Resonance two-step mechanism and the charge dependence of ($pi$$,$$pi$N) reactions

Conference · Mon Oct 01 04:00:00 EDT 1973

OSTI ID:4354620

Strobel, G L; Gibbs, W R; Gibson, B F.V. ^[1]

---

1. eds.

In lectures from the LAMPF summer school. Deviations of the ratio R for sigma ( pi /sup +/, pi /sup +/n or pi /sup 0/p)/ sigma ( pi /sup -/, pi /sup -/n) from the impulse approximation predictions are explained by including a two- step nucleon--nucleus resonance reaction mechanism. Such a mechanism dominates the 50-MeV (p,2p) reaction on /sup 16/O. In this mechanism the pion interacts with a nucleon, which is excited into a giant resonance state with the nucleus. This resonant state decays into the final state, emitting a nucleon. Depending on the relative importance of this mechanism, R can vary from the impulse value of 1/3 to a maximum of 9/8 in this model. Resonance parameters are used which are consistent with values from proton induced reaction analyses. The calculated R reproduces the trends of the experimental values. The decrease in cross section from /sup 12/C to /sup 16/O is also reproduced. The ratio of sigma ( pi /sup -/, pi /sup +/n)/ sigma ( pi /sup -/, pi /sup -/p) on a /sup 12/C target is calculated to be 1.12 which compares well with the experimental value of 1.3 plus or minus 0.4. (auth)

• Research Organization: Univ. of Georgia, Athens; Los Alamos Scientific Lab., N.Mex. (USA)
• NSA Number: NSA-29-017143
• OSTI ID: 4354620
• Report Number(s): LA--5443-C
• Country of Publication: United States
• Language: English

Related Subjects

*CARBON 12-- PION REACTIONS
*OXYGEN 16-- PION REACTIONS
*PION REACTIONS-- KNOCK-OUT REACTIONS
CROSS SECTIONS
ENERGY LEVELS
GIANT RESONANCE
MEV RANGE 10-100
N68352* --Physics (Nuclear
Theoretical)--Nuclear Properties & Reactions
6 <= A <= 19--Nuclear Reactions & Scattering
PIONS MINUS
PIONS NEUTRAL
PIONS PLUS
REACTION KINETICS
RESONANCE