Speaker
Description
In high-energy physics, crystal electromagnetic calorimeters have a key role in the measurement of the incident particle energy. Recent studies showed that the use of oriented scintillating crystals for their construction can improve their performance exploiting the coherent crystal effects [1].
In high-Z scintillating crystals, relativistic electrons, positrons or photons (with an energy larger than a few GeV) crossing the crystal nearly parallel to the crystallographic axis, interact with the continuous potential of the crystal lattice. As a consequence, the particles experience a nearly constant electric field, Lorentz-boosted in their rest frame, which can reach (or exceed) the Schwinger critical field, thereby entering the strong-field regime [2]. This leads to enhanced radiation emission by electrons/positrons and to an increased photon pair-production probability, accelerating the electromagnetic shower development and reducing the effective radiation length X₀ [3] [4].
Within this context, the ORiEnted calOrimeter (OREO) project was developed.
The main goal of the OREO project, within the CERN DRD CALO collaboration, is to assemble and test a first prototype of a compact crystal-based electromagnetic calorimeter composed of two 3 × 3 PWO-UF [5] (Ultra Fast Lead Tungstate) matrices both readout by Silicon PhotoMultipliers.
In this contribution, we present the first R&D phase of the OREO calorimeter. The preliminary results of the beamtests performed at CERN PS and SPS validate the bonding procedure used to assemble the OREO oriented layer [6], verifying the correct inter-alignment of the crystals in the matrix. Furthermore, improved longitudinal shower containment is observed in the axial configuration, i.e., when the crystallographic axis is aligned with respect to the particle beam. This improvement would enable a substantial reduction both in the cost and volume of electromagnetic calorimeters, as well as an improved particle-identification performance for γ/hadron discrimination and an enhanced γ-detection efficiency. These features make OREO a promising option for forward calorimetry at future colliders, fixed-target and beam dump experiments, as well as for space-based astrophysics detectors.
[1] L. Bandiera et al. “A highly-compact and ultra-fast homogeneous electromagnetic calorimeter based on oriented lead tungstate crystals”. (2023).
DOI: https://doi.org/10.3389/fphy.2023.1254020.
[2] U. I. Uggerhøj. “The interaction of relativistic particles with strong crystalline fields”. (2005).
DOI: https://doi.org/10.1103/RevModPhys.77.1131.
URL: https://link.aps.org/doi/10.1103/RevModPhys.77.1131.
[3] L. Bandiera et al. “Strong Reduction of the Effective Radiation Length in an Axially Oriented Scintillator Crystal”. (2018).
DOI: https://doi.org/10.1103/PhysRevLett.121.021603.
[4] M. Soldani et al. “Strong enhancement of electromagnetic shower development induced by high-energy photons in a thick oriented tungsten crystal”. (2023).
DOI: https://doi.org/10.1140/epjc/s10052-023-11247-x.
[5] M. Korzhik et al. “Ultrafast PWO scintillator for future high energy physics instrumentation”. (2022).
DOI: https://doi.org/10.1016/j.nima.2022.166781.
URL: https://www.sciencedirect.com/science/article/pii/S0168900222002881.
[6] L. Malagutti et al. “High-precision alignment techniques for realizing an ultracompact electromagnetic calorimeter using oriented high-Z scintillator crystals”. (2024).
DOI: https://doi.org/10.1016/j.nima.2024.169869.
URL: https://www.sciencedirect.com/science/article/pii/S0168900224007952.