CALCULATION OF PARTIAL DIFFERENTIAL SCATTERING CROSS SECTIONS FOR SLOW NEUTRONS

摘要: As an approach to developing methods for calculating differential scattering cross sections of materials neutrons with energy below 1 ev, five approximations the exact formalism Zemach and Glauber were applied treat by gases composed semirigid molecules. The theory is outlined following methods: (1) A quite rigorous method valid when neutron k/sub B/T are both much less than characteristic vibrational energies (2) which treats vibrations harmonically, rotations classically, neglects rotation-vibration coupling. Within these limitations at a1l energies. (3) like except that averages over orientation approximated Krieger-Nelkin introducing average values functions Eulerian angles wherever they appear. (4) a short collision time approximation. (5) such low classically. Method has feature all normal modes treated classically equation section reduces unbound particles. If some, but not all, ciassically averagesmore » as in effective mass atom attached molecule intermediate between Sachs-Teller applies exactly quantum mechanics. advantage being easily adapted treating simple models liquids amorphous solids. (auth)« less