Evidence of isospin effects in antiproton-nucleus annihilation

Balestra, F.; Bossolasco, S.; Bussa, M. P.; Busso, L.; Ferrero, L.; Panzieri, D.; Piragino, G.; Tosello, F.; Barbieri, Riccardo; Bendiscioli, G.; Rotondi, A.; Salvini, P.; Venaglioni, A.; Zenoni, A.; Batusov, Yu.A.; Falomkin, I.V.; Pontecorvo, G. B.; Rozhdestvensky, A.M.; Sapozhnikov, M. G.; Tretyak, V.I.; Guaraldo, C.; Maggiora, A.; Rizzini, E. Lodi; Haatuft, A.; Halsteinslid, A.; Myklebost, K.; Olsen, J.; Breivik, F.O.; Jacobsen, T.; Sørensen, S.O.

doi:10.1016/0375-9474(89)90518-6

Cited by 21 publications

(10 citation statements)

References 34 publications

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“…Another value of R np obtained in 4 He is smaller and energy dependent. At rest, a number R np = 0.48 (10) has been deduced from rather involved analyses of the final state mesonic interactions in the three nucleon systems [32].…”

Section: Resultsmentioning

confidence: 99%

Antiprotonic studies of nuclear neutron halos

et al. 1996

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Section: Resultsmentioning

confidence: 99%

Antiprotonic studies of nuclear neutron halos

et al. 1996

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“…As our assumed value of the ratio Im(a n )/Im(a p ) is probably the lowest acceptable (see the discussion in [53]) -these results clearly indicate the proton rich atmosphere of these two nuclei. (This would remain true for 144 Sm even if one assumes the value R np = 0.48 as obtained in the 4 He experiment [62]). The systematics presented in Fig.…”

Section: A Peripheral Neutron To Proton Density Ratiomentioning

confidence: 90%

Composition of the nuclear periphery from antiproton absorption

et al. 1998

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Thirteen targets with mass numbers from 58 to 238 were irradiated with the antiproton beam from the Low Energy Antiproton Ring facility at CERN leading to the formation of antiprotonic atoms of these heavy elements. The antiproton capture at the end of atomic cascade results in the production of more or less excited residual nuclei. The targets were selected with the criterion that both reaction products with one nucleon less than the proton and neutron number of the target are radioactive. The yield of these radioactive products after stopped-antiproton annihilation was determined using gamma-ray spectroscopy techniques. This yield is related to the proton and neutron density in the target nucleus at radial distance corresponding to the antiproton annihilation site. The experimental data clearly indicate the existence of a neutron rich nuclear periphery, a "neutron halo", strongly correlated with the target neutron separation energy Bn, and observed for targets with Bn < 10 MeV. For two target nuclei, 106 Cd and 144 Sm, with larger neutron binding energies a proton rich nuclear periphery was observed. Most of the experimental data are in reasonable agreement with calculations based on current antiproton-nucleus and pion-nucleus interaction potentials and on nuclear densities deduced with the help of the Hartree-Fock-Bogoliubov approach. This approach was, however, unable to account for the 106 Cd and 144 Sm results.

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“…Other interesting measurements of the antinucleon-nucleus interaction have been carried out and analyzed by the PS179 and OBELIX (PS201) collaborations, with more nuanced conclusions about the isospin dependence of the interaction at very low energy. See, for instance, [120,121].…”

Section: The Antinucleon-nucleus Interaction 61 Antinucleon-nucleus mentioning

confidence: 99%

Antiproton Physics

Richard

2020

Front. Phys.

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We review the physics of low-energy antiprotons, and its link with the nuclear forces. This includes: antinucleon scattering on nucleons and nuclei, antiprotonic atoms and antinucleon-nucleon annihilation into mesons. Modern perspectives 39 Outlook 39 1 A brief historyIn 1932, the positron, the antiparticle of the electron, was discovered in cosmic rays and confirmed in the β + decay of some radioactive nuclei. See, e.g., the Nobel lecture by Anderson [1]. It was then reasonably anticipated that the proton also has an antiparticle, where A denotes the target nucleus. For A = p, this is a standard exercise in relativistic kinematics to demonstrate that the kinetic energy of the incoming proton should be higher than 6 m, where m is the proton mass, and c = 1. This threshold decreases if the target is more massive. The Bevatron was completed in 1954, and the antiproton was discovered in 1955 by a team lead by Chamberlain and Segrè, who were awarded the Nobel prize in 1959. 2 Shortly after the antiproton, the antineutron,n, was also discovered at Berkeley, and up to now, for any new elementary particle, the corresponding antiparticle has also been found. The discovery of the first anti-atom was well advertised [2], but this was not the case for the earlier observation of the first antinucleus, antideuterium, because of a controversy between an European team [3] and its US competitors [4]. In experiments at very high energy, in particular collisions of heavy ions at STAR (Brookhaven) and ALICE (CERN), one routinely produces light antinuclei and even anti-hypernuclei (in which an antinucleon is replaced by an antihyperonΛ) [5][6][7].The matter-antimatter symmetry is almost perfect, except for a slight violation in the sector of weak interactions, which is nearly exactly compensated by a simultaneous violation of the left-right symmetry, i.e., the product P C of parity P and charge-conjugation C is only very marginally violated. Up to now, there is no indication of any violation of the product CP T , where T is the time-reversal operator: this implies that the proton and antiproton have the same mass, a property now checked to less than 10 −9 [8].Many experiments have been carried out with low energy antiprotons, in particular at Brookhaven and CERN in the 60s and 70s, with interesting results, in particular for the physics of the mesons produced by annihilation. However, in these early experiments, the antiprotons were part of secondary beams containing many negativelycharged pions and kaons, and with a wide momentum spread.In the 70s, Simon van der Meer, and his colleagues at CERN and elsewhere imagined and developed the method of stochastic cooling [9], which produces antiproton beams of high purity, sharp momentum resolution, and much higher intensity than in the previous devices. CERN transformed the fixed-target accelerator SpS into a protonantiproton collider, SppS, with the striking achievement of the discovery of the W ± and Z 0 , the intermediate bosons of the electro-weak interaction. A similar scheme was lat...

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Evidence of isospin effects in antiproton-nucleus annihilation

Cited by 21 publications

References 34 publications

Antiprotonic studies of nuclear neutron halos

Antiprotonic studies of nuclear neutron halos

Composition of the nuclear periphery from antiproton absorption

Antiproton Physics

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