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.

Minimizing plasma temperature for antimatter mixing experiments / E.D. Hunter, C. Amsler, H. Breuker, S. Chesnevskaya, G. Costantini, R. Ferragut, M. Giammarchi, A. Gligorova, G. Gosta, H. Higaki, Y. Kanai, C. Killian, V. Kletzl, V. Kraxberger, N. Kuroda, A. Lanz, M. Leali, V. Maeckel, G. Maero, C. Malbrunot, V. Mascagna, Y. Matsuda, S. Migliorati, D.J. Murtagh, Y. Nagata, A. Nanda, L. Nowak, E. Pasino, M. Rome', M.C. Simon, M. Tajima, V. Toso, S. Ulmer, U. Uggerhoj, L. Venturelli, A. Weiser, E. Widmann, T. Wolz, Y. Yamazaki, J. Zmeskal. - In: EPJ WEB OF CONFERENCES. - ISSN 2100-014X. - 262:(2022), pp. 01007.1-01007.7. ((Intervento presentato al convegno EXA2021 : International Conference on Exotic Atoms and Related Topics nel 2021 [10.1051/epjconf/202226201007].

Minimizing plasma temperature for antimatter mixing experiments

M. Giammarchi;G. Maero;E. Pasino;M. Rome';
2022

Abstract

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.
Settore FIS/03 - Fisica della Materia
Settore FIS/01 - Fisica Sperimentale
27-apr-2022
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/939607
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