Heavy fragment energies and angular distributions in the reaction of 86 MeV/nucleon12C with medium-A targets

Abstract

Using the thin target -thin catchers techniques, masses, mean recoil energies and angular distributions of target residues have been measured for 86 MeV/nucleon 12C induced reactions. Several different nuclear reaction processes, from peripheral to central collisions have been observed. Experimental results are partly reproduced by intranuclear cascade+evaporation calculations. Up to now, the production of the lightest masses (44<A <71) recoiling with high kinetic energies is not correctly understood by theoretical models. More exclusive experiments are needful to check if the formation of a highly excited quasi-compound nucleus could be a possible explanation of the phenomena.

124Sn target residues in the interaction of heavy ions at intermediate energies

“…1, exhibit a more complex situation. As the projectile energy increases, energy deposited in the target increases and the yield distribution becomes broader and broader and finally similar to the one previously obtained at CERN with 85MeV/u 12C ions [1]. In these extreme situations, when the total incident energy reaches roughly 1 GeV, as already mentioned El], a Monte Carlo intranuclear cascade model is able to generate a correct shape for the heavy mass product distribution.…”

“…The various beam intensities used were typically from 5.10 l~ 7.1011 ions per second. Basically, the experimental set up for the thin-target thin-catcher technique used, the off-line gamma-ray spectroscopy measurements, the identification of the radioactive products stopped in the catcher foils and the estimation of the corresponding cross sections or ranges, were the ones described previously for the 85 MeV/u 12C experiments [1]. For the recoil range measurements performed with a large number of thin evaporated aluminium catchers (1 or 2 Ixm thick), an angle 0 was defined around the beam axis by a collimator placed behind the target, in front of the stack of A1 foils; with this procedure, all the catchers were able to intercept the products emitted in the same solid angle.…”

“…In the 10-70MeV/u energy range, angular distribution measurements have not been performed systematically for each projectile. Using the cylindrical chamber described previously [1] such a measurement has been done in the 0-130 ~ range for the 124Sn+1ZC reaction at 30MeV/u. Typical curves are displayed in Fig.…”

“…If the complete fusion process is dominating at energies up to 7-8 MeV/u, the heavy products formed in central collisions have to deal with the competition between complete and incomplete fusion when the energy increases. In previous measurements performed at CERN with the 85 MeV/u t2C ions [1], based upon activation techniques and gamma-ray identification of the long lived radioactive residues, the recoil properties and the angular distributions of the heavy products were able to give an interesting insight on the various processes involved in the nuclear reaction. At 85 MeV/u incident energy, the main part of the results (mass yields, mean recoil energies, angular distributions) observed on medium -A targets as 89y, lt2Sn, 124Sn, is well reproduced by a Monte-Carlo intranuclear cascade model [2], but in addition, a low cross section of forward peaked, large recoil energy residues (40<A<71) is also easily identified.…”

Interaction of 8–46 MeV/nucleonNe20with Cu

“…The details are presented in Ref. 43. The phase-space distribution of nucleons was investigated at time intervals of 40 fm/c between 0 and 280 fm/c.…”