Vitaly Mechinsky | Searcharxiv

arXiv2024

Strong Enhancement of Electromagnetic Shower Development in Oriented Scintillating Crystals and Implications for Particle Detectors

A particle traversing a crystal aligned with one of its crystallographic axes experiences a strong electromagnetic field that is constant along the direction of motion over macroscopic distances. For $e^\pm$ and $\gamma$-rays with energies above a few $\mathrm{GeV}$, this field is amplified by the Lorentz boost, to the point of exceeding the Schwinger critical field $\mathcal{E}_0 \sim 1.32 \times 10^{16}~\mathrm{V/cm}$. In this regime, nonlinear quantum-electrodynamical effects occur, such as the enhancement of intense electromagnetic radiation emission and pair production, so that the electromagnetic shower development is accelerated and the effective shower length is reduced compared to amorphous materials. We have investigated this phenomenon in lead tungstate (PbWO$_4$), a high-$Z$ scintillator widely used in particle detection. We have observed a substantial increase in scintillation light at small incidence angles with respect to the main lattice axes. Measurements with $120$-$\mathrm{GeV}$ electrons and $\gamma$-rays between $5$ and $100~\mathrm{GeV}$ demonstrate up to a threefold increase in energy deposition in oriented samples. These findings challenge the current models of shower development in crystal scintillators and could guide the development of next-generation accelerator- and space-borne detectors.

hep-ex↗

arXiv2018

Ce-doped Gd${}_{3}$Al${}_{2}$Ga${}_{3}$O${}_{12}$ scintillator for compact, effective and high time resolution detector of the fast neutrons

Gadolinium-aluminum-gallium garnet Gd${}_{3}$Al${}_{2}$Ga${}_{3}$O${}_{12}$:Ce scintillator is demonstrated to be an excellent scintillation material for detector of fast neutrons for the first time. Moreover, its application allows to obtain different responses to neutrons depending on their energy spectrum. This is achieved because the material, firstly, has high content of Gd, which absorbs neutrons with following emission of $γ$-quanta, and, secondly, detects this radiation efficiently thanks to high stopping power, fast scintillation kinetics, high scintillation light yield and good energy resolution. It was shown by simulation that several characteristic regions could be distinguished in $γ$-quanta pulse height spectra acquired with GAGG:Ce crystal under neutron irradiation, with energies nearly 90 and 190, and 511 keV; all these lines have different relative intensities depending on incident neutrons kinetic energy. This was confirmed by followed measurements with Am-Be neutron source. Scintillator shows coincidence time resolution better than 200ps for$γ$-quanta of 511 keV energy, what makes it the material of choice to separate neutrons by time-of-flight technique. Combining of detecting properties creates prospects to construct compact and fast neutron detector, capable of detection of each particle individually and registration of its specific response. This possibility could bring benefits to neutron-based examination techniques, e.g. utilizing time of flight methods and new capabilities of accelerator based bright neutron sources.

physics.ins-det↗