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

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7233127

Mercer, D J

Measurements of neutron polarization from (p,n) reactions can provide valuable clues toward understanding the isovector nucleon-nucleus interaction. A neutron time-of-flight polarimeter (NTOF) has been constructed at the Los Alamos meson Physics Facility (LAMPF) 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(p,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(p,n)2p reaction with bombarding energies of 318 and 494 MeV to produce a polarized neutron beam. The results from (n,p) analyzing reactions within the detector agree with values anticipated from free nucleon-nucleon analyzing powers, but the results from (n,n) 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[degrees]) for (p,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[degrees]) [approx] [minus]1/3 in the plane wave limit, but a simple average of the J[pi] = 0[sup +] [r arrow] 1[sup +] results at a bombardment energy of 494 MeV gives D[sub LL](0[degrees]) = [minus]0.689 [+-] 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: Colorado Univ., Boulder, CO (United States)
• OSTI ID: 7233127
• Country of Publication: United States
• Language: English

Related Subjects

440103 -- Radiation Instrumentation-- Nuclear Spectroscopic Instrumentation
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
663430 -- Nucleon-Induced Reactions & Scattering-- (1992-)
663610* -- Neutron Physics-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCELERATORS
ANALYZING POWER
BARYON-BARYON INTERACTIONS
BARYONS
CARBON 12 TARGET
CARBON 14 TARGET
DEUTERIUM TARGET
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
GAMOW-TELLER RULES
HADRON-HADRON INTERACTIONS
HADRONS
INTERACTIONS
LAMPF LINAC
LINEAR ACCELERATORS
LITHIUM 7 TARGET
MESON FACTORIES
MEV RANGE
MEV RANGE 100-1000
NEUTRONS
NUCLEON-NUCLEON INTERACTIONS
NUCLEONS
PARTICLE INTERACTIONS
POLARIMETERS
POLARIMETRY
POLARIZATION
PROTON-NEUTRON INTERACTIONS
PROTON-NUCLEON INTERACTIONS
TARGETS
TIME-OF-FLIGHT METHOD