Neutron total cross section for tritium

Journal Article · Fri Aug 01 04:00:00 EDT 1980 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.22.384· OSTI ID:5173262

Phillips, T W; Berman, B L; Seagrave, J D

The neutron total cross sections for hydrogen, deuterium, and tritium have been measured with the neutron-time-of-flight technique. The tritium data span the neutron energy range from 60 keV to 80 MeV, with an overall systematic uncertainty which varies from 0.5% for energies below 17 MeV to 2% at the highest energy measured; the statistical uncertainties exceed these values only below 200 keV and above 7 MeV. The three-mole high-pressure gas samples were nearly isotopically pure. Excellent agreement is found with accepted cross sections for hydrogen and deuterium, and with previous Van de Graaff measurements for tritium except at the lowest-energy point at 290 keV. A minimum in the cross section near 600 keV (with a rise at lower energy) is newly observed. The cross section in the heretofore unexplored energy region between 7 and 14 MeV exhibits no structure, and thus no evidence for the existence of a bound four-neutron state. The extrapolated zero-energy cross section is found to be 1.70 +- 0.03 b, in sharp disagreement with previous thermal-energy observations, but in agreement with calculations which also yield the currently accepted coherent scattering length 3.73 fm. Agreement with a prediction from an analysis of p-/sup 3/He data is within 1% at the resonance peak near 3.5 MeV, but the data differ from this prediction by as much as 6% at lower and higher energies. Thus, within the framework of a suitable theoretical analysis, the present data might provide a measure of the departure from charge symmetry of the nuclear force.

• Research Organization: Lawrence Livermore Laboratory, University of California, Livermore, California 94550
• OSTI ID: 5173262
• Journal Information: Phys. Rev., C; (United States), Journal Name: Phys. Rev., C; (United States) Vol. 22:2; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

651225* -- Nuclear Properties & Reactions
A=1-5
Experimental-- Nuclear Reactions & Scattering-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYON REACTIONS
BOUND STATE
CHARGE DISTRIBUTION
COULOMB FIELD
CROSS SECTIONS
DEUTERIUM TARGET
ELECTRIC FIELDS
ENERGY RANGE
HADRON REACTIONS
HYDROGEN 1 TARGET
KEV RANGE
KEV RANGE 10-100
KEV RANGE 100-1000
MATRICES
MEV RANGE
MEV RANGE 01-10
MEV RANGE 10-100
NEUTRON REACTIONS
NUCLEAR REACTIONS
NUCLEON REACTIONS
R MATRIX
SCATTERING LENGTHS
TARGETS
TIME-OF-FLIGHT METHOD
TOTAL CROSS SECTIONS
TRITIUM TARGET