Towards exotic nuclei via binary reaction mechanism

Abstract

Assuming a binary reaction mechanism, the yield of isotopes near the heaviest $N=Z$ neutron-deficit nucleus $^{100}$Sn is studied with a microscopic transport model. The large influence of nuclear shell structure and isotope composition of the colliding nuclei on the production of exotic nuclei is demonstrated. It is shown that the reaction $^{54}$Fe+$^{106}$Cd seems to be most favourable for producing primary exotic Sn isotopes which may survive if the excitation energy in the entrance reaction channel is less than about 100 MeV. In the case of large differences in the charge (mass) numbers between entrance and exit channels the light fragment yield is essentially fed from the decay of excited primary heavier fragments. The existence of optimal energies for the production of some oxygen isotopes in the binary mechanism is demonstrated for the $^{32}$S+$^{197}$Au reaction.Comment: 17 pages, RevTex, 8 Postscript figures, submitted to Phys. Rev.

Possibility of production of neutron-rich isotopes in transfer-type reactions at intermediate energies

“…The nucleon pickup products have been observed among the products of projectile fragmentation reactions at the bombarding energies above the Fermi energy: 48 Ca (55 MeV/ nucleon) + 181 Ta [1], 48 Ca(64 MeV/nucleon) + 181 Ta [9], 18 9 Be and 181 Ta targets [37]. As shown in Ref.…”

“…In addition to the fragmentation reactions the multinucleon transfer reactions are actively discussed to produce exotic nuclei. These binary reactions have been known for producing exotic nuclei for many years [12][13][14][15][16][17][18][19]. In the transfer reactions the excitation energies of the fragments are smaller than in the fragmentation reactions.…”

“…Our calculations clarify that the multinucleon transfer process is the main process that contributes to the total reaction yields of the most exotic nuclei in the intermediate energy region. This means that the observed new isotopes with neutron number larger than the projectile neutron number in reactions 48 Ca (55 MeV/nucleon) + 181 Ta [1], 48 Ca (64 MeV/nucleon) + 181 Ta [9], 18 40 Ca, 48 Ca, 58,64 Ni (140 MeV/nucleon) + 9 Be, 181 Ta [37], and 48 Ca (142 MeV/nucleon) + 9 Be, nat W [10] are most probably the transfer products at large angular momentum TABLE I. The calculated production cross-sections of nuclide in the indicated reactions are compared with the available experimental data for the reactions 48 Ca(142 MeV/ nucleon) + nat W [10], 48 Ca (140 MeV/nucleon) + 181 Ta [37], and 48 Ca(64 MeV/nucleon) + 181 Ta [9].…”

Production of neutron-rich Ca isotopes in transfer-type reactions

“…Since the products of multinucleon transfer reactions have wider angular distributions, the experimental efˇciency in the collection of exotic nuclei is smaller than in the fragmentation reactions. However, the cross sections for exotic nuclei production can be much larger in the reactions in which the binary mechanism dominates [9] than the cross sections in high-energy fragmentation reactions. In the transfer reactions the total excitation energy is smaller and only binary processes are possible in which the control of excitation energy of the reaction products is simpler.…”