The neutron capture cross section of radioactive isotopes for neutron energies in the keV region will be measured by a time-of-flight (TOF) experiment.
The precise knowledge of the involved neutron capture cross sections for certain isotopes sets tight limits for stellar parameters and puts strong constraints on the age of the Universe.
3]He has an extremely strong spin dependent capture cross section with essentially all capture in one spin state.
3]He cell thickness, [sigma](v) is the unpolarized capture cross section at neutron velocity v.
3]He spin parallel to the neutron spin, the thermal capture cross section
is essentially zero, whereas for the spins anti-parallel, the cross section is 10666 b.
It is connected with that the absorption coefficient of materials with a high capture cross section
is sufficiently bigger for the low energy region and that the density of coated [.
3]He nuclear spin for which the capture cross section
is very high ([sigma] [up arrow][down arrow] [barn] [approximately equal to] 6000 * [lambda] [[Angstrom]]) are absorbed in this reaction.