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/sup 3/He(. pi. /sup -/,n)/sup 2/H and /sup 4/He(. pi. /sup -/,n)/sup 3/H at 50--295 MeV

Journal Article · · Phys. Rev. C; (United States)
OSTI ID:5987010
The cross section of ..pi../sup -/+/sup 3/He..-->..d+n and ..pi../sup -/+/sup 4/He..-->..t+n has been measured at energies between T = 50 and 295 MeV and angles between theta/sub n/roughly-equal20/sup 0/ and 150/sup 0/ covering the momentum transfer range qroughly-equal0.4 --1.0 GeV/c. A phenomenological analysis of the data is attempted to identify the characteristic T, theta, and q dependences of the (..pi..,n) reaction dynamics. Most conspicuous is the angular dependence of the /sup 4/He(..pi../sup -/,n)/sup 3/He which mirrors characteristic features of ..pi..+He elastic scattering. The T dependence of (..pi..,n) in /sup 3,4/He (for theta<70/sup 0/) is similar to ..pi..+N or ..pi..+He elastic scattering. The clear dependence of T and theta is indicative of ..pi..+N (off-shell) scattering in the basic pion-absorption process. The nuclear form factor q dependence is most pronounced for forward angles, and the largely exponential falloff with q is similar to that of analogous nuclear reactions. Comparisons with theoretical calculations show that crucial ingredients are missing in currently used models and general directions of needed refinements are indicated.
Research Organization:
University of Virginia, Charlottesville, Virginia 22901
OSTI ID:
5987010
Journal Information:
Phys. Rev. C; (United States), Journal Name: Phys. Rev. C; (United States) Vol. 24:3; ISSN PRVCA
Country of Publication:
United States
Language:
English