BASE experiment

BASE (Baryon Antibaryon Symmetry Experiment), AD-8, is a multinational collaboration at the Antiproton Decelerator facility at CERN, Geneva. The goal of the Japanese and German BASE collaboration[1] are high-precision investigations of the fundamental properties of the antiproton, namely the charge-to-mass ratio and the magnetic moment.

Antiproton decelerator
(AD)
ELENAExtra low energy antiproton ring-further decelerates antiprotons coming from AD
AD experiments
ATHENAAD-1 Antihydrogen production and precision experiments
ATRAPAD-2 Cold antihydrogen for precise laser spectroscopy
ASACUSAAD-3 Atomic spectroscopy and collisions with antiprotons
ACEAD-4 Antiproton cell experiment
ALPHAAD-5 Antihydrogen laser physics apparatus
AEgISAD-6 Antihydrogen experiment gravity interferometry spectroscopy
GBARAD-7 Gravitational behaviour of anti-hydrogen at rest
BASEAD-8 Baryon antibaryon symmetry experiment
PUMAAD-9 Antiproton unstable matter annihilation
official BASE logo

Experimental setup

The single antiprotons are stored in an advanced Penning trap system, which has a double-trap system at its core. It consists of a precision trap and an analysis trap. The precision trap is for high precision frequency measurements, the analysis trap has a strong magnetic field inhomogeneity superimposed, which is used for single particle spin flip spectroscopy. By measuring the spin flip rate as a function of the frequency of an externally applied magnetic-drive, a resonance curve is obtained. Together with a measurement of the cyclotron frequency, the magnetic moment is extracted.

BASE physics

The BASE collaboration developed techniques to observe the first spin flips of a single trapped proton[2] and applied the double-trap technique to measure the magnetic moment of the proton with a fractional precision of three parts in a billion,[3] being the most precise measurement of this fundamental property of the proton. The application of the technique to measure the magnetic moment of the antiproton with similar precision will improve the precision of this value by at least a factor of 1000, and will provide one of the most stringent tests of CPT invariance to date.

After the development of the multi-Penning-trap system and a  two-particle measurement method; this collaboration measured the antiproton magnetic moment with 350 times the precision than that measured by any other experiment, in 2017.[4][5]

In 2022 the experiment measured that the charge-to-mass ratios of protons and antiprotons are equal within a precision of 16 parts per trillion.[6][7]

BASE collaboration
Views of the BASE experimental zone
Views of the BASE experimental zone

The BASE collaboration comprises the following institutions:



See also
  1. Antiproton Decelerator
  2. TRAP experiment
  3. ATRAP experiment

References
  1. "official BASE website".
  2. Ulmer, S.; et al. (20 June 2011). "Observation of Spin Flips with a Single Trapped Proton". Physical Review Letters. 106 (25): 253001. arXiv:1104.1206. Bibcode:2011PhRvL.106y3001U. doi:10.1103/PhysRevLett.106.253001. PMID 21770638. S2CID 13997553.
  3. Mooser, A.; et al. (2014). "Direct high-precision measurement of the magnetic moment of the proton". Nature. 509 (7502): 596–599. arXiv:1406.4888. Bibcode:2014Natur.509..596M. doi:10.1038/nature13388. PMID 24870545. S2CID 4463940.
  4. Smorra, C.; Sellner, S.; Borchert, M. J.; Harrington, J. A.; Higuchi, T.; Nagahama, H.; Tanaka, T.; Mooser, A.; Schneider, G.; Bohman, M.; Blaum, K. (October 2017). "A parts-per-billion measurement of the antiproton magnetic moment". Nature. 550 (7676): 371–374. Bibcode:2017Natur.550..371S. doi:10.1038/nature24048. ISSN 1476-4687. PMID 29052625. S2CID 205260736.
  5. "Experiment of the moment". CERN Courier. 2018-02-16. Retrieved 2021-06-11.
  6. Borchert, M. J.; Devlin, J. A.; Erlewein, S. R.; Fleck, M.; Harrington, J. A.; Higuchi, T.; Latacz, B. M.; Voelksen, F.; Wursten, E. J.; Abbass, F.; Bohman, M. A. (2022-01-06). "A 16-parts-per-trillion measurement of the antiproton-to-proton charge–mass ratio". Nature. 601 (7891): 53–57. doi:10.1038/s41586-021-04203-w. ISSN 0028-0836.
  7. "BASE breaks new ground in matter–antimatter comparisons". CERN. Retrieved 2022-01-14.

Record for BASE Experiment on INSPIRE-HEP

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