Radiation of high-energy electrons when channeling in the bent silicon and germanium monocrystals

In the paper, the simulation results on propagation of high-energy charged particles in the bent crystalline (Si and Ge) media have been presented within the atomistic approach. The calculation results were compared with literary experimental data obtained by measuring the output angular distribution of 855 MeV electrons with their very low initial divergence. Moreover, the literary experimental data on output radiation spectra for short bent Si and Ge crystals with different bending radii were taken into account. A good agreement between all the results was found

Geant4 simulation model of electromagnetic processes in oriented crystals for the accelerator physics

Electromagnetic processes of charged particles interaction with oriented crystals provide a wide variety of innovative applications such as beam steering, crystal-based extraction/collimation of leptons and hadrons in an accelerator, a fixed-target experiment on magnetic and electric dipole moment measurement, X-ray and gamma radiation source for radiotherapy and nuclear physics and a positron source for lepton and muon colliders, a compact crystalline calorimeter as well as plasma acceleration in the crystal media. One of the main challenges is to develop an up-to-date, universal and fast simulation tool to simulate these applications. We present a new simulation model of electromagnetic processes in oriented crystals implemented into Geant4, which is a toolkit for the simulation of the passage of particles through matter. We validate the model with the experimental data as well as discuss the advantages and perspectives of this model for the applications of oriented crystals mentioned above.Comment: 18 pages, 9 figure

Radiation in oriented crystals: Innovative application to future positron sources

International audienceIt has been known since decades that the alignment of a beam of high-energy electrons with particular crystal directions involves a significant increase of bremsstrahlung radiation emission. This enhancement lies at the conceptual foundation of innovative positron source schemes for future lepton colliders. In particular, the so-called hybrid scheme makes use of a heavy-metal radiator in crystalline form, which is then followed by an amorphous metallic converter for positron generation from electrons by means of a two-step electromagnetic process. This work presents the most recent simulation results obtained on the development of a hybrid positron source for the FCC-ee from the standpoint of the features of both the crystalline radiator and the amorphous converter

Experimental layout for the direct measurement of electromagnetic shower acceleration in an oriented crystal scintillator

Progress in experimental high-energy physics has been closely tied to developments of high-performance calorimeters. Since their invention, crystal calorimeters have consistently achieved the best resolution for measurements of the energies of electromagnetic (e.m.) particles (electrons and photons). Recently, we experimentally demonstrated the possibility of significantly accelerating the e.m. shower development inside lead tungstate (PWO) crystal when the incident beam is aligned with the crystal axes within some tenths of a degree. Here, we present the innovative photodetection system, based on Silicon PhotoMultipliers, implemented for the direct measurement of the scintillation light enhancement in case of beam aligned to the main crystal axes, along with its characterization performed with cosmic rays at the Insulab laboratory (Insubria University, Como). In 2021 we performed a test at H2 beam line of CERN SPS with a hundred-GeV electron beam with two PWO samples (1 and 2 X0 thick) directly coupled with SiPMs. Since the angular acceptance of the crystal strong field depends weakly on particle energy, while instead the decreasing of the shower length remains pronounced at very high-energy, a crystal calorimeter based on oriented crystals would feature a consistent compactness enhancement while rivaling the current state of the art in terms of resolution in the range of interest of present and future forward detectors, beam dumps for light dark matter search and source-pointing space-borne γ-ray telescopes

Acceleration of electromagnetic shower development and enhancement of light yield in oriented scintillating crystals

We observed a substantial increase of the scintillation light output of lead tungstate (PbWO$_4$) at a small incidence angle with respect to two main lattice axes. This reflects the acceleration of electromagnetic shower development that occurs in the crystalline Strong Field. We measured the scintillation light generated by $120$-$\mathrm{GeV}$ electrons and $10$-$100$-$\mathrm{GeV}$$\gamma$ rays on thick samples. This result deepens the knowledge of the shower development mechanisms in crystal scintillators and could pave the way to the development of innovative accelerator- and space-borne calorimeters