Pairing effect and misleading regularity

Abstract

We study the nearest neighbor spacing distribution of energy levels of even-even nuclei classified according to their reduced electric quadrupole transition probability B(E2) using the available experimental data. We compare between Brody, and Abul-Magd distributions that extract the degree of chaoticity within nuclear dynamics. The results show that Abul-Magd parameter f can represents the chaotic behavior in more acceptable way than Brody, especially if a statistically significant study is desired. A smooth transition from chaos to order is observed as B(E2) increases. An apparent regularity was located at the second interval, namely: at 0.05≤B(E2)<0.1 in e2b2 units, and at 10≤B(E2)<15 in Weisskopf unit. Finally, the chaotic behavior parameterized in terms of B(E2) does not depend on the unit used.