Investigation on radiation generated by Sub-GeV electrons in ultrashort Si and Ge bent crystals

TL;DR

This study measures gamma radiation spectra generated by 855 MeV electrons in bent silicon and germanium crystals, exploring how crystal curvature affects radiation via channeling and volume reflection, with implications for radiation source development.

Contribution

First measurements of radiation spectra in bent germanium crystals, demonstrating higher radiation intensity in Ge due to higher atomic number and analyzing the effects of crystal curvature on radiation.

Findings

Volume reflection produces intense gamma radiation with higher angular acceptance than channeling.

Germanium crystals yield higher radiation intensity than silicon due to higher atomic number.

Radiation spectra depend on crystal curvature, affecting potential applications.

Abstract

We report on the measurements of the spectra of gamma radiation generated by 855 MeV electrons in bent silicon and germanium crystals at MAMI (MAinzer MIkrotron). The crystals were 15 {\mu}m thick along the beam direction to ensure high deflection efficiency. Their (111) crystalline planes were bent by means of a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature. In such a way it was possible to investigate the radiation emitted under planar channeling and volume reflection as a function of the curvature of the crystalline planes. We show that using volume reflection, one can produce intense gamma radiation with comparable intensity but higher angular acceptance than for channeling. We studied the trade-off between radiation intensity and angular acceptance at different values of the crystal curvature. The measurements of radiation spectra have been carried out for the first time in bent Germanium crystals. In particular, the intensity of radiation in the Ge crystal is higher than in the Si one due to the higher atomic number, which is important for the development of the X-ray and gamma radiation sources based on higher-Z deformed crystals, such as crystalline undulator.