Pairing effects and multistep direct and compound emission in theMo92−100(p,xn) reactions

Fission Neutrons

“…Terrell [45] investigated this problem on the basis of experimental data collected before 1960th. "It is found that all experimental energy distributions for fission neutrons are indistinguishable from Maxwellian distributions; it has been shown that distributions of essentially this form are predicted by Weisskopf's evaporation theory" (motivation for constant T).…”

The Feshbach-Kerman-Koonin multistep direct reaction theory

“…In the literature on multistep direct reactions, different positions are taken with respect to the statistics. Koning and Akkermans (1991) prove that the application of residual-system statistics alone leads to the multistep direct models of Tamura et al (1982) and Nishioka et al (1988), respectively, and that the application of leading-particle statistics alone leads to the FKK model. In other words, for the derivation of the FKK cross-section the randomness of the distribution amplitudes is not required although this randomness was explicitly assumed by Feshbach et al (1980).…”

“…In the models of Tamura et al (1982) and Nishioka et al (1988), only residual-system statistics is invoked. Moreover, in the latter model, leading-particle statistics is explicitly forbidden because of the short time scales at which the interaction processes are assumed to take place.…”

“…The value of the effective interaction strength at this energy is less than the values found at lower energies previously discussed, indicating that it decreases with increasing incident energy. Marcinkowski et al (1989) (n, n') 11.26 25 Demetriou et al (1993) (n, n') 14 33 Austin (1980) (N,N') 35 + 15 27.9 Holler et al (1985) (p,n) 26.7 27 Mordhorst et al (1986) (p, n) 25.6 25 Trabandt et al (1988Trabandt et al ( , 1989 (p, n) 80 20 ___ 1 Cowley et al (1991) (p,p') 80 23 + 1 Scobel et al (1990) (p, n) 120 16 + 1 160 12.5 __+ 1 Richter et al (1992Richter et al ( ,1994 (p,p') (See Table 2) Stamer et al (1993) (p, n) 256 8.5 + 1.5…”

“…At this energy most of the cross-section at the higher emission energies is multistep direct. The effects of pairing on pre-equilibrium emission were studied by Mordhorst et al (1986) who measured the outgoing neutron spectrum from the (p, xn) reaction at 25.6 MeV on seven molybdenum isotopes. At this energy both multistep direct and multistep compound processes contribute substantially, and the experimental data were fitted with the same value of Vo --25 MeV using a Yukawa effective interaction of range 1 fm.…”