Recent Developments from ASACUSA on Antihydrogen Detection

¹ Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
² Ulmer Fundamental Symmetry Laboratory, RIKEN, Saitama 351-0198, Japan
³ Graduate School of Advanced Science of Matter, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
⁴ Nishina Center for Accelerator-Based Science, RIKEN Saitama 351-0198, Japan
⁵ Institute of Physics, University of Tokyo, 153-8902, Japan
⁶ Dipartimento di Ingegneria dell‘ Informazione, Università degli Studi di Brescia, Istituto Nazionale di Fisica Nucleare, Sez. di Pavia I-25133 I-27100 Brescia, Pavia, Italy Italy
⁷ CERN 1211, Geneva 23, Switzerland
⁸ Department of Physics, Tokyo University of Science, Shinjuku, Tokyo 162-8601, Japan

^* e-mail: bernadette.kolbinger@oeaw.ac.at

Published online: 25 June 2018

Abstract

The ASACUSA Collaboration at CERNs Antiproton Decelerator aims to measure the ground state hyperfine splitting of antihydrogen with high precision to test the fundamental symmetry of CPT (combination of charge conjugation, parity transformation, and time reversal). For this purpose an antihydrogen detector has been developed. Its task is to count the arriving antihydrogen atoms and therefore distinguish backgroundevents (mainly cosmics) from antiproton annihilations originating from antihydrogen atoms which are produced only in small amounts. A central BGO crystal disk with position sensitive read-out detects the annihilation and a surrounding two-layered hodoscope is used for tracking charged secondaries. The hodoscope has been recently upgraded to allow precise vertex reconstruction. A machine learning analysis based on measured antiproton annihilations and cosmic rays has been developed to identify antihydrogen events.