39 research outputs found
Numerical Simulations of Hyperfine Transitions of Antihydrogen
One of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow
Antiprotons) collaboration's goals is the measurement of the ground state
hyperfine transition frequency in antihydrogen, the antimatter counterpart of
one of the best known systems in physics. This high precision experiment yields
a sensitive test of the fundamental symmetry of CPT. Numerical simulations of
hyperfine transitions of antihydrogen atoms have been performed providing
information on the required antihydrogen events and the achievable precision
Measurement of the hyperfine structure of antihydrogen in a beam
A measurement of the hyperfine structure of antihydrogen promises one of the
best tests of CPT symmetry. We describe an experiment planned at the Antiproton
Decelerator of CERN to measure this quantity in a beam of slow antihydrogen
atoms.Comment: 5th International Symposium on Symmetries in Subatomic Physics
(SSP2012), Groningen (The Netherlands), June 18 to 22, 201
First observation of two hyperfine transitions in antiprotonic He-3
We report on the first experimental results for microwave spectroscopy of the
hyperfine structure of antiprotonic He-3. Due to the helium nuclear spin,
antiprotonic He-3 has a more complex hyperfine structure than antiprotonic He-4
which has already been studied before. Thus a comparison between theoretical
calculations and the experimental results will provide a more stringent test of
the three-body quantum electrodynamics (QED) theory. Two out of four
super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were
observed. The measured frequencies of the individual transitions are
11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current
theoretical values, but still within their estimated errors. Although the
experimental uncertainty for the difference of these frequencies is still very
large as compared to that of theory, its measured value agrees with theoretical
calculations. This difference is crucial to be determined because it is
proportional to the magnetic moment of the antiproton.Comment: 8 pages, 6 figures, just published (online so far) in Physics Letters
A hydrogen beam to characterize the ASACUSA antihydrogen hyperfine spectrometer
The antihydrogen programme of the ASACUSA collaboration at the antiproton
decelerator of CERN focuses on Rabi-type measurements of the ground-state
hyperfine splitting of antihydrogen for a test of the combined
Charge-Parity-Time symmetry. The spectroscopy apparatus consists of a microwave
cavity to drive hyperfine transitions and a superconducting sextupole magnet
for quantum state analysis via Stern-Gerlach separation. However, the small
production rates of antihydrogen forestall comprehensive performance studies on
the spectroscopy apparatus. For this purpose a hydrogen source and detector
have been developed which in conjunction with ASACUSA's hyperfine spectroscopy
equipment form a complete Rabi experiment. We report on the formation of a
cooled, polarized, and time modulated beam of atomic hydrogen and its detection
using a quadrupole mass spectrometer and a lock-in amplification scheme. In
addition key features of ASACUSA's hyperfine spectroscopy apparatus are
discussed.
Spectroscopy Apparatus for the Measurement of The Hyperfine Structure of Antihydrogen
The ASACUSA CUSP collaboration at the Antiproton Decelerator (AD) of CERN is
planning to measure the ground-state hyperfine splitting of antihydrogen using
an atomic spectroscopy beamline. We describe here the latest developments on
the spectroscopy apparatus developed to be coupled to the antihydrogen
production setup (CUSP).Comment: Proceedings of the 11th International Conference on Low Energy
Antiproton Physics (LEAP 2013) held in Uppsala, Sweden, 10 to 15 June, 201
Hyperfine spectroscopy of hydrogen and antihydrogen in ASACUSA
The ASACUSA collaboration at the Antiproton Decelerator of CERN aims at a
precise measurement of the antihydrogen ground-state hyperfine structure as a
test of the fundamental CPT symmetry. A beam of antihydrogen atoms is formed in
a CUSP trap, undergoes Rabi-type spectroscopy and is detected downstream in a
dedicated antihydrogen detector. In parallel measurements using a polarized
hydrogen beam are being performed to commission the spectroscopy apparatus and
to perform measurements of parameters of the Standard Model Extension (SME).
The current status of antihydrogen spectroscopy is reviewed and progress of
ASACUSA is presented.Comment: Proceedings of the 7th International Syposium on Symmetries in
Subatomic Physics SSP2018, Aachen (Germany), 10 - 15 Jun 2018. Corrected
error in Fig. 1, updated caption, add titles to reference
Liquid helium-free cryostat and hermetically sealed cryogenic microwave cavity for hyperfine spectroscopy of antiprotonic helium
The design and properties of a new cryogenic set-up for laser–microwave–laser hyperfine structure spectroscopy of antiprotonic helium – an experiment performed at the CERN-Antiproton Decelerator (AD), Geneva, Switzerland – are described. Similar experiments for 4He have been performed at the AD for several years. Due to the usage of a liquid helium operated cryostat and therefore necessary refilling of coolants, a loss of up to 10% beamtime occurred. The decision was made to change the cooling system to a closed-circuit cryocooler. New hermetically sealed target cells with minimised 3He gas volume and different dimensions of the microwave resonator for measuring the 3He transitions were needed. A new set-up has been designed and tested at Stefan Meyer Institute in Vienna before being used for the 2009 and 2010 beamtimes at the AD
Antiproton magnetic moment determined from the HFS of pHe<sup>+</sup>
We report a determination of the antiproton magnetic moment, measured in a
three-body system, independent of previous experiments. We present results from
a systematic study of the hyperfine (HF) structure of antiprotonic helium where
we have achieved a precision more than a factor of 10 better than our first
measurement. A comparison between the experimental results and three-body
quantum electrodynamic (QED) calculations leads to a new value for the
antiproton magnetic moment is -2.7862 (83) nuclear magnetons, which agrees with
the magnetic moment of the proton within 2.9 x 10e-3