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We report a study of optical and scintillation properties of modules of a prototype electromagnetic calorimeter based on barium fluoride crystals (BaF2) measuring 25 × 25 × 160 mm3. The length of the crystal radiator of the calorimeter is optimized using the Monte Carlo method in order to improve its energy resolution. Homogeneity of the light output from different sections of the module using gamma quanta from a 137Cs source is demonstrated. The scintillation time of the crystal module under gamma excitation is measured. [ABSTRACT FROM AUTHOR]

The article presents the results of studies of the characteristics of lead tungstate crystals (PbWO4). Measurements of light transmission and light output from the passage of cosmic muons were carried out. The average light transmittance of crystals in the transverse direction is 62.82, 68.38, and 75.68% at wavelengths λ = 360, 420, and 620 nm, and the light output is ~16 pe/MeV. A prototype of an electromagnetic calorimeter was designed and built from crystals arranged in a 4 × 4 matrix which has been tested by cosmic muons. The results obtained confirm the conclusions of other groups in the Electron-Ion Collider collaboration that the quality of the crystals produced by CRYTUR meets the requirements for an electromagnetic calorimeter, and that they can be the basis for its creation. [ABSTRACT FROM AUTHOR]

Progress in high-energy physics has been closely tied to the development of high-performance electromagnetic calorimeters. Recent experiments have demonstrated the possibility to significantly accelerate the development of electromagnetic showers inside scintillating crystals typically used in homogeneous calorimeters based on scintillating crystals when the incident beam is aligned with a crystallographic axis to within a few mrad. In particular, a reduction of the radiation length has been measured when ultrarelativistic electron and photon beams were incident on a high-Z scintillator crystal along one of its main axes. Here, we propose the possibility to exploit this physical effect for the design of a new type of compact e.m. calorimeter, based on oriented ultra-fast lead tungstate (PWO-UF) crystals, with a significant reduction in the depth needed to contain electromagnetic showers produced by high-energy particles with respect to the state-of-the-art. We report results from tests of the crystallographic quality of PWO-UF samples via high-resolution X-ray diffraction and photoelastic analysis. We then describe a proof-of-concept calorimeter geometry defined with a Geant4 model including the shower development in oriented crystals. Finally, we discuss the experimental techniques needed for the realization of a matrix of scintillator crystals oriented along a specific crystallographic direction. Since the angular acceptance for e.m. shower acceleration depends little on the particle energy, while the decrease of the shower length remains pronounced at very high energy, an oriented crystal calorimeter will open the way for applications at the maximum energies achievable in current and future experiments. Such applications span from forward calorimeters, to compact beam dumps for the search for light dark matter, to source-pointing space-borne γ-ray telescopes, to decrease the size and the cost of the calorimeter needed to fully contain e.m. showers initiated by GeV to TeV particles.

The alpha magnetic spectrometer (AMS) is a high-precision particle detector onboard the International Space Station containing six different subdetectors. The transition radiation detector and electromagnetic calorimeter (ECAL) are used to separate electrons/positrons from the abundant cosmic-ray proton background. The positron flux measured in space by AMS falls with a power law which unexpectedly softens above 25 GeV and then hardens above 280 GeV. Several theoretical models try to explain these phenomena, and a more accurate measurement of positrons at higher energies is needed to help test them. The currently used methods to reject the proton background at high energies involve extrapolating shower features from the ECAL to use as inputs for boosted decision tree and likelihood classifiers. We present a new approach for particle identification with the AMS ECAL using deep learning (DL). By taking the energy deposition within all the ECAL cells as an input and treating them as pixels in an image-like format, we train an MLP, a CNN, and multiple ResNets and convolutional vision transformers (CvTs) as shower classifiers. Proton rejection performance is evaluated using Monte Carlo (MC) events and ISS data separately. For MC, using events with a reconstructed energy between 0.2–2 TeV, at 90% electron accuracy, the proton rejection power of our CvT model is more than five times that of the other DL models. Similarly, for ISS data with a reconstructed energy between 50–70 GeV, the proton rejection power of our CvT model is more than 2.5 times that of the other DL models.

The GEp-III and GEp-2γ experiments, carried out in Jefferson Lab's Hall C from 2007–2008, consisted of measurements of polarization transfer in elastic electron–proton scattering at momentum transfers of Q2=2.5,5.2,6.8, and 8.54 GeV 2. These measurements were carried out to improve knowledge of the proton electromagnetic form factor ratio R=μpGEp∕GMp at large values of Q2 and to search for effects beyond the Born approximation in polarization transfer observables at Q2=2.5GeV2. The final results of both experiments were reported in a recent archival publication. A full reanalysis of the data from both experiments was carried out in order to reduce the systematic and, for the GEp-2γ experiment, statistical uncertainties. This technical note provides additional details of the final analysis omitted from the main publication, including the final evaluation of the systematic uncertainties.

The GEp-III and GEp-2γ experiments, carried out in Jefferson Lab's Hall C from 2007–2008, consisted of measurements of polarization transfer in elastic electron–proton scattering at momentum transfers of Q2=2.5,5.2,6.8, and 8.54 GeV 2. These measurements were carried out to improve knowledge of the proton electromagnetic form factor ratio R=μpGEp∕GMp at large values of Q2 and to search for effects beyond the Born approximation in polarization transfer observables at Q2=2.5GeV2. The final results of both experiments were reported in a recent archival publication. A full reanalysis of the data from both experiments was carried out in order to reduce the systematic and, for the GEp-2γ experiment, statistical uncertainties. This technical note provides additional details of the final analysis omitted from the main publication, including the final evaluation of the systematic uncertainties.

Noble liquid calorimeters have been successfully used in particle physics experiments for decades. The project presented in this article is that of a new noble liquid calorimeter concept, where a novel design allows us to fulfil the stringent requirements on calorimetry of the physics programme of the electron-positron Future Circular Collider at CERN. High granularity is achieved through the design of specific readout electrodes and high-density cryostat feedthroughs. Excellent performance can be reached through new very light cryostat design and low electronics noise. Preliminary promising performance is achieved in simulations, and ideas for further R&D opportunities are discussed. [ABSTRACT FROM AUTHOR]

The high luminosity upgrade of the LHC (HL-LHC) at CERN will provide unprecedented instantaneous and integrated luminosities of up to 7.5 × 10 34 cm − 2 s − 1 and 4500 fb − 1 , respectively, from 2029 onwards. To cope with the extreme conditions of up to 200 collisions per bunch crossing, and increased data rates, the on- and off-detector electronics of the CMS electromagnetic calorimeter (ECAL) will be replaced. A dual gain trans-impedance amplifier and an ASIC providing two 160 MHz ADC channels, gain selection, and data compression will be used. The lead tungstate crystals and avalanche photodiodes (APDs) in the current ECAL will keep performing well and will therefore be maintained. The noise increase in the APDs, due to radiation-induced dark currents, will be minimised by reducing the ECAL operating temperature from 18 °C to around 9 °C. Prototype HL-LHC electronics have been tested and have shown promising results. In two test beam periods using the CERN SPS H4 beamline and an electron beam, the new electronics achieved the target energy resolution and a timing resolution consistent that is consistent with our requirements of 30 ps timing for energies greater than 50 GeV. [ABSTRACT FROM AUTHOR]

BackgroundThe Shashlik electromagnetic calorimeter (ECAL) is used in the Nuclotron-based Ion Collider Facility's MultiPurpose detector (NICA-MPD) of the Russian heavy ion superconducting synchrotron. It is designed as a cylindrical barrel divided into 32 sectors with a total of 43 008 towers. Each tower is composed of 220 layers of lead and 221 layers of scintillator alternately.PurposeThis study aims to simulate multiple parameters of Shashlik ECAL for NICA-MPD that affect the performance of ECAL.MethodsFirst of all, the module of ECAL tower was built based on the principle of Shashlik ECAL. Then, the GEENT4 software was employed to simulate the performance of every single tower of ECAL according to its structure composition. Considering the influence of the design parameters of the scintillator and absorber on energy deposition, energy resolution, and energy leakage after electrons were incident on the tower and the subsequent scintillator luminescence process, the influence of the reflective layer on the number of photons was in the wavelength shifted fiber and detector. Finally, factors that affected energy deposition, energy leakage, energy resolution, and photon number in the wavelength shift (WLS) and sensor, and the influence of the thickness, number of layers, and size of the scintillator and absorber in the module on energy deposition, energy leakage, and energy resolution were simulated and analyzed.ResultsThe simulation results show that the best side length of cross-section of each tower is 4 cm. When the total thickness of absorber and scintillator is 1.8 mm and the thickness of lead absorber is 0.3 mm, the energy resolution meets the experimental requirements of 5%@3 GeV. When the radiation length reaches 13X0, maximum energy deposition and obtains better energy resolution can be achieved. Adding a reflective layer to the tower side can increase the number of photons in the fiber by 10%~19% whereas adding a reflective coating to the fiber end can effectively increase the number of photons reaching the detector by 50%.ConclusionsThe photon numbers in the wavelength shift fiber and the detector are affected by the reflection layer on both the tower side and the end face of the fiber. The importance and necessity of adding reflector are verified by this study.

The Crilin calorimeter represents a novel approach in the development of electromagnetic calorimeters for future colliders, especially for a Muon Collider. This paper details the design and performance of the innovative semi-homogeneous Crilin calorimeter, highlighting its capabilities in mitigating beam-induced backgrounds (BIB) while maintaining excellent time resolution (less than 50 ps), longitudinal segmentation, and fine granularity. These performances are achieved throughout a series of stackable and interchangeable lead fluoride (PbF 2) crystal matrices readout by surface-mount UV-extended Silicon Photo-multipliers. Simulated and experimental results demonstrate the Crilin design's potential to work as an efficient and cost-effective alternative to traditional electromagnetic calorimeters. Crilin radiation tolerance is discussed, as measured in several irradiation campaigns, as well as timing performances during a beam test at CERN-H2 with 120 GeV electrons for the latest prototype, Proto-1. Additionally, a description of the results from a recent beam test conducted at the LNF Beam Test Facility with 450 MeV electrons is provided, aiming to measure light yield losses due to irradiation. [ABSTRACT FROM AUTHOR]

Electromagnetic calorimeters used in high-energy physics and astrophysics rely heavily on high-Z inorganic scintillators, such as lead tungstate (PbWO 4 or PWO). The crystalline structure and lattice orientation of inorganic scintillators are frequently underestimated in detector design, even though it is known that the crystalline lattice strongly modifies the features of the electromagnetic processes inside the crystal. A novel method has been developed for precisely bonding PWO crystals with aligned atomic planes within 100 μ rad, exploiting X-ray diffraction (XRD) to accurately measure miscut angles. This method demonstrates the possibility to align a layer of crystals along the same crystallographic direction, opening a new technological path towards the development of next-generation electromagnetic calorimeters. [ABSTRACT FROM AUTHOR]

The increase in instantaneous luminosity during the high-luminosity phase of the LHC represents a significant challenge for future detectors. A strategy to cope with high-pileup conditions is to add a fourth dimension to the measurements of the hits, by exploiting the time separation of the various proton–proton primary collisions. According to LHCb simulation studies, resolutions of about 10–20 picoseconds, at least an order of magnitude shorter than the average time span between primary interactions, would be greatly beneficial for the physics reach of the experiment. Microchannel plate (MCP) photomultipliers are compact devices capable of measuring the arrival time of charged particles with the required resolution. The technology of large-area picosecond photodetectors (LAPPDs) is under investigation to implement a timing layer that can be placed within a sampling calorimeter module with the purpose of measuring the arrival time of electromagnetic showers. LAPPD performances, using a Gen-I tile with a delay-line anode and a Gen-II with a capacitively coupled anode, have been measured thoroughly both with laser (wavelength of 405 nm and pulse width of 27.5 ps FWHM) and high-energy electron (1–5.8 GeV) beams. Time resolutions of the order of 30 ps for single photoelectrons and 15 ps for electromagnetic showers initiated by 5-GeV electrons, as measured at the shower maximum, are obtained. [ABSTRACT FROM AUTHOR]

A statistical method for extracting the η → γγ signal upon rejecting those γ clusters that form pairs with invariant masses close to that of the π0 meson is proposed. The η selection efficiency (the ratio between the numbers of selected and produced η mesons) and the signal-to-background ratio as a function of the η transverse momentum are obtained using a template of proton–proton collisions at = 13 TeV simulated with PYTHIA 8.2 (with Monash-2013 tuning). The proposed method provides for an η → γγ selection efficiency of ~80% and for a 20–50% increase in the signal-to-background ratio compared to currently implemented techniques. [ABSTRACT FROM AUTHOR]

The response simulation of an ideal KOPIO-type electromagnetic sampling calorimeter was carried out in the energy range of 50 MeV – 16 GeV using Geant4-10.6.0 toolkit. In this work, we obtained energy resolution parameters for prototypes of Shashlyk calorimeter modules (ECAL SPD) of the NICA collider SPD setup for different thicknesses of a lead absorber with different numbers of layers. The NICA scientific experiment provides a unique opportunity to study parton distributions and correlations in hadron structure when working with high-intensity polarized relativistic ion beams. The ECAL electromagnetic calorimeter is one of the key detectors of the SPD device. There are some preliminary requirements for an electromagnetic calorimeter, in particular, for energy resolution in the energy range from 50 MeV to 16 GeV. It has been shown in detail that a more accurate obtaining of stochastic as well as permanent coefficients acting as parameters of the energy resolution parameterization formula is possible when longitudinal energy leakages from the calorimeter tower are taken into account. Such leakages are always present even in small amounts. Thus, the energy resolution parameterization of an ideal sampling calorimeter with a good value is fitted with function of the type: , where the logarithm means , where is the effective critical energy. Based on the results of detailed modeling, the dependence of these parameters on the number of calorimeter plates and absorber thicknesses was found. The approach is based on careful selection and analysis of the energy spectra obtained by modeling according to the -square criterion and an adequate choice of the approximation functions of the energy resolution. The methods proposed in this paper can be easily extended to other combinations of absorber-scintillator thicknesses.

Noble liquid calorimeters have been successfully used in particle physics experiments for decades. The project presented in this article is that of a new noble liquid calorimeter concept, where a novel design allows us to fulfil the stringent requirements on calorimetry of the physics programme of the electron-positron Future Circular Collider at CERN. High granularity is achieved through the design of specific readout electrodes and high-density cryostat feedthroughs. Excellent performance can be reached through new very light cryostat design and low electronics noise. Preliminary promising performance is achieved in simulations, and ideas for further R&D opportunities are discussed.

In this work, using Geant4, we simulate a time-of-flight positron emission tomography detector based on Cherenkov radiation. We consider various materials as a basis for the detector, including a pure PMMA and PMMA used as a matrix containing small resonant particles of copper and gold. For that, in CST studio, we determine the dielectric permittivity for a composite material, which we then use for simulations in Geant4. The resonant nature of the small metal particles allows producing Cherenkov photons by secondary electrons with lower energy, increasing the output of the radiated photons. We consider it as the way to increase temporal resolution as well as efficiency of the detector. [ABSTRACT FROM AUTHOR]

The high luminosity upgrade of the LHC (HL-LHC) at CERN will provide unprecedented instantaneous and integrated luminosities of up to 7.5×1034 cm−2s−1 and 4500 fb−1, respectively, from 2029 onwards. To cope with the extreme conditions of up to 200 collisions per bunch crossing, and increased data rates, the on- and off-detector electronics of the CMS electromagnetic calorimeter (ECAL) will be replaced. A dual gain trans-impedance amplifier and an ASIC providing two 160 MHz ADC channels, gain selection, and data compression will be used. The lead tungstate crystals and avalanche photodiodes (APDs) in the current ECAL will keep performing well and will therefore be maintained. The noise increase in the APDs, due to radiation-induced dark currents, will be minimised by reducing the ECAL operating temperature from 18 °C to around 9 °C. Prototype HL-LHC electronics have been tested and have shown promising results. In two test beam periods using the CERN SPS H4 beamline and an electron beam, the new electronics achieved the target energy resolution and a timing resolution consistent that is consistent with our requirements of 30 ps timing for energies greater than 50 GeV.

The increase in instantaneous luminosity during the high-luminosity phase of the LHC represents a significant challenge for future detectors. A strategy to cope with high-pileup conditions is to add a fourth dimension to the measurements of the hits, by exploiting the time separation of the various proton–proton primary collisions. According to LHCb simulation studies, resolutions of about 10–20 picoseconds, at least an order of magnitude shorter than the average time span between primary interactions, would be greatly beneficial for the physics reach of the experiment. Microchannel plate (MCP) photomultipliers are compact devices capable of measuring the arrival time of charged particles with the required resolution. The technology of large-area picosecond photodetectors (LAPPDs) is under investigation to implement a timing layer that can be placed within a sampling calorimeter module with the purpose of measuring the arrival time of electromagnetic showers. LAPPD performances, using a Gen-I tile with a delay-line anode and a Gen-II with a capacitively coupled anode, have been measured thoroughly both with laser (wavelength of 405 nm and pulse width of 27.5 ps FWHM) and high-energy electron (1–5.8 GeV) beams. Time resolutions of the order of 30 ps for single photoelectrons and 15 ps for electromagnetic showers initiated by 5-GeV electrons, as measured at the shower maximum, are obtained.

The Muon g –2 experiment at Fermilab (E989) plans to measure the muon anomalous magnetic moment to a precision of 140 parts per billion (ppb), which corresponds to a total uncertainty of 1. 6 × 1 0 − 10. To achieve this level of precision the experiment must detect more than 1. 8 × 1 0 11 decay positrons by using the 24 calorimeters distributed around the muon storage ring. Each calorimeter consists of 54 Pb F 2 crystals read out by SiPMs. The response of each of the 1296 channels must be calibrated and monitored to keep uncertainties due to gain fluctuations at the sub-per mil level in the time interval corresponding to one beam fill (700 μ s) and at the sub-percent level on longer time scales. These requirements are much more demanding than those needed by most high energy physics experiments. This paper presents a novel laser-based calibration system that distributes light to all calorimeter cells, while allowing one to correct for laser intensity fluctuations and to monitor the distribution chain stability at unprecedented levels of accuracy. Results on the system performance during the first few months of stored muon operation in 2018 are also presented. • FNAL's Muon g-2 Experiment calorimeters are calibrated with a laser-based system. • The laser calibration system yields sub-per-mil level calorimeter gain stability. • A laser pre-beam-injection pulse provides time synchronization. • Laser stability is measured via a redundant monitoring system. [ABSTRACT FROM AUTHOR]

Abstract The Compact Muon Solenoid (CMS) electromagnetic calorimeter (ECAL) is a high-performance calorimeter which will operate also at the High Luminosity Large Hadron Collider (HL-LHC). This talk will describe the strategies that have been employed to maintain the excellent performance of the CMS ECAL throughout Run 2. Performance results from the 2015–2016 data taking periods will be shown and an outlook on the expected Run 2 performance in the years to come will be provided. The status and plans for the upgraded ECAL barrel electronics for the HL-LHC will be presented, based on recent results from simulations, laboratory tests, and test beam measurements of prototype devices. Highlights • The high-performance CMS electromagnetic calorimeter will operate at the High Luminosity LHC. • Strategies employed to maintain the excellent performance of the CMS ECAL are described. • Status and plans for the upgraded ECAL barrel electronics for the HL-LHC are presented. [ABSTRACT FROM AUTHOR]

Abstract The GEp-III and GEp-2 γ experiments, carried out in Jefferson Lab's Hall C from 2007–2008, consisted of measurements of polarization transfer in elastic electron–proton scattering at momentum transfers of Q 2 = 2. 5 , 5. 2 , 6. 8 , and 8.54 GeV 2. These measurements were carried out to improve knowledge of the proton electromagnetic form factor ratio R = μ p G E p ∕ G M p at large values of Q 2 and to search for effects beyond the Born approximation in polarization transfer observables at Q 2 = 2. 5 GeV 2. The final results of both experiments were reported in a recent archival publication. A full reanalysis of the data from both experiments was carried out in order to reduce the systematic and, for the GEp-2 γ experiment, statistical uncertainties. This technical note provides additional details of the final analysis omitted from the main publication, including the final evaluation of the systematic uncertainties. [ABSTRACT FROM AUTHOR]

The paper discusses new method for electron/pion and muon/pion separation in the Belle II detector at transverse momenta below 0.7 GeV/c, which is essential for efficient measurements of semi-leptonic decays of B mesons with tau lepton in the final state. The method is based on the analysis of patterns in the electromagnetic calorimeter by using a Convolutional Neural Network (CNN). [ABSTRACT FROM AUTHOR]