Initial distributions, cascade, and annihilation of p p atoms formed in p +H and p +H sup minus collisions in near vacuum

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Physical Review, A (General Physics); (USA)

DOI:https://doi.org/10.1103/PhysRevA.41.3460· OSTI ID:6902845

Cohen, J S; Padial, N T ^[1]

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1. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA)

The initial-capture conditions and subsequent near-vacuum cascade are described for protonium ({ital {bar p}p}) formation in collisions of antiprotons ({ital {bar p}}) with the neutral H atom or with the negative ion H{sup {minus}}. The {ital {bar p}p} cascade is simulated by Monte Carlo with the initial states determined by previous classical-trajectory Monte Carlo calculations of the cross sections for {bar {ital p}} capture. The cascades of {ital {bar p}p} formed in corotating beams of {bar {ital p}} and H{sup {minus}} or in extremely low-density hydrogen gas are very similar, both yielding {approx}97% {ital {bar p}}-{ital p} annihilation in the 2{ital p} state of {ital {bar p}p} and {approx}1% each in the 1{ital s}, 3{ital d}, and higher-{ital p} states; the sensitivity to the strong-interaction parameters is examined. The time for the purely radiative cascade is quite long ({much gt}1 {mu}s) for {ital {bar p}p} atoms formed at the upper end of the 0.4{approx lt}{ital E}{sub lab}{approx lt}1.4 a.u. reaction window for {ital {bar p}}+H{sup {minus}} collisions. Possible experimental ramifications are discussed.

• OSTI ID: 6902845
• Journal Information: Physical Review, A (General Physics); (USA), Journal Name: Physical Review, A (General Physics); (USA) Vol. 41:7; ISSN PLRAA; ISSN 0556-2791
• Country of Publication: United States
• Language: English

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