N. Tosi

Abstract The Deep Underground Neutrino Experiment (DUNE) is a next generation experiment aimed to study neutrino oscillation. Its long-baseline configuration will exploit a Near Detector (ND) and a Far Detector (FD) located at a distance of ∼1300 km. The FD will consist of four Liquid Argon Time Projection Chamber (LAr TPC) modules. A Photon Detection System (PDS) will be used to detect the scintillation light produced inside the detector after neutrino interactions. The PDS will be based on light collectors coupled to Silicon Photomultipliers (SiPMs). Different photosensor technologies have been proposed and produced in order to identify the best samples to fullfill the experiment requirements. In this paper, we present the procedure and results of a validation campaign for the Hole Wire Bonding (HWB) MPPCs samples produced by Hamamatsu Photonics K.K. (HPK) for the DUNE experiment, referring to them as `SiPMs'. The protocol for a characterization at cryogenic temperature (77 K) is reported. We present the down-selection criteria and the results obtained during the selection campaign undertaken, along with a study of the main sources of noise of the SiPMs including the investigation of a newly observed phenomenon in this field.

In this paper we present a study of the neutrons-induced damage in Silicon Photo-Multipliers. Twenty-six devices, produced by AdvanSiD, Hamamatsu and SensL, have been irradiated at the Geel Electron LINear Accelerator (GELINA) in Belgium with a nearly white neutron beam. The total 1 MeV equivalent integrated dose was 6.2 × 109 neq/cm2. Photodetector performances have been measured during the whole irradiation period and a gradual worsening of the detector properties, such as dark current and charge spectra, has been observed. An extensive comparison of the performances of all the tested devices will be presented.

The Pixel Luminosity Telescope is a silicon pixel detector dedicated to luminosity measurement at the CMS experiment at the LHC. It is located approximately 1.75 m from the interaction point and arranged into 16 "telescopes", with eight telescopes installed around the beam pipe at either end of the detector and each telescope composed of three individual silicon sensor planes. The per-bunch instantaneous luminosity is measured by counting events where all three planes in the telescope register a hit, using a special readout at the full LHC bunch-crossing rate of 40 MHz. The full pixel information is read out at a lower rate and can be used to determine calibrations, corrections, and systematic uncertainties for the online and offline measurements. This paper details the commissioning, operational history, and performance of the detector during Run 2 (2015-18) of the LHC, as well as preparations for Run 3, which will begin in 2022.

The light yield and the time resolution of different types of 3 m long scintillating bars instrumented with wavelength shifting fibres and read out by different models of silicon photomultipliers have been measured at a test beam at the T9 area at the CERN Proton Synchrotron. The results obtained with different configurations are presented. A time resolution better than 800 ps, constant along the bar length within 20%, and a light yield of ~ 140 (70) photoelectrons are obtained for bars 3 m long, 4.5 (5) cm wide and 2 (0.7) cm thick. These results nicely match the requirements for the Muon Detector of the SHiP experiment.

We studied the light collection in plastic scintillator strips, optimized for the detection of Minimum Ionizing Particles (MIPs). The light is collected by Wave Length Shifter (WLS) fibers and detected by Silicon Photo Multipliers (SiPMs). The study is based on prototypes developed for the muon detector of SuperB experiment. In parallel to measurement made on various type of geometries, a complete simulation suite, based on FLUKA, was developed. The simulation parameters were tuned by comparison with real data. In this way, we were able to study the effects of geometries and assembling procedures on light collection and provide a useful simulation tool for the design of future prototypes.

A novel Beam Halo Monitor (BHM) has been designed and built for the CMS experiment at the LHC. It will provide an online, bunch-by-bunch measurement of background particles created by interactions of the proton beam with residual gas molecules in the vacuum chamber or with collimator material upstream of CMS. The BHM consists of two arrays of twenty detectors that are mounted around the outer forward shielding of the CMS experiment. Each detector is comprised of a cylindrical quartz radiator, optically coupled to a fast ultraviolet-sensitive photomultiplier tube from one end and painted black at the opposite end. Particles moving towards the photomultiplier tube will be detected with time resolution of a few nanoseconds, allowing to measure the flux of background particles produced upstream of CMS and suppress signals from collision-induced products. Monte Carlo simulations were performed to optimise the detector design. Prior to installation, the performance of the prototype detectors was measured in test beams quantifying the detector's direction-sensitive response and time resolution. The BHM was installed during the first LHC long shutdown (LS1) and is currently being commissioned. Design considerations, results from the test-beams supporting the design and the installation of the BHM in the CMS are presented.

Abstract The light yield, the time resolution and the efficiency of different types of scintillating tiles with direct Silicon Photomultiplier readout and instrumented with a customised front-end electronics have been measured at the Beam Test Facility of Laboratori Nazionali di Frascati and several test stands. The results obtained on minimum ionising particles with different detector configurations are presented. A time resolution of the order of 300 ps, a light yield of more than 230 photo-electrons, and an efficiency better than 99.8% are obtained with ∼ 225 cm 2 large area tiles. This technology is suitable for a wide range of applications in high-energy physics, in particular for large area muon and timing detectors.

We report radiation hardness tests performed, with a white neutron beam, at the Geel Electron LINear Accelerator in Belgium on silicon Photo-Multipliers. These are semiconductor photon detectors made of a square matrix of Geiger-Mode Avalanche photo-diodes on a silicon substrate. Several samples from different manufacturers have been irradiated integrating up to about 6.2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> 1-MeV-equivalent neutrons per cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

The Silicon Photomultiplier (SiPM) is a silicon device capable of single photon detection that was developed in the late '90s. It is very promising for High Energy Physics and Medical applications. In order to simplify the operation of such a device for the R&D of small detector prototypes in laboratory and test beams, we developed a versatile readout and control system. It is based on a custom electronic board that contains both the analog front-end and the digital acquisition section for eight channels. The system can be easily adapted to a specific setup and provides the biasing, calibration and gain monitoring of SiPMs as well the triggering functionalities and the collection of integrated charge information of the detector under test.

The capture of scintillation light emitted by liquid Argon and Xenon under molecular excitations by charged particles is still a challenging task. Here we present a first attempt to design a device able to grab sufficiently high luminosity in order to reconstruct the path of ionizing particles. This preliminary study is based on the use of masks to encode the light signal combined with single-photon detectors. In this respect, the proposed system is able to detect tracks over focal distances of about tens of centimeters. From numerical simulations it emerges that it is possible to successfully decode and recognize signals, even complex, with a relatively limited number of acquisition channels. Such innovative technique can be very fruitful in a new generation of detectors devoted to neutrino physics and dark matter search. Indeed the introduction of coded masks combined with SiPM detectors is proposed for a liquid-Argon target in the Near Detector of the DUNE experiment.

The CMS Beam Halo Monitor has been successfully installed in the CMS cavern in LHC Long Shutdown 1 for measuring the machine induced background for LHC Run II. The system is based on 40 detector units composed of synthetic quartz Cherenkov radiators coupled to fast photomultiplier tubes (PMTs). The readout electronics chain uses many components developed for the Phase 1 upgrade to the CMS Hadronic Calorimeter electronics, with dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal is digitized by a charge integrating ASIC (QIE10), providing both the signal rise time, with few nanosecond resolution, and the charge integrated over one bunch crossing. The backend electronics uses microTCA technology and receives data via a high-speed 5 Gbps asynchronous link. It records histograms with sub-bunch crossing timing resolution and is read out via IPbus using the newly designed CMS data acquisition for non-event based data. The data is processed in real time and published to CMS and the LHC, providing online feedback on the beam quality. A dedicated calibration monitoring system has been designed to generate short triggered pulses of light to monitor the efficiency of the system. The electronics has been in operation since the first LHC beams of Run II and has served as the first demonstration of the new QIE10, Microsemi Igloo2 FPGA and high-speed 5 Gbps link with LHC data.

In this paper we present a study of the neutrons-induced damage in Silicon Photo-Multipliers. Twenti-six devices, produced by AdvanSiD, Hamamatsu and SensL, have been irradiated at the Geel Electron LINear Accelerator (GELINA) in Belgium on a nearly white neutron beam. The total 1 MeV equivalent integrated dose was 6.2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eq</sub> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Photodetector performances have been measured during the whole irradiation period and a gradual worsening of the detector properties, like dark current and charge spectra, has been observed. An extensive comparison of the performances of all the devices will be presented.

In the context of increasing beam energy and luminosity of the LHC accelerator at CERN, it will be important to accurately measure the Machine Induced Background. A new monitoring system will be installed in the CMS cavern for measuring the beam background at high radius. This detector, called the Beam Halo Monitor, will provide an online, bunch-by-bunch measurement of background induced by beam halo interactions, separately for each beam. The detector is composed of synthetic quartz Cherenkov radiators, coupled to fast UV sensitive photomultiplier tubes. The directional and fast response of the system allows the discrimination of the background particles from the dominant flux in the cavern induced by pp collision debris, produced within the 25 ns bunch spacing. The readout electronics of this detector will make use of many components developed for the upgrade of the CMS Hadron Calorimeter electronics, with a dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal will be digitized by a charge integrating ASIC, providing both the signal rise time and the charge integrated over one bunch crossing. The backend electronics will record bunch-by-bunch histograms, which will be published to CMS and the LHC using the newly designed CMS beam instrumentation specific DAQ. A calibration and monitoring system has been designed to generate triggered pulses of UV light to monitor the efficiency of the system. The experimental results validating the design of the detector, the calibration system and the electronics will be presented.

SHiP is a new proposed beam dump experiment at the SPS to Search for Hidden Particles beyond the Standard Model. It is composed of several subdetectors, of which the most downstream is dedicated to the identification of muons. The muon detector will cover an area of 6×12m and will be equipped with 3 planes of scintillator interposed with iron absorbers. In the SHiP experiment, one of the main contributions to the generally very small background is the caused by combinatorial muon tracks accidentally mimicking a signal signature by forming a fake vertex in the fiducial volume. This background can be reduced by requiring the tracks that form a vertex to be within a very short time window. This drives the requirement of the detector time resolution, while its spatial resolution is not as critical. In order to cover such a large area with a fast and robust detector, a system based on 200 cm2 scintillator tiles, read out at the corners by SiPMs, has been developed, which improves over the baseline described in the SHiP Technical Proposal. Measurements indicate that the timing resolution can be pushed below 300 ps; this contribution will present optimization studies aimed at maximizing performance, as well as test beam results on the first prototypes.

We propose a new beam-dump experiment, SHADOWS, to search for a large variety of feebly-interacting particles possibly produced in the interactions of a 400 GeV proton beam with a high-Z material dump. SHADOWS will use the 400 GeV primary proton beam extracted from the CERN SPS currently serving the NA62 experiment in the CERN North area and will take data off-axis when the P42 beam line is operated in beam-dump mode. SHADOWS can accumulate up to a ~2 x10^19 protons on target per year and expand the exploration for a large variety of FIPs well beyond the state-of-the-art in the mass range of MeV-GeV in a parameter space that is allowed by cosmological and astrophysical observations. So far the strongest bounds on the interaction strength of new feebly-interacting light particles with Standard Model particles exist up to the kaon mass; above this threshold the bounds weaken significantly. SHADOWS can do an important step into this still poorly explored territory and has the potential to discover them if they have a mass between the kaon and the beauty mass. If no signal is found, SHADOWS will push the limits on their couplings with SM particles between one and four orders of magnitude in the same mass range, depending on the model and scenario.

In the context of increasing luminosity of LHC, it will be important to accurately measure the Machine Induced Background.A new monitoring system will be installed in the cavern of the Compact Muon Solenoid (CMS) experiment for measuring the beam background at high radius.This detector is composed of synthetic quartz Cherenkov radiators, coupled to fast photomultiplier tubes (PMT).The readout chain of this detector will make use of many components developed for the Phase 1 upgrade to the CMS Hadron Calorimeter electronics, with a dedicated firmware and readout adapted to the beam monitoring requirements.The PMT signal will be digitized by a charge integrating ASIC (QIE10), providing both the signal rise time and the charge integrated over one bunch crossing.The backend electronics will record bunch-by-bunch histograms, which will be published to CMS and the LHC using the newly designed CMS beam instrumentation specific DAQ.A calibration monitoring system has been designed to generate triggered pulses of light to monitor the efficiency of the system.

Figure 1 kQ of modelled NE2561 chamber with beams with the flattening filter (closed shapes), beams with the flattening filter removed (open shapes) and beams with thin replacement filter (red shapes).(a) shows the results for Elekta beams and (b) shows the results for Varian beams.The dashed grey line shows the average of kQ from TRS-398 and Muir et al. Conclusion:The average difference between linac outputs measured with TRS-398 and TG-51 protocols was less than 0.2 % for 6 MV FFF and 10 MV FFF.Modelling suggests a 2-3 mm metal plate used in place of the flattening filter offers sufficient filtration for the FFF beam to produce a similar kQ to WFF beams.

Introduction: IORT breast carcinoma treatment clinical practice has evidenced the need of real time monitoring the dose delivery on the target. The commercially available in vivo dosimetry technologies allow either a real time measurement in one point (MOSFET type detectors) or a non real time measurement over a surface (radio chromic films). A cooperation between ASMN Reggio Emilia, INFN and SIT has led to the conceptual design of a new device capable of satisfying the above mentioned needs. Such device has been patented (Italian Patent # TO2014A000943). The new dosimeter consists in four leaf shaped plastic scintillators positioned between the two parts of the radiation protection disc. Such device can measure in real time the dose in the four sectors, providing both the integral dose and a measurement of the field symmetry on the target.

A fast and directional monitoring system for the CMS experiment is designed to provide an online, bunch-by-bunch measurement of beam background induced by beam halo interactions, separately for each beam.The background detection is based on Cherenkov radiation produced in synthetic fused silica read out by a fast, UV sensitive photomultiplier tube.Twenty detector units per end will be azimuthally distributed around the rotating shielding of CMS, covering ~408 cm 2 at 20.6m from the interaction point, at a radius of ~180 cm.The directional and fast response of the system allows the discrimination of the background particles from the dominant flux in the cavern induced by pp collision debris, produced within the 25 ns bunch spacing.A robust multi-layered shielding will enclose each detector unit to protect the photomultiplier tube from the magnetic field and to eliminate the occupancy from low energy particles.The design of the front-end units is validated by experimental results.An overview of the new system to be integrated in CMS during the current shutdown of LHC will be presented, and its perspective for monitoring in High Luminosity LHC.

The superB project foresees the construction of a high intensity super-flavor factory at the Cabibbo Lab, in Tor Vergata (near Rome). The experiment, based on a high intensity asymmetric electron-positron collider, and on the related detector, is expected to reach a very high luminosity: 2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">36</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , that will allow the high statistic study of rare decays and, possibly, will show evidences of new physics. The Muon Detector plays the fundamental role of identifying (mainly) muons tracks, present in many important decays. In order to cope with the very high particle flux, the detector must provide a very fast response and has to be very robust with respect to radiation damage and aging effects. The adopted technique exploits extruded plastic scintillators as active material, WLS fibers for the light collection and Silicon Photon Multipliers (SiPM) as photo-detectors In this manuscript, a complete description of the designed Muon detector and of all the related studies will be presented. In particular, we will focus on the results of a beam tests performed at Fermilab on a large scale prototype and on radiation tests of the most sensitive parts of the detector.

In the CMS experiment, the Fast Beam Conditions Monitor provides an online, bunch-by-bunch measurement of luminosity and machine induced background. The Beam Pickup Transformer provides a precise measurement of beam intensity and arrival time. Upgraded back-end electronics have been developed for the Beam Conditions Monitor, based on the μTCA standard. This system is slated to replace the current readout systems of both detectors for the next LHC run.