Erratum: Enhanced Fusion-Evaporation Cross Sections in Neutron-RichSn132onNi64[Phys. Rev. Lett.91, 152701 (2003)]

Abstract

We have discovered an error in our data analysis that affects the result presented in our recent Letter. The evaporation residue cross sections were calculated using the residue yield and the integrated beam. Because elements of the data array used to store the integrated beam did not have sufficient range (maximum 2 16 ), an overflow caused the integrated beam to be counted incorrectly. This was discovered by repeating some of the measurements and checked by reanalyzing the previous data with an appropriately sized data array, and using the originally sized data array but breaking up the analysis into smaller subsets. The correct cross section is presented here in Fig. 1 which replaces Fig. 2 of the original Letter. The size of the correction increases as the beam energy decreases because measurements at lower energies take longer times. At the lowest energy, the corrected cross section is a factor of 4 less than the previously published value. Since a thick target was used, the effective reaction energy was deduced by taking a cross-section-weighted average over the range of the energy loss in the target. The corrected excitation function has a steeper slope at lower energies; therefore, the calculated effective reaction energy is shifted to higher values. Fusion is still enhanced in 132 Sn on 64 Ni at sub-barrier energies with respect to a one-dimensional barrier penetration model prediction. The enhancement of fusion relative to lighter Sn isotopes is no larger than would be expected due to the larger nuclear radius of 132 Sn and transfer does not appear to play a major role in the sub-barrier fusion for this system.[1] W. S. Freeman et al., Phys. Rev. Lett. 50, 1563 (1983.[2] R. Bass, Nucl. Phys. A231, 45 (1974). FIG. 1 (color online). Fusion-evaporation excitation functions of 132 Sn 64 Ni and 64 Ni on even 112-124 Sn [1]. The reaction energy is scaled by the fusion barrier predicted by the Bass model [2] and the evaporation residue (ER) cross section is scaled by the size of the reactants using R 1:2A 1=3 p A 1=3 t , where A p (A t ) is the mass of the projectile (target). The filled circles are corrected data and the open circle is our measurement using a 124 Sn beam.

Density-constrained time-dependent Hartree-Fock calculation of 16O + 208Pb fusion cross-sections

“…Fusion studies using neutron-rich nuclei are becoming increasingly available. Examples include the experiments with heavy neutron-rich 132 Sn beams on 64 Ni [1,2], and the fusion measurements for the 64 Ni+ 64 Ni system [3]. What characterized these experiments was the measurement of the fusion cross-sections at very low bombarding energies.…”

Search for inverse fission of uranium

“…Since this study was constrained by the acceptable counting rates of the Oak Ridge evaporation residue detection system [16,17], it would be feasible, with technical improvements, to further explore this system.…”

“…Any potential EVRs were identified by time of flight and energy loss in the ion chamber. (See [16,17] for details of the operation of this detector. )…”

Dynamics of Massive Systems and Synthesis of Superheavy Elements

“…(If it is ≈ 0.8, all the results are one to two orders of magnitude larger than those shown in the figure). Of course, there is no consideration of the possible special enhancement mechanisms due to a neutron skin 25 . Nevertheless, the present results show rather large fusion cross section, i.e., the hindrance is not very strong.…”