A measurement of. Delta. sigma. sub L (np), the difference between neutron-proton total cross sections in pure longitudinal spin states
A measurement off {Delta}{sigma}{sub L}(np), the difference between neutron-proton total cross sections in pure longitudinal spin states, is described. The results will help determine the isospin-zero (I = 0) scattering amplitudes, which are not well known above laboratory energies of 500 MeV, whereas the isospin-one (I = 1) amplitudes are fairly well-determined to 1 GeV. Data points were taken at the Los Alamos Meson Physics Facility (LAMPF) at Los Alamos, New Mexico, for five neutron beam energies: 484, 568, 634,720 and 788 MeV; they are the first in this energy range. Polarized neutrons were produced by charge-exchange of polarized protons on a liquid deuterium target (LD{sub 2}). Large-volume neutron counters detected the neutrons that passed through a polarized proton target. The counters subtended a range of solid angles large enough to allow extrapolation of the scattered neutrons to 0{degree}. Two modifications to the LAMPF accelerator system which were made for this work are described. They included a beam buncher,'' which modified the normal rf-time structure of the proton beam and allowed for the selection of peak-energy neutrons by time-of-flight means, and a computerized beam steering program, which reduced systematic effects due to beam motion at the LD{sub 2} target. The experimental values of {Delta}{sigma}{sub L}(np) are found to be consistent with other np data, including preliminary data from SIN and Saclay, but not with some results from Argonne which used a polarized proton beam and a polarized deuteron target. The I = 0 component was extracted from {Delta}{sigma}{sub L}(np) using existing pp data (I = 1), with the unexpected result that {Delta}{sigma}{sub L}(I = 0) was found to be essentially identical in shape to {Delta}{sigma}{sub L}(I = 1). The significance of this is not yet understood.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- W-7405-ENG-36; FG04-88ER40403
- OSTI ID:
- 6784251
- Report Number(s):
- LA-11905-T; ON: DE91000885; TRN: 90-033086
- Resource Relation:
- Other Information: Thesis (Ph.D.). Thesis. Submitted to New Mexico State University, Las Cruces, NM
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
NUCLEON-NUCLEON INTERACTIONS
SCATTERING AMPLITUDES
TOTAL CROSS SECTIONS
BEAM BUNCHING
DATA ACQUISITION SYSTEMS
DATA ANALYSIS
DEUTERIUM TARGET
EXPERIMENTAL DATA
ISOSPIN
LINEAR ACCELERATORS
MEASURING METHODS
NEUTRON DETECTORS
NEUTRON REACTIONS
PARTIAL WAVES
POLARIZED BEAMS
PROTON REACTIONS
SPIN
ACCELERATORS
AMPLITUDES
ANGULAR MOMENTUM
BARYON REACTIONS
BARYON-BARYON INTERACTIONS
BEAM DYNAMICS
BEAMS
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DATA
HADRON REACTIONS
HADRON-HADRON INTERACTIONS
INFORMATION
INTERACTIONS
MEASURING INSTRUMENTS
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUMERICAL DATA
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
RADIATION DETECTORS
TARGETS
645103* - High Energy Physics- Particle Interactions & Properties-Experimental- Strong Interactions & Baryon & Meson Properties
651000 - Nuclear Physics