Speaker
Description
The ASACUSA Cusp collaboration aims to measure the ground-state hyperfine splitting of antihydrogen to a relative precision of parts per million, using a spin polarised antihydrogen beam in a low magnetic field region [1].
The first antihydrogen was successfully synthesised in the ASACUSA-Cusp experiment in 2010 [2] by mixing antiprotons and positrons in the so-called Cusp trap, which is a Penning-Malmberg trap with a cusped magnetic field. The principle quantum number (n) distribution was measured 2.7m away from the production region a few years later [3]. This measurement revealed that most atoms were produced in high Rydberg states and only a small fraction in lower n-states.
The production rate of antihydrogen increases with lower temperature and high densities of the positron plasma [4]. In order to increase the number of antihydrogen atoms produced in the Cusp trap, it was upgraded with a focus on decreasing the temperature of the plasma.
In addition, the positron system was upgraded and a third stage accumulator was added to accumulate several bunches of the buffer gas trap. Pumping out the gases used for trapping and accumulating positrons, which was not possible in the previous design, decreased the contamination of the UHV of the Cusp trap during the transfer of positrons.
This poster will present the upgrades of the positron system and the Cusp trap, as well as results on the on the plasma temperature and density control and the results of last year’s antihydrogen run.
References:
[1] A. Mohri, & Y. Yamazaki (2003). A possible new scheme to synthesize antihydrogen and toprepare a polarised antihydrogen beam. Europhysics Letters, 63(2), 207.
[2] Enomoto, Y., Kuroda, N., Michishio, K., et al. (2010). Synthesis of Cold Antihydrogen in a Cusp Trap. Phys. Rev. Lett., 105, 243401.
[3] Kolbinger, B., Amsler, C., Cuendis, S.A. et al. (2021). Measurement of the principal quantum number distribution in a beam of antihydrogen atoms. Eur. Phys. J. D 75, 91
[4] Radics, B., Murtagh, D., Yamazaki, Y., & Robicheaux, F. (2014). Scaling behavior of the ground-state antihydrogen yield as a function of positron density and temperature from classical-trajectory Monte Carlo simulations. Phys. Rev. A, 90, 032704.
