Phys. Rev. C 64, 064606 (2001) [12 pages]Analyzing power reduction in quasifree pion-nucleon knockout reactions |
Received 21 May 2001; published 19 November 2001
Unpolarized cross sections and vector target analyzing powers for the 7Li→(π+,π+′p) proton knockout reaction were measured using a vector polarized 7LiH target and a 240 MeV π+ beam at the πM1 channel of PSI. Typical target polarizations were >30% for 7Li. Coincident π+-p data are presented for three emitted pion angles (60°, 85°, and 108°). For each π+ angle coincident data with adequate statistics were obtained for three proton angles near the quasifree π+-p angle. The π+ angles were chosen to emphasize and isolate contributions to the target analyzing powers from the two-body π-nucleon interaction with a polarized nucleon whose polarization resulted from either the target polarization or from the distortion-induced effective polarization. The data are compared with factorized-amplitude distorted-wave impulse approximation (DWIA) calculations. The unpolarized cross sections are rather well described by these calculations. However, for all three angles the target analyzing powers are substantially reduced from predictions of conventional DWIA calculations. This result suggests a rather strong spin dependence in the Δ-nucleus spreading potential.
©2001 The American Physical Society
URL: http://link.aps.org/abstract/PRC/v64/e064606
DOI: 10.1103/PhysRevC.64.064606
PACS: 25.80.Hp, 29.25.Pj
* Present address: Integral Systems, Inc. 5000 Philadelphia Way, Suite A, Lanham, MD 20706-4417.
† Present address: Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
‡ Present address: ioWave, Inc., 2100 Washington Blvd., Suite 1001, Arlington, VA 22204.
§ Present address: Research and Data Systems Corp., 7833 Walker Dr., Suite 550, Greenbelt, MD 20770.
** Present address: Cable & Wireless USA, 1919 Gallows Road, Vienna, VA 22182.
†† Present address: SAIC, 4001 N. Fairfax Drive, Suite 400, Arlington, VA 22203.
‡‡ Present address: Dept. of Chemistry and Physics, University of North Carolina at Pembroke, Pembroke, NC 28372-1510.
¶ Present address: Comark, 444 Scott Drive, Bloomingdale, IL 60108.
a Present address: Institute of Physics, University of Túbingen, Tübingen, Germany.
b Present address: Dept. of Physics, University of Virginia, Charlottesville, VA.
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