Pion absorption in nuclei: The (. pi. /sup + -/,p) reactions

Technical Report · Fri May 01 04:00:00 EDT 1987

DOI:https://doi.org/10.2172/6565916· OSTI ID:6565916

Mishra, C S

Reported here is the first experiment to measure the excitation of discrete final states following the (..pi../sup -/,p) reaction. The Energetic Pion Channel and Spectrometer (EPICS) at the Los Alamos National Laboratory and the High Resolution Pion Channel and Spectrometer (..pi..M1-SUSI) at the Swiss Institute for Nuclear Physics were used for this high resolution study of (..pi../sup + -/,p) reactions. An average energy resolution of 500 KeV and 700 KeV was achieved at EPICS and ..pi..M1-SUSI respectively. At EPICS these reactions were measured at T/sub ..pi../ = 120 MeV and theta/sub lab/ = 25/sup 0/ on /sup 24/Mg, /sup 27/Al, /sup 40/Ca and /sup 58/Ni; /sup 12/C(..pi../sup -/,p) was measured at T/sub ..pi../ = 145 MeV. At ..pi..M1-SUSI these reactions were measured at T/sub ..pi../ = 90 MeV and at theta/sub lab/ = 20/sup 0/ on /sup 23/Na and /sup 24/Mg. The measurement includes both the differential cross sections and continuum up to an excitation energy of 40 MeV. In /sup 23/Na, /sup 24/Mg, and /sup 27/Al there are peaks in the low excitation region. The shape of the continuum in an excitation energy range of 10 to 40 MeV was found to be independent of pion charge and target mass. The magnitude of proton yield from all the targets at T/sub ..pi../ = 120 MeV is more than twenty four times larger for ..pi../sup +/ than for ..pi../sup -/. Also, the cross sections for both reactions on /sup 24/Mg is slightly enhanced compared to other nuclei. At T/sub ..pi../ = 90 MeV the ratio of the proton yield for ..pi../sup +/ to ..pi../sup -/ absorption drops down to fourteen. This high ratio and its energy dependence supports the idea of a two nucleon pion absorption model. Pion absorption in the context of both the reaction mechanism and nuclear structure is discussed. 99 refs., 64 figs., 11 tabs.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6565916
• Report Number(s): LA-10997-T; ON: DE87009485
• Country of Publication: United States
• Language: English

Related Subjects

651420* -- Nuclear Properties & Reactions
A=20-38
Experimental
651520 -- Nuclear Properties & Reactions
A=39-58
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ABSORPTION
ALUMINIUM 27 TARGET
CALCIUM 40 TARGET
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
ENERGY RANGE
HADRON REACTIONS
HADRON-HADRON INTERACTIONS
INTERACTIONS
KINETICS
MAGNESIUM 24 TARGET
MESON REACTIONS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
MEV RANGE
MEV RANGE 100-1000
NICKEL 58 TARGET
NUCLEAR REACTIONS
NUCLEAR STRUCTURE
PARTICLE INTERACTIONS
PION MINUS REACTIONS
PION MINUS-PROTON INTERACTIONS
PION PLUS REACTIONS
PION PLUS-PROTON INTERACTIONS
PION REACTIONS
PION-NUCLEON INTERACTIONS
PION-PROTON INTERACTIONS
REACTION KINETICS
TARGETS