https://doi.org/10.1051/epjconf/202226201007
Minimizing plasma temperature for antimatter mixing experiments
1 Stefan Meyer Institute
2 Ulmer Fundamental Symmetries Laboratory, RIKEN
3 Dipartimento di Ingegneria dell’Informazione, Università degli Studi di Brescia and INFN Pavia
4 Politechnico di Milano
5 INFN Milano
6 Graduate School of Advanced Science and Engineering, Hiroshima University
7 Nishina Center for Accelerator-Based Science, RIKEN
8 Institute of Physics, the University of Tokyo
9 Dipartimento di Fisica, Università degli Studi di Milano
10 Experimental Physics Department, CERN
11 Department of Physics, Tokyo University of Science
12 Department of Physics and Astronomy, Aarhus University
* e-mail: eric.david.hunter@cern.ch
Published online: 27 April 2022
The ASACUSA collaboration produces a beam of antihydrogen atoms by mixing pure positron and antiproton plasmas in a strong magnetic field with a double cusp geometry. The positrons cool via cyclotron radiation inside the cryogenic trap. Low positron temperature is essential for increasing the fraction of antihydrogen atoms which reach the ground state prior to exiting the trap. Many experimental groups observe that such plasmas reach equilibrium at a temperature well above the temperature of the surrounding electrodes. This problem is typically attributed to electronic noise and plasma expansion, which heat the plasma. The present work reports anomalous heating far beyond what can be attributed to those two sources. The heating seems to be a result of the axially open trap geometry, which couples the plasma to the external (300 K) environment via microwave radiation.
© The Authors, published by EDP Sciences, 2022
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.