A cryogenic tracking detector for antihydrogen detection in the AEgIS experiment

TL;DR

The paper introduces the FACT cryogenic detector for antihydrogen detection in the AEgIS experiment, highlighting its design, operation, and background characterization to improve antihydrogen identification.

Contribution

It presents the development, hardware, and software implementation of a cryogenic scintillating fiber detector for antihydrogen detection, including efficiency assessment and background analysis.

Findings

Successful operation of FACT at 4 K with ns timing resolution

Characterization of background signals from positron interactions

Assessment of antihydrogen detection efficiency

Abstract

We present the commissioning of the Fast Annihilation Cryogenic Tracker detector (FACT), installed around the antihydrogen production trap inside the 1 T superconducting magnet of the AE\=gIS experiment. FACT is designed to detect pions originating from the annihilation of antiprotons. Its 794 scintillating fibers operate at 4 K and are read out by silicon photomultipliers (MPPCs) at near room temperature. FACT provides the antiproton/antihydrogen annihilation position information with a few ns timing resolution. We present the hardware and software developments which led to the successful operation of the detector for antihydrogen detection and the results of an antiproton-loss based efficiency assessment. The main background to the antihydrogen signal is that of the positrons impinging onto the positronium conversion target and creating a large amount of gamma rays which produce a sizeable signal in the MPPCs shortly before the antihydrogen signal is expected. We detail the characterization of this background signal and its impact on the antihydrogen detection efficiency.