2020 Impact factor 3.043
Hadrons and Nuclei
Eur. Phys. J. A 7, 429-434

Antiproton annihilation on light nuclei at very low energies

K.V. Protasov1 - G. Bonomi2 - E. Lodi Rizzini2 - A. Zenoni2

1 Institut des Sciences Nucléaires, IN2P3-CNRS, UJFG, 53, Avenue des Martyrs, 38026 Grenoble, Cedex, France
2 Dipartimento di Chimica e Fisica per l'Ingegneria e per i Materiali, Università di Brescia and INFN Sez. di Pavia, Via Valotti 9, 25123 Brescia, Italy

Received: 3 November 1999 / Revised version: 15 December 1999 Communicated by Th. Walcher

Abstract
Recent experimental data obtained by the OBELIX collaboration on pD and p4He total annihilation cross sections are analyzed. The combined analysis of these data with existing antiprotonic atom data allows, for the first time, the imaginary parts of the S-wave scattering lengths for the two nuclei to be extracted. The obtained values are: $\mbox {Im } a^{sc}_0 = [- 0.62 \pm 0.02 (\mbox{stat}) \pm 0.04
(\mbox{sys})]
\mbox { fm}$ for pD and $\mbox {Im } a^{sc}_0 = [- 0.36\pm
0.03(\mbox{stat})^{+0.19}_{-0.11}(\mbox{sys})]
\mbox { fm}$for $\bar{\mbox{p}}\:^4$He. This analysis indicates an unexpected behaviour of the imaginary part of the p-nucleus S-wave scattering length as a function of the atomic weight A:

$\vert\mbox {Im } a^{sc}_0\vert$ (pp) > $\vert\mbox {Im }~a^{sc}_0\vert$ (pD) > $\vert\mbox {Im }~a^{sc}_0\vert$ (p4He).

PACS
25.43.+t Antiproton-induced reactions - 36.10.-k Exotic atoms and molecules


Copyright Società Italiana di Fisica, Springer-Verlag 2000