At LEAR of CERN the annihilation of antiprotons, stopping in He-3 and He-4 filling a self-shunted streamer chamber in a magnetic field, has been studied. The charged-particle multiplicities have been measured and the relative probabilities of pi(-) production in pbar He-3 and pbar He-4 annihilation events have been obtained. The ratio between the pbar annihilation probability on the neutron and the proton for He-3 and He-4 has been deduced to be about half the value obtained for H-2 in bubble chamber experiments. The analysis of the results shows that this difference cannot be due only tfo the pion final-state interaction or to the shadow effect of the nucleons of the nuclei. The probability of pbar annihilation at rest on a proton bound in the nucleus results to be twice as high as that on a bound neutron, showing the dominance of annihilation in the I = 0 isospin states.

Annihilation of Antiprotons At Rest In He-3 and He-4

BALESTRA, Ferruccio;BUSSA, Maria Pia;BUSSO, Luigi;FERRERO, Livio;PANZIERI, Daniele;PIRAGINO, Guido;
1987

Abstract

At LEAR of CERN the annihilation of antiprotons, stopping in He-3 and He-4 filling a self-shunted streamer chamber in a magnetic field, has been studied. The charged-particle multiplicities have been measured and the relative probabilities of pi(-) production in pbar He-3 and pbar He-4 annihilation events have been obtained. The ratio between the pbar annihilation probability on the neutron and the proton for He-3 and He-4 has been deduced to be about half the value obtained for H-2 in bubble chamber experiments. The analysis of the results shows that this difference cannot be due only tfo the pion final-state interaction or to the shadow effect of the nucleons of the nuclei. The probability of pbar annihilation at rest on a proton bound in the nucleus results to be twice as high as that on a bound neutron, showing the dominance of annihilation in the I = 0 isospin states.
474
651
661
self-shunted streamer chamber; PS179; antiproton-He-4 annihilation; antiproton He-3 annihilation; isospin dependence; annihilation on bound nucleons
F. BALESTRA;S. BOSSOLASCO;M. P. BUSSA;L. BUSSO;L. FAVA;L. FERRERO;D. PANZIERI;G. PIRAGINO;F. TOSELLO;G. BENDISCIOLI;A. ROTONDI;P. SALVINI;A. ZENONI;Y. A. BATUSOV;S. A. BUNYATOV;I. V. FALOMKIN;F. NICHITIU;G. B. PONTECORVO;M. G. SAPOZHNIKOV;V. I. TRETYAK;C. GUARALDO;A. MAGGIORA;E. L. RIZZINI;A. HAATUFT;A. HALSTEINSLID;K. MYKLEBOST;J. M. OLSEN;F. O. BREIVIK;T. JACOBSEN;S. O. SORENSEN
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/115617
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