Production cross sections of elements near theN=126shell inCa48-induced reactions with

Abstract

Ho with the maxima at 12.6 ± 1.9 mb, 12.6 ± 1.7 mb, and 9.4 ± 1.3 mb, respectively. For the reaction with 154 Gd, the maximum is slightly lower at 4.0 ± 0.6 mb. A simple model to describe the measured production cross sections was employed. Capture was estimated using the "diffused barrier formula" from the "fusion by diffusion" model proposed byŚwiątecki et al. The fusion probability was estimated using a phenomenological expression presented by Siwek-Wilczyńska et al. The survival probability was calculated according to the formula of Vandenbosch and Huizenga, derived from transition-state theory. Best agreement is reached between calculation and experiment upon inclusion of collective effects in the calculation of the survival probability, shown previously to be important for production of weakly deformed nuclei. This, in turn, challenges the expectation of strong shell-stabilization benefiting the production cross section. The present data is compared with earlier studies on production of neutron-deficient nuclei in Ca-induced reactions with lanthanide targets. PACS number(s): 25.70.Gh, 25.70.Jj

Hot fusion-evaporation cross sections ofSc45-induced reactions with lanthanide targets

“…A similar model was described in our previous publication to explain the measured xn cross sections of 48 Ca-induced reactions with lanthanide targets [5]. In that work, good agreement with the data was achieved while considering only neutron emission and fission competition from the excited CN.…”

“…More recently, we reported similar findings in the bombardment of lanthanide targets with 48 Ca projectiles, where large yields of the weakly deformed xn evaporation channels but weak contributions from pxn channels were observed [5]. Reactions with 45 Sc (Z = 21) projectiles have been largely ignored as a candidate for heavy-ion fusion-evaporation reactions and very little literature data exists.…”

“…The desired reaction products were tuned through MARS by estimating the most probable charge state in LISE++ using the method of Schiwietz and Grande [28]. The efficiency of MARS has been previously determined to be (3.5 ± 0.7)% and (2.2 ± 0.5)% for the 40 Ar + 118 Sn, 165 Ho reactions, respectively [5,24]. A linear interpolation of the mass asymmetry parameter η = |A p -A t |/(A p + A t ) was used to give efficiencies in the range of (2.7 ± 0.6)% to (2.8 ± 0.6)%, and the efficiency was assumed to be constant for the xn and pxn exit channels.…”

“…[5]). In this work, ζ was chosen to be 2.5 to be consistent with our previous work, and typical values of P CN for these 45 Sc-induced reactions on deformed lanthanide targets are calculated to be ≈0.1 for * CN E ≈ 50 MeV.…”

“…Several publications have focused on the production of neutron-deficient compound nuclei (CN) with Z = 83-87 [1][2][3][4][5] and comparisons of the experimental data with model calculations. Various models [6][7][8][9][10][11][12][13] have been proposed to reproduce EvR cross sections by adjusting parameters such as the fission barrier height or including phenomena such as collective enhancements [14] and fission dissipation [15]; however, there is still no consensus on how to best reproduce the experimental data.…”