Calculations of neutron spectra after neutron-neutron scatteringстатья
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Дата последнего поиска статьи во внешних источниках: 18 февраля 2017 г.
Местоположение издательства:[Bristol, UK], England
Первая страница:1269
Последняя страница:1285
Аннотация:A direct neutron–neutron scattering length, ann, measurement with the goal
of 3 \% accuracy (0.5 fm) is under preparation at the aperiodic pulsed reactor
YAGUAR. A direct measurement of ann will not only help resolve conflicting
results of ann by indirect means, but also in comparison to the proton–proton
scattering length, app, shed light on the charge-symmetry of the nuclear force.
We discuss in detail the analysis of the nn-scattering data in terms of a simple
analytical expression. We also discuss calibration measurements using the
time-of-flight spectra of neutrons scattered on He and Ar gases and the neutron
activation technique. In particular, we calculate the neutron velocity and
time-of-flight spectra after scattering neutrons on neutrons and after scattering
neutrons on He and Ar atoms for the proposed experimental geometry, using a
realistic neutron flux spectrum—Maxwellian plus epithermal tail. The shape
of the neutron spectrum after scattering is appreciably different from the initial
spectrum, due to collisions between thermal–thermal and thermal–epithermal
neutrons. At the same time, the integral over the Maxwellian part of the
realistic scattering spectrum differs by only about 6 per cent from that of a pure
Maxwellian nn-scattering spectrum.