The positive odd-even effects observed in cold fragmentation - Are they real?
The experimental fission-fragment-nuclide yield in the cold region of the spontaneous fission of 252Cf was evaluated for bins of constant total excitation energy (TXE). The result showed that the previously observed undulatory structure of five to six mass units in the proton odd-even effect as a function of mass delta(Z)(A(L)) disappeared. These undulatory structures are artificial and depend on the way the evaluation cut through the nuclide-yield landscape is made with respect to the Q-value surface Q(A(L),Z(L)). The TXE-bin-integrated odd-even effects for protons and neutrons delta(Z) and delta(N) became negative, where delta(N) has a 1.5 to 2.5 times larger negative value than delta(Z). These negative values imply a preference for odd neutron and proton numbers compared with even ones for fragmentations with low total excitation energy. The reason for this behaviour could be the higher level density for odd-odd deformed nuclei compared to even-even nuclei.
Bibliographic Reference: Article: Nuclear Physics A554 (1993) pp. 209-222
Record Number: 199310899 / Last updated on: 1994-11-29
Original language: en
Available languages: en