Fusion cross sections forLi6,7+

Abstract

Measurement of fusion cross sections for the 6,7 Li + 24 Mg reactions by the characteristic γray method has been done at energies from below to well above the respective Coulomb barriers. The fusion cross sections obtained from these γ-ray cross sections for the two systems are found to agree well with the total reaction cross sections at low energies. The decrease of fusion cross sections with increase of energy is consistent with the fact that other channels, in particular breakup open up with increase of bombarding energy. This shows that there is neither inhibition nor enhancement of fusion cross sections for these systems at above or below the barrier. The critical angular momenta (l cr ) deduced from the fusion cross sections are found to have an energy dependence similar to other Liinduced reactions. PACS number(s) : 25.70. Jj; 25.70. Gh Keywords: NUCLEAR REACTIONS 24 Mg( 6 Li,X), Ec.m. = 4.6-23.7 MeV; 24 Mg( 7 Li,X), Ec.m. = 5.2-22.9 MeV; measured σ γ ; deduced partial, total fusion σ, statistical model, optical model calculations and barrier penetration model calculations.

Recent developments in fusion and direct reactions with weakly bound nuclei

“…Using predictions of an statistical code, the authors suggest that the larger cross section of 6 Li can be attributed to ICF and/or transfer processes, which are stronger for this projectile. Therefore, all the available experimental TF excitation functions for collisions of 6,7 Li with light systems, ranging from 12 C to 64 Ni [72,[324][325][326]330,[357][358][359][360]356,151], are in good agreement with predictions of coupled channel calculations. From 2006 to the present, many authors measured CF cross sections in reactions induced by 9 Be beams.…”

“…However, for energies more than twice the barrier, the TF cross sections showed some suppression compared with the barrier penetration model. Ray et al [324] measured TF of the 6,7 Li + 24 Mg systems at BARC-Mumbai, with the gamma ray method. They compared their results with the total reaction cross section, obtained by optical model analysis, and with the theoretical TF cross section obtained with a coupled channel calculation.…”

Fusion ofLi6withTb159at near-barrier energies

“…In contrast, in fusion measurements for medium-and lightmass systems [23][24][25][26][27][28][29][30][31], where CF and ICF products could not be experimentally distinguished, only total fusion (CF + ICF) cross sections were measured. Such measurements show that the breakup has no significant effect on the total fusion at above-barrier energies.…”

Coupled-Channel Effects in Collisions Between Heavy Ions Near the Coulomb Barrier

“…For reactions induced by weakly bound nuclei [16,17,25,26,27,28,39,40,41] and exotic nuclei [18,19,20,21,22,38,42,43,44,45,46], the breakup channel is open and plays a key role in the fusion process near the Coulomb barrier similarly to the transfer-channel coupling described in the previous section. It is therefore appropriate to use the Continuum-Discretized Coupled-Channel (CDCC) approach [47,48,49,50] to describe the influence of the breakup channel in both the elastic scattering and the fusion process at sub-barrier energies.…”

“…Their ratios are presented in Fig. 2 with comparisons with other lighter targets [25,26,27,28]. The theoretical curves (1D-BPM [1,2] and Wong [15] do not take into account the breakup channel coupling that is discussed in one of the following sections in more details.…”