Salvatore Buontempo

A bstract The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km. The measurement is based on data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies. An arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of $ \left( {6.5\pm 7.4\left( {\mathrm{stat}.} \right)_{-8.0}^{+8.3}\left( {\mathrm{sys}.} \right)} \right)\mathrm{ns} $ was measured corresponding to a relative difference of the muon neutrino velocity with respect to the speed of light $ {{{\left( {\upsilon -c} \right)}} \left/ {c} \right.}=\left( {2.7\pm 3.1\left( {\mathrm{stat}.} \right)_{-3.3}^{+3.4}\left( {\mathrm{sys}.} \right)} \right)\times {10^{-6 }} $ . The above result, obtained by comparing the time distributions of neutrino interactions and of protons hitting the CNGS target in 10.5 μ s long extractions, was confirmed by a test performed at the end of 2011 using a short bunch beam allowing to measure the neutrino time of flight at the single interaction level.

The OPERA neutrino oscillation experiment has been designed to prove the appearance of ντ in a nearly pure νμbeam (CNGS) produced at CERN and detected in the underground Hall C of the Gran Sasso Laboratory, 730 km away from the source. In OPERA, τ leptons resulting from the interaction of ντare produced in target units called bricks made of nuclear emulsion films interleaved with lead plates. The OPERA target contains 150000 of such bricks, for a total mass of 1.25 kton, arranged into walls interleaved with plastic scintillator strips. The detector is split into two identical supermodules, each supermodule containing a target section followed by a magnetic spectrometer for momentum and charge measurement of penetrating particles. Real time information from the scintillators and the spectrometers provide the identification of the bricks where the neutrino interactions occurred. The candidate bricks are extracted from the walls and, after X-ray marking and an exposure to cosmic rays for alignment, their emulsion films are developed and sent to the emulsion scanning laboratories to perform the accurate scan of the event. In this paper, we review the design and construction of the detector and of its related infrastructures, and report on some technical performances of the various components. The construction of the detector started in 2003 and it was completed in Summer 2008. The experiment is presently in the data taking phase. The whole sequence of operations has proven to be successful, from triggering to brick selection, development, scanning and event analysis.

The OPERA neutrino detector in the underground Gran Sasso Laboratory (LNGS) has been designed to perform the first detection of neutrino oscillations in direct appearance mode through the study of the $\nu_\mu\rightarrow\nu_\tau$ channel. The hybrid apparatus consists of an emulsion/lead target complemented by electronic detectors and it is placed in the high energy long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. Runs with CNGS neutrinos were successfully carried out in 2008 and 2009. After a brief description of the beam, the experimental setup and the procedures used for the analysis of the neutrino events, we describe the topology and kinematics of a first candidate $\nu_\tau$ charged-current event satisfying the kinematical selection criteria. The background calculations and their cross-check are explained in detail and the significance of the event is assessed.

The OPERA experiment was designed to search for ν_{μ}→ν_{τ} oscillations in appearance mode, i.e., by detecting the τ leptons produced in charged current ν_{τ} interactions. The experiment took data from 2008 to 2012 in the CERN Neutrinos to Gran Sasso beam. The observation of the ν_{μ}→ν_{τ} appearance, achieved with four candidate events in a subsample of the data, was previously reported. In this Letter, a fifth ν_{τ} candidate event, found in an enlarged data sample, is described. Together with a further reduction of the expected background, the candidate events detected so far allow us to assess the discovery of ν_{μ}→ν_{τ} oscillations in appearance mode with a significance larger than 5σ.

This work is devoted to a feasibility analysis for the development of fiber optic humidity sensors to be applied in high-energy physics (HEP) applications and in particular in experiments actually running at the European Organization for Nuclear Research (CERN). Due to the stringent sensors requirements concerning radiation hardness capability and low temperature operation, we focus our attention on the investigation of fiber optic humidity sensors based on polyimide-coated fiber Bragg gratings (FBG). Data here reported, obtained during a wide experimental campaign carried out in the laboratories of CERN, demonstrate that the selected technological platform is able to perform relative humidity (RH) measurements with percent resolution in the temperature range −15 to 20 °C as well as in presence of ionizing radiations up to 10 kGy, largely outperforming conventional humidity sensors, currently employed within CERN environment.

The OPERA experiment is designed to search for ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ oscillations in appearance mode, i.e., through the direct observation of the $\ensuremath{\tau}$ lepton in ${\ensuremath{\nu}}_{\ensuremath{\tau}}$-charged current interactions. The experiment has taken data for five years, since 2008, with the CERN Neutrino to Gran Sasso beam. Previously, two ${\ensuremath{\nu}}_{\ensuremath{\tau}}$ candidates with a $\ensuremath{\tau}$ decaying into hadrons were observed in a subsample of data of the 2008--2011 runs. Here we report the observation of a third ${\ensuremath{\nu}}_{\ensuremath{\tau}}$ candidate in the ${\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}$ decay channel coming from the analysis of a subsample of the 2012 run. Taking into account the estimated background, the absence of ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ oscillations is excluded at the $3.4\text{ }\ensuremath{\sigma}$ level.

The OPERA experiment was designed to study ν_{μ}→ν_{τ} oscillations in the appearance mode in the CERN to Gran Sasso Neutrino beam (CNGS). In this Letter, we report the final analysis of the full data sample collected between 2008 and 2012, corresponding to 17.97×10^{19} protons on target. Selection criteria looser than in previous analyses have produced ten ν_{τ} candidate events, thus reducing the statistical uncertainty in the measurement of the oscillation parameters and of ν_{τ} properties. A multivariate approach for event identification has been applied to the candidate events and the discovery of ν_{τ} appearance is confirmed with an improved significance level of 6.1σ. |Δm_{32}^{2}| has been measured, in appearance mode, with an accuracy of 20%. The measurement of the ν_{τ} charged-current cross section, for the first time with a negligible contamination from ν[over ¯]_{τ}, and the first direct evidence for the ν_{τ} lepton number are also reported.

We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A dataset of proton-proton collisions at sqrt[s]=13.6 TeV collected by SND@LHC in 2022 is used, corresponding to an integrated luminosity of 36.8 fb^{-1}. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudorapidity region of 7.2<η<8.4, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8 ν_{μ} interaction candidate events remain with an estimated background of 0.086 events, yielding a significance of about 7 standard deviations for the observed ν_{μ} signal.

The employability of photonics technology in the modern era's highly demanding and sophisticated domain of aerospace and submarines has been an appealing challenge for the scientific communities. In this paper, we review our main results achieved so far on the use of optical fiber sensors for safety and security in innovative aerospace and submarine applications. In particular, recent results of in-field applications of optical fiber sensors in aircraft monitoring, from a weight and balance analysis to vehicle Structural Health Monitoring (SHM) and Landing Gear (LG) monitoring, are presented and discussed. Moreover, underwater fiber-optic hydrophones are presented from the design to marine application.

After completion of the data taking for the νμ→ντ oscillation search, the CHORUS lead–scintillator calorimeter was used in the 1998 run as an active target. High-statistics samples of charged-current interactions were collected in the CERN SPS west area neutrino beam. This beam contained predominantly muon (anti-)neutrinos from sign-selected pions and kaons. We measure the flux and energy spectrum of the incident neutrinos and compare them with beam simulations. The neutrino–nucleon and anti-neutrino–nucleon differential cross-sections are measured in the range 0.01<x<0.7, 0.05<y<0.95, 10<Eν<200GeV. We extract the neutrino–nucleon structure functions F2(x,Q2), xF3(x,Q2), and R(x,Q2) and compare these with results from other experiments.

The technique of nuclear emulsions for high-energy physics experiments is being revived, thanks to the remarkable progress in measurement automation achieved in the past years. The present paper describes the features and performances of the European Scanning System, a last-generation automatic microscope working at a scanning speed of 20cm2/h. The system has been developed in the framework of the OPERA experiment, designed to unambigously detect νμ→ντ oscillations in nuclear emulsions.

In the framework of the LAA project, prototypes for a new type of calorimeter, intended for the detection of both electromagnetic (e.m.) and hadronic showers, muons and missing energy (e.g. neutrinos) at high-luminosity multi-TeV pp colliders, were tested. The detector consists of scintillating plastic fibres embedded in a lead matrix at a volume ratio 1:4, such as to achieve compensation. The optimization of the construction of the detector modules is described, as well as the performance concerning e.m. shower and muon detection and e/π separation. We used electron, pion and muon beams in the energy range 10–150 GeV for this purpose. For the energy resolution of electrons we found 13%/trE, with a constant term of 1%. The signal uniformity was better than 3% over the total surface of projective modules. The signal linearity for e.m. shower detection was better than 1%, and the e/π separation was better than 5 × 10−4 for isolated particles. Channeling effects are negligible, provided that the angle between the incoming particles and the fibre axis is larger than 2°.

A new method of momentum measurement of charged particles through multiple Coulomb scattering (MCS) in the OPERA lead-emulsion target is presented. It is based on precise measurements of track angular deviations carried out thanks to the very high resolution of nuclear emulsions. The algorithm has been tested with Monte Carlo pions. The results are found to describe within the expected uncertainties the data obtained from test beams. We also present a comparison of muon momenta evaluated through MCS in the OPERA lead-emulsion target with those determined by the electronic detectors for neutrino-charged current interaction events. The two independent measurements agree within the experimental uncertainties, and the results validate the algorithm developed for the emulsion detector of OPERA.

We report on the performance of a fine-grained 13-ton lead/scintillating-fiber calorimeter, in particular on its response to electrons, pions and multiparticles (reaction products from pions interacting in a target upstream of the detector). The detector signals were studied for particles in the energy range 5–150 GeV. The energy resolution was measured to be 12.9%√E for electrons, plus a constant term dependent on the angle θZ between the particle's direction and the fiber axis. This term, which is 1.2% for θz = 3°, is shown to be due to anomalous sampling in the early shower stage. It is greatly reduced when only electrons entering the detector in the lead are considered. A 1.7X0 thick preshower detector, installed 12 cm in front of the calorimeter, only affected the signal linearity for electrons at low energy. The effect on the energy resolution was negligible. Single pions were detected with an energy resolution of ∼ 30%/√E plus a constant term, which turned out to be mainly due to the effects of light attenuation in the fibers. Knowing the impact point of the particles, these effects could be efficiently removed for single pions. For jets (multiparticles), the effects of light attenuation are much less important, leading to considerably better on-line energy resolutions. The eπ signal ratio was measured to range from 1.03 at 80 GeV to 1.10 at 5 GeV, for a detector with an effective radius of 49 cm. After correcting for the instrumental effects, we found the intrinsic eh value of this detector (with our particular choice of fibers and sampling fraction) to be 1.15±0.02. Detailed results are given on the detector performance (energy resolution, eπ signal ratio, e/jet signal ratio) as a function of the lateral detector size and as a function of the jet multiplicity.

The use of nuclear emulsions in very large physics experiments is now possible thanks to the recent improvements in the industrial production of emulsions and to the development of fast automated microscopes. In this paper the hardware performances of the European Scanning System (ESS) are described. The ESS is a very fast automatic system developed for the mass scanning of the emulsions of the OPERA experiment, which requires microscopes with scanning speeds of ∼20cm2/h in an emulsion volume of 44μm thickness.

The nuclear emulsion target of the CHORUS detector was exposed to the wide-band neutrino beam of the CERN SPS of 27 GeV average neutrino energy from 1994 to 1997. In total, about 100 000 charged-current (CC) neutrino interactions with at least one identified muon were located in the emulsion target and fully reconstructed, using newly developed automated scanning systems. Charmed particles were searched for by a program recognizing particle decays. The observation of the decay in nuclear emulsion makes it possible to select a sample with very low background and minimal kinematical bias. In all, 2013 CC interactions with a charmed hadron candidate in the final state were selected and confirmed through visual inspection. The charm production rate induced by neutrinos relative to the CC cross-section is measured to be σ(νμN→μ−CX)/σ(CC)=(5.75 ± 0.32(stat)±0.30(syst))%. The charm production cross-section as a function of neutrino energy is also obtained. The results are in good agreement with previous measurements. The charm-quark hadronization produces the following charmed hadrons with relative fractions (in %): fD0=43.7±4.5, fΛc+=19.2±4.2, fD+=25.3±4.2 and fDs+=11.8±4.7.

One of the fundamental advantages in the employment of the Fiber Bragg Grating (FBG) sensors lies in their capability to allow measurements in extreme environmental conditions with also very high immunity toward external electromagnetic interference factors. The behavior of a polymer-coated FBG sensor, tested in cryogenic conditions at the laboratories of the European Organization for the Nuclear Research (CERN) in Geneva, has been analyzed and will be discussed in this paper. Magnets used in the Large Hadron Collider (LHC) for the High Energy Physics Researches at CERN need in fact extreme cooling conditions to preserve the internal superconductivity highly crucial for their performances. The magnets, built with NbTi based superconductors, are cooled with liquid helium and they operate at 1.9 K. The aim of the present work is to estimate the thermal expansion coefficient of two polymers based on epoxy and methacrylate (PMMA) used as coating of FBGs, in the temperature range from 4 K to 300 K and to check their suitability for the use in temperature monitoring of the superconducting magnets. A standard numerical derivative method has been employed to estimate thermal expansion coefficients; moreover the correlated fluctuation analysis (CFA) based procedure is proposed, as a reliable alternative, to overcome numerical derivative drawbacks at very low temperatures within the range of 4–20 K. The calculated values of thermal expansion coefficient for both systems are in agreement with literature data on similar material.

A bstract A first result of the search for ν μ → ν e oscillations in the OPERA experiment, located at the Gran Sasso Underground Laboratory, is presented. The experiment looked for the appearance of ν e in the CNGS neutrino beam using the data collected in 2008 and 2009. Data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. A further analysis of the same data constrains the non-standard oscillation parameters θ new and $ \varDelta m_{\mathrm{new}}^2 $ suggested by the LSND and MiniBooNE experiments. For large $ \varDelta m_{\mathrm{new}}^2 $ values ( &gt; 0.1 eV 2 ), the OPERA 90% C.L. upper limit on sin 2 (2 θ new ) based on a Bayesian statistical method reaches the value 7 . 2 × 10 −3 .

A bstract The OPERA neutrino experiment is designed to perform the first observation of neutrino oscillations in direct appearance mode in the ν μ → ν τ channel, via the detection of the τ -leptons created in charged current ν τ interactions. The detector, located in the underground Gran Sasso Laboratory, consists of an emulsion/lead target with an average mass of about 1.2 kt, complemented by electronic detectors. It is exposed to the CERN Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17 GeV. The observation of the first ν τ candidate event and the analysis of the 2008-2009 neutrino sample have been reported in previous publications. This work describes substantial improvements in the analysis and in the evaluation of the detection efficiencies and backgrounds using new simulation tools. The analysis is extended to a sub-sample of 2010 and 2011 data, resulting from an electronic detector-based pre-selection, in which an additional ν τ candidate has been observed. The significance of the two events in terms of a ν μ → ν τ oscillation signal is of 2.40 σ .

This paper presents a fast approach to simulating muons produced in interactions of the SPS proton beams with the target of the SHiP experiment. The SHiP experiment will be able to search for new long-lived particles produced in a 400 GeV/c SPS proton beam dump and which travel distances between fifty metres and tens of kilometers. The SHiP detector needs to operate under ultra-low background conditions and requires large simulated samples of muon induced background processes. Through the use of Generative Adversarial Networks it is possible to emulate the simulation of the interaction of 400 GeV/c proton beams with the SHiP target, an otherwise computationally intensive process. For the simulation requirements of the SHiP experiment, generative networks are capable of approximating the full simulation of the dense fixed target, offering a speed increase by a factor of (106). To evaluate the performance of such an approach, comparisons of the distributions of reconstructed muon momenta in SHiP's spectrometer between samples using the full simulation and samples produced through generative models are presented. The methods discussed in this paper can be generalised and applied to modelling any non-discrete multi-dimensional distribution.

The Search for Hidden Particles (SHiP) Collaboration has shown that the CERN SPS accelerator with its 400 GeV/c proton beam offers a unique opportunity to explore the Hidden Sector [1–3]. The proposed experiment is an intensity frontier experiment which is capable of searching for hidden particles through both visible decays and through scattering signatures from recoil of electrons or nuclei. The high-intensity experimental facility developed by the SHiP Collaboration is based on a number of key features and developments which provide the possibility of probing a large part of the parameter space for a wide range of models with light long-lived super-weakly interacting particles with masses up to (10) GeV/c2 in an environment of extremely clean background conditions. This paper describes the proposal for the experimental facility together with the most important feasibility studies. The paper focuses on the challenging new ideas behind the beam extraction and beam delivery, the proton beam dump, and the suppression of beam-induced background.

In order to complete this set of three companion papers, in this last, we focus our attention on environmental monitoring by taking advantage of photonic technologies. After reporting on some configurations useful for high precision agriculture, we explore the problems connected with soil water content measurement and landslide early warning. Then, we concentrate on a new generation of seismic sensors useful in both terrestrial and under water contests. Finally, we discuss a number of optical fiber sensors for use in radiation environments.

The OPERA experiment, designed to conclusively prove the existence of νμ→ντ oscillations in the atmospheric sector, makes use of a massive lead-nuclear emulsion target to observe the appearance of ντ's in the CNGS νμ beam. The location and analysis of the neutrino interactions in quasi real-time required the development of fast computer-controlled microscopes able to reconstruct particle tracks with sub-micron precision and high efficiency at a speed of ∼20 cm2/h. This paper describes the performance in particle track reconstruction of theEuropean Scanning System, a novel automatic microscope for the measurement of emulsion films developed for OPERA.

The OPERA experiment is based on a hybrid technology combining electronic detectors and nuclear emulsions. OPERA collected muon-neutrino interactions during the 2008 and 2009 physics runs of the CNGS neutrino beam, produced at CERN with an energy range of about 5-35 GeV. A total of $5.3 \times 10^{19}$ protons on target equivalent luminosity has been analysed with the OPERA electronic detectors: scintillator strips target trackers and magnetic muon spectrometers equipped with resistive plate gas chambers and drift tubes, allowing a detailed reconstruction of muon-neutrino interactions. Charged Current (CC) and Neutral Current (NC) interactions are identified, using the measurements in the electronic detectors, and the NC/CC ratio is computed. The momentum distribution and the charge of the muon tracks produced in CC interactions are analysed. Calorimetric measurements of the visible energy are performed for both the CC and NC samples. For CC events the Bjorken-$y$ distribution and the hadronic shower profile are computed. The results are compared to a detailed Monte Carlo simulation of the electronic detectors' response.

The increasing use of Carbon nuclei in cancer therapy centres is motivated by their potential advantages as a very precise high LET radiation. The knowledge of the fragmentation of Carbon nuclei when they interact with the human body is important to evaluate the spatial profile of their energy deposition in the tissues, hence the damage to the tissues neighbouring the tumour. We report here a study of the fragmentation with the nuclear emulsion experimental technique. We have designed, built and exposed to a Carbon nuclei beam a chamber made of Lexan plates alternated with nuclear emulsion films. Lexan plates acted as passive material simulating human body tissues while nuclear emulsion films were used as both tracking devices with micrometric accuracy and ionisation detectors. Such a detector allowed the detection of Carbon interactions produced along their path, the identification of the fragments produced and the measurement of their scattering angle. We have measured the Carbon ion survival probability and studied their interactions. We report on the secondary particle multiplicity and the electrical charge distribution. We give results of the scattering angle of final state fragments as well as the range for H and He. Finally we give the total and partial charge-changing cross-sections for Δz=1,2,3,4 which are compared with previous results when available. The present work aims at providing data required as input to Monte Carlo simulations of Carbon ion interactions in the human body and ultimately of their therapeutic effectiveness.

This work is devoted to a feasibility analysis for the development of novel fiber optic humidity sensors to be applied in high-energy physics (HEP) applications and in particular in experiments actually running at the European Organization for Nuclear Research (CERN). On this line of argument and due to the wide investigations carried out in the last years aimed to assess the radiation hardness capability of fiber optic technology in high energy physics environments, our multidisciplinary research group has been recently engaged in the development of near-field fiber optic sensors based on particle layers of tin dioxide to perform the monitoring of low values of relative humidity RH even at low temperatures. While this sensor type has been successfully employed for ppm and sub-ppm chemical detection in air and water environments, it is the first reported use for relative humidity measurements. The RH sensing performance of fabricated probes was analyzed during a deep experimental campaign carried out in the laboratories of CERN, in Genève. A very good agreement was observed between humidity measurements provided by the optical fiber sensors and commercial polymer-based hygrometers at 20 °C and 0 °C, with limits of detection for low RH regimes below 0.1%.

This Letter deals with a feasibility analysis for the development of radiation-tolerant fiber-optic humidity sensors based on long-period grating (LPG) technology to be applied in high-energy physics (HEP) experiments currently running at the European Organization for Nuclear Research (CERN). In particular, here we propose a high-sensitivity LPG sensor coated with a finely tuned titanium dioxide (TiO2) thin layer (&#x223C;100&#x2009;&#x2009;nm thick) through the solgel deposition method. Relative humidity (RH) monitoring in the range 0%&#x2013;75% and at four different temperatures (in the range &#x2212;10&#xB0;C&#x2013;25&#xB0;C) was carried out to assess sensor performance in real operative conditions required in typical experiments running at CERN. Experimental results demonstrate the very high RH sensitivities of the proposed device (up to 1.4&#xA0;nm/% RH in correspondence to very low humidity levels), which turned out to be from one to three orders of magnitude higher than those exhibited by fiber Bragg grating sensors coated with micrometer-thin polyimide overlays. The radiation tolerance capability of the TiO2-coated LPG sensor is also investigated by comparing the sensing performance before and after its exposure to a 1&#xA0;Mrad dose of &#x3B3;-ionizing radiation. Overall, the results collected demonstrate the strong potential of the proposed technology with regard to its future exploitation in HEP applications as a robust and valid alternative to the commercial (polymer-based) hygrometers currently used.

The OPERA experiment is searching for nu_mu -> nu_tau oscillations in appearance mode i.e. via the direct detection of tau leptons in nu_tau charged current interactions. The evidence of nu_mu -> nu_tau appearance has been previously reported with three nu_tau candidate events using a sub-sample of data from the 2008-2012 runs. We report here a fourth nu_tau candidate event, with the tau decaying into a hadron, found after adding the 2012 run events without any muon in the final state to the data sample. Given the number of analysed events and the low background, nu_mu -> nu_tau oscillations are established with a significance of 4.2sigma.

Abstract Radiochromic film dosimetry has been widely employed in most of the applications of radiation physics for over twenty years. This is due to a number of appealing features of radiochromic films, such as reliability, accuracy, ease of use and cost. However, current radiochromic film reading techniques, based on the use of commercial densitometers and scanners, provide values of dose only after the exposure of the films to radiation. In this work, an innovative methodology for the real-time reading of radiochromic films is proposed for some specific applications. The new methodology is based on opto-electronic instrumentation that makes use of an optical fiber probe for the determination of optical changes of the films induced by radiation and allows measurements of dose with high degree of precision and accuracy. Furthermore, it has been demonstrated that the dynamic range of some kinds of films, such as the EBT3 Gafchromic films (intensively used in medical physics), can be extended by more than one order of magnitude. Owing to the numerous advantages with respect to the commonly used reading techniques, a National Patent was filed in January 2018.

Our group, involving researchers from different universities in Campania, Italy, has been working for the last twenty years in the field of photonic sensors for safety and security in healthcare, industrial and environment applications. This is the first in a series of three companion papers. In this paper, we introduce the main concepts of the technologies employed for the realization of our photonic sensors. Then, we review our main results concerning the innovative applications for infrastructural and transportation monitoring.

The OPERA neutrino detector in the underground Gran Sasso Laboratory (LNGS) was designed to perform the first detection of neutrino oscillations in appearance mode through the study of νμ → ντ oscillations. The apparatus consists of an emulsion/lead target complemented by electronic detectors and it is placed in the high energy long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. Runs with CNGS neutrinos were successfully carried out in 2007 and 2008 with the detector fully operational with its related facilities for the emulsion handling and analysis. After a brief description of the beam and of the experimental setup we report on the collection, reconstruction and analysis procedures of first samples of neutrino interaction events.

The OPERA experiment, designed to perform the first observation of $$\nu _\mu \rightarrow \nu _\tau $$ oscillations in appearance mode through the detection of the $$\tau $$ leptons produced in $$\nu _\tau $$ charged current interactions, has collected data from 2008 to 2012. In the present paper, the procedure developed to detect $$\tau $$ particle decays, occurring over distances of the order of $$1~\mathrm{mm}$$ from the neutrino interaction point, is described in detail and applied to the search for charmed hadrons, showing similar decay topologies as the $$\tau $$ lepton. In the analysed sample, 50 charm decay candidate events are observed while $$54\pm 4$$ are expected, proving that the detector performance and the analysis chain applied to neutrino events are well reproduced by the OPERA simulation and thus validating the methods for $$\nu _\tau $$ appearance detection.

Dark photons are hypothetical massive vector particles that could mix with ordinary photons. The simplest theoretical model is fully characterised by only two parameters: the mass of the dark photon m$_{\gamma^{\mathrm{D}}}$ and its mixing parameter with the photon, $\varepsilon$. The sensitivity of the SHiP detector is reviewed for dark photons in the mass range between 0.002 and 10 GeV. Different production mechanisms are simulated, with the dark photons decaying to pairs of visible fermions, including both leptons and quarks. Exclusion contours are presented and compared with those of past experiments. The SHiP detector is expected to have a unique sensitivity for m$_{\gamma^{\mathrm{D}}}$ ranging between 0.8 and 3.3$^{+0.2}_{-0.5}$ GeV, and $\varepsilon^2$ ranging between $10^{-11}$ and $10^{-17}$.

Abstract The Search for Hidden Particles (SHiP) Collaboration has proposed a general-purpose experimental facility operating in beam-dump mode at the CERN SPS accelerator to search for light, feebly interacting particles. In the baseline configuration, the SHiP experiment incorporates two complementary detectors. The upstream detector is designed for recoil signatures of light dark matter (LDM) scattering and for neutrino physics, in particular with tau neutrinos. It consists of a spectrometer magnet housing a layered detector system with high-density LDM/neutrino target plates, emulsion-film technology and electronic high-precision tracking. The total detector target mass amounts to about eight tonnes. The downstream detector system aims at measuring visible decays of feebly interacting particles to both fully reconstructed final states and to partially reconstructed final states with neutrinos, in a nearly background-free environment. The detector consists of a 50 $$\mathrm { \,m}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace /> <mml:mi>m</mml:mi> </mml:mrow> </mml:math> long decay volume under vacuum followed by a spectrometer and particle identification system with a rectangular acceptance of 5 m in width and 10 m in height. Using the high-intensity beam of 400 $$\,\mathrm {GeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace /> <mml:mi>GeV</mml:mi> </mml:mrow> </mml:math> protons, the experiment aims at profiting from the $$4\times 10^{19}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>4</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>19</mml:mn> </mml:msup> </mml:mrow> </mml:math> protons per year that are currently unexploited at the SPS, over a period of 5–10 years. This allows probing dark photons, dark scalars and pseudo-scalars, and heavy neutral leptons with GeV-scale masses in the direct searches at sensitivities that largely exceed those of existing and projected experiments. The sensitivity to light dark matter through scattering reaches well below the dark matter relic density limits in the range from a few $${\mathrm {\,MeV\!/}c^2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mrow> <mml:mspace /> <mml:mi>MeV</mml:mi> <mml:mspace /> <mml:mo>/</mml:mo> </mml:mrow> <mml:msup> <mml:mi>c</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> up to 100 MeV-scale masses, and it will be possible to study tau neutrino interactions with unprecedented statistics. This paper describes the SHiP experiment baseline setup and the detector systems, together with performance results from prototypes in test beams, as it was prepared for the 2020 Update of the European Strategy for Particle Physics. The expected detector performance from simulation is summarised at the end.

A first analysis of the complete set of data collected by CHORUS in the years 1994–1997 is presented. The search for ντ charged current events has been performed for both leptonic and hadronic decays of the τ lepton. No τ candidate has been found. A νμ→ντ mixing is excluded down to sin22θμτ=6.8×10−4 for large Δm2 (90% C.L.).

The charge collection efficiency (CCE) of heavily irradiated silicon diode detectors was investigated at temperatures between 77 and 200 K. The CCE was found to depend on the radiation dose, bias voltage value and history, temperature, and bias current generated by light. The detector irradiated to the highest fluence 2×1015 n/cm2 yields a MIP signal of at least 15000 e− both at 250 V forward bias voltage, and at 250 V reverse bias voltage in the presence of a light-generated current. The “Lazarus effect” was thus shown to extend to fluences at least ten times higher than was previously studied.

We report on an experimental study of the signals from high-energy (5–225 GeV) muons traversing a 9.5 interaction lengths deep electromagnetic/hadronic calorimeter consisting of lead and scintillating plastic fibers, constructed at CERN in the framework of the LAA project. The muons lose on average between 2.6 GeV (at 5 GeV) and 8.8 GeV (at 225 GeV) in this process. This energy loss can be measured with a precision of a fraction of a GeV in most of the events. Accuracy in the energy loss measurements is important since the rms spread in the energy loss of muons traversing this calorimeter is not smaller than ∼6% at any energy. The nominal calibration constants, derived from the calorimeter response to electromagnetic showers, are found to be incorrect for the muon signals. On average, these calibration constants are between 40% (for low energy muons) and 15% (high energy) too high. The fiber bunches sticking out of the back plane of the calorimeter for readout purposes cause the muon signals to be position dependent. This can cause an anomalous enhancement of the muon signal of up to 35%. A moderate position resolution of ∼ 1 cm is sufficient to correct for this effect. The e/mip ratio was found to be 0.72±0.03.

We present the first automated momentum measurement in an Emulsion Cloud Chamber, consisting of multiple sandwiches of lead plates and nuclear emulsion sheets. The measurement is based on the detection of the multiple Coulomb scattering analysed by the so-called angular method. A 3X0 chamber was exposed to 2, 3 and 4GeV/c π−. A pion momentum resolution of 36% at 4GeV/c, 35% at 3GeV/c and 28% for 2GeV/c was achieved.

We report on the development of an automated scanning system for nuclear emulsions aiming at very precise spatial and angular measurements. An accuracy of 0.06μm in position was achieved with the emulsion films used for the measurement. An accuracy of 0.4 mrad was achieved for tracks penetrating orthogonally the emulsion films while an accuracy of 1 mrad was obtained for tracks inclined by about 300 mrad with respect to the perpendicular direction. This result shows unprecedented position and angular resolutions achieved by automated measurements.

We report on an experimental study of a variety of techniques for discriminating between (isolated) electrons and pions in a lead and scintillating fiber calorimeter without longitudinal segmentation. Using information from the lateral shower development, from a pre-shower detector, from the time structure of the signals, or from a combination of these we measure pion rejection factors of up to several thousand while maintaining electron efficiencies of 95% or higher.

We report on the performance of a fine-grained 13-ton compensating lead/scintillating-fiber calorimeter, and in particular on its capability of localizing the particles that produce showers in it. The RMS position resolution was found to be 1.7 mm for electromagnetic showers and 5.1 mm for hadronic showers at 80 GeV, averaged over a tower with an effective radius of 39 mm. Pion-pion separation through analysis of the energy deposit pattern was achieved in more than 95% of the cases for distances down to 8 cm at 80 GeV. Because of the good lateral position resolution, detailed information on the longitudinal shower development could be obtained, with the help of tracking information, when single particles entered the (longitudinally unsegmented) detector at a small angle with respect to the fiber axis. This information made it possible to eliminate the effects of light attenuation in the fibers on the hadronic energy resolution and allowed e/π separation at the 10−4 level.

In spring 2012 CERN provided two weeks of a short bunch proton beam dedicated to the neutrino velocity measurement over a distance of 730 km. The OPERA neutrino experiment at the underground Gran Sasso Laboratory used an upgraded setup compared to the 2011 measurements, improving the measurement time accuracy. An independent timing system based on the Resistive Plate Chambers was exploited providing a time accuracy of $\sim$1 ns. Neutrino and anti-neutrino contributions were separated using the information provided by the OPERA magnetic spectrometers. The new analysis profited from the precision geodesy measurements of the neutrino baseline and of the CNGS/LNGS clock synchronization. The neutrino arrival time with respect to the one computed assuming the speed of light in vacuum is found to be $\delta t_\nu \equiv TOF_c - TOF_\nu= (0.6 \pm 0.4\ (stat.) \pm 3.0\ (syst.))$ ns and $\delta t_{\bar{\nu}} \equiv TOF_c - TOF_{\bar{\nu}} = (1.7 \pm 1.4\ (stat.) \pm 3.1\ (syst.))$ ns for $\nu_{\mu}$ and $\bar{\nu}_{\mu}$, respectively. This corresponds to a limit on the muon neutrino velocity with respect to the speed of light of $-1.8 \times 10^{-6} < (v_{\nu}-c)/c < 2.3 \times 10^{-6}$ at 90% C.L. This new measurement confirms with higher accuracy the revised OPERA result.

This work investigates the performance and the radiation hardness capability of optical thermo-hygrometers based on Fibre Bragg Gratings (FBG) for humidity monitoring in the Compact Muon Solenoid (CMS), one of the four experiments running at CERN in Geneva. A thorough campaign of characterization was performed on 80 specially produced Polyimide-coated RH FBG sensors and 80 commercial temperature FBG sensors. Sensitivity, repeatability and accuracy were studied on the whole batch, putting in evidence the limits of the sensors, but also showing that they can be used in very dry conditions. In order to extract the humidity measurements from the sensor readings, commercial temperature FBG sensors were characterized in the range of interest. Irradiation campaigns with ionizing radiation (γ-rays from a Co60 source) at incremental absorbed doses (up to 210 kGy for the T sensors and up to 90 kGy for the RH sensors) were performed on sample of T and RH-Sensors. The results show that the sensitivity of the sensors is unchanged up to the level attained of the absorbed dose, while the natural wavelength peak of each sensor exhibits a radiation-induced shift (signal offset). The saturation properties of this shift are discussed.

The SHiP experiment is designed to search for very weakly interacting particles beyond the Standard Model which are produced in a 400 GeV/c proton beam dump at the CERN SPS. An essential task for the experiment is to keep the Standard Model background level to less than 0.1 event after 2× 1020 protons on target. In the beam dump, around 1011 muons will be produced per second. The muon rate in the spectrometer has to be reduced by at least four orders of magnitude to avoid muon-induced combinatorial background. A novel active muon shield is used to magnetically deflect the muons out of the acceptance of the spectrometer. This paper describes the basic principle of such a shield, its optimization and its performance.

Production of neutrinos is abundant at LHC. Flavour composition and energy reach of the neutrino flux from proton-proton collisions depend on the pseudorapidity $\eta$. At large $\eta$, energies can exceed the TeV, with a sizeable contribution of the $\tau$ flavour. A dedicated detector could intercept this intense neutrino flux in the forward direction, and measure the interaction cross section on nucleons in the unexplored energy range from a few hundred GeV to a few TeV. The high energies of neutrinos result in a larger $\nu$N interaction cross section, and the detector size can be relatively small. Machine backgrounds vary rapidly while moving along and away from the beam line. Four locations were considered as hosts for a neutrino detector: the CMS quadruplet region (~25 m from CMS Interaction Point (IP)), UJ53 and UJ57 (90 and 120 m from CMS IP), RR53 and RR57 (240 m from CMS IP), TI18 (480 m from ATLAS IP). The potential sites are studied on the basis of (a) expectations for neutrino interaction rates, flavour composition and energy spectrum, (b) predicted backgrounds and in-situ measurements, performed with a nuclear emulsion detector and radiation monitors. TI18 emerges as the most favourable location. A small detector in TI18 could measure, for the first time, the high-energy $\nu$N cross section, and separately for $\tau$ neutrinos, with good precision, already with 300 fb$^{-1}$ in the LHC Run3.

In this work, we report on a novel approach for measuring the dose absorbed by the EBT3 Gafchromic™ films exposed to 1 MeV electron beam and 250 kV X-rays in the range 0.5–100 Gy. Although EBT3 is specifically designed to obtain best performance for applications where the maximum dose is less than 10 Gy, there are certain clinical applications requiring dose ranges well above this value. In order to cover wider dose ranges, further models characterized by a thinner sensitive layer and/or different chemical composition have been released. Another method exploiting the three-channel flatbed scanner to delay the saturation point of EBT3 has been also reported. The technique proposed here, aimed at extending the sensitivity of the EBT3 film to high doses up to 100 Gy while ensuring a low dose uncertainty, is based on a broadband analysis of the absorption spectrum of the film in response to irradiation. By combining a wavelength-based approach with the monitoring of two characteristic peaks of the EBT3 absorption spectrum, we demonstrated the capability of measuring the dose in the range 0.5–100 Gy with an experimental uncertainty below 4% for doses lower than 5.52 Gy and below 2% for higher dose levels. Finally, through a dynamic fitting procedure integrating the two aforesaid approaches, a total uncertainty lower than 4%, including both the experimental and fitting errors, was achieved in the whole range 0.5–100 Gy. These results are promising in view of a potential application of this technique in the field of clinical dosimetry at high dose levels.

The i-pipe system is a peculiar structural health monitoring system, based on Fiber Bragg Grating technology, installed on the central beam pipe of the compact Muon solenoid (CMS) experiment at CERN. In this contribution, i-pipe temperature sensors, originally conceived as thermal compensator for the strain sensors, are employed to monitor central beam pipe thermal behavior in correlation with the parameters of the particle beam travelling inside, in order to directly measure possible Beam RF induced heating effect. The i-pipe system turned out to be capable of monitoring, directly and without interference, the parameters of the particle beam circulating in the LHC ring. Hence, the results presented in this work pave the way to the use of the i-pipe as monitoring system of an accelerated high energy particle beam.

A bstract Dark matter is a well-established theoretical addition to the Standard Model supported by many observations in modern astrophysics and cosmology. In this context, the existence of weakly interacting massive particles represents an appealing solution to the observed thermal relic in the Universe. Indeed, a large experimental campaign is ongoing for the detection of such particles in the sub-GeV mass range. Adopting the benchmark scenario for light dark matter particles produced in the decay of a dark photon, with α D = 0 . 1 and m A ′ = 3 m χ , we study the potential of the SHiP experiment to detect such elusive particles through its Scattering and Neutrino detector (SND). In its 5-years run, corresponding to 2 · 10 20 protons on target from the CERN SPS, we find that SHiP will improve the current limits in the mass range for the dark matter from about 1 MeV to 300 MeV. In particular, we show that SHiP will probe the thermal target for Majorana candidates in most of this mass window and even reach the Pseudo-Dirac thermal relic.

In this work, we propose a novel and cost effective fiber optic platform for the continuous monitoring of soil water content to be exploited in the agri-food sector and, in particular, in the field of precision agriculture to promote the rational use of water resources. The proposed platform arises from the judicious connection of optical fiber technology and functional materials able to exhibit a change in their optical properties depending on the water content in the environment. Al2O3 disks have been used as functional materials, taking advantage of their capability to absorb water and exhibit a correlated absorbance increase in the wavelength range corresponding to the absorption peak of water. A detailed study has been carried out to obtain the best coupling conditions between optical fibers and the functional disk. The final prototype has been tested directly in soil and the collected results show its capability to detect soil water content variation in the range 0–35% of volumetric water content (VWC) with a sensitivity of 2.3%/%VWC and a VWC resolution lower than 1%. Such performances allow the proposed device to be used for soil water content measurements for applications in several fields and in different hydrogeological conditions, such as, e.g., in smart farming applications, to support farmers in defining a correct irrigation strategy, or for the real-time monitoring of hydrogeological hazard, to prevent rainfall-induced landslide. Moreover, thanks to the capability of optical fibers technology to multiplex different fiber probes while sharing the same interrogation equipment, the proposed platform is endowed with multiplexing capabilities and presents a solid basis for a continuous monitoring of soil moisture monitoring over large areas.

Next generation High Energy Physics (HEP) accelerators will require new devices and technologies capable of operating in extreme environments characterized by ultra-high radiation doses up to the MGy levels. To this aim, we report on an innovative Lab-On-Fiber (LOF) probe for the real-time dose monitoring. The proposed platform is based on a metallo-dielectric nanostructured grating made of gold and poly(methyl methacrylate) (PMMA) patterned on the termination of single mode fibers. The nanostructure has been judiciously designed to support a plasmonic resonance in the reflection spectrum occurring at near infrared wavelengths. Electron beam lithography was used for the fabrication of two LOF prototypes, which in turn, were exposed to X-rays with a total dose of 2.02 MGy and a dose rate of 88 kGy/h. Reflection spectra acquired during the irradiation revealed a clear dependence of the LOF resonance wavelength and depth on the absorbed dose, confirming the outcomes of our previous proton campaign. Morphological characterization of the irradiated samples showed that the main radiation induced effect is the reduction of the PMMA thickness (ranging between 26 % and 40 %), which in turn strongly affects the resonance behavior. Quantitative morphological measurements have been used to achieve a fair and objective correlation with our numerical modelling. Moreover, we investigated the effect of ultra-high doses of several radiation types, including X-rays, electrons and protons, on the thickness of PMMA nanolayers deposited on planar substrates. Experimental results revealed that the amount of absorbed dose (1.9–16.06 MGy) is the main parameter affecting the PMMA relative compaction (9.5–59.1 %), while the influence of the radiation type, dose rate and initial PMMA thickness can be considered negligible. Overall, these results pave the way to the development of radiation type independent PMMA assisted LOF dosimeters operating at MGy doses for the radiation monitoring in future HEP experiments.

The construction of modules and the assembly of the calorimeter for CHORUS, an experiment that searches for νμ ↔ ντ oscillation, have been completed. Within the experiment, the calorimeter is required to measure the energy of hadronic showers produced in neutrino interactions with a resolution of /∼30%/√E(GeV). To achieve this performance, the technique, developed in recent years, of embedding scintillating fibers of 1 mm diameter into a lead matrix has been adopted for the most upstream part of the calorimeter. A more conventional system, of alternating layers of lead and scintillator strips, was used for the rest. Details of module construction as well as results obtained when modules were exposed to electron and muon beams are presented.

The lateral profile of the energy deposition in a prototype of a lead and scintillating fiber calorimeter, constructed in the framework of the LAA project at CERN, has been measured for both electromagnetic and hadronic showers in the energy range from 5 to 150 GeV. The distributions are well described by analytic functions whose parameters allow one to determine the radial scaling of the shower development. In the electromagnetic case, the data are compared to Monte Carlo calculations. Estimates of the lateral leakage outside of the detector are made as well as calculations of the average π0 content of hadronic showers and event-to-event fluctuations in this electromagnetic component. A method is developed whereby knowledge of the hadronic shower profile can be used to determine the relative calibration constants of neighboring towers in such a calorimeter.

The fine granularity of the CHARM-II detector has been exploited to search, in the CERN-SPS wide band neutrino beam, for quasi-elastic ντ interactions followed by the decay τ → πντ. Since the sampling thickness of the target calorimeter corresponds to ∼ 19 of an interaction length, these events appear in the detector as a single track followed by a hadronic shower. The study of the “single pion” events is used to set limits on the νμ → ντ oscillation parameters. The maximum sensitivity to the mixing angle θ is reached for Δm2 = 50 eV2 allowing to exclude values of sin22θ greater than 6.4 × 10−3 at 90% CL.

New methods for efficient and unambiguous interconnection between electronic position sensitive detectors and target units based on nuclear photographic emulsion films have been developed. The application to the OPERA experiment, that aims at detecting νμ⇌ντ oscillations in the CNGS neutrino beam, is reported in this paper. In order to reduce background due to latent tracks collected before installation in the detector, on-site large-scale treatments of the emulsions (''refreshing'') have been applied. Changeable Sheet (CSd) packages, each made of a doublet of emulsion films, have been designed, assembled and coupled to the OPERA target units (''ECC bricks''). A device has been built to print X-ray spots for accurate interconnection both within the CSd and between the CSd and the related ECC brick. Sample emulsion films have been extensively scanned with state-of-the-art automated optical microscopes. Efficient track-matching and powerful background rejection have been achieved in tests with electronically tagged penetrating muons. Further improvement of in-doublet film alignment was obtained by matching the pattern of low-energy electron tracks. The commissioning of the overall OPERA alignment procedure is in progress.

The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used to measure the atmospheric muon charge ratio $R_{\mu}=N_{\mu^{+}}/N_{\mu^{-}}$ in the TeV energy region. We analyzed 403069 atmospheric muons corresponding to 113.4 days of livetime during the 2008 CNGS run. We computed separately the muon charge ratio for single and for multiple muon events in order to select different energy regions of the primary cosmic ray spectrum and to test the R μ dependence on the primary composition. The measured R μ values were corrected taking into account the charge-misidentification errors. Data have also been grouped in five bins of the "vertical surface energy" ℰ μ cos θ. A fit to a simplified model of muon production in the atmosphere allowed the determination of the pion and kaon charge ratios weighted by the cosmic ray energy spectrum.

In this paper, we report a comparative study of fiber optic sensors for applications of relative humidity (RH) monitoring in high-radiation environments. In particular, we present investigations carried out since 2011 by our multidisciplinary research group, in collaboration with the European Organization for Nuclear Research (CERN) in Geneva. Our research has been first focused on the development of polyimide-coated fiber Bragg grating (FBG) sensors, and recently, it has been extended to nanoscale metal oxide-coated long-period gratings (LPGs). Experimental tests in the [0-70] %RH range at different temperatures, before and after γ-ionizing radiation exposures, have been carried out to assess the sensors' performances in conditions required in experiments running at CERN. The advantages and disadvantages of the two proposed technologies are discussed in this paper in light of their possible application in high-energy physics environments. In particular, reported results suggest that LPG-based sensors can be preferred in some applications (particularly in presence of very low humidity levels) mainly because they are able to provide very high RH sensitivity (up to 1.4 nm/% RH), which is up to three orders of magnitude higher than that exhibited by FBG-based hygrometers. On the other side, compared with FBGs, LPGs are more difficult to multiplex due to limitations in terms of available bandwidth.

The OPERA detector, designed to search for $$\nu _{\mu } \rightarrow \nu _{\tau }$$ oscillations in the CNGS beam, is located in the underground Gran Sasso laboratory, a privileged location to study TeV-scale cosmic rays. For the analysis here presented, the detector was used to measure the atmospheric muon charge ratio in the TeV region. OPERA collected charge-separated cosmic ray data between 2008 and 2012. More than 3 million atmospheric muon events were detected and reconstructed, among which about 110000 multiple muon bundles. The charge ratio $$R_{\mu } \equiv N_{\mu ^+}/N_{\mu ^-}$$ was measured separately for single and for multiple muon events. The analysis exploited the inversion of the magnet polarity which was performed on purpose during the 2012 Run. The combination of the two data sets with opposite magnet polarities allowed minimizing systematic uncertainties and reaching an accurate determination of the muon charge ratio. Data were fitted to obtain relevant parameters on the composition of primary cosmic rays and the associated kaon production in the forward fragmentation region. In the surface energy range 1–20 TeV investigated by OPERA, $$R_{\mu }$$ is well described by a parametric model including only pion and kaon contributions to the muon flux, showing no significant contribution of the prompt component. The energy independence supports the validity of Feynman scaling in the fragmentation region up to $$200$$ TeV/nucleon primary energy.

We present a leading order QCD analysis of a sample of neutrino induced charged-current events with two muons in the final state originating in the lead-scintillating fibre calorimeter of the CHORUS detector. The results are based on a sample of 8910 neutrino and 430 antineutrino induced opposite-sign dimuon events collected during the exposure of the detector to the CERN Wide Band Neutrino Beam between 1995 and 1998. % with $E_{\mu 1},E_{\mu 2} > 5$ GeV and $Q^2 > 3$ GeV$^2$ collected %between 1995 and 1998. The analysis yields a value of the charm quark mass of $\mc = (1.26\pm 0.16 \pm 0.09) \GeVcc $ and a value of the ratio of the strange to non-strange sea in the nucleon of $\kappa = 0.33 \pm 0.05 \pm 0.05$, improving the results obtained in similar analyses by previous experiments.

The OPERA neutrino experiment in the underground Gran Sasso Laboratory (LNGS) was designed to perform the first detection of neutrino oscillations in direct appearance mode in the ν µ → ν τ channel, the ν τ signature being the identification of the τ -lepton created in its charged current interaction.

The OPERA experiment, exposed to the CERN to Gran Sasso $ν_μ$ beam, collected data from 2008 to 2012. Four oscillated $ν_τ$ Charged Current interaction candidates have been detected in appearance mode, which are consistent with $ν_μ\to ν_τ$ oscillations at the atmospheric $Δm^2$ within the "standard" three-neutrino framework. In this paper, the OPERA $ν_τ$ appearance results are used to derive limits on the mixing parameters of a massive sterile neutrino.

The CMS collaboration considers upgrading the muon forward region which is particularly affected by the high-luminosity conditions at the LHC. The proposal involves Gas Electron Multiplier (GEM) chambers, which are able to handle the extreme particle rates expected in this region along with a high spatial resolution. This allows to combine tracking and triggering capabilities, which will improve the CMS muon High Level Trigger, the muon identification and the track reconstruction. Intense R&D has been going on since 2009 and it has lead to the development of several GEM prototypes and associated detector electronics. These GEM prototypes have been subjected to extensive tests in the laboratory and in test beams at the CERN Super Proton Synchrotron (SPS). This contribution will review the status of the CMS upgrade project with GEMs and its impact on the CMS performance.

In this work, we report on the first demonstration of Lab on Fiber (LOF) dosimeter for ionizing radiation monitoring at ultra-high doses. The new dosimeter consists in a metallo-dielectric resonator at sub-wavelength scale supporting localized surface plasmon resonances realized on the optical fiber (OF) tip. The resonating structure involves two gold gratings separated by a templated dielectric layer of poly(methyl methacrylate) (PMMA). Two LOF prototypes have been manufactured and exposed at the IRRAD Proton Facility at CERN in Geneva to 23 GeV protons for a total fluence of 0.67 × 1016 protons/cm2, corresponding to an absorbed dose of 1.8 MGy. Experimental data demonstrated the "radiation resistance" feature of the LOF devices and a clear dependence of the reflected spectrum versus the total dose, expressed by a cumulative blue-shift of ~1.4 nm of the resonance combined with a slight increase of 0.16 dBm in the reflected spectrum. The numerical analysis carried out to correlate the experimental results with the dimensional and physical properties of the resonator, expected to be tightly connected to the absorbed dose, suggests that the main phenomenon induced by exposure to proton beam and able to explain the measured spectral behavior is the reduction of the PMMA thickness, which is also consistent with past literature in the field. Preliminary results demonstrated the potentiality of the proposed platform as dosimeter at MGy dose levels for high energy physics experiments.

In this contribution we present results concerning the very first application of fiber optic sensors (FOSs) for relative humidity (RH) monitoring in high radiations environments. After a few years of investigations at CERN in Geneva, since December 2013 our multidisciplinary research group has successfully installed 72 thermo-hygrometers based on Fiber Bragg Grating (FBG) technology, organized in multi-points arrays, in cold areas of the Tracker Bulkhead of the Compact Muon Solenoid (CMS) experiment, where hundreds of electrical connectors are housed and thousands of services, including many cold pipes, cross the volumes through them. In such a complicated environment, a constant hygrometric monitoring is vital, in order to avoid dangerous phenomena of condensation. The collected results in the last year of operation of the proposed sensors are effective and reliable, with temperature, relative humidity and dew point temperature measurements from the FBG-based devices in full agreement with the readings of conventional sensors, temporarily present in the detector. However, experience in operation has shown some limitations of this technology, which are fully detailed in the last section of the paper.

In this paper we describe the main characteristics and experimental results, recorded in more than four years of data acquisition, of a temperature and strain monitoring system, called i-pipe, based on Fiber Bragg Grating (FBG) sensors arrays applied for the first time to a sector of the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN): the central beam pipe (BP) of the Compact Muon Solenoid (CMS). The monitoring system, consisting of four arrays of 16 FBG sensors each, as better described in the text, is placed on four directives of the LHC section that passes inside the CMS experiment, namely the CMS central BP. The mechanical complexity of the central BP structure is described and the monitoring results of its thermal conditions and online unpredictable mechanical deformations are discussed in this paper. In spite of the harsh working conditions this monitoring system is operational since 2015 continuously (24/7) and the data collected are a confirmation of its reliability. This FBG sensors system represents the ideal solution to realize an accurate and robust sensing system to be used in harsh environments, like the CMS experimental facility and all the other High Energy Physics experimental infrastructures.

The OPERA experiment discovered muon neutrino into tau neutrino oscillations in appearance mode, detecting tau leptons by means of nuclear emulsion films. The apparatus was also endowed with electronic detectors with tracking capability, such as scintillator strips and resistive plate chambers. Because of its location, in the underground Gran Sasso laboratory, under 3800 m.w.e., the OPERA detector has also been used as an observatory for TeV muons produced by cosmic rays in the atmosphere. In this paper the measurement of the single muon flux modulation and of its correlation with the seasonal variation of the atmospheric temperature are reported.

In this work, experimental tests of a full analog fiber optic monitoring system are reported. The proposed concept is conceived to satisfy the constrains imposed to be used for safety application, in terms of robustness and reliability, due to full passive optical devices and an analog-based circuitry. Moreover, it is compatible with the stringent requirements imposed by the Detector Safety System (DSS) of the Compact Muon Solenoid (CMS) experiment at CERN. From the optical side, the main device is the Arrayed Waveguide Grating (AWG), with the aim to filter and address the optical signal through a determined output channel, that is then transduced in electrical by means of a photodiode. From the electronic side, the designed board has the purpose to manipulate the signal in order to have an increasing monotone output current, in the range 4-20 mA, standard widely employed in safety system environment. In this way, the circuit gain can be set in order to match the value to the physical quantity under monitoring threshold. To give proof of its characteristics, the system is subjected to many test led at CERN, in which two Fiber Bragg Grating (FBG) sensors are under test into a custom climate box. Step temperature variation, as well as fast oscillating test and long term stability measurement are reported, confirming its key strength and field-validating it.

In the field of accelerator physics it is crucial to account for heating caused by the passage of high intensity beams into accelerator components. This phenomenon is known as Radio Frequency (RF) Beam Induced Heating (BIH) and requires, other than an accurate design stage, to constantly monitor temperature-related parameters during the accelerator operations. This enables to warn for critical malfunctions and to prevent possible damages. Monitoring needs to meet various requirements, such as multiplexing capabilities, distributed sensing possibilities, and robustness in harsh environments. Fiber Bragg Grating sensors (FBGs) have been proven to be an ideal solution that meets all these requirements. This study aims to validate the use of FBGs for direct measurement of RF BIH. A section of the beam pipe in the CERN Large Hadron Collider was modeled in terms of impedance, and the resulting RF BIH was computed based on the traveling beam. The results of the numerical simulation were compared with experimental data obtained by FBGs installed along the beam pipe. The analysis shows that FBGs can be a valuable beam diagnostic tool for monitoring accelerated high energy particle beams by measuring RF BIH and may provide useful insights for improving the design and operation of future accelerators. The study highlights the significant advancements of FBG technology in direct temperature measurement and assessment of RF BIH and serves as a promising solution for mitigating RF BIH in the demanding environment of particle accelerators.

The improved Resistive Plate Chambers (iRPC) are designed using thin low resistivity High-Pressure Laminate (HPL) gaps. They are proposed to equip the very forward region of the Compact Muon Solenoid (CMS) detector, as they can stand rates ∼2kHz/cm2. To withstand 3 times higher rates than the installed CMS RPC chambers, the HPL electrode thickness was reduced from 2 mm to 1.4 mm. The gas gain of the detector is dependent on the gas pressure and temperature which requires correcting for the applied voltage to keep detector operational characteristics such as efficiency, cluster size and noise rate constant. Herein, we study the pressure correction at constant temperature for CMS iRPC and compare its correction coefficient with the one for the 2 mm RPC gap technology. Pressure correction parameters for both technologies are found compatible.

Abstract The Scattering and Neutrino Detector at the LHC (SND@LHC) started taking data at the beginning of Run 3 of the LHC. The experiment is designed to perform measurements with neutrinos produced in proton-proton collisions at the LHC in an energy range between 100 GeV and 1 TeV. It covers a previously unexplored pseudo-rapidity range of $$7.2&lt;\eta &lt;8.4$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>7.2</mml:mn> <mml:mo>&lt;</mml:mo> <mml:mi>η</mml:mi> <mml:mo>&lt;</mml:mo> <mml:mn>8.4</mml:mn> </mml:mrow> </mml:math> . The detector is located 480 m downstream of the ATLAS interaction point in the TI18 tunnel. It comprises a veto system, a target consisting of tungsten plates interleaved with nuclear emulsion and scintillating fiber (SciFi) trackers, followed by a muon detector (UpStream, US and DownStream, DS). In this article we report the measurement of the muon flux in three subdetectors: the emulsion, the SciFi trackers and the DownStream Muon detector. The muon flux per integrated luminosity through an 18 $$\times $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>×</mml:mo> </mml:math> 18 cm $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow /> <mml:mn>2</mml:mn> </mml:msup> </mml:math> area in the emulsion is: $$\begin{aligned} 1.5 \pm 0.1(\text {stat}) \times 10^4\,\text {fb/cm}^{2}. \end{aligned}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtable> <mml:mtr> <mml:mtd> <mml:mrow> <mml:mn>1.5</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.1</mml:mn> <mml:mrow> <mml:mo>(</mml:mo> <mml:mtext>stat</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>4</mml:mn> </mml:msup> <mml:mspace /> <mml:msup> <mml:mtext>fb/cm</mml:mtext> <mml:mn>2</mml:mn> </mml:msup> <mml:mo>.</mml:mo> </mml:mrow> </mml:mtd> </mml:mtr> </mml:mtable> </mml:mrow> </mml:math> The muon flux per integrated luminosity through a 31 $$\times $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>×</mml:mo> </mml:math> 31 cm $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow /> <mml:mn>2</mml:mn> </mml:msup> </mml:math> area in the centre of the SciFi is: $$\begin{aligned} 2.06\pm 0.01(\text {stat})\pm 0.12(\text {sys}) \times 10^{4} \text {fb/cm}^{2} \end{aligned}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtable> <mml:mtr> <mml:mtd> <mml:mrow> <mml:mn>2.06</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.01</mml:mn> <mml:mrow> <mml:mo>(</mml:mo> <mml:mtext>stat</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>±</mml:mo> <mml:mn>0.12</mml:mn> <mml:mrow> <mml:mo>(</mml:mo> <mml:mtext>sys</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>4</mml:mn> </mml:msup> <mml:msup> <mml:mtext>fb/cm</mml:mtext> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:mtd> </mml:mtr> </mml:mtable> </mml:mrow> </mml:math> The muon flux per integrated luminosity through a 52 $$\times $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>×</mml:mo> </mml:math> 52 cm $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow /> <mml:mn>2</mml:mn> </mml:msup> </mml:math> area in the centre of the downstream muon system is: $$\begin{aligned} 2.35\pm 0.01(\text {stat})\pm 0.10(\text {sys}) \times 10^{4}\,\text {fb/cm}^{2} \end{aligned}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtable> <mml:mtr> <mml:mtd> <mml:mrow> <mml:mn>2.35</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.01</mml:mn> <mml:mrow> <mml:mo>(</mml:mo> <mml:mtext>stat</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>±</mml:mo> <mml:mn>0.10</mml:mn> <mml:mrow> <mml:mo>(</mml:mo> <mml:mtext>sys</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>4</mml:mn> </mml:msup> <mml:mspace /> <mml:msup> <mml:mtext>fb/cm</mml:mtext> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:mtd> </mml:mtr> </mml:mtable> </mml:mrow> </mml:math> The total relative uncertainty of the measurements by the electronic detectors is 6 $$\%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>%</mml:mo> </mml:math> for the SciFi and 4 $$\%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>%</mml:mo> </mml:math> for the DS measurement. The Monte Carlo simulation prediction of these fluxes is 20–25 $$\%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>%</mml:mo> </mml:math> lower than the measured values.

In view of the High Luminosity upgrade of the CERN LHC, the forward CMS Muon spectrometer will be extended with two new stations of improved Resistive Plate Chambers (iRPC) covering the pseudorapidity range from 1.8 to 2.4. Compared to the present RPC system, the gap thickness is reduced to lower the avalanche charge, and an innovative 2D strip readout geometry is proposed. These improvements will allow iRPC detector to cope with higher background rates. A new Front-End-Board (FEB) is designed to readout iRPC signals with a threshold as low as 30 fC and an integrated Time Digital Converter with a resolution of 30 ps. In addition, the communication bandwidth is significantly increased by using optical fibers. The history, final design, certification, and calibration of this FEB are presented.

The technique of glass capillaries filled with liquid scintillator allows the reconstruction of ionizing particle tracks with high spatial resolution. Detectors based on this technique consist of coherent arrays of capillaries having diameters of the order of 20 μm. Light signals are amplified by an optoelectronic chain composed of a series of image intensifiers: the readout is performed through a CCD. The ongoing research in the field of liquid scintillators has led to excellent results in terms of information density (≥ 5 hits/mm) and radiation resistance (order of 1 MGy). In this paper new results about the effect of ageing and purification of liquid scintillators will be presented. The RD46 collaboration has developed a completely new detector having a readout chain composed of only one image intensifier followed by a new device: a Megapixel Electron Bombarded CCD. First images of neutrino interactions will be shown, together with preliminary measurements of the resolution of the detector.

From 1994 to 1997, the emulsion target of the CHORUS detector was exposed to the wideband neutrino beam of the CERN SPS. In total about 100 000 charged-current neutrino interactions were located in the nuclear emulsion target and fully reconstructed. From this sample of events based on the data acquired by new automatic scanning systems, 2013 charm-decay events were selected by a pattern recognition program. They were confirmed as decays through visual inspection. Based on these events, the effective branching ratio of charmed particles into muons was determined to be B¯μ=[7.3±0.8(stat)±0.2(syst)]×10−2. In addition, the muonic branching ratios are presented for dominating charm-decay topologies. Normalization of the muonic decays to charged-current interactions provides σμ−μ+/σcc=[3.16±0.34(stat)±0.09(syst)]×10−3. Selecting only events with visible energy greater than 30 GeV gives a value of B¯μ that is less affected by the charm production threshold and quasi-elastic Λc+ production. Combining this value with the current average of B¯μ×|Vcd|2 at the leading order yields the value of |Vcd|LO=0.236±0.016.

Beams of Carbon nuclei are used or planned to be used in various centers for cancer treatment around the world because of their therapeutic advantages over proton beams. The knowledge of the fragmentation of Carbon nuclei when they interact with the human body is important to evaluate the spatial profile of their energy deposition in the tissues, hence the damage to the tissues neighboring the tumor. In this respect, the identification of the fragmentation products is a key element. We present in this paper the charge measurement of about 3000 fragments produced by the interaction of 12C nuclei with an energy of 400 MeV/nucleon in a detector simulating the density of the human body. The nuclear emulsion technique is used, by means of the so-called Emulsion Cloud Chamber. In order to achieve the large dynamical range required for the charge measurement, the recently developed techniques of the emulsion controlled fading are used. The nuclear emulsions are inspected using fast automated microscopes recently developed. A charge assignment efficiency of more than 99% is achieved. The separation of Hydrogen, Helium, Lithium, Berillium, Boron and Carbon can be achieved at two standard deviations or considerably more, according to the track length available for the measurement.

The CMS RPC muon detector utilizes a gas recirculation system called closed loop (CL) to cope with large gas mixture volumes and costs.A systematic study of CL gas purifiers has been carried out over 400 days between July 2008 and August 2009 at CERN in a low-radiation test area, with the use of RPC chambers with currents monitoring, and gas analysis sampling points.The study aimed to fully clarify the presence of pollutants, the chemistry of purifiers used in the CL, and the regeneration procedure.Preliminary results on contaminants release and purifier characterization are reported.

In this work, we study the effect of anisotropic magnetostriction on Terfenol-D based fiber Bragg grating magnetic sensors under different types of magneto-mechanical loading. We demonstrate that a Terfenol-D rod is subjected to axial strain also when the magnetic field is perpendicular to the rod axis and as consequence we question the hypothesis of uniaxial behavior that is normally found in the literature for this kind of sensors. In order to address this issue, we propose a calibration model that introduces transverse sensitivity coefficients in good agreement with the experimental data. Moreover, the dependence of the sensitivity coefficients on the magnetic field intensity and mechanical prestress has been retrieved revealing that accurate magnetic measurements are possible only taking into account the transversal magnetostriction of Terfenol D.

In this work the design of a constant fraction discriminator (CFD) to be used in the VFAT3 chip for the read-out of the triple-GEM detectors of the CMS experiment, is described. A prototype chip containing 8 CFDs was implemented using 130 nm CMOS technology and test results are shown.

The recovery of the charge collection efficiency (CCE) at low temperatures, the so-called ”Lazarus effect”, was studied in Si detectors irradiated by fast reactor neutrons, by protons of medium and high energy, by pions and by gamma-rays. The experimental results show that the Lazarus effect is observed: (a) after all types of irradiation; (b) before and after space charge sign inversion; (c) only in detectors that are biased at voltages resulting in partial depletion at room temperature. The experimental temperature dependence of the CCE for proton-irradiated detectors shows non-monotonic behaviour with a maximum at a temperature defined as the CCE recovery temperature. The model of the effect for proton-irradiated detectors agrees well with that developed earlier for detectors irradiated by neutrons. The same midgap acceptor-type and donor-type levels are responsible for the Lazarus effect in detectors irradiated by neutrons and by protons. A new, abnormal “zigzag”-shaped temperature dependence of the CCE was observed for detectors irradiated by all particles (neutrons, protons and pions) and by an ultra-high dose of γ-rays, when operating at low bias voltages. This effect is explained in the framework of the double-peak electric field distribution model for heavily irradiated detectors. The redistribution of the space charge region depth between the depleted regions adjacent to p+ and n+ contacts is responsible for the “zigzag”- shaped curves. It is shown that the CCE recovery temperature increases with reverse bias in all detectors, regardless of the type of radiation.

During the years 1994–1997, the emulsion target of the CHORUS detector was exposed to the Wide Band Neutrino Beam from the CERN-SPS. About 170 000 neutrino interactions were successfully located in the emulsion. Improvements in the automatic emulsion scanning systems and application of different criteria allowed the sample of located events to be used for studies of charm production. We present a measurement of the production rate of D0 mesons based on a sample of 25 693 located νμ charged-current (CC) interactions analysed so far. After reconstruction of the event topology in the vertex region, 283 D0 decays were observed with an estimated background of 9.2 K0 and Λ decays. The ratio of cross-section of D0 production and νμ CC interactions is found to be (1.99±0.13(stat.)±0.17(syst.))×10−2 at 27 GeV average νμ energy.

During the years 1994–1997, the emulsion target of the CHORUS detector was exposed to the wide-band neutrino beam of the CERN SPS of 27 GeV average neutrino energy. In total about 100 000 charged-current neutrino interactions were located in the nuclear emulsion target and fully reconstructed. From this sample of events which was based on the data acquired by new automatic scanning systems, 1048 charged-current interactions with a D0 in the final state were selected by a pattern recognition program and confirmed as neutral-particle decays through visual inspection. The ratio of decay branching fractions of the D0 into four charged particles to two charged particles was measured to be B(D0→V4)/B(D0→V2)=0.207±0.016±0.004. The inclusive measurement of the observed production rate of the D0 with a decay into four charged prongs in combination with external measurements of this topological branching ratio was used to determine the total D0 production rate by neutrinos without additional assumption on the branching fractions. The value of this rate relative to the charged-current cross-section was found to be σ(D0)/σ(CC)=0.0269±0.0018±0.0013. In addition, the same normalization method was used to deduce the inclusive topological decay rate into final states with neutral particles only. A value of 0.218±0.049±0.036 was found for this branching fraction. From an observed number of three charged six-prong events the branching ratio into six charged particles was determined to be (1.2−0.9+1.3±0.2)×10−3. A measurement of the energy dependence of the D0 production by neutrinos relative to the total charged-current cross-section is also reported. This measurement was used to deduce for mc, the effective charm-quark mass, a value of (1.42±0.08)GeV/c2.

The OPERA experiment has conclusively observed the appearance of tau neutrinos in the muon neutrino CNGS beam. Exploiting the OPERA detector capabilities, it was possible to isolate high purity samples of $\nu_{e}$, $\nu_{\mu}$ and $\nu_{\tau}$ charged current weak neutrino interactions, as well as neutral current weak interactions. In this Letter, the full dataset is used for the first time to test the three-flavor neutrino oscillation model and to derive constraints on the existence of a light sterile neutrino within the framework of the $3+1$ neutrino model. For the first time, tau and electron neutrino appearance channels are jointly used to test the sterile neutrino hypothesis. A significant fraction of the sterile neutrino parameter space allowed by LSND and MiniBooNE experiments is excluded at 90% C.L. In particular, the best-fit values obtained by MiniBooNE combining neutrino and antineutrino data are excluded at 3.3 $\sigma$ significance.

Fiber Optic Sensors (FOS), whose advantages have made them widely used in many applications, are up to now not so diffusely used for the monitoring of industrial processes, mainly due to two aspects: the expensiveness and complexity of the sensors monitoring systems. For these reasons, these sensor systems are usually substituted with low performance but easier to manage sensors, in agreement with industrial monitoring standards. The read-out system described in this document overcomes the limitations suffered by the commonly used FOS interrogation system and extends the fields in which FOS can be employed. The circuit handles the transduction of an optical signal to an electrical signal, going from wavelength encoding to voltage or current. Moreover, the proposed system relies on a totally analog and fully modular circuit in combination with a power fluctuation rejection circuit. The system is tested through temperature measurements highlighting it's characteristics of reliability and repeatability. The temperature variation is given by a heat plate and monitored with a calibrated sensor close to the Fiber Bragg Grating sensor under test.

We built and tested on charged particle beams the high energy-resolution calorimeter for the CHORUS experiment, which searches for νμ-ντ oscillations in the CERN Wide Band Neutrino Beam. This calorimeter is longitudinally divided into three sectors: one electromagnetic and two hadronic. The first two upstream sectors are made of lead and plastic scintillating fibers in the volume ratio of 41, and they represent the first large scale application of this technique for combined electromagnetic and hadronic calorimetry. The third sector is made of a sandwich of lead plates and scintillator strips and complements the measurement of the hadronic energy flow. In this paper, we briefly describe the calorimeter design and we show results on its response to electrons and pions, obtained from tests performed at the CERN SPS and PS. An energy resolution of σ(E)/E=(32.3±2.4)%/E(GeV) + (1.4±0.7)% was achieved for pions, and σ(E)/E=(13.8±0.9)%/E(GeV) + (−0.2±0.4)% for electrons.

A measurement of Λc+ production in neutrino nucleon charged-current interactions is presented. In a subsample of about 50 000 interactions located in the emulsion target of the CHORUS detector, exposed to the wide band neutrino beam of the CERN SPS, candidates for decays of short-lived particles were identified using new automatic scanning systems and later confirmed through visual inspection. Criteria based on the flight length allowed a statistical separation among the different charm species thus enabling a sample particularly rich in Λc+ to be defined. At an average neutrino energy of 27 GeV, the product σ(Λc+)/σ(CC)×BR(Λc+→3p) was measured to be (0.37±0.10(stat)±0.02(syst))×10−2, while the values of (1.54±0.35(stat)±0.18(syst))×10−2 and of 0.24±0.07(stat)±0.04(syst) were obtained for σ(Λc+)/σ(CC) and BR(Λc+→3p), respectively.

We have studied the performance of a new algorithm for electron/pion separation in an Emulsion Cloud Chamber (ECC) made of lead and nuclear emulsion films. The software for separation consists of two parts: a shower reconstruction algorithm and a Neural Network that assigns to each reconstructed shower the probability to be an electron or a pion. The performance has been studied for the ECC of the OPERA experiment [1].

In this paper, the results of the long-term temperature monitoring of the compact muon solenoid experiment (CMS) at CERN are shown. The measurements were carried out by means of a system based on fiber Bragg grating (FBG) sensors in wavelength-division multiplexing (WDM). Due to the harsh working conditions at the CMS, the FBG sensor represents the ideal candidate to realize a reliable and accurate sensing system. The sensing principles of the FBG sensor and its temperature characteristics are introduced. A temperature monitoring system based on FBG for high-energy physics applications is designed and installed. The sensing system was used successfully last year in monitoring the temperature of CMS bulkhead. The reported results show good reliability and high accuracy of the FBG sensing system during the long-time working stage.

Resistive Plate Chambers have been chosen as dedicated trigger muon detector for the Compact Muon Solenoid experiment [1] at the Large Hadron Collider [2] at CERN. The system consists of about 3000 m2 of double gap RPC chambers placed in both the barrel and endcap muon regions.

The Search for Hidden Particles (SHiP) experiment proposal at CERN demands a dedicated dipole magnet for its scattering and neutrino detector. This requires a very large volume to be uniformly magnetized at B > 1.2 T, with constraints regarding the inner instrumented volume as well as the external region, where no massive structures are allowed and only an extremely low stray field is admitted. In this paper we report the main technical challenges and the relevant design options providing a comprehensive design for the magnet of the SHiP Scattering and Neutrino Detector.

Abstract The SHiP experiment has been proposed at CERN to shed light on phenomena still unexplained in the framework of the Standard Model, such as the nature of dark matter, the baryonic asymmetry of the Universe and the neutrino oscillations, searching for hints of New Physics. A section of the detector will be dedicated to the study of neutrino physics with special emphasis on tau neutrino properties, still very poorly measured. A system to identify the muons produced in neutrino interactions, based on RPC technology, has been proposed and it is presented in detail in this paper.

We report on an experimental study of longitudinal leakage phenomena in hadronic shower development. Pions in the energy range of 10–150 GeV were sent into a lead/scintillating-fiber calorimeter with a thickness of 9.6 nuclear interaction lengths. The average fraction of the energy leaking out at the back of this calorimeter ranges from 0.04% at 10 GeV to 0.4% at 150 GeV. This leakage has a very small effect on the hadronic energy resolution. We measured the probability of the creation of escaping muons in the shower development process. This probability ranges from 0.2% at 10 GeV to 2.1% at 150 GeV. Assuming that these muons are produced from π- or K-decay, we find an exponentially decaying muon spectrum with a typical momentum of 2.8 GeV/c, at 80 GeV incident energy. Also the rates at which hadrons and soft neutrons escape from the calorimeter are measured. Within the acceptance of the leakage calorimeter, neutrons are observed about 10 times as often as muons. Escaping hadrons dominate muons for shower energies above 20 GeV. The experiments were performed at CERN in the framework of the LAA project.

We report on a search for associated charm production in neutrino charged-current interactions in the CHORUS experiment, based on the visual observation of charmed-particle decays. The search differs from those carried out so far in which the production of cc̄ has been inferred from measurements of events with two or three muons in the final state, resulting from the decay of charmed hadrons. One event with a double charm-decay topology has been found and a corresponding background of 0.04 events has been evaluated.

A study of quasi-elastic production of charmed baryons in charged-current interactions of neutrinos with the nuclear emulsion target of CHORUS is presented. In a sample of about 46 000 interactions located in the emulsion, candidates for decays of short-lived particles were identified by using new automatic scanning systems and later confirmed through visual inspection. Criteria based both on the topological and kinematical characteristics of quasi-elastic charm production allowed a clear separation between events of this type and those in which charm is produced in deep inelastic processes. A final sample containing 13 candidates consistent with quasi-elastic production of a charmed baryon with an estimated background of 1.7 events was obtained. At the average neutrino energy of 27 GeV the cross-section for the total quasi-elastic production of charmed baryons relative to the νN charged-current cross-section was measured to be σ(QE)/σ(CC)=(0.23+0.12−0.06(stat)+0.02−0.03(syst))×10−2. Through an analysis of the topology at the production and decay vertices the relative cross-sections were measured separately for singly (Λc+,Σc+,Σc+∗) and doubly (Σc++,Σc++∗) charged baryons.

The OPERA neutrino oscillation experiment is based on the use of the Emulsion Cloud Chamber (ECC). In the OPERA ECC, nuclear emulsion films acting as very high precision tracking detectors are interleaved with lead plates providing a massive target for neutrino interactions. We report on studies related to the effects occurring from the contact between emulsion and lead. A low radioactivity lead is required in order to minimize the number of background tracks in emulsions and to achieve the required performance in the reconstruction of neutrino events. It was observed that adding other chemical elements to the lead, in order to improve the mechanical properties, may significantly increase the level of radioactivity on the emulsions. A detailed study was made in order to choose a lead alloy with good mechanical properties and an appropriate packing technique so as to have a low enough effective radioactivity.

The measurements performed in Japan have shown that muon radiography is an “imaging technique” capable of providing information of the internal structure of volcanoes with a resolution and richness of details beyond the reach of conventional, non-imaging techniques. The measurements have been performed using electronic detectors or nuclear emulsions. The latter have shown excellent muon tracking capabilities and space resolution, but are lacking of the capability of electronic detectors to provide data in real time. In this paper, we examine the possibility of developing an electronic detector giving a resolution comparable to that of nuclear emulsions and with a larger area than used so far, in order to see deeper structures inside volcanoes in spite of the strong muon absorption in the rock. We specifically discuss the very challenging application of muon radiography to Mt. Vesuvius, driven by the strong social interest coming from the enormous potential danger which it represents. Applications to other volcanoes can be envisaged.

Results are presented on the activity carried out by our research group, in collaboration with the SME Optosmart s.r.l. (an Italian spin-off company), on the application of Fiber Optic Sensor (FOS) techniques to monitor high-energy physics (HEP) detectors. Assuming that Fiber Bragg Grating sensors (FBGs) radiation hardness has been deeply studied for other field of application, we have applied the FBG technology to the HEP research domain. We present here the experimental evidences of the solid possibility to use such a class of sensors also in HEP detector very complex environmental side conditions. In particular we present more than one year data results of FBG measurements in the Compact Muon Solenoid (CMS) experiment set up at the CERN, where we have monitored temperatures (within CMS core) and strains in different locations by using FBG sensors during the detector operation with the Large Hadron Collider (LHC) collisions and high magnetic field. FOS data and FOS readout system stability and reliability is demonstrated, with continuous 24/24 h 7/7d data taking under severe and complex side conditions.

This contribution introduces a new type of Micropattern Gaseous Detector, the Fast Timing Micropattern (FTM) detector, utilizing fully Resistive WELL structures. The structure of the prototype will be described in detail and the results of the characterization study performed with an X-ray gun will be presented, together with the first results on time resolution based on data collected with muon/pion test beams.

The OPERA experiment was designed to search for $$\nu _{\mu } \rightarrow \nu _{\tau }$$ oscillations in appearance mode through the direct observation of tau neutrinos in the CNGS neutrino beam. In this paper, we report a study of the multiplicity of charged particles produced in charged-current neutrino interactions in lead. We present charged hadron average multiplicities, their dispersion and investigate the KNO scaling in different kinematical regions. The results are presented in detail in the form of tables that can be used in the validation of Monte Carlo generators of neutrino–lead interactions.

The Resistive Plate Chambers (RPCs) are employed in the CMS experiment at the LHC as dedicated trigger system both in the barrel and in the endcap. This note presents results of the RPC detector uniformity and stability during the 2011 data taking period, and preliminary results obtained with 2012 data. The detector uniformity has been ensured with a dedicated High Voltage scan with LHC collisions, in order to determine the optimal operating working voltage of each individual RPC chamber installed in CMS. Emphasis is given on the procedures and results of the High Voltage calibration. Moreover, an increased detector stability has been obtained by automatically taking into account temperature and atmospheric pressure variations in the CMS cavern.