Definition of cross sections 1 - Moodle

Resonances 4The first three values of the penetrability coefficient arev 0 (e exc ) = 1( [R̷λ) 2 ( ]R̷λ) 2−1v 1 (e exc ) = 1+(20)v 2 (e exc ) =( [R̷λ) 4 (9+3 R̷λ) 2 ( ]R̷λ) 4−1+where R is the hard sphere radius of the nucleus. It can be computed in term of the atomicmass ratio A using R = ( 0.123A 1/3 +0.08 ) ×10 −12 cm, and where ̷λ is the reducedwavelength of the neutron, defined by the relation(21)̷λ =m 0 V R=√ 2m0 e excwhere m 0 is the reduced mass of the neutron.ENE6101: Week 4 Cross sections – 19/37