Violence of Heavy-Ion Reactions from Neutron Multiplicity: (11 to 20)A-MeVNe20+

Abstract

The suitability of the neutron multiplicity as a gauge for the violence of medium-energy heavyion reactions is investigated for the first time. For this purpose the number of neutrons emitted from fission reactions induced by 220-, 290-, and 400-MeV 20 Ne on 238 U is registered event by event with a large 4TT scintillator tank. It is shown that the neutron multiplicity is indeed closely related to the two quantities characterizing the violence: the induced total intrinsic excitation and the linear momentum transfer.

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

“…3 results from a kinematical calculation assuming no transverse component, symmetric splitting in mass and a velocity of the fission fragments as deduced from the Viola systematics [22]. The most probable momentum transfer (96% __ 4.5%) is in good agreement with the one derived independently for the same system and using as an observable the ratio of the forward-to-backward fission yields [20].…”

“…It was checked in previous experiments on the Nc + U system [20] between 220 MeV and 400 MeV bombarding energy that the simultaneous determination of momentum transfer (through forward and backward measurements of the fission yields) and excitation energy (through neutron multiplicity measurements) led to a satisfactory interpretation of the data in terms of a massive transfer or incomplete fusion process. The investigation has been pursued further in the present experiment by deriving the transferred momentum from the folding angle of the fission fragments.…”

Correlations between reaction product yields as a tool for probing heavy-ion reaction scenarios

“…As shown in Fig. 2, the average size of the IMFs produced is correlated prominently with the joint multiplicity of neutrons and LCPs, which reflects the dissipated and "thermalized" energy in heavy-ion collisions [27][28][29]. Hence, larger IMF sizes are associated with higher excitation energies.…”

“…It is well known from the literature [27][28][29] that the joint multiplicity distributions of neutrons and LCPs can be used as measures of kinetic energy dissipation achieved in individual reaction events. This distribution for the 136 Xe + 209 Bi reaction at E/A = 40 MeV is shown in Fig.…”