TY - JOUR
T1 - Saturation of low-energy antiproton annihilation on nuclei
AU - Gal, A.
AU - Friedman, E.
AU - Batty, C. J.
PY - 2000/10/19
Y1 - 2000/10/19
N2 - Recent measurements of very low-energy (p(L) < 100 MeV/c) p̄ annihilation on light nuclei reveal apparent suppression of annihilation upon increasing the atomic charge Z and mass number A. Using p̄-nucleus optical potentials V(opt), fitted to p̄-atom energy-shifts and -widths, we resolve this suppression as due to the strong effective repulsion produced by the very absorptive V(opt). The low-energy p̄-nucleus wavefunction is kept substantially outside the nuclear surface and the resulting reaction cross section saturates as function of the strength of Im V(opt). This feature, for E > 0, parallels the recent prediction, for E < 0, that the level widths of p̄ atoms saturate and, hence, that p̄ deeply bound atomic states are relatively narrow. Antiproton annihilation cross sections are calculated at p(L) = 57 MeV/c across the periodic table, and their dependence on Z and A is classified and discussed with respect to the Coulomb focussing effect at very low energies. (C) 2000 Elsevier Science B.V.
AB - Recent measurements of very low-energy (p(L) < 100 MeV/c) p̄ annihilation on light nuclei reveal apparent suppression of annihilation upon increasing the atomic charge Z and mass number A. Using p̄-nucleus optical potentials V(opt), fitted to p̄-atom energy-shifts and -widths, we resolve this suppression as due to the strong effective repulsion produced by the very absorptive V(opt). The low-energy p̄-nucleus wavefunction is kept substantially outside the nuclear surface and the resulting reaction cross section saturates as function of the strength of Im V(opt). This feature, for E > 0, parallels the recent prediction, for E < 0, that the level widths of p̄ atoms saturate and, hence, that p̄ deeply bound atomic states are relatively narrow. Antiproton annihilation cross sections are calculated at p(L) = 57 MeV/c across the periodic table, and their dependence on Z and A is classified and discussed with respect to the Coulomb focussing effect at very low energies. (C) 2000 Elsevier Science B.V.
KW - Antiproton annihilation
KW - Low-energies
KW - Optical potentials
KW - Saturation
UR - http://www.scopus.com/inward/record.url?scp=0034687317&partnerID=8YFLogxK
U2 - 10.1016/S0370-2693(00)01040-6
DO - 10.1016/S0370-2693(00)01040-6
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AN - SCOPUS:0034687317
SN - 0370-2693
VL - 491
SP - 219
EP - 224
JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
IS - 3-4
ER -