Multinucleon phenomena and proton spectra characterizing antiproton annihilation at rest in nuclei

Abstract

Spectra of protons with momenta greater than 500 MeV/c following antiproton annihilation at rest in carbon and uranium nuclei have been measured. They are compared to recent results from other experiments and to predictions of an intranuclear cascade model. Evidence is presented for a substantial B > 0 component in the annihilation process, and an estimate of the magnitude of that component is made.

Pion and fast proton production in $$\bar p$$ A annihilation at rest

“…In Table 4 we compare the fast proton multiplicities calculated for/~C and/3U annihilation with experimental data [16]. The agreement between experimental results and our results is quite acceptable.…”

“…on carbon a and uranium b at rest. Curve, our result; points: experimental data from [16] It is important to observe that we found the pion absorption probability increases significantly for heavy nuclei, whereas the scattering probability decreases. We consider the method discussed is more accurate and reliable for derivation of these probabilities from experimental data compared with the cascade model.…”

Fast deuteron production from antiproton annihilation at rest on carbon and uranium targets

“…Our previous studies of fast proton production in fil2C and /5238U annihilation at rest [6,7] resulted in two essential conclusions. First, because nucleons already exist inside the nucleus, one needs an energetic projectile to knock them out.…”

“…We hypothesize that a second component of very high energy nucleons can be produced via antiproton interaction with several bound nucleons, followed by the transfer of annihilation energy to one of the nucleons. Experimental data on proton production in /512C and /523su annihilation at rest show significant yields of fast protons with energy above ~600 MeV [6]. Although interpretation of these results by means of the two-step process seems reasonable to the first approximation [-7], it was necessary to incorporate a large probability for antiproton absorption on two bound nucleons, or sixquark objects (q6), inside the nucleus to explain the data in detail [6,7].…”

“…alpha particles, is < 1%. As in the previous study of proton spectra [6], data from another experiment [12] on low-energy deuterons have been used to provide a complete deuteron spectrum above 20 MeV kinetic energy.…”