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Helium atom6/11/2023 ![]() ![]() Application of the DRS chip for fast waveform digitizing. IPAC10 1309–1313 (Asian Committee for Future Accelerators, 2010).Ībela, R., Foroughi, F. Production of a 1.3 MW proton beam at PSI. Collisional shift and broadening of the transition lines of pionic helium. Polarizability of the pionic helium atom. ![]() Negative-pion trapping by a metastable state in liquid helium. ![]() ![]() Measurement of the π − meson cascade transition time in gaseous 3He. Moderation and cascade time of negative pions and negative kaons in liquid helium. Moderation time for nuclear capture of negative pions in liquid 4He. Experimental study of the cascade time of negative mesons in a liquid helium bubble chamber. Precision spectroscopy of light exotic atoms. The capture of negative mesotrons in matter. Werner Heisenberg and the beginning of nuclear physics. On the interaction of elementary particles. Energy spectra of single neutrons and charged particles emitted following the absorption of stopped negative pions in 4He. Relativistic calculations of pionic and kaonic atoms’ hyperfine structure. Quadrupole interaction in pionic and kaonic atoms. Proposed method for laser spectroscopy of pionic helium to determine the charged-pion mass. Structure of neutral mesonic atoms formed in liquid helium. Metastable states of απ − e −, αK − e −, and \(\alpha \bar\) atoms. On the absorption of negative pions by liquid helium. The charged and neutral pion masses revisited. Measurement of the charged pion mass using X-ray spectroscopy of exotic atoms. Upper limit of the muon-neutrino mass and charged-pion mass from momentum analysis of a surface muon beam. Constraints on exotic spin-dependent interactions between matter and antimatter from antiprotonic helium spectroscopy. Bounds on the fifth forces at sub-Å length scale. Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio. Buffer-gas cooling of antiproton helium to 1.5 to 1.7 K, and antiproton-to-electron mass ratio. mα 7-order corrections in the hydrogen molecular ions and antiprotonic helium. High-precision comparison of the antiproton-to-proton charge-to-mass ratio. One-particle measurement of the antiproton magnetic moment. Observation of the 1S–2S transition in trapped antihydrogen. Pions and Nuclei (Clarendon Press, 1988).Īhmadi, M. This work enables the use of the experimental techniques of quantum optics to study a meson.Įricson, T. The detection of emerging neutron, proton and deuteron fragments signals the laser-induced resonance in the atom, thereby confirming the presence of π 4He . The laser initiates electromagnetic cascade processes that end with the nucleus absorbing the π − and undergoing fission 20, 21. Here we synthesize π 4He in a superfluid-helium target and excite the transition ( n, l) = (17, 16) → (17, 15) of the π −-occupied π 4He orbital at a near-infrared resonance frequency of 183,760 gigahertz. Its atomic structure is unique owing to the absence of hyperfine interactions 18, 19 between the spin-0 π − and the 4He nucleus. The π 4He atom is predicted to have an anomalously long nanosecond-scale lifetime, which could allow laser spectroscopy to be carried out 17. Metastable pionic helium ( π 4He ) is a hypothetical 14, 15, 16 three-body atom composed of a helium-4 nucleus, an electron and a π − occupying a Rydberg state of large principal ( n ≈ 16) and orbital angular momentum ( l ≈ n − 1) quantum numbers. However, laser excitations of mesonic atoms have not been previously achieved because of the small number of atoms that can be synthesized and their typically short (less than one picosecond) lifetimes against absorption of the mesons into the nuclei 1. Determining the mass of the π − meson in particular could help to place direct experimental constraints on the mass of the muon antineutrino 10, 11, 12, 13. Laser spectroscopy of these atoms should permit the mass and other properties of the meson to be determined with high precision and could place upper limits on exotic forces involving mesons (as has been done in other experiments on antiprotons 2, 3, 4, 5, 6, 7, 8, 9). Mesonic atoms are formed when an orbital electron in an atom is replaced by a negatively charged meson. Charged pions 1 are the lightest and longest-lived mesons. ![]()
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