The EXTRA-BL4S experiment for the measurement of the energy and angular distributions of transition radiation X-rays

TL;DR

This experiment measured the energy and angular distributions of transition radiation X-rays produced by high-energy electrons and positrons crossing radiators, confirming theoretical models with experimental data.

Contribution

The study presents the first detailed measurements of transition radiation X-ray distributions using a high-purity beam and silicon pixel detectors at DESY, validating existing theoretical models.

Findings

Results align with theoretical predictions of transition radiation.

Demonstrated feasibility of measuring X-ray distributions with high-energy beams.

Provided new data for transition radiation in multilayer radiators.

Abstract

We have designed and implemented an experiment to measure the angular distributions and the energy spectra of the transition radiation X-rays emitted by fast electrons and positrons crossing different radiators. Our experiment was selected among the proposals of the 2021 Beamline for Schools contest, a competition for high-school students organized every year by CERN and DESY, and was performed at the DESY II Test Beam facility area TB21, using a high-purity beam of electrons or positrons with momenta in the range from 1 to 6 GeV/c. The measurements were performed using a 100 um thick silicon pixel detector, with a pitch of 55 um. Our results are consistent with the expectations from the theoretical models describing the production of transition radiation in multilayer regular radiators.