Measurement of effective analyzing powers for the NTOF polarimeter at LAMPF and D[sub LL](0[degree]) for Gamow-Teller transitions in p-shell nuclei

Technical Report · Fri Jan 01 04:00:00 EST 1993

OSTI ID:7027135

Mercer, D J ^[1]

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1. Colorado Univ., Boulder, CO (United States). Dept. of Physics

Measurements of neutron polarization from ([rvec p],[rvec n]) reactions can provide valuable clues toward understanding the isovector nucleon-nucleus interaction. A neutron time-of-flight polarimeter has been constructed at the Los Alamos Meson Physics Facility to perform such measurements, but before the polarimeter can be used, its effective analyzing powers must be determined. This is accomplished by using the [sup 14]C([rvec p],[rvec n])[sup 14]N reaction at a bombarding energy of 494 MeV to produce a beam of neutrons with known polarization, illuminating the detector with these neutrons, and measuring the azimuthal asymmetries after scattering from a hydrogenous analyzer fluid within the detector. Secondary measurements are made using the [sup 2]H([rvec p],[rvec n])[sup 2]p reaction with bombarding energies of 318 and 494 MeV to produce a polarized neutron beam. The results from ([rvec n]p) analyzing reactions within the detector agree with values anticipated from free nucleon-nucleon analyzing powers, but the results from ([rvec n]p) analyzing reactions display a more than 33% reduction from the anticipated values. Additionally, measurements are made of the polarization transfer coefficient D[sub LL](0[degree]) for [rvec p],[rvec n] Gamow-Teller reactions on [sup 2]H, [sup 7]Li[sup 12]C, and [sup 14]C targets. For a purely central interaction, one would expect that D[sub LL](0[degree]) [approximately] [minus]1/3 in the plane wave limit, but a simple average of the J[pi] = 0[sup +] [yields] 1[sup +] results at a bombardment energy of 494 MeV gives D[sub LL](0[degree]) = [minus]0.689 [plus minus] 0.044. Thus, the measurements indicate that the nucleon-nucleus interaction -- which is largely central at 200 MeV -- has strong tensor contributions at higher energy.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 7027135
• Report Number(s): LA-12486-T; ON: DE93006918
• Country of Publication: United States
• Language: English

Related Subjects

440103* -- Radiation Instrumentation-- Nuclear Spectroscopic Instrumentation
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
663100 -- Nuclear Structure-- (1992-)
663430 -- Nucleon-Induced Reactions & Scattering-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALKALI METAL ISOTOPES
ANALYZING POWER
BARYON REACTIONS
BARYON-BARYON INTERACTIONS
CARBON 12 TARGET
CARBON 14 TARGET
CHARGED-PARTICLE REACTIONS
DEUTERIUM
DEUTERIUM TARGET
DIRECT REACTIONS
GAMOW-TELLER RULES
HADRON REACTIONS
HADRON-HADRON INTERACTIONS
HYDROGEN ISOTOPES
INTERACTIONS
ISOTOPES
LIGHT NUCLEI
LITHIUM 7
LITHIUM ISOTOPES
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEON-NUCLEON INTERACTIONS
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PARTICLE INTERACTIONS
POLARIMETERS
PROTON REACTIONS
STABLE ISOTOPES
TARGETS
TIME-OF-FLIGHT METHOD
TRANSFER REACTIONS