV/n are available at present in the literature, and they are affected by strong limitations in both energy reach and statistics. In this Letter, we present a measurement of the differential energy spectrum of nickel in the energy range from 8.8 to 240 GeV/n, carried out with unprecedented precision by the Calorimetric Electron Telescope (CALET) in operation on the International Space Station since 2015. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z=40). The particle's energy is measured by a homogeneous calorimeter (1.2 proton interaction lengths, 27 radiation lengths) preceded by a thin imaging section (3 radiation lengths) providing tracking and energy sampling. This Letter follows our previous measurement of the iron spectrum [1O. Adriani et al. (CALET Collaboration), Phys. Rev. Lett. 126, 241101 (2021).PRLTAO0031-900710.1103/PhysRevLett.126.241101], and it extends our investigation on the energy dependence of the spectral index of heavy elements. It reports the analysis of nickel data collected from November 2015 to May 2021 and a detailed assessment of the systematic uncertainties. In the region from 20 to 240 GeV/n our present data are compatible within the errors with a single power law with spectral index -2.51±0.07.

The CMS experiment at the LHC will comprise a large silicon strip tracker. This article highlights some of the results obtained in the R&D studies for the optimization of its silicon sensors. Measurements of the capacitances and of the high voltage stability of the devices are presented before and after irradiation to the dose expected after the full lifetime of the tracker.

Tracker systems based on silicon detectors are one of the possible choices for experiments at the future upgrade of the Large Hadron Collider (LHC) the Super-LHC (SLHC). Optimization of material and detector design are key factors to develop ultra radiation hard silicon devices. Most advanced research activity in this field identified Magnetic Czochralski (MCz) material as a candidate for the processing of such a detectors. This paper summarizes more relevant results achieved by the CERN RD50 and SMART INFN collaborations. Recent studies on test structures and micro-strip detectors processed on MCz material, n-type and p-type doped, and the radiation hardness performance after heavy irradiation tests are described. Charge collection from particles has been evaluated on diodes and micro-strip detectors and extrapolation of tracking performances up to the fluence expected at SLHC has been studied. Promising results in terms of radiation hardness parameters have been achieved.

Experience at high luminosity hadron collider experiments shows that tracking information enhances the trigger rejection capabilities while retaining high efficiency for interesting physics events [F. Palla and G. Parrini, Tracking in the trigger: from the CDF experience to CMS upgrade, 2007. Published in PoS VER-TEX2007:034, 2007]. The design of a tracking based trigger for Super LHC (S-LHC), the already envisaged high luminosity upgrade of the LHC collider, is an extremely challenging task, and requires the identification of high-momentum particle tracks as a part of the Level 1 Trigger. Simulation studies show that this can be achieved by correlating hits on two closely spaced silicon strip sensors. This work focuses on the design and development of micro-strip stacked prototype modules and will also discuss the technical challenges in the construction and the final detector performance. Studies of possible sensor geometries and wire-bonding techniques will be also presented. The prototypes have been built with the silicon sensors and electronics used to equip the present CMS Tracker [CMS Collaboration, The CMS experiment at the CERN LHC, JINST 3:S08004:26-89, 2008]. Correlation of signals collected from sensors are processed off detector. We will present the results of tests performed on the prototype modules in terms of the noise performance of the proposed stack geometry. Preliminary results in terms of signal over noise and tracking performance with cosmic rays will also be shown.

During the high luminosity upgrade of the LHC (HL-LHC) the CMS tracking system will face a more intense radiation environment than the present system was designed for. In order to design radiation tolerant silicon sensors for the future CMS tracker upgrade it is fundamental to complement the measurement with device simulation. This will help in both the understanding of the device performance and in the optimization of the design parameters. One of the important ingredients of the device simulation is to develop a radiation damage model incorporating both bulk and surface damage. In this paper we will discuss the development of a radiation damage model by using commercial TCAD packages (Silvaco and Synopsys), which successfully reproduce the recent measurements like leakage current, depletion voltage, interstrip capacitance and interstrip resistance, and provides an insight into the performance of irradiated silicon strip sensors.

Experience at high luminosity hadrons collider experiments shows that tracking information enhances the trigger rejection capabilities while retaining high efficiency for interesting physics events.The design of a tracking based trigger for Super LHC (S-LHC), the already envisaged high luminosity upgrade of the LHC collider, is an extremely challenging task, and requires the identification of high-momentum particle tracks as a part of the Level 1 Trigger.Simulation studies show that this can be achieved by correlating hits on two closely spaced silicon strip sensors.The progresses on the design and development of this micro-strip stacked prototype modules and the performance of few prototype detectors will be presented.The prototypes have been built with the silicon sensors and electronics used to equip the present CMS[1] Tracker.Preliminary results of a simulated tracker layout equipped with stacked modules are discussed in terms of p T resolution and triggering capabilities.The study of real prototypes in terms of signal over noise and tracking performance with cosmic rays and a dedicated beam test experiment will also be shown.©2011 CERN, for the benefit of CMS Collaboration.