Fusion near the threshold: A comparative study of the systems 40Ar + 112, 116, 122sn and 40Ar + 144, 148, 154Sm

doi:10.1016/0375-9474(85)90125-3

Nuclear Physics A

Volume 438, Issue 1, 13 May 1985, Pages 212-252

https://doi.org/10.1016/0375-9474(85)90125-3 Get rights and content

Abstract

Fusion excitation functions for the systems ⁴⁰Ar + ^{112, 116, 122}Sn and ⁴⁰Ar + ^{144, 148, 154}Sm have been determined, covering cross sections ranging from several hundred mb down to the μb level. The data show a pronounced correlation of the subbarrier behaviour with low-energy collective properties of the nuclei involved and are well reproduced by simplified coupled-channel calculations coupling fusion to inelastic channels. The possibilities of parameterizing the data in terms of a simple dynamic barrier-fluctuation phenomenon are discussed and result in the prediction of remarkably diffuse partial-wave distributions above the barrier. This is shown to be important for the analysis of deexcitation phenomena following fusion reactions.

References (58)

H. Holm et al.
Phys. Lett.
(1969)
J.O. Rasmussen et al.
Nucl. Phys.
(1971)
A.S. Jensen et al.
Nucl. Phys.
(1971)
U. Jahnke et al.
Phys. Rev. Lett.
(1982)
R. Pengo et al.
Nucl. Phys.
(1983)
S. Landowne et al.
Nucl. Phys.
(1981)
M. Beckerman
Phys. Rev. Lett.
(1980)
Phys. Rev.
(1981)
M. Beckerman
Phys. Rev. Lett.
(1982)
W. Faust
GSI-report...K. Schlitt
L.C. Northcliffe et al.
Nucl. Data Tables
(1970)

W. ReisdorfW. Reisdorf

Z. Phys.

(1981)

W. Reisdorf et al.

Z. Phys.

(1981)

D.A. Eastham

Nucl. Instr. Meth.

(1975)

V.S. Nikolaev et al.

Sov. J. Techn. Phys.

(1971)

R. Bass

Nucl. Phys.

(1974)

M.J. Rhoades-Brown et al.

Phys. Lett.

(1984)

S. Landowne et al.

Phys. Rev.

(1984)

S. Sen et al.

Nucl. Phys.

(1976)

Nucl. Data Sheets

(1977)

A.H. Shaw et al.

Phys. Rev.

(1974)

J. Randrup et al.

Phys. Lett.

(1978)

K.E.G. Löbner et al.

Nucl. Data Tables

(1970)

R.A. Broglia et al.

H.J. Krappe et al.

Z. Phys.

(1983)

P.W. Riesenfeldt et al.

Phys. Rev.

(1970)

W. Scobel et al.

Phys. Rev.

(1975)

B. Sikora et al.

Phys. Rev.

(1979)

R.G. Stokstad et al.

Phys. Rev. Lett.

(1978)

Phys. Rev.

(1980)

R.G. Stokstad et al.

Phys. Rev.

(1981)

R.G. Stokstad et al.

Z. Phys.

(1980)

Cited by (153)

Role of multi-neutron transfer channels on fusion enhancement
2024, Nuclear Physics A
Fusion reactions ⁴⁰Ar + ¹¹⁶Sn, ⁴⁰Ar + ¹²²Sn and ⁴⁰Ca + ¹²⁴Sn have been examined by employing coupled channel (CC) approach using code-CCFULL. Here we aim to investigate the influence of multi-neutron transfer channels in addition to coupling of collective excitations on sub-barrier fusion enhancement. Incorporation of inelastic excitations alone reproduced the experimental results for ⁴⁰Ar + ¹¹⁶Sn system while for ⁴⁰Ar + ¹²²Sn contribution of 2n transfer channel is required to explain the experimental data. However, CC calculations with 2n transfer could not explain the enhancement at sub-barrier energies for ⁴⁰Ca + ¹²⁴Sn system. Therefore, the empirical coupled channel (ECC) calculations have been carried out to include the effect of multi-neutron transfer channels and it is found that the incorporation of sequential 4n transfer channel reproduced the experimental results in entire energy region. Nevertheless, it is observed that multi-neutron transfer coupling significantly contributed in raising the sub-barrier fusion cross sections particularly for the reactions where colliding partners are spherical. Importantly, it is also found that transfer of even number of neutrons play dominating role in sub-barrier fusion enhancement.
Systematic study of fusion barriers with energy dependent barrier radius
2023, Atomic Data and Nuclear Data Tables
Considering energy dependence of the barrier radius in heavy-ion fusion reactions, a modified Siwek-Wilczyński (MSW) fusion cross section formula is proposed. With the MSW formula, the fusion barrier parameters for 367 reaction systems are systematically extracted, based on 443 datasets of measured cross sections. We find that the fusion excitation functions for about 60% reaction systems can be better described by introducing the energy dependence of the barrier radius which is due to the dynamical effects at energies near and below the barrier. Considering both the influence of the geometry radii and that of the reduced de Broglie wavelength of the colliding nuclei, the barrier heights are well reproduced with only one model parameter. The extracted barrier radius parameters linearly decrease with the effective fissility parameter, and the width of the barrier distribution relates to the barrier height, as well as the reduced de Broglie wavelength at energies around the Coulomb barrier.
Sub-barrier heavy-ion fusion/capture: Accurate accounting for zero-point quadrupole shape oscillations with realistic nucleus-nucleus potential
2023, Chinese Journal of Physics
Although the study of collisions of heavy ions resulting in formation of dinuclear systems has a long history this process still is a subject of experimental and scientific activities, partly because nowadays the heavy-ion fusion process is the only practical way for extending further the Periodic Table. Yet the heavy-ion capture cross sections are calculated theoretically with significant uncertainties. In particular, these cross sections below the barrier sometimes underestimate the experimental ones by orders of magnitude. In the literature, it had been shown that accounting for the Zero-Point Oscillations (ZPO) of the shape of colliding nuclei increased significantly the calculated capture cross sections. However, those calculations had been performed in a simplified way with a schematic nucleus-nucleus potential and for few reactions. The purpose of the present paper is to account for the ZPO in a more realistic way and to compare systematically the resulting capture cross sections with the experimental data. In the present paper, the nucleus-nucleus potential is evaluated using the semi-microscopical double-folding model with M3Y-Paris nucleon-nucleon forces. The nucleon densities needed for finding this potential are generated from the experimental three-parameter Fermi charge densities. The calculated capture cross sections are compared with the data for reactions $^{16} O +^{54} Fe$ , $^{58} Ni$ , $^{144} Nd$ , $^{148} Sm$ and $^{58} Ni +^{54} Fe$ , $^{58} Ni$ , $^{60} Ni$ . We show that there are certain regularities in the relationship between the experimental and theoretical cross sections with respect to the period of the quadrupole vibrations of the colliding nuclei at their ground states.
Exploring the possibilities of sub barrier fusion enhancement in fusion reactions induced by 28Si on 64Ni, 96Zr, 100Mo and 154Sm at energies around Coulomb barrier
2023, Nuclear Physics A
The fusion excitation functions of reactions induced by ²⁸Si on ⁶⁴Ni, ⁹⁶Zr, ¹⁰⁰Mo and ¹⁵⁴Sm targets at around Coulomb barrier energies have been analysed theoretically within coupled channel approach. Here we have examined the sensitivity of fusion cross section at sub-barrier energies towards coupling of inelastic excitations of fusing partners and positive Q-value neutron transfer (PQNT) channels. Along with the transfer channel, the influence of variation in deformation of fusing nuclei after transfer and of nuclear structure of fusing nuclei has also been considered. With a view to investigate the influence of nuclear structure here we have taken targets with different structural properties. It is found that coupling of neutron transfer channels produced a significant enhancement in sub-barrier fusion for the systems where one of the interacting nuclei is spherical or less deformed and no influence of transfer coupling has been observed for the system where both the participating nuclei are deformed.
Competing asymmetric fusion-fission and quasifission in neutron-deficient sub-lead nuclei
2020, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
To disentangle the role of shell effects and dynamics, fission fragment mass distributions of ¹⁹¹Au, a nucleus in the newly identified island of mass asymmetric fission in the sub-lead region, have been measured down to excitation energy of ≈20 MeV above the fission barrier via two different entrance channels, viz. ¹⁶O+¹⁷⁵Lu and ³⁷Cl+¹⁵⁴Sm reactions. Apart from having signature of the shell effects in both the cases, clear experimental evidence of quasifission has been observed in the mass distributions of the Cl induced reaction, that has also been substantiated by the theoretical calculations. This crucial evidence along with a systematic analysis of the available experimental data has revealed that the dynamics in the entrance channel has significant influence on most of the reactions used earlier to explore the persistence of recently discovered mass asymmetry in β-delayed fission at low energy in this mass region, ignoring which might lead to ambiguity in interpreting the heavy-ion data.
Recent experimental results in sub- and near-barrier heavy ion fusion reactions (2nd edition)
2023, European Physical Journal A

View all citing articles on Scopus

View full text