Search

A new fibre-sampling dual-readout calorimeter prototype has been qualified on beam at two facilities (DESY and CERN) using electrons from 1 to 100 GeV. The prototype was designed to almost fully contain electromagnetic showers and a central module (highly granular readout) was equipped with 320 Silicon Photomultipliers (SiPMs) spaced by 2 mm and individually read out. The test beams performed in 2021, allowed to qualify the readout boards used to operate the SiPMs, to define the calibration procedure and to measure the light yield for scintillating and Cherenkov signals produced by the shower development. This paper reports the first results obtained with the highly granular readout and discusses the ongoing R&D to address some open questions concerning the mechanical integration and the scalable readout scheme that will allow to build and operate the next prototype designed for hadronic showers containment. [ABSTRACT FROM AUTHOR]

A high detection efficiency thermal neutron detector based on the 6LiF/ZnS(Ag) scintillation screens, wavelength-shifting fibers (WLSF) and Silicon photomultiplier (SiPM) readout is under development at China Spallation Neutron Source (CSNS) for the Engineering Material Diffractometer (EMD).A prototype with a sensitive volume of 180mm×192mm has been built. Signals from SiPMs are processed by the self-design Application Specific Integrated Circuit (ASIC).The performances of this detector prototype are as follows: neutron detection efficiency could reach 50.5% at 1 Å, position resolution of 3, the dark count rate 200KHz. Such detector prototype could be an elementary unit for applications in the EMD detector arrays.

Purpose: Detectors for positron emission tomography (PET) typically use two types of scintillation crystals, pixelated or monolithic. A variant of these types of scintillators are the so‐called semi‐monolithic crystals. They consist of a monolithic crystal segmented in one direction in pieces called slabs. These scintillators have the potential to successfully combine the benefits of pixelated and monolithic configurations, providing good timing and spatial resolutions as well as the capacity to decode the depth of interaction (DOI) information. In this work, the timing performance of a detector based on semi‐monolithic crystals was studied in depth. The energy response was also evaluated. Methods: The semi‐monolithic detector consists of 1 × 24 LYSO slabs of 25.4 × 12 × 0.95 mm3 each. The bottom surface of the slabs is coupled to an array of 8 × 8 silicon photomultipliers (SiPMs) of 3 × 3 mm2 active area, 50 μm cell size and 3.2 mm pitch. The 64 output signals were independently readout by the TOFPET2 ASIC. In order to achieve the best coincidence time resolution (CTR), four different time walk corrections were tested. Additional work investigated the best method of combining the timestamps belonging to the same event. Results: The resolvability of the slabs in the measured flood maps improves with the thickness of a light guide placed in between the scintillators and photosensors. The energy resolution does not change significantly with values as good as 13.7%. Regarding the CTR, values of 335.8, 363, 369.8, and 402.5 ps have been obtained for the whole detector for no light guide, 0.5, 1.0, and 1.5 mm thickness light guide cases, respectively. These values further improve to 276.1, 302.6, 305.6 and 336.2 ps, respectively, when energy‐weighted averaging of timestamps is applied. Conclusions: We have shown both an excellent timing resolution and good energy resolution for a PET detector based on semi‐monolithic crystals. The use of light guides of different thicknesses does not significantly affect the energy resolution of the whole detector, but the timing capabilities slightly worsen with the increasing thickness of the light guide. [ABSTRACT FROM AUTHOR]

A new fibre-sampling dual-readout calorimeter prototype has been qualified on beam at two facilities (DESY and CERN) using electrons from 1 to 100 GeV. The prototype was designed to almost fully contain electromagnetic showers and a central module (highly granular readout) was equipped with 320 Silicon Photomultipliers (SiPMs) spaced by 2 mm and individually read out. The test beams performed in 2021, allowed to qualify the readout boards used to operate the SiPMs, to define the calibration procedure and to measure the light yield for scintillating and Cherenkov signals produced by the shower development. This paper reports the first results obtained with the highly granular readout and discusses the ongoing R&D to address some open questions concerning the mechanical integration and the scalable readout scheme that will allow to build and operate the next prototype designed for hadronic showers containment.

Monolithic scintillators are more frequently used in PET instrumentation due to their advantages in terms of accurate position estimation of the impinging gamma rays both planar and depth of interaction, their increased efficiency, and expected timing capabilities. Such timing performance has been studied when those blocks are coupled to digital photosensors showing an excellent timing resolution. In this work we study the timing behaviour of detectors composed by monolithic crystals and analog SiPMs read out by an ASIC. The scintillation light spreads across the crystal towards the photosensors, resulting in a high number of SiPMs and ASIC channels fired. This has been studied in relation with the Coincidence Timing Resolution (CTR). We have used LYSO monolithic blocks with dimensions of 50 × 50 × 15 mm3 coupled to SiPM arrays (8 × 8 elements with 6 × 6 mm2 area) which compose detectors suitable for clinical applications. While a CTR as good as 186 ps FWHM was achieved for a pair of 3 × 3 × 5 mm3 LYSO crystals, when using the monolithic block and the SiPM arrays, a raw CTR over 1 ns was observed. An optimal timestamp assignment was studied as well as compensation methods for the time-skew and time-walk errors. This work describes all steps followed to improve the CTR. Eventually, an average detector time resolution of 497 ps FWHM was measured for the whole thick monolithic block. This improves to 380 ps FWHM for a central volume of interest near the photosensors. The timing dependency with the photon depth of interaction and planar position are also included. [ABSTRACT FROM AUTHOR]

In this paper we report on the characterization of the Hamamatsu VUV4 (S/N: S13370-6152) Vacuum Ultra-Violet (VUV) sensitive Multi-Pixel Photon Counters (MPPC)s as part of the development of a solution for the detection of liquid xenon scintillation light for the nEXO experiment. Various MPPC features, such as: dark noise, gain, correlated avalanches, direct crosstalk and Photon Detection Efficiency (PDE) were measured in a dedicated setup at TRIUMF. MPPCs were characterized in the range 163 K ≤ T ≤ 233 K. At an over voltage of 3. 1 ± 0. 2 V and at T = 163 K we report a number of Correlated Avalanches (CAs) per pulse in the 1 μ s interval following the trigger pulse of 0. 161 ± 0. 005. At the same settings the Dark-Noise (DN) rate is 0. 137 ± 0. 002 Hz/mm 2. Both the number of CAs and the DN rate are within nEXO specifications. The PDE of the Hamamatsu VUV4 was measured for two different devices at T = 233 K for a mean wavelength of 189 ± 7 nm. At 3. 6 ± 0. 2 V and 3. 5 ± 0. 2 V of over voltage we report a PDE of 13. 4 ± 2. 6 % and 11 ± 2 % , corresponding to a saturation PDE of 14. 8 ± 2. 8 % and 12. 2 ± 2. 3 % , respectively. Both values are well below the 24 % saturation PDE advertised by Hamamatsu. More generally, the second device tested at 3. 5 ± 0. 2 V of over voltage is below the nEXO PDE requirement. The first one instead yields a PDE that is marginally close to meeting the nEXO specifications. This suggests that with modest improvements the Hamamatsu VUV4 MPPCs could be considered as an alternative to the FBK-LF Silicon Photo-Multipliers for the final design of the nEXO detector. [ABSTRACT FROM AUTHOR]

The Mu2e experiment at Fermilab will search for the charged-lepton flavor violating neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus. The calorimeter plays an important role in providing a fast trigger filter, excellent particle identification and a seeding for track reconstruction. Its requirements are to provide an energy (timing) resolution better than 10% (0.5 ns) and a position resolution below 1 cm, for 100 MeV electrons. The calorimeter consists of two disks, each one made of 674 un-doped CsI crystals readout by two large area arrays of 2 × 3 UV-extended SiPMs of 6 × 6 mm 2 dimensions. A large scale prototype (Module-0) has been constructed and tested with an electron beam in the energy range between 60 and 120 MeV at the BTF of Frascati National Laboratories. Results demonstrated that this calorimeter satisfies the Mu2e requirements. [ABSTRACT FROM AUTHOR]

Abstract We present characterization results of two silicon photomultipliers; the Hamamatsu LVR-6050-CN and the Ketek PM3325 WB. With our measurements of the bias dependence of the breakdown probability we are able to draw conclusions about the location and spatial extension of the avalanche region. For the KETEK SiPM we find that the avalanche region is located close to the surface. In the Hamamatsu SiPM the high-field region is located 0. 5 μ m below the surface, while the volume above is depleted almost until the surface. Furthermore, for the Hamamatsu SiPM we find that charge carriers produced by optical-crosstalk photons enter a cell below the avalanche region as opposed to an earlier device where most of the photoelectrons enter a cell from above. The present paper is an attempt to spur further interest in the use of the bias dependence of the breakdown probability and establish it as a standard tool not only to determine the location of the high-field region but also to determine the origin of charge carriers relative to the high-field region. With the knowledge of where the charges come from it should be possible to further improve the optical crosstalk, dark count, and afterpulsing characteristics of SiPM. [ABSTRACT FROM AUTHOR]

Abstract The IRIS group of IFIC-Valencia is developing a Compton telescope for treatment monitoring in hadron therapy. The system is composed of three detector layers, each of them consisting of a monolithic LaBr 3 scintillator crystal coupled to Silicon Photomultiplier (SiPM) arrays. A first version of the prototype was developed within the European project ENVISION. Tests with point-like sources and in-beam were carried out with successful results, demonstrating the feasibility of the proposed technology. The limitations of the system were also identified. A new version of the prototype is under development with the aim of improving the performance of the telescope detector planes. To this end, the initial tests of a detector plane based on a new SiPM array have been carried out. The first characterization, coincidence and imaging tests with this new version of the detector plane are presented. In addition, the suitability of CeBr 3 scintillator crystals for this application is being investigated. Highlights • An improved version of a Compton telescope for hadron therapy is under development. • First characterization, coincidence and imaging tests have been carried out. • Results show a general improvement of the system performance. [ABSTRACT FROM AUTHOR]

The design of a radioxenon detection system utilizing a CdZeTe crystal and a plastic scintillator coupled to an array of SiPMs to conduct beta-gamma coincidence detection for atmospheric radioxenon monitoring, as well as the measurement of 135 Xe and 133∕133m Xe, have been detailed previously. This paper presents recent measurements of 133∕133m Xe and 131m Xe and the observation of conversion electrons in their coincidence spectra, as well as a 48-hour background measurement to calculate the Minimum Detectable Concentration (MDC) of radioxenon isotopes in the system. The identification of Regions of Interest (ROIs) in the coincidence spectra yielded from the radioxenon measurements, and the subsequent calculation of the MDCs of the system for 135 Xe, 133∕133m Xe, and 131m Xe, are also discussed. Calculated MDCs show that the detection system preforms respectably when compared to other state of the art radioxenon detection systems and achieved an MDC of less than 1 mBq/m 3 for 131m Xe, 133 Xe, and 133m Xe, in accordance with limits set by the Comprehensive Nuclear-Test-Ban Treaty (CTBTO). The system also provides the advantage of room temperature operation, compactness, low noise operation and having simple readout electronics. [ABSTRACT FROM AUTHOR]

The high energy physics community has recently identified an e + e − Higgs factory as one of the next-generation collider experiments, following the completion of the High Luminosity LHC program at CERN. The moderate radiation levels expected at such colliders compared to hadron colliders, enable the use of less radiation tolerant but cheaper technologies for the construction of the particle detectors. This opportunity has triggered a renewed interest in the development of scintillating glasses for the instrumentation of large detector volumes such as homogeneous calorimeters. While the performance of such scintillators remains typically inferior in terms of light yield and radiation tolerance compared to that of many scintillating crystals, substantial progress has been made over the recent years. In this paper we discuss the time resolution of cerium-doped Alkali Free Fluorophosphate scintillating glasses, read-out with silicon photo-multipliers in detecting single charged tracks and at different positions along the longitudinal development of an electromagnetic shower, using respectively 150 GeV pions and 100 GeV electron beams at the CERN SPS H2 beam line. A single sensor time resolution of 14.4 ps and 5–7 ps was measured respectively in the two cases. With such a performance the present technology has the potential to address an emerging requirement of future detectors at collider experiments: measuring the time-of-flight of single charged particles as well as that of neutral particles showering inside the calorimeter and the time development of showers. [ABSTRACT FROM AUTHOR]

This paper presents the design and characterization of a prototype compact beta-gamma radioxenon detection system that utilizes a coplanar CdZnTe crystal, an array of SiPMs, and a plastic scintillator. The detector is directly mounted on a custom PCB. The system provides the advantage of room-temperature operation, while being compact, low noise, and with simple readout electronics. Preliminary measurements using Cs, Xe, and Xe were conducted to optimize various system parameters to achieve optimal resolution of key photopeaks. The purpose of this research was to explore the potential of these radiation detection elements for use in beta-gamma coincidence applications. [ABSTRACT FROM AUTHOR]

There is an increasing interest to use silicon photomultipliers (SiPMs) in medical applications like Photoplethysmography or Functional Near Infrared Spectroscopy, allowing the monitoring of physiological signs through non-invasive equipment. The use of large area SiPMs with embedded color filters for environmental light rejection could bring relevant advantages in these applications in terms of higher signal-to-noise ratio of the measurements. Here, we report on the first electro-optical characterization results obtained on n-on-p SiPMs with green interference bandpass filters glued on the top side of the detector SMD package. We will show how the use of the filter considerably increases, especially for large overvoltage values, the SiPM dark noise rate, due to the significant amplification of optical cross-talk effects (up to 150% of dark current increase at 50%-OV). This makes necessary a careful evaluation of the SiPMs performances in order to define the best operating conditions and layout characteristics of the detectors that will be used in the final applications. [ABSTRACT FROM PUBLISHER]

We report the performances of a compact gamma-ray detection prototype, based on a 2" LaBr 3 scintillator crystal coupled to a matrix of 64 SiPMs, designed as a single unit for a future SPECT system for dose monitoring in BNCT. The aim of the module is to detect the 478 keV gamma rays emitted by the boron neutron capture reactions, in order to map the 10B distribution in the patient. The spectroscopic capabilities of the module have been validated by irradiating borated vials with thermal neutrons fluxes in the order of 1 × 105 n/cm2/s. The good energy resolution of the detector (2.7% at 662 keV) has allowed to resolve the boron neutron capture photopeak, achieving excellent linear correlation between the number of detected events at 478 keV and the boron concentration in the vials irradiated. Preliminary imaging results based on a Convolutional Neural Network and obtained by irradiating a 5 cm × 5 cm × 2 cm square crystal with a 1 mm collimated 137Cs source (662 keV) are also reported. [ABSTRACT FROM AUTHOR]

The ORIGIN project targets the production and qualification of a real-time radiation dose imaging and source localization system for both Low Dose Rate (LDR) and High Dose Rate (HDR) brachytherapy treatments, namely radiotherapy based on the use of radioactive sources implanted in the patient's body. This goal will be achieved through a 16-fiber sensor system, engineered to house in a clear-fiber tip a small volume of the scintillator to allow point-like measurements of the delivered dose. Each fiber is optically coupled to a sensor with single photon sensitivity (Silicon Photomultipliers — SiPMs) operating in counting mode. The readout is based on the CITIROC1A ASIC by WEEROC, embedded in the FERS-DT5202 scalable platform designed by CAEN S.p.A. Linearity and sensitivity together with the fiber response uniformity, system stability, and measurement reproducibility are key features for a instrument aiming to perform dose measurements. Characterization was carried out in the laboratory, using an X-ray cabinet; preliminary dose rate measurements were performed in clinical conditions. [ABSTRACT FROM AUTHOR]

A recent entry into the rapidly evolving field of integrated PET/MR scanners is presented in this paper: a whole body hybrid PET/MR system (SIGNA PET/MR, GE Healthcare) capable of simultaneous acquisition of both time-of-flight (TOF) PET and high resolution MR data. The PET ring was integrated into an existing 3T MR system resulting in a (patient) bore opening of 60 cm diameter, with a 25 cm axial FOV. PET performance was evaluated both on the standalone PET ring and on the same detector integrated into the MR system, to assess the level of mutual interference between both subsystems. In both configurations we obtained detector performance data. PET detector performance was not significantly affected by integration into the MR system. The global energy resolution was within 2% (10.3% versus 10.5%), and the system coincidence time resolution showed a maximum change of < 3% (385 ps versus 394 ps) when measured outside MR and during simultaneous PET/MRI acquisitions, respectively. To evaluate PET image quality and resolution, the NEMA IQ phantom was acquired with MR idle and with MR active. Impact of PET on MR IQ was assessed by comparing SNR with PET acquisition on and off. B0 and B1 homogeneities were acquired before and after the integration of the PET ring inside the magnet. In vivo brain and whole body head-to-thighs data were acquired to demonstrate clinical image quality. [ABSTRACT FROM AUTHOR]

We describe a new positron emission time-of-flight apparatus using liquid xenon. The detector is based in a liquid xenon scintillating cell. The cell shape and dimensions can be optimized depending on the intended application. In its simplest form, the liquid xenon scintillating cell is a box in which two faces are covered by silicon photomultipliers and the others by a reflecting material such as Teflon. It is a compact, homogenous and highly efficient detector which shares many of the desirable properties of monolithic crystals, with the added advantage of high yield and fast scintillation offered by liquid xenon. Our initial studies suggest that good energy and spatial resolution comparable with that achieved by lutetium oxyorthosilicate crystals can be obtained with a detector based in liquid xenon scintillating cells. In addition, the system can potentially achieve an excellent coincidence resolving time of better than 100 ps. [ABSTRACT FROM AUTHOR]

The Phase 1 upgrade of the CMS Hadron Calorimeter (HCAL) involved the installation of new silicon photomultiplier devices (SiPMs), which replaced older hybrid photodiodes (HPDs). SiPMs measure the scintillator light output with better signal/noise. The upgraded readout electronics also allow for increased longitudinal segmentation and better performance. This report describes the design, testing, installation, and commissioning of the HCAL Barrel Phase 1 upgrade. Performance results for the HCAL Endcap during Run 2 are presented and expectations for the HCAL Barrel during Run 3 are discussed. [ABSTRACT FROM AUTHOR]

We report the experimental validation of a detection module based on a LaBr 3 (Ce＋Sr) scintillator crystal, read by a matrix of Silicon Photomultipliers (SiPMs), for the development of a SPECT system for dose monitoring in Boron Neutron Capture Therapy (BNCT). The goal of the system is to detect the gamma rays at 478 keV emitted by the excited 7Li produced in the 10B(n, α)7Li reaction, to have a real-time localization and quantification of the local dose released to a patient during BNCT treatment. The good energy resolution of the detector (< 3 % at 662 keV) allows to resolve the photopeak at 478 keV from the adjacent annihilation photons photopeak at 511 keV, originated from pair production of high energy gamma rays, such as the hydrogen neutron capture gamma rays at 2.2 MeV. The results shown in this article demonstrate the suitability of our detector in view of future application in BNCT real-time dose monitoring. Good linearity (RMSE < 2.5 cps) between the number of events detected at 478 keV and the boron concentration of the 10B-loaded samples has been achieved, down to a boron concentration of 62 ppm with a neutron flux of approximately 1 × 105 n/cm2/s. [ABSTRACT FROM AUTHOR]

We present a first prototype for a multiplicity counter of fast neutrons and γ rays, based on plastic scintillators coupled to silicon photomultiplier arrays, where the SiPMs are read out individually by the TOFPET2 ASIC providing time-stamps and charge information. We demonstrate the capabilities of our counter by measuring the Singles-, Doubles- and Triples-event rates of neutrons and γ rays (without pulse shape discrimination), for a 252Cf source with a nominal activity of 4.9 μ Ci, and comparing them with a GEANT4 simulation of the process. [ABSTRACT FROM AUTHOR]

For simultaneous imaging with fast neutrons and gammas we have developed a 16-pixel detector that uses the organic scintillator stilbene as active material. Sixteen stilbene cuboids of size 5 × 5 × 25 mm 3 are arranged in a 4 × 4 grid and read out by silicon photomultipliers. The usage of stilbene allows to distinguish neutron and gamma signals via pulse shape discrimination techniques. In this paper, attenuation measurements and first tomographies of objects containing aluminum and PMMA are presented. Fast neutrons and gammas are delivered by an Americium–Beryllium source. The performance of the tomographic reconstructions with neutrons and gammas is evaluated. It is shown that the combination of the two images can improve the material distinction in the reconstructed object. [ABSTRACT FROM AUTHOR]

Abstract: In this work we present the energy and spatial resolutions we have obtained for a detector based on a monolithic LYSO crystal coupled to an array of 256 SiPMs. Two crystal configurations of the same trapezoidal shape have been tried. In one approach all surfaces were black painted but the exit one facing the photosensor array which was polished. The other approach included a retroreflector (RR) layer coupled to the entrance face of the crystal powering the amount of transmitted light to the photosensors. Two coupling media between the scintillator and the SiPM array were used, namely direct coupling by means of optical grease and coupling through an array of light guides. Since the same operational voltage was supplied to the entire array, it was needed to equalize their gains before feeding their signals to the Data Acquisition system. Such a job was performed by means of 4 scalable Application Specific Circuits (ASICs). An energy resolution of about 24.4% has been achieved for the direct coupling with the RR layer together with a spatial resolution of approximately 2.9mm at the detector center. With the light guides coupling the effects of image compression at the edges are significantly minimized, but worsening the energy resolution to about 33.1% with a spatial resolution nearing 4mm at the detector center. [Copyright &y& Elsevier]

Abstract: In this work we present a method to efficiently collect scintillation light when using monolithic scintillator crystals. The acceptance angle of the scintillation light has been reduced by means of optical devices reducing the border effect which typically affects continuous crystals. We have applied this procedure on gamma detectors for PET systems using both position sensitive PMTs and arrays of SiPMs. In the case of using SiPMs, this approach also helps to reduce the photosensor active area. We evaluated the method using PMTs with a variety of different crystals with thicknesses ranging from 10 to 24mm. We found that our design allows the use of crystal blocks with a thickness of up to 18mm without degrading the spatial resolution caused by edge effects and without a significant detriment to the energy resolution. These results were compared with simulated data. The first results of monolithic LYSO crystals coupled to an array of 256 SiPMs by means of individual optical light guides are also presented. [Copyright &y& Elsevier]

The aim of this work is to provide the characteristics of MPPC arrays with an active area of 6\times 6\ mm^2 in gamma-ray spectrometry with CsI:Tl, LSO:Ce:Ca, LaBr3:Ce and BGO scintillators. The chosen scintillators have significantly different decay times of the scintillation pulses and different wavelengths of emission peaks. This allowed an investigation into the dependence of MPPC readout features on the MPPC and scintillator characteristics. The study of influence of effective dead time and the number of MPPC pixels on a readout response in relation to the brightness and speed of the scintillator were performed. The measurements covered a selection of MPPC optimum operating voltage, verification of the linearity range for a given decay time of the crystals, verification of the excess noise factor for the optimal voltage and evaluation of the Photon Detection Efficiency (PDE). The results of energy resolution and non-proportionality obtained with the MPPC array readout of CsI:Tl and BGO were compared to those obtained for the same crystals with the XP2020Q PMT readout. The results show that an MPPC can be used as effectively as a PMT for gamma spectrometry measurements in the whole tested energy ranges (up to 1.3 MeV) and for many types of scintillation crystals (BGO, CsI:Tl). [ABSTRACT FROM AUTHOR]

We give an analytic treatment of the time resolution and efficiency of Single Photon Avalanche Diodes (SPADs) and Silicon Photomultipliers (SiPMs). We provide closed-form expressions for structures with uniform electric fields and efficient numerical prescriptions for arbitrary electric field configurations. We discuss the sensor performance for single photon detection and also for charged particle detection. [ABSTRACT FROM AUTHOR]

Developed as NASA Astrophysics Probe-class mission, the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is designed to identify the sources of ultra-high energy cosmic rays (UHECRs) and to observe cosmic neutrinos. POEMMA consists of two spacecraft flying in a loose formation at 525 km altitude, 28.5°inclination orbits. Each spacecraft hosts a Schmidt telescope with a large collecting area and wide Field-of-View (FoV). A novel focal plane is employed that is optimized to observe both the UV fluorescence signal from extensive air showers (EASs) and the optical Cherenkov signals from EASs. In UHECR stereo fluorescence mode, POEMMA will measure the spectrum, composition, and full-sky distribution of the UHECRs above 20 EeV with high statistics along with remarkable sensitivity to UHE neutrinos. The POEMMA spacecraft are designed to quickly re-orient to a Target-of-Opportunity (ToO) neutrino mode to observe transient astrophysical sources with unique sensitivity. In this mode, POEMMA will be able to detect cosmic tau neutrino events above 20 PeV by measuring the upward-moving EASs for τ -lepton decays induced from tau neutrino interactions in the Earth. In this paper, POEMMA's science goals and instrument design are summarized with a focus on the SiPM implementation in POEMMA, along with a detailed discussion of the properties of the Cherenkov EAS signal in the context of wide wavelength sensitivity offered by SiPMs. A comparison of the fluorescence response between SiPMs and the MAPMTs currently planned for use in POEMMA will also be discussed, assessing the potential for SiPMs to perform EAS fluorescence measurements. [ABSTRACT FROM AUTHOR]

The Circular Electron Positron Collider (CEPC) has been under developing for the precision measurements of the Higgs Boson. The requirement of jet energy resolution is 3 % ∼ 4% and the calorimeters should have high energy resolution. Particle Flow Algorithm (PFA) oriented highly granular calorimeters based on Arbor algorithm could achieve it and one option of Hadronic Calorimeter (HCAL) is Analog Hcal (AHCAL) composed of stainless steel as absorber and scintillator as active medium, individually read out by Silicon photomultipliers (SiPMs). In this paper, 6 types of SiPMs from Hamamatsu and Novel Device Laboratory (NDL) are compared for the CEPC-AHCAL. The performance on crosstalk, Dark Count Rate (DCR), gain and Minimum Ionization Particles (MIP) spectrum combined the front-end electronics (SPIROC2E) and different SiPMs are studied. The better performance among them is the SiPMs typed 13360-1325PE from Hamamatsu from our measurements. [ABSTRACT FROM AUTHOR]

The use of Silicon Photomultipliers (SiPMs) in high radiation environments (e.g. detectors at collider experiments) or in outdoor conditions (e.g. LIDAR applications), requires to deal with a high level of dark count noise. An undesired effect emerging under these conditions is the self-heating of the SiPM due to a large power dissipation that causes variations of the breakdown voltage and thus affects operating parameters such as gain and PDE. A method to evaluate the heat dissipation properties of different SiPM packages and the temperature stability of SiPMs during operation under extremely high dark count rates (larger than 30 GHz) is presented in this paper. Starting from a condition in which the SiPM is at thermal equilibrium with the environment, a change in the current measured under intense illumination with a LED can be attributed to a temperature variation of the SiPM due to self-heating. Under certain assumptions, a quantitative estimate of the local change of temperature can be obtained if certain parameters of the SiPM are known: gain, photon detection efficiency, equivalent charge factor and drift of the SiPM breakdown voltage with temperature. The method is applied to evaluate the thermal conductivity of different SiPM package configurations, which is a key requirement for reliable operation in conditions of extremely high dark count rate. Among the SiPM package configurations tested, the one consisting of a ceramic substrate coupled to a copper heat sink provided the best performance in terms of good heat dissipation with less than 0.5 °C temperature variation for 100 mW dissipated power. [ABSTRACT FROM AUTHOR]

Liquid xenon offers several features, which make it suitable for applications in nuclear medicine, such as high scintillation yield and fast scintillation decay time. Moreover, being a continuous medium with a uniform response, liquid xenon allows one to avoid most of the geometrical distortions of conventional detectors based on scintillating crystals. In this paper, we describe how these properties have motivated the development of a novel concept for positron emission tomography scanners with Time-Of-Flight measurement, which combines a liquid xenon scintillating volume and silicon photomultipliers as sensors. A Monte Carlo investigation has pointed out that this technology would provide an excellent intrinsic time resolution, down to 70 ps. Also, the transparency of liquid xenon to UV and blue wavelengths opens the possibility of exploiting both scintillation and Cherenkov light for a high-sensitivity positron emission tomography scanner with Time-Of-Flight capabilities. Monte Carlo simulations point to a time resolution of 30-50 ps obtained using Cherenkov light. A prototype is being built to demonstrate the high resolution in energy, time and reconstruction of spatial coordinates of this concept, using a ring of 30 cm internal diameter and a depth of 3 cm instrumented with VUV-sensitive silicon photomultipliers. [ABSTRACT FROM AUTHOR]

The Mu2e experiment at Fermilab searches for the coherent neutrino-less muon to electron conversion in the Coulomb field of an aluminum nucleus. This charged-lepton flavor violating process is characterized by a distinctive signature of a mono-energetic electron (∼ 105 MeV/c) and its observation will be a clear signature of new physics beyond the Standard Model. The Mu2e goal is to improve by four orders of magnitude the search sensitivity with respect to the previous experiments. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter and an external veto for cosmic rays. The calorimeter plays an important role in providing excellent particle identification capabilities, a fast online trigger filter while aiding the track reconstruction capabilities. It consists of 1348 pure CsI crystals divided in two annular disks, each one readout by two large area Silicon Photomultipliers. A large scale prototype has been tested with an electron beam, demonstrating to largely satisfy the Mu2e requirements. At the moment of writing, the crystals and SiPMs production phase is halfway through the completion. An overview of the characterization tests is reported, together with a description of the final mechanical and electronical design. [ABSTRACT FROM AUTHOR]

The CMS detector at the CERN Large Hadron Collider is undergoing an extensive Phase II upgrade programme to prepare for the challenging conditions of the High-Luminosity LHC. In particular, a new timing detector, the MTD, will measure minimum ionizing particles with a time resolution of 30–50 ps and hermetic coverage up to a pseudo-rapidity of | η | = 3. The MTD will consist of a central barrel region based on L(Y)SO:Ce crystals read out with SiPMs and two end-caps instrumented with radiation-tolerant low gain avalanche detectors. The precision time information from the MTD will reduce the effects of the high levels of pile-up expected at the High-Luminosity LHC and will bring new and unique capabilities to the CMS detector. The time information assigned to each track will enable the use of 4D reconstruction algorithms and will further discriminate interaction vertices within the same bunch crossing to recover the track purity of vertices in current LHC conditions. We present the motivations for precision timing at the High-Luminosity LHC, the overall detector design and technological choices including ongoing R&D studies targeting enhanced timing performance and radiation tolerance. [ABSTRACT FROM AUTHOR]

We have developed a new laser-based time calibration system for highly segmented scintillator counters like the MEG II pixelated Timing Counter (pTC), consisting of 512 centimetre-scale scintillator counters read out by silicon photomultipliers (SiPMs). It is difficult to apply previous laser-based calibration methods for conventional metre-scale Time-Of-Flight detectors to the MEG II pTC from the implementation and the accuracy points of view. This paper presents a new laser-based time calibration system which can overcome such difficulties. A laser pulse is split into each scintillator counter via several optical components so that we can directly measure the time offset of each counter relative to the laser-emitted time. We carefully tested all the components and procedures prior to the actual operation. The laser system was installed into the pTC and thoroughly tested under the real experimental condition. The system showed good stability and being sensitive to any change of timing larger than ∼ 10 ps. Moreover, it showed an uncertainty of 48 ps in the determination of the time offsets, which meets our requirements. The new method provides an example of the implementation of a precise timing alignment for the new type of detectors enabled by the advance of SiPM technology. [ABSTRACT FROM AUTHOR]