Abstract
The total neutron cross sections of the helium isotopes were measured in the energy range from 1.5 to 40 MeV. A continuous energy neutron source was used in connection with a 190 m long flight path and high resolution time-of-flight techniques. The energy resolution achieved enabled us to improve considerably the parameters of the narrow resonance in the n+ system. The position of the resonance was found to be 22 133±10 keV, with a total width of 76±12 keV and a neutron width of 37±5 keV. This agrees well with previous analyses, which yield . Absolute values for the cross sections were determined with an overall error smaller than 3%. Comparison with older data shows agreement within the total errors. Our data are 4% to 5% higher than the most recent data set; however, in the case of , the data are still below the predictions from an -matrix analysis. It was pointed out recently that a slight disagreement exists between the total neutron cross section of and the sum of the partial n- cross sections. This discrepancy is removed by our new data.
NUCLEAR REACTIONS Measured for , , 1.5-40 MeV, high resolution TOF techniques, high pressure gas samples, four-nucleon system, level parameters.
- Received 10 May 1983
DOI:https://doi.org/10.1103/PhysRevC.28.995
©1983 American Physical Society