ABSTRACT
Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart-hydrogen--is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy.
ABSTRACT
The kaonic 3He and 4He [Formula: see text] transitions in gaseous targets were observed by the SIDDHARTA experiment. The X-ray energies of these transitions were measured with large-area silicon-drift detectors using the timing information of the [Formula: see text] pairs produced by the DAΦNE [Formula: see text] collider. The strong-interaction shifts and widths both of the kaonic 3He and 4He 2p states were determined, which are much smaller than the results obtained by the previous experiments. The "kaonic helium puzzle" (a discrepancy between theory and experiment) was now resolved.
ABSTRACT
The kaonic (3)He and (4)He X-rays emitted in the [Formula: see text] transitions were measured in the SIDDHARTA experiment. The widths of the kaonic (3)He and (4)He 2p states were determined to be [Formula: see text], and [Formula: see text], respectively. Both results are consistent with the theoretical predictions. The width of kaonic (4)He is much smaller than the value of [Formula: see text] determined by the experiments performed in the 70's and 80's, while the width of kaonic (3)He was determined for the first time.
ABSTRACT
The first observation of the kaonic (3)He 3dâ2p transition was made, using slow K- mesons stopped in a gaseous (3)He target. The kaonic atom X-rays were detected with large-area silicon drift detectors using the timing information of the K+K- pairs of Ï-meson decays produced by the DAΦNE e+e- collider. The strong interaction shift of the kaonic (3)He 2p state was determined to be -2±2(stat)±4(syst) eV.
