Pierluigi Zotto

A determination of branching ratios for D meson decays into all charged particle final states is reported. The values obtained: (D± → K∓π±π±/all D±) = (14 ± 6)% and (D0/D0 → K±π∓π+π−/all D0/D0) = (10 ± 4)%, are higher than those currently accepted. This result, if confirmed, implies a corresponding reduction in the accepted values for some total cross section measurements. Revised inclusive cross sections for D meson production in the forward hemisphere in π−p and pp interactions at 360 GeV/c, are presented.

The European Hybrid Spectrometer is described in its preliminary version for the NA16 charm experiment. The performance of the small hydrogen bubble chamber LEBC and the detectors of the spectrometer is discussed. In particular the combination of the bubble chamber information with the spectrometer data is described in detail. The track reconstruction efficiency is 90%. The precision with which vertices seen in the bubble chamber are reconstructed is around 10 μm and the two track resolution is 40 μm. Therefore very complex event configurations, in particular charm particle decays, can be reconstructed correctly.

Results are presented on charm meson lifetimes. The sample of charm particle decays was obtained by exposing the high resolution rapid cycling hydrogen bubble chamber (LEBC) coupled with the European Hybrid Spectrometer to π− and p beams at 360 GeV/c ffrom the CERN SPS. The analysis of ∼850 k pictures has yielded 77 events containing a total of 60 charm decays. From these, an unbiased sample of 31 D decays (15± and 16 D0) is issued in the lifetime analysis. The measured mean lifetimes for D± and D0 are (where the symbol D0 means D0 and D0):τ(D±)=8.4+3.5−2.2 × 10−13sτ(D0)=4.1+1.3−0.9 ×10−13s. Three unambiguous examples of F± decay have also been observed and the corresponding lifetime, based on 2 decays, is τ(F±)=2.1 +3.6−0.8 × 10 −13s

Charm D-meson production in 360 GeV pp interactions has been studied using the high-resolution hydrogen bubble chamber LEBC and the European Hybrid Spectrometer. D-mesons are produced with a differential cross section of the form d2σdx dpT2δ(1-x)n exp (-apT2), withn=1.8± 0.8 and a=1.1±0.03 GeV/c−2 for the Feynman x and Transverse momentum pT behaviour. The inclusive partle prticle crossssection for D and D̄;measured to be: σ(D/D̄) = (56−12 25μb (for all x). The ΛcD̄ cross section can be estimated to be ≈20μb. No strong correlation is observed between DD̄ pairs. The results are compared with results from a study of D-meaon production in 360 GeV/c π−p interactions also using LEBC-EHS.

A novel method was developed to obtain precise timing of muon hits in drift tubes at the first trigger level, and hence to associate a detected muon with the bunch crossing in which it originated. A very good time resolution of ∼ 2 ns was obtained. Some other topics related to muon detection were investigated.

A solid-state silicon detector is a challenging device for microdosimetry, mainly because it can provide sensitive zones of the order of a micrometer. Moreover, these detectors are characterized by a high spatial and a good energy resolution. However, they may present some limitations, such as: (i) the minimum detectable energy which is limited by the electronic noise; (ii) radiation hardness; (iii) the geometry of the sensitive volume; (iv) the field-funnelling effect; (v) the non-tissue-equivalence of silicon. This work discusses a feasibility study of a microdosimeter based on a monolithic silicon telescope, consisting of a ΔE and an E stage-detector, about 1 and 500 μm thick, respectively. Charges are collected separately in the two stage-detectors. The use of the ΔE stage coupled with a tissue-equivalent converter was investigated as a solid-state microdosimeter. Irradiations with monoenergetic neutrons were performed at the INFN-Laboratori Nazionali di Legnaro (Italy). The field-funnelling effect appears to be negligible from the comparison of the experimental data with the results of Monte Carlo simulations, performed with the FLUKA code. The preliminary results of an analytical approach for the correction for geometrical effects and tissue-equivalence are also presented.

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

A neutron spectrometer was set-up by coupling a polyethylene converter with a monolithic silicon telescope, consisting of a DeltaE and an E stage-detector (about 2 and 500 microm thick, respectively). The detection system was irradiated with monoenergetic neutrons at INFN-Laboratori Nazionali di Legnaro (Legnaro, Italy). The maximum detectable energy, imposed by the thickness of the E stage, is about 8 MeV for the present detector. The scatter plots of the energy deposited in the two stages were acquired using two independent electronic chains. The distributions of the recoil-protons are well-discriminated from those due to secondary electrons for energies above 0.350 MeV. The experimental spectra of the recoil-protons were compared with the results of Monte Carlo simulations using the FLUKA code. An analytical model that takes into account the geometrical structure of the silicon telescope was developed, validated and implemented in an unfolding code. The capability of reproducing continuous neutron spectra was investigated by irradiating the detector with neutrons from a thick beryllium target bombarded with protons. The measured spectra were compared with data taken from the literature. Satisfactory agreement was found.

A neutron spectrometer consisting of a commercial p–i–n diode coupled with a polyethylene converter was developed and tested. The spectra of the energy deposited by recoil-protons in the silicon detector were measured with mono-energetic neutron beams. The spectra of deposited energy were also calculated analytically and with Monte Carlo simulations using the FLUKA code. The effect of secondary charged particles produced by thermal and fast neutron interactions in the silicon diode was also investigated. Further measurements were made for neutrons generated by 5MeV protons striking a thick beryllium target. The derived neutron spectrum was compared with spectra from the literature. Satisfactory agreement was found. The use of the spectrometer is limited by the effect of photons.

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

We describe the construction and performance of the improved muon detection system of the UA1 experiment. The new position detectors, that complement the original muon detection system based on large planar drift chambers, are limited-streamer chambers for a total surface of 800 m2. The coordinate parallel to the wires is readout through the especially developed STAR electronics that integrates and digitizes the signal from the strips. The intrinsic spatial resolution, determined in a test beam, is 400 μm, that achieved so far in the real system is 1.2 mm. The efficiency is evaluated to be (94.9±0.6)%.

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

In an experiment with 360 GeV/cπ− beam at the CERN SPS using the high resolution hydrogen bubble chamber LEBC and the European Hybrid Spectrometer, an event has been observed of the type π−p→D0D0+ 8 prongs. The fully reconstructed decay modes are D0→K−π+π0π0andD0→K+π+π−π− , with all six charged tracks being detected in the spectrometer and all four photons from the π0 decays detected in the lead glass gamma detection system. The D0 has momentum 119.0 ± 0.6 GeV/c, xF = 0.31, length 4.1 ± 0.1 mm and proper lifetime (2.1 ± 0.1) × 10−13 s. The D0 has momentum 78.5 ± 0.3 GeV/c, xF = 0.19, length 7.5 ± 0.1 mm and proper lifetime (5.9 ± 0.1) × 10−13 s.

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

Telescopes of position sensitive detectors are common layouts in charged particles tracking, and programmable logic devices, such as FPGAs, represent a viable choice for the real-time reconstruction of track segments in such detector arrays. A compact implementation of the Hough Transform for fast triggers in High Energy Physics, exploiting a parameter reduction method, is proposed, targeting the reduction of the needed storage or computing resources in current, or next future, state-of-the-art FPGA devices, while retaining high resolution over a wide range of track parameters. The proposed approach is compared to a Standard Hough Transform with particular emphasis on their application to muon detectors. In both cases, an original readout implementation is modeled.

An innovative silicon device based on the monolithic silicon telescope was recently presented and investigated for solid state microdosimetry (of neutron field and hadron beams) and for neutron spectrometry.This device consists of a surface ΔE stage, about 2 µm in thickness, coupled to an E stage, about 500 µm in thickness, made out of a single silicon wafer.The ΔE-E device is capable of providing information about the kind and the energy of the impinging particles.This feature can be exploited for an optimized i) tissue-equivalent correction of microdosimetric distributions measured with the silicon device and ii) gamma-neutron discrimination.This work discusses the characterization of the direct response of this detector to charged particles To this aim, a sample device with a sensitive area of about 1 mm 2 was irradiated with mono-energetic protons and alpha particles of energy between 1 MeV and 5 MeV at the Van De Graaff CN accelerator of the Legnaro National Laboratories of the Italian Institute of Nuclear Physics (LNL-INFN).The experimental ΔE-E scatter plots were analyzed in details and compared with results of an analytical model.The agreement between the results was satisfactory for events distributed over the theoretical ΔE-E curve.Events of the experimental scatter-plots characterized by a linear correlation between energy deposited in the ΔE and in the E detector highlighted were attributed to channeling effect.

The total punchthrough probability of showers produced by negatively charged pions of momenta 30, 40, 50, 75, 100, 200 and 300 GeV/c, has been measured in the RD5 experiment at CERN using a toroidal spectrometer. The range of the measurement extends to 5.3 m of equivalent iron. Our results have been obtained by two different analysis methods and are compared with the resutls of a previous experiment.

Abstract Single layer honeycomb strip chambers have been constructed for the tracking calorimeter TRACAL. This detector is a component of the RD5 experimental test setup at CERN, where aspects of muon detection in LHC conditions are studied. The construction of the chambers is described and the excellent spatial resolution obtained from strip signals (σ

The feasibility of fully floating high voltage (HV) generation was demonstrated producing a prototype of a modular HV system. The primary power source is provided by a high efficiency semiconductor power cell illuminated by a laser system ensuring the floating nature of each module. The HV is then generated by dc-dc conversion and a HV multiplier. The possibility of series connection among modules was verified.

A Proton Irradiation Chamber aiming to perform radiation tests of electronic components was developed. The precision on the measurement of the ion currents was pushed beyond the resolution of the picoammeter by means of a series of collimators on the beam showing a linear correlation among the currents measured on them and the smaller, not measurable, current on the target. As an example of the obtained results the tests done on a Si microdosimeter and a power p-MOS are reported.

Abstract The barrel muon chambers of the CMS detector consist of three sets of four layers of rectangular drift tubes. The performance of several prototypes was measured in a muon beam for various experimental conditions. Special emphasis was given to study performance aspects related to the trigger capability of the chambers.

We present results from the barrel depleted uranium/TMP calorimeter modules constructed by the UA1 Collaboration. Electromagnetic and hadronic energy resolutions have been measured using electron and pion beams with momenta in the range 7 to 70 GeV/c. Results on the energy linearity and the spatial uniformity of response are reported. The electromagnetic shower position resolution has been measured as a function of energy using a fine grained position detector placed at a depth of − 3.5χ0. The noise arising both from the electronics chain and from the uranium radioactivity is compared with 70 GeV/c muon signals. The ratio of the electron to pion response has been measured both as a function of the energy and of the electric field. The high lateral and longitudinal granularity of the calorimeter and the presence of a position detector have been used to determine the electron pion separation as a function of energy.

Abstract Extruded plastic tubes coated with a resistive material, having a 1 cm 2 profile and central 100 μm anode wire are operated in limited streamer mode. The charge induced on an external layer of cathode strips aligned perpendicularly to the anode wire is measured and used to compute the streamer coordinate. Test results both with an X-ray source and a particle beam are presented. Spatial resolution of the other of 400 μm is observed over the 40 cm 2 area studied.

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

A thin silicon diode formed by a deep p+ implantation under a shallow n+ one is proposed as a solid state microdosimeter. The thickness of the sensitive layer of the tested device is about two micrometers and the active area is about 10 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Due to the very large electric capacitance of the diode (about 1 nF) a low noise read-out circuit based on a discrete JFET has been developed. The noise due to the parasitic resistance of the detector itself dominates and fixes the lower threshold of the energy spectrum. A prototype of the proposed microdosimeter covered with a polyethylene converter has been irradiated with fast monoenergetic neutrons at the INFN-Legnaro Labs (I). The first experimental spectra are in good agreement with the simulated ones. The effect of direct interactions of thermal neutrons in silicon has been measured

A high voltage generator built by a series connection of 100 kV modules was produced. The series connection feasibility is ensured by the inherent floating character of each module which is wireless powered by high efficiency photovoltaic cells illuminated by a laser system. Each module is equipped with a control and monitoring board allowing excellent stabilization of the high voltage output. The performance of the system in terms of reliability, stability, and efficiency was evaluated. In particular using a three module setup, we achieved a maximum voltage of 234 kV with stability better than 0.1%.

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

The electronics employed around particle accelerators can be disturbed or damaged because of single event effects (SEE). The most likely effect is the single event upset (SEU) which may affect all memory devices. In the case of high energy accelerators, SEUs are mostly produced by secondary charged particles generated by neutron interactions. The measurement of the energy and the lineal energy distribution of these neutron-induced charged particles was proposed. As a first approach, a commercial p-i-n photodiode was employed. This device was irradiated with thermal and monoenergetic fast neutrons. Some effects limiting the use of such a detector as a SEE spectrometer were observed, giving guidelines for the design of an application specific integrated circuit (ASIC). The possibility of creating a solid state microdosemeter by coupling the ASIC with a tissue-equivalent radiator is discussed. Moreover, the p-i-n photodiode covered with a hydrogenated plastic radiator may be employed as a proton-recoil spectrometer.

The MICRO-SI experiment, funded by INFN from 2008 up to 2010, aimed at developing a silicon microdosimeter capable of responding to neutrons and to hadron-therapy beams down to a few keV μm-1. The main goals which were achieved in the framework of this experiment are described in details. The detector, designed and fabricated by exploiting the monolithic telescope technology, demonstrated to provide charge confinement inside the micrometric sensitive volume, thus minimizing the field-funnelling effect. An innovative segmented telescope device was developed in order to have a silicon detector offering sensitive volume dimensions similar to those which can be simulated by a tissue-equivalent proportional counter (TEPC). The response of the segmented device to hadron beams was characterized with clinical protons and with 62 AMeV carbon ions at the INFN-Laboratori Nazionali del Sud (Catania, Italy). Irradiations with mono-energetic neutrons at the INFN-Laboratori Nazionali di Legnaro (Legnaro, Italy) were also performed. The agreement with the spectra measured with a TEPC is very satisfactory and gives confidence on the application of such a silicon device to assess the quality of hadrontherapy beams.

Three simplified prototypes of the first-level trigger front-end device for the muon barrel drift chambers of CMS were tested on a chamber prototype. Tests were performed at several incidence angles of a muon beam and with different magnetic field configurations. The recorded drift times were also used to test a full software model reproducing the actual algorithm applied in the final ASIC being produced. The efficiency performance of this software model and of the tested prototype are presented in this paper.

Abstract The performance of a small prototype chamber of the baseline project for the muon barrel detector for CMS has been studied in a muon beam. Its efficiency with different gases and wire diameters, the trigger possibilities and the response in presence of a large number of electromagnetic secondaries associated to the muon are evaluated. The results are compared with a full Monte Carlo simulation.

Neutron irradiation tests of the available electronics for the CMS barrel muon detector were performed using thermal and fast neutrons. The Single Event Upset rates on static RAMs were measured, while upper limits are derived for devices having experienced no failure. The results are used to guess the mean time between failures in the whole barrel muon detector.

A recoil-proton spectrometer was created by coupling a p-i-n diode with a polyethylene converter. The maximum detectable energy, imposed by the thickness of the totally depleted layer, is approximately 6 MeV. The minimum detectable energy is limited by the contribution of secondary electrons generated by photons in the detector assembly. This limit is approximately 1.5 MeV at full-depletion voltage and was decreased using pulse-shape discrimination. The diode was set up in the 'reverse-injection' configuration (i.e. with the N+ layer adjacent to the converter). This configuration provides longer collection times for the electron-hole pairs generated by the recoil-protons. The pulse-shape discrimination was based on the zero-crossing time of bipolar signals from a (CR)2-(RC)2 filter. The detector was characterised using monoenergetic neutrons generated in the Van De Graaff CN accelerator at the INFN-Laboratori Nazionali di Legnaro. The energy limit for discrimination proved to be approximately 900 keV.

Abstract A sample of ASIC prototypes of the first-level trigger front-end device for the muon barrel drift chambers of CMS was tested on a full size chamber prototype. Tests were performed at several incident angles on cosmic rays and at normal incidence using a muon beam. The chamber was irradiated using a 137 C s gamma source to simulate the LHC radiation environment. The performance of the tested prototypes with respect to efficiency, resolution and noise issues is reported.

The neutron spectrometer discussed in this work consists of a PIN diode coupled with a polyethylene converter. Neutrons are detected through the energy deposited by recoil-protons in silicon. The maximum detectable energy is ∼6 MeV and is imposed by the thickness of the fully depleted layer (300 µm for the present device). The minimum detectable energy which can be assessed with pulse-shape discrimination (PSD) is ∼0.9 MeV. PSD is performed with a crossover method and setting the diode in the ‘reverse-injection’ configuration (i.e. with the N+ layer adjacent to the converter). This configuration provides longer collection times for the electron–hole pairs generated by the recoil-protons. The limited interval of detectable energies restricts the application of this spectrometer to low-energy neutron fields, such as the ones which can be produced at facilities hosting low-energy ion accelerators. The capacity to reproduce continuous neutron spectra was investigated by optimising the electronic chain for pulse-shape discrimination. In particular, the spectrometer was irradiated with neutrons that were generated by striking a thick beryllium target with protons of several energies and the measured spectra were compared with data taken from the literature.

The LHC program at 13 and 14 TeV, after the observation of the candidate SM Higgs boson, will help clarify future subjects of study and shape the needed tools. Any upgrade of the LHC experiments for unprecedented luminosities, such as the High Luminosity-LHC ones, must then maintain the acceptance on electroweak processes that can lead to a detailed study of the properties of the candidate Higgs boson. The acceptance of the key lepton, photon and hadron triggers should be kept such that the overall physics acceptance, in particular for low-mass scale processes, can be the same as the one the experiments featured in 2012. In such a scenario, a new approach to early trigger implementation is needed. One of the major steps will be the inclusion of high-granularity tracking sub-detectors, such as the CMS Silicon Tracker, in taking the early trigger decision. This contribution can be crucial in several tasks, including the confirmation of triggers in other subsystems, and the improvement of the on-line momentum measurement resolution. A muon track-trigger for the CMS experiment at the High Luminosity-LHC is presented. A back-extrapolation of Drift Tubes trigger primitives is proposed to match tracks found at Level 1 with muon candidates. The main figures-of-merit are presented, featuring sharp thresholds and less contamination from lower momentum muons, and an expected rate reduction of a factor of 5–10 at typical thresholds with respect to the muon trigger configuration used in 2012.

A major upgrade of the readout and trigger electronics of the CMS Drift Tubes muon detector is foreseen in order to allow its efficient operation at the High Luminosity LHC. A proposal for a new L1 Trigger Primitives Generator for this detector is presented, featuring an algorithm operating on the time of charge collection measurements provided by the asynchronous readout of the new TDC system being developed. The algorithm is being designed around the implementation in state-of-the-art FPGA devices of the original development of a Compact Hough Transform (CHT) algorithm combined with a Majority Mean-Timer, to identify both the parent bunch crossing and the muon track parameters. The current state of the design is presented along with the performance requirements, focusing on the future developments.

A muon position detector based on limited streamer tubes has been built for the UA1 experiment at the CERN pp collider. The tubes are arranged in chambers equipped with electronics to allow for analog readout of the induced signals on strips. The electronics module for charge amplification and conversion (STAR), the data acquisition system based on the VME standard and the performance of the detector will be described.

A full characterization of a ΔE/E monolithic silicon detector especially developed for microdosimetry was performed using monochromatic beams of α-particles and protons at the Italian National Laboratories of Legnaro at the CN van de Graaff accelerator. The investigation was performed in order to evaluate the limitations and the systematic effects affecting its use as a microdosimeter. The results can be extended to the standard use of these kind of devices as particle identifiers.

A novel muon detector concept for LHC was studied in a test beam. The application of mean-timer technique to arrays of drift tubes provides the space and time resolution needed for first level trigger and track reconstruction using only the drift time information. A complete study of the performance of this new detector was done.

The feasibility of the discrimination between protons and secondary electrons was investigated in order to decrease the lower limit of a recoil-proton spectrometer for neutrons based on a silicon p-i-n diode. The simulation of the ionization generated in the detector by protons and electrons and the simulation of the relevant induced currents show that such discrimination is feasible provided that the "rear side injection" configuration and a low noise setup are adopted. The difference between the collecting times of the two pulses is maximized and used for the rising time based discrimination. The neutron spectrometer consists of a 3 mm/sup 2/ area, 300 /spl mu/m-thick silicon p-i-n diode covered with a polyethylene foil on the n-side. The ENC is 720 rms electrons at 20 ns shaping time. Experimental results on monoenergetic neutrons show the effectiveness of this discrimination in decreasing the lower limit of the recoil proton energy spectrum from 1.1 to 0.6 MeV.

Abstract The development of the barrel drift chambers for the CMS muon detector at the CERN Large Hadron Collider is supported by a variety of simulation calculations, based on the GARFIELD drift chamber simulation program and the GEANT detector simulation package. This study surveys the results influencing the actual chamber design. The dependence of the drift cell performance on shape and position of the cell electrodes as well as on the mechanical tolerances is shown. The results obtained for space-time relation and spatial resolution are in good agreement to test beam measurements on prototypes.

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

Abstract A new detector of ionizing particles, the Proportional Inclined Chamber, is described. The detector provides a resolution better than 100 μm in the measured coordinate, independent in first approximation of drift velocity variations. It has good, about 300 μm two-track resolution and gives a rough measurement of the angle of the track with a resolution of about 1°. Results obtained with PIC in physics experiments at the European Hybrid Spectrometer are reported.

A module of a wireless high voltage generator was tested immersed in both gaseous and liquid environments providing electrical insulation. The overall performance of the module as well as a detailed performance of the key components are reported, and a comparison between the results in gas and liquid is given. The tests performed on the liquid dielectric show that it is a valid alternative to high pressure gas electrical insulation.

A thin silicon diode formed by a deep p/sup +/ implantation under a shallow n/sup +/ one is proposed as a solid state microdosimeter. The thickness of the sensitive volume of the tested device is about two micrometers and the active area is about ten millimeters square. Due to the very large electric capacitance of the diode (about 1 nF) a low noise read-out circuit based on a discrete JFET has been developed. The noise due to the parasitic resistance of the detector itself dominates and fixes the lower threshold of the energy spectrum. A prototype of the proposed microdosimeter covered with a polyethylene converter has been irradiated with fast monoenergetic neutrons at the INFN-Legnaro Labs (I). The first experimental spectra are in good agreement with the simulated ones. The effect of direct interactions of thermal neutrons in silicon has been measured.

Several irradiation tests of the electronics of the CMS barrel muon detector were performed using neutrons, protons and heavy ions. The Single Event Upset rate on some tested devices was measured, while upper limits were obtained for devices having experienced no failure. Single Event Transients on front-end electronics and destructive effects on the High-voltage distribution electronics were observed. Overcurrent protection and error correction circuits were included in the irradiated boards and were tested.

The operation of the compact muon solenoid drift tubes (DTs) muon detectors at the high-luminosity large hadron collider will be possible only with an upgrade of the current readout and trigger electronics, which are based on very old technology and directly exposed to radiation, hence particularly sensitive to aging. A new level 1 trigger primitive generator, based on the use of an original compact Hough transform (CHT) algorithm, is being designed with the goal of its implementation in the state-of-the-art field programmabla gate array (FPGA) devices. The algorithm can identify the muon track segment parameters and must be combined with a majority mean-timer in order to assign the muon to its parent bunch crossing. The algorithm is expected to be deployed on FPGAs and has a few μs latency for decision taking, with efficiency and resolution equal or higher with respect to the ones provided by the currently running algorithm. The major challenges are parallelization of the algorithm, fast readout of the CHT parameter matrix, the capability of handling data from a large array of DTs in the minimal number of FPGAs, and coping with the latency requirements. These issues will be addressed proposing constructive solutions.

A complete description of the CMS muon detector is given. Results of the research and development studies on the chamber prototypes and on the trigger strategy are reported.

The momentum and angular distributions of punchthrough muons have been measured after a 10 λ calorimeter using an iron toroid magnet with 1.5 T as spectrometer. The calorimeter was inside a variable magnetic field of 0 to 3 T. The incident momentum of the π− beam ranged from 20 to 300 GeV/c. Measurements were also done at some beam momenta for π+, K+ and p. The results are compared with Monte Carlo predictions. A parameterization for the momentum spectrum of punchthrough muons was derived from the data.

We investigated the possibility to use a liquid as insulator in a High Voltage generator which is wireless powered by a laser system. The liquid must be transparent to the laser light wavelength, must not attack the control circuits, which are immersed in it, and the support materials. An adequately performing liquid was identified and we characterized the liquid performance in intense electric field, by measuring its breakdown voltage and the leakage current, and checked its optical and thermal behaviour.

The first running implementation on FPGA of a histogram-based trigger primitive generator for the CMS Drift Tubes at the High Luminosity LHC is presented. The foreseen architecture requires that raw charge collection times, measured for each tube by means of a TDC, are processed in the back-end to generate trigger primitives, identifying the parent bunch crossing and measuring the track parameters. We review the design of a parent bunch crossing evaluation, its implementation on FPGAs of the Xilinx UltraScale family by means of High-Level Synthesis, and the performance of a demonstrator board of such a trigger.

A proton-recoil spectrometer for neutrons was realized by coupling a commercial P-I-N photodiode with a polyethylene radiator. The minimum and maximum neutron energies which can be detected depend on the thickness of the depletion layer (i.e on the diode bias voltage). It is worth mentioning that the detector has proved to work unbiased, exploiting the field funnelling effect. This effect is due to a local distortion of the electric field in the depletion layer, leading to the collection of pairs produced in the substrate. The response functions were measured by irradiating the spectrometer with monoenergetic neutron beams, generated at the Van De Graaff accelerator of the Legnaro National Laboratories. Monte Carlo simulations were also performed with the FLUKA code. The effect of secondary charged particles produced by thermal and fast neutrons interactions in the silicon device was also investigated.

The total punchthrough probability of showers produced by negative pions, positive pions, positive kaons and protons, has been measured as a function of depth in an absorber in a magnetic field ranging from 0 to 3 Tesla. The incident particle momentum varied from 10 to 300 GeV/c. The lateral shower development and particle multiplicity at several absorber depths have been determined. The measurements are compared with the predictions of Monte Carlo simulation programs.