Cross measurements of linear momentum transfer and energy dissipation in collisions between 290 MeV20Ne and238U

Abstract

The 2~reactions are investigated at 290MeV bombarding energy. The linear momentum transfer and excitation energy are deduced eventwise from the respective measurements of the folding angle between correlated fission fragments and the neutron multiplicity. A simple incomplete fusion picture is shown to essentially account for the data. The sensitivity of the two measurements in order to infer the violence of a collision is discussed in details.Nuclear Reactions: U(2~ fission, xn) E=290 MeV; measured fission fragment folding angle distribution, neutron multiplicity distribution. Deduced linear momentum transfer, E*.

Total neutron multiplicities as a measure of the violence in heavy ion reactions

“…Similar agreement can be obtained [22] for 4~ + 238U. [8,11]) and 14.5 MeV/u projectiles (2~ + 238U [7]) shown as mooth lines through the respective experimental data; the results for a2S + 232Th were obtained from a moving source fit [10] I 700 On these grounds, the neutron multiplicities found for several reaction systems in the fissility range x = 0.82-0.91 are displayed in Fig. 7 with the LMT dependence being converted into a common E*N scale.…”

“…7, M4~ turns out to be correlated with E*N in a monotonic and very similar way. However, M4~ is much less a precise measure of E* N -and therefore also of p -than was observed for 2~ + 238U at e = 14.5 MeV/u [7] in the range E*N < 220 MeV.…”

“…They originate from the enhanced charged particle emission in the early stages of deexcitation [11,21] and cause a stronger statistical fluctuation of M4,~ for a given E~N. Indeed is the standard deviation a(M4~),,~ 5 n for 2~ [7], but >8n for 328-t-197Au, cf. Fig.…”

“…A recent study [7] of the reaction 2~ at a projectile energy per nucleon e = 14.5 MeV/u revealed a strong correlation of E'N, measured as neutron multiplicity M4~ with a 4re liquid scintillator sphere, and p, the relative LMT deduced from a measurement of O12.…”

“…This saturation starts beyond the peripheral LMT peak and is fully attributed to effects broadening the distribution of O12, in particular neutron evaporation [2,[7][8][9].…”