Hot fusion-evaporation cross sections ofCa44-induced reactions with lanthanide targets

Abstract

Background: Previously reported cross sections of 45 Sc-induced reactions with lanthanide targets are much smaller than 48 Ca-induced reactions on the same targets. 44 Ca is one proton removed from 45 Sc and could be used to produce nuclei with a relative neutron content between those produced in the 45 Sc-and 48 Ca-induced reactions.Purpose: As part of a systematic investigation of fusion-evaporation reactions, cross sections of 44 Cainduced reactions on lanthanide targets were measured. These results are compared to available data for 48 Sc-induced fusion-evaporation cross sections on the same lanthanide targets. Collectively, these data provide insight into the importance of the survival against fission of excited compound nuclei produced near spherical shell closures. Gd once differences in capture cross sections and compound nucleus formation probabilities are corrected for. Methods Conclusions: Excitation functions were measured in44 Ca-induced reactions on lanthanide targets. Evaporation residue cross sections were two orders of magnitude larger than 45 Sc-induced reactions on the same targets due to an increase in the survival probability of the compound nucleus. However, little evidence of cross section enhancement due to shell stabilization of the compound nucleus was observed.

Measurement of fusion-evaporation cross sections for reactions of Ca44 with Gd154,156,Werke1, Salas2, Glennon3 et al. 2022Phys. Rev. CSelf Cite2000View full textAdd to dashboardCite

“…Our previous paper included a systematic study of EvR cross sections for 44 Ca projectiles reacting with lanthanide targets of varying Z [12]. The current article expands the previous work by studying the influence of target neutron number while continuing to use 44 Ca as a projectile.…”

“…These three latter foils were used for an efficiency calibration of the Rutherford scattering detectors as discussed below. The 158 Gd2O3 target was used to check the MARS efficiency by comparing the EvR detection rate to previous studies done by our group [12]. The most downstream ladder held a phosphor-painted metal target with crosshairs used to visually view and align the beam spot, an electron-suppressed Faraday cup to measure the beam intensity inside the target chamber, and the 50 µg/cm 2 nat C stripper foil.…”

“…The MARS efficiency was measured by inserting a 158 Gd2O3 target and measuring the production of the 198 Po EvR in the 4n exit channel. This reaction was studied previously using MARS with a well-defined efficiency [12]. In this experiment, the center-of-target beam energy…”

“…ECoT of the 44 Ca on the 158 Gd target was 184.9 MeV. The 198 Po cross section was extrapolated from the measured excitation function [12] with three different linear fits to calculate the cross section of 1.88 mb. From the known 198 Po cross section EvR, the MARS efficiency MARS was determined using Eq.…”

“…This has been attributed to a strong influence of survival probability on the average difference in fission barrier (Bf) and neutron binding energy (Sn) of the compound nucleus [11], represented as fn  BS . In a previous series of studies [12][13][14][15], our group systematically investigated the influence of heavy-ion projectiles on the fusion-evaporation cross section and observed this same effect. Additionally, we observed that collective enhancement to level density (CELD) (see, for example, [16] and references therein) has a significant impact on the production of the spherical evaporation residues (EvRs), which were generally near doubly magic 208 Pb.…”