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

Abstract

The production cross sections of neutron-rich isotopes of Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, and Ti in the multinucleon transfer reactions 48 Ca(64 MeV/nucleon, 140 MeV/nucleon) + 181 Ta and 48 Ca(142 MeV/nucleon)+ nat W are estimated. A good agreement of the calculated results with the available experimental data confirms the mechanism of multinucleon transfer at almost peripheral collisions at intermediate energies. The global trend of production cross section with the charge (mass) number of target in reactions with 48 Ca beam is discussed for the future experiments.Projectile fragmentation at intermediate energies is a wellestablished method for the production of rare isotopes [1][2][3][4][5][6][7][8][9][10][11]. 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. The control of excitation energy of the reaction products in the binary processes is much simpler. So, the yields of exotic nuclei can be even larger in the transfer reactions than the yields in the high-energy fragmentation reactions in spite of the smaller experimental efficiency in the collection of exotic nuclei in the transfer reactions than in the fragmentation reactions. In Refs. [20] we have shown the possibility to produce the neutron-rich nuclei in the transfertype reactions at incident energies close to the Coulomb barrier. This process in the 238 U(5.5 MeV/nucleon) + 48 Ca reaction has been used to produce the odd and even neuron-rich Ca isotopes and study their low-lying states [21].As shown in Refs. [22,23], in the 209 Bi + 136 Xe and 197 Au + 208 Pb reactions at the lower boundary of the Fermi energy domain the total reaction cross section is almost entirely accounted for by binary collisions irrespective of a possible further disassembly of the two highly excited primary partners. The dissipative binary dynamics at these bombarding energies have been also observed in Refs. [24][25][26]. The observed influence of the target isospin on the final isospin of the projectile-like fragments and broadening of the projectilelike fragments charge distributions with increasing energy dissipation is similar to that encountered in damped reactions at lower bombarding energies of only a few MeV/nucleon above the Coulomb barrier. As clearly shown in Refs. [27][28][29][30][31][32][33][34], the transfer process is a very strong component for the projectile-like products in the peripheral collisions.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 O(80 MeV/nucleon) + 27 Al, 181 Ta [35], 112 Sn (63 MeV/ nucleon) + nat Ni [2], 86 Kr(70 MeV/nucleon) + 27 Al [36], and pri...

Production of fragments with more neutrons than the projectile at intermediate energies

“…The production of these fragments with more neutrons than the projectile must proceed via a transfer mechanism as described in Ref. [21], rather than via a deep inelastic collision in the low energy region leading to the transfer of a few neutrons and sizable velocity damping.…”

“…According to Ref. [21], in the collisions a short-living dinuclear system (DNS) is probably formed in which the diffusion of nucleons occurs. So, the details of neutron and proton density profiles at the projectile and target surfaces would influence the process of the nucleon exchange just like the situations happening in the Fermi energy region.…”

“…The nuclear reaction mechanism leading to the production of these fragments at intermediate energies has been described theoretically using the binary deep inelastic process [21]. The dynamics of the binary deep inelastic process is considered as the diffusive multinucleon transfer between the interacting nuclei in the peripheral collisions when the excitation energy of the produced exotic isotope is lower than the threshold for the neutron emission.…”

Production of exotic isotopes in complete fusion reactions with radioactive beams

“…show the calculated excitation functions for fusion reactions of 123,125 Cs beams with 69 Ga target. The survival probabilities of the excited compound nuclei in the neutron evaporation channels xn (x = 2 − 4) are calculated by employing the modified statistical code GROGIF[19] with the same parameters as in Ref [20]…”

“…. The capture cross sections and fusion probabilities are calculated with the quantum diffusion approach[6,7] and the dinuclear system fusion model[20], respectively. Radioactive Cs beams are already now available with high intensities for a broad variety of isotopes and are therefore favourable projectiles.…”