Two-symmetry Penning-Ioffe trap for antihydrogen cooling and spectroscopy

E. Tardiff, X. Fan, G. Gabrielse, D. Grzonka, C. Hamley, E.A. Hessels, N. Jones, G. Khatri, W.S. Kolthammer, D. Martinez Zambrano, C. Meisenhelder, T. Morrison (+3 others)
2020 Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment  
A B S T R A C T High-accuracy spectroscopic comparisons of trapped antihydrogen atoms (H) and hydrogen atoms (H) promise to stringently test the fundamental CPT symmetry invariance of the standard model of particle physics. ATRAP's nested Penning-Ioffe trap was developed for such studies. The first of its unique features is that its magnetic Ioffe trap for H atoms can be switched between quadrupole and octupole symmetries. The second is that it allows laser and microwave access perpendicular to
more » ... the central axis of the traps. (G. Gabrielse). Meanwhile, others used an octupole Penning-Ioffe trap [9] to confine H atoms [10] . A third trap, ATRAP's second-generation trap, differs in that it can produce either a quadrupole field, an octupole field, or a combination. Recent simulations carried out for laser cooling of trapped H atoms and for spectroscopy of H atoms, soon to be reported, will explore the relative advantages and disadvantages of the two symmetries. These include a relatively harmonic H potential well for spectroscopy in a quadrupole field, and reduced distortion of the Penning trap in an octupole field. The scheme used to produce trappable H involves bringing the e + and p plasmas into a Ioffe trap, energizing the trap, and inducing the e + and p to interact to form H. To count trapped H, the trap can be shut off and annihilation products detected. ATRAP's first Penning-Ioffe trap was slow to turn on (∼15 min) and off (∼10 min as designed). The shape and speed of this trap both contributed to loss of constituent particles during the turn-on period, and the slow turn-off time increased the difficulty of separating the H annihilation signal from the background rate. ATRAP's second generation trap addresses these limitations. The focus of this report is the design and construction of this second-generation trap (Section 4), and a demonstrated performance comparable to design expectations (Section 5). The biggest challenge came from the unique choice to include radial sideports to allow laser beams and microwaves to enter the Penning-Ioffe traps perpendicular https://doi.
doi:10.1016/j.nima.2020.164279 fatcat:wix6fpg2ejekpf5yxiro4nhs7y