A. Staiano

The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured over a large x range (0.01<x<0.7). The spin-dependent structure function g1(x) for the proton has been determined and its integral over x found to be 0.114±0.012±0.026, in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Bjorken sum rule, this result implies a significant negative value for the integral of g1 for the neutron. These values for the integrals of g1 lead to the conclusion that the total quark spin constitutes a rather small fraction of the spin of the nucleon.

The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured in the range 0.01<×<0.7. The spin dependent structure function g1(x) for the proton has been determined and, combining the data with earlier SLAC measurements, its integral over x found to be 0.126±0.010(stat.)±0.015(syst.), in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Biorken sum rule, this result implies a significant negative value for the integral of g1 for the neutron. These integrals lead to the conclusion, in the naïve quark parton model, that the total quark spin constitutes a rather small fraction of the spin of the nucleon. Results are also presented on the asymmetries in inclusive hadron production which are consistent with the above picture.

Experimental results obtained at the CERN Super Proton Synchrotron on the structure-function ratio F2n/F2p in the kinematic range 0.004<x<0.8 and 0.4<Q2<190 GeV2, together with the structure function F2d determined from a fit to published data, are used to derive the difference F2p(x)-F2n(x). The value of the Gottfried sum F(F2p-F2n)dx/x=0.240±0.016 is below the quark-parton-model expectation of 1/3.Received 23 January 1991DOI:https://doi.org/10.1103/PhysRevLett.66.2712©1991 American Physical Society

The muon-proton and muon-deuteron inclusive deep inelastic scattering cross sections were measured in the kinematic range 0.002 < × < 0.60 and 0.5 < Q2 < 75 GeV2 at incident muon energies of 90, 120, 200 and 280 GeV. These results are based on the full data set collected by the New Muon Collaboration, including the data taken with a small angle trigger. The extracted values of the structure functions F2p and F2d are in good agreement with those from other experiments. The data cover a sufficient range of y to allow the determination of the ratio of the longitudinally to transversely polarised virtual photon absorption cross sections, R = σLσT, for 0.002 < × < 0.12. The values of R are compatible with a perturbative QCD prediction; they agree with earlier measurements and extend to smaller x.

We present a new determination of the nonsinglet structure function ${\mathit{F}}_{2}^{\mathit{p}}$ - ${\mathit{F}}_{2}^{\mathit{n}}$ at ${\mathit{Q}}^{2}$=4 ${\mathrm{GeV}}^{2}$ using recently measured values of ${\mathit{F}}_{2}^{\mathit{d}}$ and ${\mathit{F}}_{2}^{\mathit{n}}$/${\mathit{F}}_{2}^{\mathit{p}}$. A new evaluation of the Gottfried sum is given, which remains below the simple quark-parton model value of 1/3.

The structure functions Fp2 and Fd2 measured by deep inelastic muon scattering at incident energies of 90 and 280 GeV are presented. These measurements cover a large kinematic range, 0.006⩽x⩽0.6 and 0.5⩽Q2⩽55GeV2, and include the first precise data at small x, where large scaling violations are observed. The data agree with earlier results from SLAC and BCDMS but exhibit differences with respect to those of EMC-NA2. Extrapolations to small x of recent phenomenological parton distributions are shown to disagree with the present results.

Results are presented on the ratios of the deep inelastic muon-nucleus cross sections for carbon, copper and tin nuclei to those measured on deuterium. The data confirm that the structure functions of the nucleon measured in nuclei are different from those measured on quasi-free nucleons in deuterium. The kinematic range of the data is such that 〈Q2〉 ∼ 5 GeV2 at x ∼ 0.03, increasing to 〈Q2〉 ∼ 35 GeV2 for x ∼ 0.65. The measured cross section ratios are less than unity for x ≲ 0.05 and for 0.25 ≲ x < 0.7. The decrease of the ratio below unity for low x becomes larger as A increases as might be expected from nuclear shadowing. However, this occurs at relatively large values of Q2 (∼ 5 GeV2) indicating that such shadowing is of patrionic origin.

The proton and deuteron structure funtions F2p and F2d were measured in the kinematic range 0.006 < x < 0.6 and 0.5 < Q2 < 75 GeV2, by inclusive deep inelastic muon scattering at 90, 120, 200 and 280 GeV. The measurements are in good agreement with earlier high precision results. The present and earlier results together have been parametrised to give descriptions of the proton and deuteron structure functions F2 and their uncertainties over the range 0.006 < x < 0.9.

In this paper we report on the timing resolution obtained in a beam test with pions of 180 GeV/c momentum at CERN for the first production of 45 µm thick Ultra-Fast Silicon Detectors (UFSD). UFSD are based on the Low-Gain Avalanche Detector (LGAD) design, employing n-on-p silicon sensors with internal charge multiplication due to the presence of a thin, low-resistivity diffusion layer below the junction. The UFSD used in this test had a pad area of 1.7 mm2. The gain was measured to vary between 5 and 70 depending on the sensor bias voltage. The experimental setup included three UFSD and a fast trigger consisting of a quartz bar readout by a SiPM. The timing resolution was determined by doing Gaussian fits to the time-of-flight of the particles between one or more UFSD and the trigger counter. For a single UFSD the resolution was measured to be 34 ps for a bias voltage of 200 V, and 27 ps for a bias voltage of 230 V. For the combination of 3 UFSD the timing resolution was 20 ps for a bias voltage of 200 V, and 16 ps for a bias voltage of 230 V.

In this paper, we report on the radiation resistance of 50-micron thick LGAD detectors manufactured at the Fondazione Bruno Kessler employing several different doping combinations of the gain layer. LGAD detectors with gain layer doping of Boron, Boron low-diffusion, Gallium, Carbonated Boron and Carbonated Gallium have been designed and successfully produced. These sensors have been exposed to neutron fluences up to $\phi_n \sim 3 \cdot 10^{16}\; n/cm^2$ and to proton fluences up to $\phi_p \sim 9\cdot10^{15}\; p/cm^2$ to test their radiation resistance. The experimental results show that Gallium-doped LGADs are more heavily affected by initial acceptor removal than Boron-doped LGAD, while the presence of Carbon reduces initial acceptor removal both for Gallium and Boron doping. Boron low-diffusion shows a higher radiation resistance than that of standard Boron implant, indicating a dependence of the initial acceptor removal mechanism upon the implant width. This study also demonstrates that proton irradiation is at least twice more effective in producing initial acceptor removal, making proton irradiation far more damaging than neutron irradiation.

We present the structure function ratios measured in deep inelastic muonnucleus scattering at a nominal incident muon energy of 200 GeV The kinematic range is covered. For values of x less than 0.002 both ratios indicate saturation of shadowing at values compatible with photoabsorption results.

Results are presented for F2d/F2p and Rd − Rp from simultaneous measurements of deep inelastic muon scattering on hydrogen and deuterium targets, at 90, 120, 200 and 280 GeV. The difference Rd − Rp, determined in the range 0.002 < x < 0.4 at an average Q2 of 5 GeV2, is compatible with zero. The x and Q2 dependence of F2d/F2p was measured in the kinematic range 0.001 < x < 0.8 and 0.1 < Q2 < 145 GeV2 with small statistical and systematic errors. For x > 0.1 the ratio decreases with Q2.

Results are presented on the ratio of neutron and proton structure functions, F2n/F2p, deduced from deep inelastic scattering of muon from hydrogen and deuterium. The data, which were obtained at the CERN muon beam at 90 and 280 GeV incident energy, cover the kinematic range x = 0.002−0.80 and Q2 = 0.1−190 GeV2. The measured structure function ratios have small statistical and systematic errors, particularly at small and intermediate x. The observed Q2 dependence in the range x = 0.1−0.4 is stronger than predicted by perturbative QCD. From the present data together with results from other experiments it is suggested that the twist-four coefficient for the proton is smaller than that for the neutron for x larger than 0.2.

In this contribution we will review the progresses toward the construction of a tracking system able to measure the passage of charged particles with a combined precision of ∼10 ps and ∼10 μm, either using a single type of sensor, able to concurrently measure position and time, or a combination of position and time sensors.

This paper presents the principles of operation of Resistive AC-Coupled Silicon Detectors (RSDs) and measurements of the temporal and spatial resolutions using a combined analysis of laser and beam test data. RSDs are a new type of n-in-p silicon sensor based on the Low-Gain Avalanche Diode (LGAD) technology, where the n+ implant has been designed to be resistive, and the read-out is obtained via AC-coupling. The truly innovative feature of RSD is that the signal generated by an impinging particle is shared isotropically among multiple read-out pads without the need for floating electrodes or an external magnetic field. Careful tuning of the coupling oxide thickness and the n+ doping profile is at the basis of the successful functioning of this device. Several RSD matrices with different pad width-pitch geometries have been extensively tested with a laser setup in the Laboratory for Innovative Silicon Sensors in Torino, while a smaller set of devices have been tested at the Fermilab Test Beam Facility with a 120 GeV/c proton beam. The measured spatial resolution ranges between 2.5μm for 70–100 pad-pitch geometry and 17μm with 200–500 matrices, a factor of 10 better than what is achievable in binary read-out (binsize∕12). Beam test data show a temporal resolution of ∼40ps for 200 μm pitch devices, in line with the best performances of LGAD sensors at the same gain.

We present the structure function ratiosF 2 He /F 2 D ,F 2 C /F 2 D andF 2 Ca /F 2 D measured in deep inelastic muon-nucleus scattering at an incident muon momentum of 200 GeV. The kinematic range 0.0035<x<0.65 and 0.5<Q 2<90 GeV2 is covered. At lowx the three ratios are significantly smaller than unity and the size of the depletion grows with decreasingx and increasing mass numberA. At intermediatex the ratios show an enhancement of about 2% above unity for C/D and Ca/D, possibly less for He/D. There are indications of someQ 2 dependence in the Ca/D data. The integrals of the structure function differencesF 2 A −F 2 D are discussed.

Exclusive ϱ0 and φ muoproduction on deuterium, carbon and calcium has been studied in the kinematic range 2< Q2< 25 GeV2 and 40 < ν < 180GeV. We discuss the Q2 dependence of the cross sections, the transverse momentum distributions for the vector mesons, the decay angular distributions and, in the case of the ϱ0, nuclear effects. The data for 0 production are compatible with a diffractive mechanism. The distinct features of φ production are a smaller cross section and less steep pt2 distributions than those for the 0 mesons.

Differential multiplicities of forward produced hadrons in deep inelastic muon scattering on nuclear targets have been compared with those from deuterium. The ratios are observed to increase towards unity as the virtual photon energy increases with no significant dependence on the other muon kinematic variables. The hadron transverse momentum distribution is observed to be broadened in nuclear targets. The dependence on the remaining hadron variables is investigated and the results are discussed in the framework of intranuclear interaction models and in the context of the EMC effect.

In order to extend the tracking acceptance, to improve the primary and secondary vertex reconstruction and thus enhancing the tagging capabilities for short lived particles, the ZEUS experiment at the HERA Collider at DESY installed a silicon strip vertex detector. The barrel part of the detector is a 63 cm long cylinder with silicon sensors arranged around an elliptical beampipe. The forward part consists of four circular shaped disks. In total just over 200k channels are read out using 2.9m2 of silicon. In this report a detailed overview of the design and construction of the detector is given and the performance of the completed system is reviewed.

Is it possible to design a detector able to concurrently measure time and position with high precision? This question is at the root of the research and development of silicon sensors presented in this contribution. Silicon sensors are the most common type of particle detectors used for charged particle tracking, however their rather poor time resolution limits their use as precise timing detectors. A few years ago we have picked up the gantlet of enhancing the remarkable position resolution of silicon sensors with precise timing capability. I will be presenting our results in the following pages.

In this paper we report results from a neutron irradiation campaign of Ultra-Fast Silicon Detectors (UFSD) with fluences of 1e14, 3e14, 6e14, 1e15, 3e15 and 6e15 neq/cm2. The UFSD used in this study are circular 50 μ m thick Low-Gain Avalanche Detectors (LGAD), with a 1.0 mm diameter active area. Hamamatsu Photonics (HPK), Japan, produced the UFSD with pre-irradiation internal gain in the range 5–70 depending on the bias voltage. The sensors were tested pre-irradiation and post-irradiation with minimum ionizing particles (MIPs) from a 90Sr β-source. The leakage current, internal gain and the timing resolution were measured as a function of bias voltage at −20 °C and −30 °C. The timing resolution of each device under test was extracted from the time difference with a second calibrated UFSD in coincidence, using the constant fraction discriminator (CFD) method for both. The dependence of the gain upon the irradiation fluence is consistent with the acceptor removal mechanism; at −20 °C the highest gain decreases from 70 before radiation to 2 after a fluence of 6e15 n/cm2. Consequently, the timing resolution was found to deteriorate from 20 ps to 50 ps. The results indicate that the most accurate time resolution is obtained varying with fluence the CFD value used to determine the time of arrival, from 0.1 for pre-irradiated sensors to 0.6 at the highest fluence. Key changes to the pulse shape induced by irradiation, i.e. (i) the contribution of charge multiplication not limited to the gain layer zone, (ii) the shortening of the rise time and (iii) the reduced pulse height, were compared with the WF2 simulation program and were found to be in agreement.

Fondazione Bruno Kessler (FBK, Trento, Italy) has recently delivered its first 50 $\mu$m thick production of Ultra-Fast Silicon Detectors (UFSD), based on the Low-Gain Avalanche Diode design. These sensors use high resistivity Si-on-Si substrates, and have a variety of gain layer doping profiles and designs based on Boron, Gallium, Carbonated Boron and Carbonated Gallium to obtain a controlled multiplication mechanism. Such variety of gain layers will allow identifying the most radiation hard technology to be employed in the production of UFSD, to extend their radiation resistance beyond the current limit of $\phi \sim$ 10$^{15}$ n$_{eq}$/cm$^2$. In this paper, we present the characterisation, the timing performances, and the results on radiation damage tolerance of this new FBK production.

Results are presented on the ratios of the nucleon structure function in copper to deuterium from two separate experiments. The data confirm that the nucleon structure function,F 2, is different for bound nucleons than for the quasi-free ones in the deuteron. The redistribution in the fraction of the nucleon's momentum carried by quarks is investigated and it is found that the data are compatible with no integral loss of quark momenta due to nuclear effects.

X-ray computed tomography (CT) is now used in the cultural heritage field because it is non-invasive and it can give a large amount of information on the inner structure of the object under study. Until recently mainly medical CT scanners or micro-CT setups have been used, limiting the analysis to relatively small artworks or requiring multiple acquisition and difficult image-joining for objects larger than detector dimensions. To overcome the limitations of ordinary CT devices, a facility for the X-ray tomography of large size artefacts has recently been designed and installed in a protected area of the Fondazione Centro Conservazione e Restauro "La Venaria Reale", a Centre for Preservation and Restoration. This facility, based on a X-ray source, a linear X-ray detector and a high precision mechanical system, has been and will be used to gather information on materials, manufacturing techniques and conservative conditions of artworks undergoing the restoration process. In this paper the results of the tomography of the first analyzed large artistic object are presented, giving an idea of the wealth of information obtained from the CT scan. The presented artwork is the writing cabinet called "doppio corpo", a masterpiece of furniture more than 3 m high, inlaid for Savoy Residences by Pietro Piffetti, the most famous cabinet-maker in Piedmont in the XVIII century. The artwork is now housed in the Quirinale Palace, the official residence of the Italian President in Rome. The CT analysis permitted us to obtain valuable information about the conservative conditions, the presence of previous interventions, the distribution of various materials and the dimensions and arrangement of several wooden pieces, thus allowing for interesting hypotheses about the building technique of this masterpiece.

The Q2 dependence of the structure functions F2p and F2d recently measured by the NMC is compared with the predictions of perturbative QCD at next-to-leading order. Good agreement is observed, leading to accurate determinations of the quark and gluon distributions in the range 0.008 ⩽ × ⩽ 0.5. The strong coupling constant is measured from the low x data; the result agrees with previous determinations.

In this paper we present the numerical simulation of silicon detectors with internal gain as the main tool for 4-dimensional (4D) particle trackers design and optimization. The Low-Gain Avalanche Diode (LGAD) technology and its present limitations are reviewed with the aim of introducing the Resistive AC-Coupled Silicon Detectors (RSD) paradigm as a case study of our investigation. Authors here present Spice-like and 2D/3D Technological Computer-Aided Design (TCAD) simulations to characterize sensors in terms of both their electrostatic behavior, capacitive (dynamic) coupling and radiation-hardness performances, showing the methodological approach used in order to extract the set of layout rules allowing the release of RSD1, the incoming production run at Fondazione Bruno Kessler (FBK) of next-generation silicon detectors for 4D tracking with intrinsic 100% fill-factor.

Several future high-energy physics facilities are currently being planned. The proposed projects include high energy e+e− circular and linear colliders, hadron colliders, and muon colliders, while the Electron–Ion Collider (EIC) is expected to construct at the Brookhaven National Laboratory in the future. Each proposal has its advantages and disadvantages in terms of readiness, cost, schedule, and physics reach, and each proposal requires the design and production of specific new detectors. This paper first presents the performances necessary for future silicon tracking systems at the various new facilities. Then it illustrates a few possibilities for the realization of such silicon trackers. The challenges posed by the future facilities require a new family of silicon detectors, where features such as impact ionization, radiation damage saturation, charge sharing, and analog read-out are exploited to meet these new demands.

We present results on J/ψ production in muon interactions with tin and carbon targets at incident muon energies of 200 and 280 GeV. The ratio of cross sections per nucleon for J/ψ production on tin and carbon, R(Sn/C), is studied as a function of pT2, z and x. We find an enhancement for coherent J/ψ production Rcoh(Sn/C) = 1.54 ± 0.07, a suppression for quasielastic production Rqe(Sn/C) = 0.79 ± 0.06 and for inelastic production Rin(Sn/C) = 1.13 ± 0.08. The inelastic cross section ratio can be interpreted within the Colour Singlet model as an enhancement of the gluon distribution in tin with respect to that in carbon. The dependence of the ratio on z and pT2 can explain the discrepancy between the results obtained in previous experiments.

Abstract RSDs (Resistive AC-Coupled Silicon Detectors) are n-in-p silicon sensors based on the LGAD (Low-Gain Avalanche Diode) technology, featuring a continuous gain layer over the whole sensor area. The truly innovative feature of these sensors is that the signal induced by an ionising particle is seen on several pixels, allowing the use of reconstruction techniques that combine the information from many read-out channels. In this contribution, the first application of a machine learning technique to RSD devices is presented. The spatial resolution of this technique is compared to that obtained with the standard RSD reconstruction methods that use analytical descriptions of the signal sharing mechanism. A Multi-Output regressor algorithm, trained with a combination of simulated and real data, leads to a spatial resolution of less than 2 μm for a sensor with a 100 μm pixel. The prospects of future improvements are also discussed.

Results are presented on the difference in R, the ratio of longitudinally to transversely polarised virtual photon absorption cross sections, for the deuteron and the proton. They are obtained by comparing the ratio of cross sections for the deep inelastic scattering of muons from deuterium and hydrogen targets at 90 and 280 GeV incident energy. The results cover the range x=0.01–0.30, at an average Q2 of 9 GeV2. The measured difference Rd-Rp shows no significant x dependence and is compatible with zero, as well as with expectations from perturbative QCD. We use the same method to obtain the difference RCa-RC from cross section ratios measured on carbon and calcium targets at 90 and 200 GeV incident energy.

Final data measured with the EMC forward spectrometer are presented on the production of forward charged hadrons in μp and μd scattering at incident beam energies between 100 and 280 GeV. The large statistic of 373 000 events allows a study of the semi-inclusive hadron production as a function ofz,p 2 and 〈p 2 〉 in smallQ 2,x Bj andW bins. Charge multiplicity ratios and differences as a function ofz andx Bj are given forp, d andn-targets. From the differences of charge multiplicities the ratio of the valence quark distributions of the protond v (x)/u v (x) is determined for the first time in charged lepton scattering. The Gronau et al. sum rule is tested, the measured sum being 0.31±0.06 stat. ±0.05 syst., compared with the theoretical expectation of 2/7≈0.286. The measured sum corresponds to an absolute value of the ratio of thed andu quark charge of 0.44±0.10 stat.±0.08 syst.

In the past few years, there has been growing interest in the development of silicon sensors able to simultaneously measure accurately the time of passage and the position of impinging charged particles. In this contribution, a review of the progresses in the design of UFSD (Ultra-Fast Silicon Detectors) sensors, manufactured at the FBK (Fondazione Bruno Kessler) Foundry, aiming at tracking charged particles in 4 dimensions, is presented. The state-of-the-art UFSD sensors, with excellent timing capability, are planned to be used in both ATLAS and CMS experiments detector upgrade, in order to reduce the background due to the presence of overlapping events in the same bunch crossing. The latest results on sensors characterization including time resolution, radiation resistance and uniformity of the response are here summarized, pointing out the interplay between the design of the gain layer and the UFSD performances. The research is now focusing on the maximization of the sensor fill factor, to be able to reduce the pixel size, exploring the implementation of shallow trenches for the pixel isolation and the development of resistive AC-coupled UFSD sensors. In conclusion, a brief review on research paths tailored for detection of low energy X-rays or for low material budget applications is given.

We review the progress toward the development of a novel type of silicon detectors suited for tracking with a picosecond timing resolution, the so called Ultra-Fast Silicon Detectors. The goal is to create a new family of particle detectors merging excellent position and timing resolution with GHz counting capabilities, very low material budget, radiation resistance, fine granularity, low power, insensitivity to magnetic field, and affordability. We aim to achieve concurrent precisions of ∼ 10 ps and ∼ 10 μm with a 50 μm thick sensor. Ultra-Fast Silicon Detectors are based on the concept of Low-Gain Avalanche Detectors, which are silicon detectors with an internal multiplication mechanism so that they generate a signal which is factor ∼ 10 larger than standard silicon detectors.

To fully exploit the physics potentials of particle therapy in delivering dose with high accuracy and selectivity, charged particle therapy needs further improvement. To this scope, a multidisciplinary project (MoVeIT) of the Italian National Institute for Nuclear Physics (INFN) aims at translating research in charged particle therapy into clinical outcome. New models in the treatment planning system are being developed and validated, using dedicated devices for beam characterization and monitoring in radiobiological and clinical irradiations. Innovative silicon detectors with internal gain layer (LGAD) represent a promising option, overcoming the limits of currently used ionization chambers. Two devices are being developed: one to directly count individual protons at high rates, exploiting the large signal-to-noise ratio and fast collection time in small thicknesses (1 ns in 50 μm) of LGADs, the second to measure the beam energy with time-of-flight techniques, using LGADs optimized for excellent time resolutions (Ultra Fast Silicon Detectors, UFSDs). The preliminary results of first beam tests with therapeutic beam will be presented and discussed.

Results are presented for six nuclei from Be to Pb on the structure function ratios F2A/F2C(x) and their A dependence in deep inelastic muon scattering at 200 GeV incident muon energy. The data cover the kinematic range 0.01 < x < 0.8 with Q2 ranging from 2 to 70 GeV2. The A dependence of nuclear structure function ratios is parametrised and compared to various models.

The structure function ratiosF 2 C /F 2 Li ,F 2 Ca /F 2 Li andF 2 Ca /F 2 C were measured in deep inelastic muonnucleus scattering at an incident muon energy of 90 GeV, covering the kinematic range 0.0085<x<0.6 and 0.8<Q 2<17GeV2. The sensitivity of the nuclear structure functions to the size and mean density of the target nucleus is discussed.

In this paper we report measurements of the uniformity of time resolution, signal amplitude, and charged particle detection efficiency across the sensor surface of low-gain avalanche detectors (LGAD). Comparisons of the performance of sensors with different doping concentrations and different active thicknesses are presented, as well as their temperature dependence and radiation tolerance up to 6×1014 n/cm2. Results were obtained at the Fermilab test beam facility using 120 GeV proton beams, and a high precision pixel tracking detector. LGAD sensors manufactured by the Centro Nacional de Microelectrónica (CNM) and Hamamatsu Photonics (HPK) were studied. The uniformity of the sensor response in pulse height before irradiation was found to have a 2% spread. The signal detection efficiency and timing resolution in the sensitive areas before irradiation were found to be 100% and 30–40 ps, respectively. A “no-response” area between pads was measured to be about 130 μm for CNM and 170μm for HPK sensors. After a neutron fluence of 6×1014 n/cm2 the CNM sensor exhibits a large gain variation of up to a factor of 2.5 when comparing metalized and non-metalized sensor areas. An irradiated CNM sensor achieved a time resolution of 30 ps for the metalized area and 40 ps for the non-metalized area, while a HPK sensor irradiated to the same fluence achieved a 30 ps time resolution.

The properties of 50 um thick Low Gain Avalanche Diode (LGAD) detectors manufactured by Hamamatsu photonics (HPK) and Fondazione Bruno Kessler (FBK) were tested before and after irradiation with 1 MeV neutrons. Their performance were measured in charge collection studies using b-particles from a 90Sr source and in capacitance-voltage scans (C-V) to determine the bias to deplete the gain layer. Carbon infusion to the gain layer of the sensors was tested by FBK in the UFSD3 production. HPK instead produced LGADs with a very thin, highly doped and deep multiplication layer. The sensors were exposed to a neutron fluence from 4e14 neq/cm2 to 4e15 neq/cm2. The collected charge and the timing resolution were measured as a function of bias voltage at -30C, furthermore the profile of the capacitance over voltage of the sensors was measured.

Quasielastic production of J/ψ mesons has been measured in muon interactions with hydrogen, deuterium, carbon and tin targets at incident muon energies of 200 and 280 GeV. The hydrogen and deuterium data were used to study the transverse momentum distribution of the J/ψ's. These data have been analysed together with previously published ϱ0 data in the framework of the vector meson dominance model. The radii of the Jψ and the ϱ0 as well as the total J/ψ-N and ϱ0-N cross sections were deduced. From the tin and carbon data the ratio of the quasielastic J/ψ production cross sections, Rqe(Sn/C), has been extracted and found to be less than unity. In the Glauber approach this suppression can be related to the J/ψ absorption probability in nuclei. The suppression is also compared to those predicted by various colour transparency models.

We have studied transverse momentum distributions for exclusiveρ 0 muoproduction on protons and heavier nuclei at 2<Q 2<25 GeV2. TheQ 2 dependence of the slopes of thep 2 andt′ distributions is discussed. The influence of the non-exclusive background is investigated. Thep 2 -slope for exclusive events is 4.3±0.6±0.7 GeV−2 at largeQ 2. Thep 2 spectra are much softer than inclusivep 2 spectra of leading hadrons produced in deep inelastic scattering.

The 40 MHz bunched muon beam set up at CERN was used in May 2003 to make a full test of the drift tubes local muon trigger. The main goal of the test was to prove that the integration of the various devices located on a muon chamber was adequately done both on the hardware and software side of the system. Furthermore the test provided complete information about the general performance of the trigger algorithms in terms of efficiency and noise. Data were collected with the default configuration of the trigger devices and with several alternative configurations at various angles of incidence of the beam. Tests on noise suppression and di-muon trigger capability were performed.

Data are presented on exclusive ρ0 and ϕ production in deep inelastic muon scattering from a target consisting mainly of nitrogen. The ratio of the total cross sections for ρ0 and ϕ production is found to be 9∶(1.6±0.4) at 〈Q 2〉=7.5 GeV2, consistent with theSU(3) prediction of 9∶2. Thet dependence for exclusive ρ0 production is found to become shallover asQ 2 increases and, for largeQ 2, thet dependence is typical of that for a hard scattering process. Furthermore, the ratio of the cross sections for coherent: incoherent production from nitrogen is found to decrease rapidly withQ 2. Such behaviour indicates that even for exclusive vector meson production the virtual photon behaves predominantly as an electromagnetic probe.

The neu_ART project aims at developing state of the art transmission imaging and computed tomography techniques, applied to art objects, by using neutrons as well as more conventional X-rays. In this paper a facility for digital X-ray radiography of large area paintings on canvas or wooden panels and for the X-ray tomography of large size wooden artifacts, recently installed in a protected area, is presented. The results of a K-edge radiography facility that will soon be installed in the same area are also shown.

Fast procedures for the beam quality assessment and for the monitoring of beam energy modulations during the irradiation are among the most urgent improvements in particle therapy. Indeed, the online measurement of the particle beam energy could allow assessing the range of penetration during treatments, encouraging the development of new dose delivery techniques for moving targets. Towards this end, the proof of concept of a new device, able to measure in a few seconds the energy of clinical proton beams (from 60 to 230 MeV) from the Time of Flight (ToF) of protons, is presented. The prototype consists of two Ultra Fast Silicon Detector (UFSD) pads, featuring an active thickness of 80 um and a sensitive area of 3 x 3 mm2, aligned along the beam direction in a telescope configuration, connected to a broadband amplifier and readout by a digitizer. Measurements were performed at the Centro Nazionale di Adroterapia Oncologica (CNAO, Pavia, Italy), at five different clinical beam energies and four distances between the sensors (from 7 to 97 cm) for each energy. In order to derive the beam energy from the measured average ToF, several systematic effects were considered, Monte Carlo simulations were developed to validate the method and a global fit approach was adopted to calibrate the system. The results were benchmarked against the energy values obtained from the water equivalent depths provided by CNAO. Deviations of few hundreds of keV have been achieved for all considered proton beam energies for both 67 and 97 cm distances between the sensors and few seconds of irradiation were necessary to collect the required statistics. These preliminary results indicate that a telescope of UFSDs could achieve in a few seconds the accuracy required for the clinical application and therefore encourage further investigations towards the improvement and the optimization of the present prototype.

The properties of 60-μm thick Ultra-Fast Silicon Detectors (UFSD) detectors manufactured by Fondazione Bruno Kessler (FBK), Trento (Italy) were tested before and after irradiation with minimum ionizing particles (MIPs) from a 90Sr β-source. This FBK production, called UFSD2, has UFSDs with gain layer made of Boron, Boron low-diffusion, Gallium, carbonated Boron and carbonated Gallium. The irradiation with neutrons took place at the TRIGA reactor in Ljubljana, while the proton irradiation took place at CERN SPS. The sensors were exposed to a neutron fluence of 4⋅1014, 8⋅1014, 1.5⋅1015, 3⋅1015, 6⋅ 1015 neq/cm2 and to a proton fluence of 9.6⋅ 1014 p/cm2, equivalent to a fluence of 6⋅ 1014 neq/cm2. The internal gain and the timing resolution were measured as a function of bias voltage at -20oC. The timing resolution was extracted from the time difference with a second calibrated UFSD in coincidence, using the constant fraction method for both.

The combination of precision space and time information in particle tracking, the so called 4D tracking, is being considered in the upgrade of the ATLAS, CMS and LHCb experiments at the High-Luminosity LHC, set to start data taking in 2024–2025. Regardless of the type of solution chosen, space–time tracking brings benefits to the performance of the detectors by reducing the background and sharpening the resolution; it improves tracking performances and simplifies tracks combinatorics. Space–time tracking also allows investigating new physics channels, for example it opens up the possibilities of new searches in long-living particles by measuring accurately the time of flight between the production and the decay vertexes. The foreseen applications of 4D tracking in experiments with very high acquisition rates, for example at HL-LHC, add one more dimension to the problem, increasing dramatically the complexity of the read-out system and that of the whole detector design: we call 5D tracking the application of 4D tracking in high rate environments.

Pile-up effects due to the overlap of signals within the system dead-time (τ) influence the counting capability of radiation detection devices, necessitating the use of correction algorithms to compensate for the count-losses at high radiation rates. Count-rate linearity is especially critical for clinical applications like X-ray imaging or beam monitoring in particle therapy. In particular, in proton therapy the number of delivered particles must be measured online during the treatment session with a maximum error of 1 % up to an average input beam flux of about 1010cm−2s−1. For a segmented detector used to identify and count the single beam particles, assuming a channel area of 1 mm2 and a dead-time τ=2ns, a maximum counting inefficiency of 1 % is required up to τ.fin=0.2 for each detector channel, where fin represents the input rate. Moreover, the beam is often delivered in bunches with higher instantaneous particle rates, and the saturation model of the detector and electronic chain could not be easily determined. Similar considerations are applicable for pixelated detectors used for photon counting. Two methods are proposed to mitigate counting inefficiencies with radiation sources of variable time-structures. Both methods are based on the collection of logic signals provided by two independent detector channels exposed to the same radiation field after discriminating the detector analog outputs with a fixed threshold, assuming that the duration of the discriminator output signal corresponds to the system dead-time. The correction algorithms employ the measurements of the time durations, the number of signals from the two channels and of their AND/OR combinations. The methods provide count-loss corrections without the need to know the dead-time model. The performances of the proposed algorithms are evaluated by using simulations of ideal boxcar signals of fixed duration τ, distributed randomly in time to emulate the dead-time behavior of the system. Both methods provide an effective count-loss correction with a maximum deviation of 1% for different input rates up to τ.fin=1, assuming a uniform random time distribution of input events for both paralyzable and non-paralyzable systems. The simulations of pulsed radiation fluxes provide the same results as a function of the instantaneous input rates. These results are similar to those obtainable by the standard live-time correction algorithm. However, the latter algorithm can only be applied to continuous particle fluxes, while the proposed algorithms work also for pulsed beams, without any hypothesis on the bunch duration or frequency. The robustness of the algorithms with respect to the resolution of the time measurement is studied and the potential limitations in more realistic systems are discussed. The algorithms can be easily implemented in standard logical circuits with multiple input signals provided by segmented detectors. Even if the methods are intended for real-time correction in beam particle counting, they could be applied in a wider range of applications of radiation measurements.

A prototype of the CMS Barrel Muon Detector incorporating all the features of the final chambers was built using the mass production assembly procedures and tools. The performance of this prototype was studied in a muon test beam at CERN and the results obtained are presented in this paper.

In this contribution we present our most recent numerical investigations towards the development of silicon particle detectors able to provide accurate measurements in both space and time (4D tracking). In particular, we discuss the performances of different Low-Gain Avalanche Diode (LGAD) detectors, by presenting comparisons between measurements and TCAD (Technology Computer-Aided Design) simulations, performed on several detectors fabricated by Fondazione Bruno Kessler (FBK, Italy), Centro Nacional de Microelectrónica (CNM, Spain) and Hamamatsu Photonics K.K. (HPK, Japan). To have a satisfactory timing resolution, carriers multiplication in LGAD has to be properly controlled through the implantation of a specific highly-dopedp-type layer underneath the n-cathode. This internal multiplication process is so crucial in view of having large output signals for accurate time measurements, that numerical simulation turns out to be one of the main tools in designing LGADs. For this reason, in this paper we present a simulation framework, where the most robust avalanche models - Massey, van Overstraeten-de Man and Okuto-Crowell - have been tested. Thus, at the end, we propose a reliable designing tool which is highly predictive in the field of research and development of LGADs.

In October 2001 the first produced CMS Barrel Drift Tube (DT) Muon Chamber was tested at the CERN Gamma Irradiation Facility (GIF) using a muon beam. A Resistive Plate Chamber (RPC) was attached to the top of the DT chamber, and, for the first time, both detectors were operated coupled together. The performance of the DT chamber was studied for several operating conditions, and for gamma rates similar to the ones expected at LHC. In this paper we present the data analysis; the results are considered fully satisfactory.

Abstract Beam monitoring in particle therapy is a critical task that, because of the high flux and the time structure of the beam, can be challenging for the instrumentation. Recent developments in thin silicon detectors with moderate internal gain, optimized for timing applications (Ultra Fast Silicon Detectors, UFSD), offer a favourable technological option to conventional ionization chambers. Thanks to their fast collection time and good signal-to-noise ratio, properly segmented sensors allow discriminating and counting single protons up to the high fluxes of a therapeutic beam, while the excellent time resolution can be exploited for measuring the proton beam energy using time-of-flight techniques. We report here the results of the first tests performed with UFSD detector pads on a therapeutic beam. It is found that the signal of protons can be easily discriminated from the noise, and that the very good time resolution is confirmed. However, a careful design is necessary to limit large pile-up inefficiencies and early performance degradation due to radiation damage.

The Ultra Fast Silicon Detectors (UFSD) are a novel concept of silicon detectors based on the Low Gain Avalanche Diode (LGAD) technology, which are able to obtain time resolution of the order of few tens of picoseconds. First prototypes with different geometries (pads/pixels/strips), thickness (300 and 50 μm) and gain (between 5 and 20) have been recently designed and manufactured by CNM (Centro Nacional de Microelectrónica, Barcelona) and FBK (Fondazione Bruno Kessler, Trento). Several measurements on these devices have been performed in laboratory and in beam test and a dependence of the gain on the temperature has been observed. Some of the first measurements will be shown (leakage current, breakdown voltage, gain and time resolution on the 300 μm from FBK and gain on the 50 μm-thick sensor from CNM) and a comparison with the theoretically predicted trend will be discussed.

Abstract The Italian Neutron Experimental Station (INES) located at the ISIS pulsed neutron source (Didcot, United Kingdom) provides a thermal neutron beam mainly used for diffraction analysis. A neutron transmission imaging system was also developed for beam monitoring and for aligning the sample under investigation. Although the time-of-flight neutron diffraction is a consolidated technique, the neutron imaging setup is not yet completely characterized and optimized. In this paper the performance for neutron radiography and tomography at INES of two scintillator screens read out by two different commercial CCD cameras is compared in terms of linearity, signal-to-noise ratio, effective dynamic range and spatial resolution. In addition, the results of neutron radiographies and a tomography of metal alloy test structures are presented to better characterize the INES imaging capabilities of metal artifacts in the cultural heritage field.

Within the neu_ART project, funded by Regione Piemonte (Italy), a team of specialists in different scientific fields coming from Istituto Nazionale di Fisica Nucleare (INFN), Physics Department of University of Torino and Centro Conservazione e Restauro (CCR) “La Venaria Reale” has developed a new digital X-ray apparatus expressly designed for painted canvas and panels up to about 3 m × 4 m. Compared to all other systems scanning time is faster, the procedure to obtain the whole radiography is easier and images are available in real time. This apparatus has been widely tested on artworks restored at CCR “La Venaria Reale”, allowing to study and optimize the operating parameters and to evaluate its performance, thanks to the feedback provided by professionals involved in the activities of conservation. Supported by the results presented in this work, restorers had the possibility to investigate the materials characteristics and to plan the operating strategy in advance: indeed, radiographs revealed areas with losses of paint, repainted areas, canvas damages, hidden pictures, writings and previous restorations. The X-Ray system for Digital Radiography is integrated in a more complex apparatus that can be used also for computed tomography of voluminous objects up to 2.5 m in height and 2 m in width, making the apparatus developed in the neu_ART project a unique and comprehensive tool at conservators' disposal.

Two drift tubes (DTs) chambers of the CMS muon barrel system were exposed to a 40 MHz bunched muon beam at the CERN SPS, and for the first time the whole CMS Level-1 DTs-based trigger system chain was tested. Data at different energies and inclination angles of the incident muon beam were collected, as well as data with and without an iron absorber placed between the two chambers, to simulate the electromagnetic shower development in CMS. Special data-taking runs were dedicated to test for the first time the Track Finder system, which reconstructs track trigger candidates by performing a proper matching of the muon segments delivered by the two chambers. The present paper describes the results of these measurements.

Measurements are presented of the inclusive distributions of theJ/Ψ meson produced by muons of energy 200 GeV from an ammonia target. The gluon distribution of the nucleon has been derived from the data in the range 0.04<x<0.36 using a technique based on the colour singlet model. An arbitrary normalisation factor is required to obtain a reasonable integral of the gluon distribution. Some comments are made on the use ofJ/Ψ productionby virtual photons to extract the gluon distribution at HERA.

In this contribution we review the progress towards the development of a novel type of silicon detectors suited for tracking with a picosecond timing resolution, the so called Ultra-Fast Silicon Detectors. The goal is to create a new family of particle detectors merging excellent position and timing resolution with GHz counting capabilities, very low material budget, radiation resistance, fine granularity, low power, insensitivity to magnetic field, and affordability. We aim to achieve concurrent precisions of ∼ 10 ps and ∼ 10 μm with a 50 μm thick sensor. Ultra-Fast Silicon Detectors are based on the concept of Low-Gain Avalanche Detectors, which are silicon detectors with an internal multiplication mechanism so that they generate a signal which is factor ∼10 larger than standard silicon detectors. The basic design of UFSD consists of a thin silicon sensor with moderate internal gain and pixelated electrodes coupled to full custom VLSI chip. An overview of test beam data on time resolution and the impact on this measurement of radiation doses at the level of those expected at HL-LHC is presented. First I-V and C-V measurements on a new FBK sensor production of UFSD, 50 μm thick, with B and Ga, activated at two diffusion temperatures, with and without C co-implantation (in Low and High concentrations), and with different effective doping concentrations in the Gain layer, are shown. Perspectives on current use of UFSD in HEP experiments (UFSD detectors have been installed in the CMS-TOTEM Precision Protons Spectrometer for the forward physics tracking, and are currently taking data) and proposed applications for a MIP timing layer in the HL-LHC upgrade are briefly discussed.

In this contribution, we present an innovative design of the Low-Gain Avalanche Diode (LGAD) gain layer, the p+ implant responsible for the local and controlled signal multiplication. In the standard LGAD design, the gain layer is obtained by implanting ∼5E16/cm3 atoms of an acceptor material, typically Boron or Gallium, in the region below the n++ electrode. In our design, we aim at designing a gain layer resulting from the overlap of a p+ and an n+ implants: the difference between acceptor and donor doping will result in an effective concentration of about 5E16/cm3, similar to standard LGADs. At present, the gain mechanism of LGAD sensors under irradiation is maintained up to a fluence of ∼1–2E15/cm2, and then it is lost due to the acceptor removal mechanism. The new design will be more resilient to radiation, as both acceptor and donor atoms will undergo removal with irradiation, but their difference will maintain constant. The compensated design will empower the 4D tracking ability typical of the LGAD sensors well above 1E16/cm2.

Abstract The University and the National Institute for Nuclear Physics of Torino are developing LGAD-based prototypes for beam monitoring in proton therapy. The direct measurement of single beam particles could overcome some features of currently used ionization chambers, such as slow charge collection and reduced sensitivity, which limit the implementation of advanced delivery techniques (e.g. rescanning). LGAD strip sensors have been designed and produced by Bruno Kessler Foundation (FBK, Trento) specifically for this project. A counter prototype to directly count individual protons at clinical fluence rates (10 6 –10 10 protons/cm 2 ·s) and a telescope system to measure the beam energy with time-of-flight (TOF) techniques are described. Tests of LGAD silicon strip sensors performed on synchrotron and cyclotron beams of therapeutic centers, using a pin-hole ionization chamber for the independent measurement of the particle flux, already showed the possibility to keep the counting error &lt;1% up to a beam fluence rate of few 10 8 protons/cm 2 ·s. The ongoing tests of counting sensors readout by a dedicated fast charge sensitive amplifier chip are reported. The telescope system, made of two sensors at a distance up to 95 cm, allows measuring the beam energy in the clinical range (70–230 MeV) with a maximum deviation of 310 keV in respect to the nominal one, with an uncertainty of 500 keV, thus achieving the prescribed clinical accuracy of 1 mm in the range in water.

μ+μ− pairs have been observed in deep inelastic muon-nucleon scattering and their masses measured with high resolution. No significant signal was observed at the D0 mass. These data allow an upper limit of 3.4 × 10−4 (90% confidence level) to be placed on the branching ratio for the decay mode D0 → μ+μ−.

The drift tubes based CMS barrel muon trigger, which uses self-triggering arrays of drift tubes, is able to perform the identification of the muon parent bunch crossing using a rather sophisticated algorithm. The identification is unique only if the trigger chain is correctly synchronized. Some beam test time was devoted to take data useful to investigate the synchronization of the trigger electronics with the machine clock. Possible alternatives were verified and the dependence on muon track properties was studied.

In this paper we report results from a neutron irradiation campaign of Ultra-Fast Silicon Detectors (UFSD) with fluences of 1e14, 3e14, 6e14, 1e15, 3e15, 6e15 n/cm2. The UFSD used in this study are circular 50 micro-meter thick Low-Gain Avalanche Detectors (LGAD), with a 1.0 mm diameter active area. They have been produced by Hamamatsu Photonics (HPK), Japan, with pre-radiation internal gain in the range 10-100 depending on the bias voltage. The sensors were tested pre-irradiation and post-irradiation with minimum ionizing particle (MIPs) from a 90Sr based \b{eta}-source. The leakage current, internal gain and the timing resolution were measured as a function of bias voltage at -20C and -30C. The timing resolution was extracted from the time difference with a second calibrated UFSD in coincidence, using the constant fraction method for both. The dependence of the gain upon the irradiation fluence is consistent with the concept of acceptor removal and the gain decreases from about 80 pre-irradiation to 7 after a fluence of 6e15 n/cm2. Consequently, the timing resolution was found to deteriorate from 20 ps to 50 ps. The results indicate that the most accurate time resolution is obtained at a value of the constant fraction discriminator (CFD) threshold used to determine the time of arrival varying with fluence, from 10% pre-radiation to 60% at the highest fluence. Key changes to the pulse shape induced by irradiation, i.e. (i) a reduce sensitivity of the pulse shape on the initial non-uniform charge deposition, (ii) the shortening of the rise time and (iii) the reduced pulse height, were compared with the WF2 simulation program and found to be in agreement.

The drift chambers in the barrel region of the CMS detector are exposed to magnetic stray fields. To study the performance of the muon reconstruction and the drift time-based muon trigger, prototypes were tested under the expected magnetic field conditions at the H2 test facility at CERN. The results indicate that the overall chamber performance will not be affected. Only the bunch crossing identification capability in the small region near η=1.1, corresponding to the border of the solid angle region covered by the barrel, will be weakened.

Being close to the completion of CMS installation, the three levels of the final read-out system of the Drift Tube (DT) chambers are presented. Firstly, the Read Out Boards (ROB), responsible for time digitalization of the signals generated by a charged particle track. Secondly, the Read Out Server (ROS) boards receive data from 25 ROB channels through a 240 Mbps copper link and perform data merging for further transmission through a 800 Mbps optical link. Finally, the Detector Dependent Unit (DDU) boards merge data from 12 ROS to build an event fragment and send it to the global CMS DAQ through an SLINK64 output at 320 MBps. These boards also receive synchronization commands from the TTC system (Timing, Trigger and Control), perform errors detection on data and send a fast feedback to the TTS (Trigger Throttling System). The functionality of these electronics has been validated in laboratory and in several test-beams, including an exercise integrated with a fraction of the whole CMS detector and electronics that demonstrated proper operation and integration within the final CMS framework.

The MIUR PRIN 4DInSiDe collaboration aims at developing the next generation of 4D (i.e., position and time) silicon detectors based on Low-Gain Avalanche Diodes (LGAD) that guarantee to operate efficiently in the future high-energy physics experiments. To this purpose, different areas of research have been identified, involving the development, design, fabrication and test of radiation-hard devices. This research has been enabled thanks to ad-hoc advanced TCAD modelling of LGAD devices, accounting for both technological issues as well as physical aspects, e.g. different avalanche generation models and combined surface and bulk radiation damage effects modelling. In this contribution, it is reviewed the progress and the relevant detector developments obtained during the research activities in the framework of the 4DInSiDe project. • TCAD modelling for the design of radiation-hard LGAD sensors for 4D tracking. • Gain layer compensation, (p ＋ - and n ＋ -doping) to preserve the gain at high fluences. • New design approach to resistive read-out sensors: DC-coupled RSD. • DC-RSD employs a direct coupling of the resistive layer to the read-out pads. • DC-coupled low resistivity strips between read-out pads to improve the resolution.

The Ultra Fast Silicon Detectors (UFSDs) are a new kind of silicon detectors based on Low Gain Avalanche Diodes technology. The UFSDs are optimised for time measurements with the goal of both excellent space and time resolution, which makes them a very good candidate for 4D tracking. In this paper, we will briefly explain their innovative design and show the status of the latest development. Recent measurements at the H8 beam line (CERN) will be reported, based on the UFSDs from two manufacturers: FBK and HPK. In particular, UFSDs of different thicknesses, with different doping concentrations and with different dopants of the gain layer have been studied. A time resolution of 35 ps has been achieved for a 50μm thick design and the results have been found to be in very good agreement with the expectations.

The recent development in the design of Ultra Fast Silicon Detector (UFSD), aimed at combining radiation resistance up to fluences of 1015 neq/cm2 and fine read-out segmentation, makes these sensors suitable for high energy physics applications. UFSD is an evolution of standard silicon sensor, optimized to achieve excellent timing resolution (∼30 ps), thanks to an internal low gain (∼20). UFSD sensors are n in p Low Gain Avalanche Diode (LGAD) with an active thickness of ∼5 μm. The internal gain in LGAD is obtained by implanting an appropriate density of acceptors (of the order of ∼ 1016/cm3) close to the p-n junction, that, when depleted, locally generates an electric field high enough to activate the avalanche multiplication; this layer of acceptors is called gain layer. The two challenges in the development of UFSD for high energy physics detectors are the radiation hardness and the fine segmentation of large area sensors. Irradiation fluences of the order of 1015 neq/cm2 have a dramatic effect on the UFSD: neutrons and charged hadrons reduce the active acceptor density forming the gain layer; this mechanism, called initial acceptor removal, causes the complete disappearance of the internal gain above fluence of 1015 neq/ cm2. For the segmentation of UFSDs, the crucial point is the electrical insulation of pads and the extension of the inactive area between pads. In this paper we present the latest results on radiation resistance of LGADs with different gain layer designs, irradiated up to 3⋅1015 neq/ cm2. Three different segmentation technologies, developed by Fondazione Bruno Kessler in Trento, will also be discussed in detail in the second part of the paper.

Abstract The University of Torino (UniTO) and the National Institute for Nuclear Physics (INFN-TO) are investigating the use of Ultra Fast Silicon Detectors (UFSD) for beam monitoring in radiobiological experiments with therapeutic proton beams. The single particle identification approach of solid state detectors aims at increasing the sensitivity and reducing the response time of the conventional monitoring devices, based on gas detectors. Two prototype systems are being developed to count the number of beam particles and to measure the beam energy with time-of-flight (ToF) techniques. The clinically driven precision (&lt; 1%) in the number of particles delivered and the uncertainty &lt; 1 mm in the depth of penetration (range) in radiobiological experiments (up to 10 8 protons/s fluxes) are the goals to be pursued. The future translation into clinics would allow the implementation of faster and more accurate treatment modalities, nowadays prevented by the limits of state-of-the-art beam monitors. The experimental results performed with clinical proton beams at CNAO (Centro Nazionale di Adroterapia Oncologica, Pavia) and CPT (Centro di Protonterapia, Trento) showed a counting inefficiency &lt;2% up to 100 MHz/cm 2 , and a deviation of few hundreds of keV of measured beam energies with respect to nominal ones. The progresses of the project are reported.

Next generation Low Gain Avalanche Diodes (LGAD) produced by Hamamatsu photonics (HPK) and Fondazione Bruno Kessler (FBK) were tested before and after irradiation with ~1MeV neutrons at the JSI facility in Ljubljana. Sensors were irradiated to a maximum 1-MeV equivalent fluence of 2.5E15 N eq /cm 2 . The sensors analysed in this paper are an improvement after the lessons learned from previous FBK and HPK productions that were already reported in precedent papers. The gain layer of HPK sensors was fine-tuned to optimize the performance before and after irradiation. FBK sensors instead combined the benefit of Carbon infusion and deep gain layer to further the radiation hardness of the sensors and reduced the bulk thickness to enhance the timing resolution. The sensor performance was measured in charge collection studies using β-particles from a 90Sr source and in capacitance-voltage scans (C-V) to determine the bias to deplete the gain layer. The collected charge and the timing resolution were measured as a function of bias voltage at -30C. Finally a correlation is shown between the bias voltage to deplete the gain layer and the bias voltage needed to reach a certain amount of gain in the sensor. HPK sensors showed a better performance before irradiation while maintaining the radiation hardness of the previous production. FBK sensors showed exceptional radiation hardness allowing a collected charge up to 10 fC and a time resolution of 40 ps at the maximum fluence.

The CMS muon barrel drift tubes system has been recently fully installed and commissioned in the experiment. The performance and the current status of the detector are briefly presented and discussed.

The DDU board (Detector Dependent Unit, also called DT FED) is part of the Read-Out system of the CMS Drift-Tube detector. It merges data coming from the front-end electronics, in order to build an event fragment and send it to the global CMS DAQ through a S-LINK64 output. The DDU board also receives synchronization commands from the TTC system (Timing, Trigger and Control system), performs error detection on data and sends a fast feedback to the trigger system through the TTS output (Trigger Throttling System). The complete functionality of the DDU has been validated in laboratory and in the Cosmic Challenge exercise performed during summer 2006.

Abstract The assembly and testing of the components which make up a detector plane for the Leading Proton Spectrometer is described. The spectrometer, a part of the ZEUS detector, utilizes single-sided DC-coupled silicon strip detectors and custom VLSI front-end electronics for readout.

In this contribution we review the growing interest in implementing large-area fast-timing detectors with a time resolution of 30 -35 ps, based on Low-Gain Avalanche Detectors.Precise time information added to tracking brings benefits to the performance of the detectors by reducing the background and sharpening the resolution; it improves tracking performances and simplifies tracking combinatorics.Large-scale high-precision timing detectors have to face formidable challenges in almost every aspect: sensors performance, segmentation and radiation tolerance, very low-power and low-noise electronics, cooling, low material budget, and large data volumes.We will report on the current status and new development of such detectors for high energy physics, in view of their possible use in the experiment upgrades at the High Luminosity LHC and beyond.

In this paper we report on the timing resolution of the first production of 50 micro-meter thick Ultra-Fast Silicon Detectors (UFSD) as obtained in a beam test with pions of 180 GeV/c momentum. UFSD are based on the Low-Gain Avalanche Detectors (LGAD) design, employing n-on-p silicon sensors with internal charge multiplication due to the presence of a thin, low-resistivity diffusion layer below the junction. The UFSD used in this test belongs to the first production of thin (50 {\mu}m) sensors, with an pad area of 1.4 mm2. The gain was measured to vary between 5 and 70 depending on the bias voltage. The experimental setup included three UFSD and a fast trigger consisting of a quartz bar readout by a SiPM. The timing resolution, determined comparing the time of arrival of the particle in one or more UFSD and the trigger counter, for single UFSD was measured to be 35 ps for a bias voltage of 200 V, and 26 ps for a bias voltage of 240 V, and for the combination of 3 UFSD to be 20 ps for a bias voltage of 200 V, and 15 ps for a bias voltage of 240 V.

The medical physics group of the Turin section of the National Institute of Nuclear Physics, on the behalf of the MoVeIT collaboration, is working for the development of a new prototype of silicon strip detector for particle therapy applications. This device, based on 50 μm thin silicon sensors with internal gain, aims to detect the single beam particle and count their number up to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /s fluxes, with a pileup probability <; 1%. A similar approach would lead to a drastic step forward, compared to the classical and widely used monitoring system based on ionization chambers. The better sensitivity, the higher dynamic range and the fact that the particle counting is independent of the beam energy, pressure and temperature, make this silicon detector suitable for the on-line dose monitoring in particle therapy applications. The prototype detector will cover a 3×3 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area and at the moment, two sets of strip sensors with different geometry and custom design, have been produced and are currently under investigation. The classic orthogonal strip positioning is used for beam profile measures. For what concerns the front-end electronics, the design of two different solutions is ongoing: one based on a transimpedance preamplifier, with a resistive feedback and the second one based on a charge sensitive amplifier. The challenging task for the design is the expected 3 fC - 130 fC wide input charge range (due to the Landau fluctuation spreading and different beam energies), dealing with a hundreds of MHz instantaneous rate (from 200 MHz up to 500 MHz ideally). To effectively design these components, it is crucial to perform preliminary investigation of the sensor response to the expected stimuli. For this reason an extensive work has been done and is still on going, using 1.2 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area and 50μm silicon pads with gain, performing test with the clinical beam of the Italian National Center of Oncological Hadrontherapy (CNAO) in Pavia, Italy.

In this contribution we review the progress towards the development of a novel type of silicon detectors suited for tracking with a picosecond timing resolution, the so called Ultra-Fast Silicon Detectors.The goal is to create a new family of particle detectors merging excellent position and timing resolution with GHz counting capabilities, very low material budget, radiation resistance, fine granularity, low power, insensitivity to magnetic field, and affordability.We aim to achieve concurrent precisions of ∼ 10 ps and ∼ 10µm with a 50 µm thick sensor.The first part of this contribution explains the basic concepts of low-gain silicon sensors, while in the following the main results are presented, together with the efforts to make the design radiation resistance.

Results are presented for F-2(d)/F-2(p) and R(d) - R(p) from simultaneous measurements of deep inelastic muon scattering on hydrogen and deuterium targets, at 90, 120, 200 and 280 GeV. The difference R(d) - R(p), determined in the range 0.002 0.1 the ratio decreases with Q(2).

Low Gain Avalanche Detectors (LGADs) are a type of thin silicon detector with a highly doped gain layer. LGADs manufactured by Fondazione Bruno Kessler (FBK) were tested before and after irradiation with neutrons. In this study, the Inter-pad distances (IPDs), defined as the width of the distances between pads, were measured with a TCT laser system. The response of the laser was tuned using $\beta$-particles from a 90Sr source. These insensitive "dead zones" are created by a protection structure to avoid breakdown, the Junction Termination Extension (JTE), which separates the pads. The effect of neutron radiation damage at \fluence{1.5}{15}, and \fluence{2.5}{15} on IPDs was studied. These distances are compared to the nominal distances given from the vendor, it was found that the higher fluence corresponds to a better matching of the nominal IPD.

Purpose For beam monitoring in particle therapy, silicon detectors could overcome the limitations of ionization chambers. In particular, silicon sensors with internal gain (Ultra Fast Silicon Detectors, UFSDs) provide high signal-to-noise ratio and fast collection times ( ∼1 ns in 50 μm thickness). A segmented sensor could allow discriminating and counting single protons up to high fluxes of therapeutic beams. Moreover, the excellent time resolution suggests using time-of-flight techniques for measuring the proton beam energy. Materials and Methods Several 50 μm thick UFSD prototypes, both single pads or segmented in strips, doped with Boron or Gallium, and with different doping concentrations were fully characterized at the Turin university laboratory and tested on the clinical proton beam of the CNAO particle therapy facility, up to fluxes of 109  p/s. Signal-to-noise ratio, pileup probability, internal gain and gain degradation with beam fluence were determined from the offline analysis of the collected waveforms and compared, whenever possible, to the laboratory measurements. Conclusions UFSDs are found to be a viable option for improving the qualification and the monitoring of a therapeutic proton beams. However, a careful design is necessary to avoid large pileup inefficiencies and early performance degradation.

The research of a few tens of pico-seconds accuracy in timing measurements is currently a hot topic not only in the field of high energy physics but also in several applied physics branches. The Ultra Fast Silicon Detector group of the Turin section of the INFN is involved in this challenge, developing extremely fast silicon sensors. This group spent the recent years simulating and designing UFSD devices, which are essentially a particular type of Low Gain Avalanche Diodes optimized for timing application. These innovative devices for particle tracking are furthermore suitable for a very accurate time measure. The novelty improving the time tagging capability is enabled by the inclusion of a controlled low gain in the detector response, therefore increasing the detector output signal amplitude while keeping controlled the noise. A fast detecting system requires a high-performance front-end electronics to be coupled with the sensors. In cutting-edge experiments like the High-Luminosity LHC, both high spatial and time resolutions are strict constraints. Therefore, highly segmented sensors are employed, implying high density of channels and integrated VLSI electronics. Thanks to the experience gained with the development and the characterization of other timing ASICs, the group is currently exploring various design possibilities for low power front-end electronics to be coupled with UFSDs. The design approach is based on the study of different amplifier architectures, with a dedicated study on the delays introduced by parasitic components. Moreover, taking advantage of different scaled and ultra-scaled CMOS technology nodes, it will be possible to compare among various technology features changing with thThe research of a few tens of pico-seconds accuracy in timing measurements is currently a hot topic not only in the field of high energy physics but also in several applied physics branches. The Ultra Fast Silicon Detector group of the Turin section of the INFN is involved in this challenge, developing extremely fast silicon sensors. This group spent the recent years simulating and designing Ultra-Fast Silicon Detectors (UFSDs), pe of Low Gain Avalanche Diodes optimized for timing application. These innovative devices for particle tracking are furthermore suitable for a very accurate time measure. The novelty improving the time tagging capability is enabled by the inclusion of a controlled low gain in the detector response, therefore increasing the detector output signal amplitude while keeping controlled the noise. A fast detecting system requires a high-performance front-end electronics to be coupled with the sensors. In cutting-edge experiments like the High-Luminosity LHC, both high spatial and time resolutions are strict constraints. Therefore, highly segmented sensors are employed, implying high density of channels and integrated VLSI electronics. Thanks to the experience gained with the development and the characterization of other timing ASICs, the group is currently exploring various design possibilities for low power front-end electronics to be coupled with UFSDs. The design approach is based on the study of different amplifier architectures, with a dedicated study on the delays introduced by parasitic components. Moreover, taking advantage of different scaled and ultra-scaled CMOS technology nodes, it will be possible to compare among various technology features changing with the technology scaling. After an extensive phase of study and design simulation, our group is planning to develop a multichannel ASIC in a commercial 110 μm technology. The planned prototype is a 2 mm × 5 mm chip consisting of 24 channels.

The Move-IT research project of the National Institute for Nuclear Physics aims at the study of models for biologically optimized treatment planning systems in particle therapy and the development of dedicated devices for plan verification. On behalf of this collaboration, the Turin medical physics group is working for the development of a new prototype of silicon strips detector. This device, based on 50 μm thin silicon sensors with internal gain, aims to detect the single beam particle and count their number up to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /s fluxes, with a precision ≥ 99%. The prototype detector will cover a 3×3 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area, segmented in strips. The classic orthogonal strip positioning is used for beam profile measures. At the moment, two types of sensor geometry with different silicon design features have been characterized with laser, radioactive sources and with a clinical proton beam. For what concerns the front-end electronics, the challenging tasks are represented by the charge and dynamic range which are respectively the 3-150 fC and the hundreds of MHz instantaneous rate (at least 100 MHz, 250 MHz ideally). On this purpose, our group is exploring different solutions with the design of two prototypes of custom front-end electronics: one based on a resistive feedback differential transimpedance amplifier and a second one based on a charge sensitive amplifier with gain boost and a discrimination-activated reset of the feedback capacitance. Preliminary results on the ASIC characterization are presented in the following sections.