arXiv subjects

M. Korjik

Publications and source records attributed to M. Korjik.

3 recordsLinked to original sources

arXiv2025

R&D on a high-performance electromagnetic calorimeter based on oriented crystalline scintillators

Although inorganic scintillators are widely used in the design of electromagnetic calorimeters for high-energy physics and astrophysics, their crystalline nature and, hence, their lattice orientation are generally neglected in the detector design. However, in general, the features of the electromagnetic field experienced by the particles impinging on a crystal at a small angle with respect to a lattice axis affect their interaction mechanisms. In particular, in case of electrons/photons of $\mathcal{O} (10~\mathrm{GeV})$ or higher impinging on a high-$Z$ crystal at an angle of $\lesssim 1~\mathrm{mrad}$, the so-called strong field regime is attained: the bremsstrahlung and pair production cross sections are enhanced with respect to the case of amorphous or randomly oriented materials. Overall, the increase of these processes leads to an acceleration of the electromagnetic shower development. These effects are thoroughly investigated by the OREO (ORiEnted calOrimeter) team, and pave the way to the development of innovative calorimeters with a higher energy resolution, a higher efficiency in photon detection and an improved particle identification capabilities due to the relative boost of the electromagnetic interactions with respect to the hadronic ones. Moreover, a detector with the same resolution as the current state of the art and reduced thickness could be developed. An overview of the lattice effects at the foundation of the shower boost and of the current status of the development of an operational calorimeter prototype are presented. This concept could prove pivotal for both accelerator fixed-target experiments and satellite-borne $γ$-ray observatories.

physics.ins-det↗

arXiv2025

A highly-compact and ultra-fast homogeneous electromagnetic calorimeter based on oriented lead tungstate crystals

Progress in high-energy physics has been closely tied to the development of highperformance 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 ultrafast 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.

physics.ins-det↗

arXiv2021

Test beam characterization of sensor prototypes for the CMS Barrel MIP Timing Detector

The MIP Timing Detector will provide additional timing capabilities for detection of minimum ionizing particles (MIPs) at CMS during the High Luminosity LHC era, improving event reconstruction and pileup rejection. The central portion of the detector, the Barrel Timing Layer (BTL), will be instrumented with LYSO:Ce crystals and Silicon Photomultipliers (SiPMs) providing a time resolution of about 30 ps at the beginning of operation, and degrading to 50-60 ps at the end of the detector lifetime as a result of radiation damage. In this work, we present the results obtained using a 120 GeV proton beam at the Fermilab Test Beam Facility to measure the time resolution of unirradiated sensors. A proof-of-concept of the sensor layout proposed for the barrel region of the MTD, consisting of elongated crystal bars with dimensions of about 3 x 3 x 57 mm$^3$ and with double-ended SiPM readout, is demonstrated. This design provides a robust time measurement independent of the impact point of the MIP along the crystal bar. We tested LYSO:Ce bars of different thickness (2, 3, 4 mm) with a geometry close to the reference design and coupled to SiPMs manufactured by Hamamatsu and Fondazione Bruno Kessler. The various aspects influencing the timing performance such as the crystal thickness, properties of the SiPMs (e.g. photon detection efficiency), and impact angle of the MIP are studied. A time resolution of about 28 ps is measured for MIPs crossing a 3 mm thick crystal bar, corresponding to an MPV energy deposition of 2.6 MeV, and of 22 ps for the 4.2 MeV MPV energy deposition expected in the BTL, matching the detector performance target for unirradiated devices.

physics.ins-det↗