The odd–even effect of²⁰Ne fragmentation cross sections

Abstract

Projectile fragmentation cross sections are calculated for reactions of 20 Ne on the C, Al, Cu, Sn and Pb targets at 400 A MeV by using the improved quantum molecular dynamics model together with the statistical model code GEMINI. The improved quantum molecular dynamics model is applied to describe the dynamical process, and the GEMINI model is used to simulate the de-excitation process of excited primary fragments. It is found that the total cross sections increase as a function of the target mass, which is in good agreement with the experimental results and other theoretical predictions. The odd-even effect of the partial cross sections observed in experiments is well reproduced, which appears in the de-excitation process of the excited primary fragments as a result of pairing effect and is mainly formed in the grazing collisions. The results of isospin distributions demonstrate that the odd-even effect of partial cross sections mainly comes from the fragments with T Z = 0, ±0.5.

The odd–even effect of fragmentation cross sections for 36Ar and 40Ar

“…The ABRA-ABLA model reproduced a good quantitative reproduction of the odd-even effect, but the effect is overestimated by the theoretical calculations. It suggests that the odd-even effect fluctuations are produced in later stage of the de-excitation process, which is agreement with our work [40]. There are some theoretical and experimental analyses on the effect [41][42][43][44][45][46][47][48].…”

“…. C N Knott et al studied the isotopic production cross sections of 36 Ar and 40 Ar beams on an H target [15]. For the 36 Ar ( = T 0 Z ) projectile, the even A fragments with = T 0…”

“…Previously, we have analyzed the fragmentation of the 20 Ne projectile on different targets [13,40]. The reactions of 400 A MeV 20 Ne on C, Al, and CH 2 targets are performed at HIMAC in NIRS.…”

Methods for a quantitative evaluation of odd-even staggering effects

“…and its effect is indicated by the arrows pointing from the experimental Y (Z) (crosses) to Y(Z) (circles). This method is similar to that applied by Zeitlin [18] (and later by others [38,39]) in high-energy fragmentation studies. Note that in his original version, Zeitlin [18] took as a reference for each given Z the line (fine dotted in figure) joining Y (Z −1) and Y (Z +1): in this way he obtained an odd-even effect (distance from cross to triangle, shown only for Z=7) exactly twice as large as the present one (distance from cross to full circle).…”

New measurement of the elemental fragmentation cross sections of 218 MeV/nucleon 28 Si on a carbon target

“…Such divergence in experimental data could be due to the systematic uncertainties in the relevant experiments. This hampers our understanding of the underlying reaction mechanism in fragmentation reactions, e.g., the formation of odd-even staggering in charge distribution [10][11][12].…”