Speaker
Description
The ASACUSA-Cusp collaboration intends to perform precision microwave spectroscopy of the antihydrogen ground-state hyperfine splitting to compare with analogous measurements in hydrogen [1]. This comparison can place limits on CPT violation and probes the matter-antimatter asymmetry. The beam needs to be spin polarised in the ground-state, with a velocity of <1500 m/s, to be compatible with our spectroscopy apparatus [2].
The beam is produced using the slow-merge mixing technique of combining antiproton and positron plasmas inside a Penning-Malmberg trap [3], where antihydrogen is formed primarily through three-body recombination [4]. A small fraction of the antihydrogen escapes out of the trap into the beamline, which is free of strong electric or magnetic fields. The beam has approximately 320 antihydrogen atoms per 15 minute experimental cycle, and is primarily comprised of Rydberg atoms. Using modulated electric field ionisation we have measured the velocity and quantum number distribution of the beam using time-of-flight techniques. These results will be presented, along with the requirements for producing an antihydrogen beam in this manner.
[1] E. Widmann et al., NIM B 214, 31-34 (2009)
[2] C. Malbrunot et al., NIM A 935, 110-120 (2019)
[3] The ALPHA Collaboration, Nat. Comm. 8 (2017)
[4] B. Radics, PRA 90, 032704 (2014)"
