Non-Coplanar Nuclei in Heavy-Ion Reactions

Authors: Sahila Chopra, Hemdeep, Arshdeep Kaur, Raj K. Gupta

Abstract:

In recent times, we noticed an interesting and important role of non-coplanar degree-of-freedom (Φ = 00) in heavy ion reactions. Using the dynamical cluster-decay model (DCM) with Φ degree-of-freedom included, we have studied three compound systems 246Bk∗, 164Yb∗ and 105Ag∗. Here, within the DCM with pocket formula for nuclear proximity potential, we look for the effects of including compact, non-coplanar configurations (Φc = 00) on the non-compound nucleus (nCN) contribution in total fusion cross section σfus. For 246Bk∗, formed in 11B+235U and 14N+232Th reaction channels, the DCM with coplanar nuclei (Φc = 00) shows an nCN contribution for 11B+235U channel, but none for 14N+232Th channel, which on including Φ gives both reaction channels as pure compound nucleus decays. In the case of 164Yb∗, formed in 64Ni+100Mo, the small nCN effects for Φ=00 are reduced to almost zero for Φ = 00. Interestingly, however, 105Ag∗ for Φ = 00 shows a small nCN contribution, which gets strongly enhanced for Φ = 00, such that the characteristic property of PCN presents a change of behaviour, like that of a strongly fissioning superheavy element to a weakly fissioning nucleus; note that 105Ag∗ is a weakly fissioning nucleus and Psurv behaves like one for a weakly fissioning nucleus for both Φ = 00 and Φ = 00. Apparently, Φ is presenting itself like a good degree-of-freedom in the DCM.

Keywords: Dynamical cluster-decay model, fusion cross sections, non-compound nucleus effects, non-coplanarity.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1339291

References:

[1] R. K. Gupta, in Clusters in Nuclei, Lecture Notes in Physics 818, edited by C. Beck, Vol.I, (Springer Verlag, Berlin, 2010), pp. 223-265; and earlier references there in it.
[2] J. Blocki et al., Proximity Forces, Ann. Phys. (N.Y.) 105, 427 (1977).
[3] R. K. Gupta and M. Bansal, Heavy Ion Reactions Studied on Wong and Dynamical Cluster-Decay Models Using Proximity Potential for Non-Coplanar Nuclei, Int. Rev. Phys. (IREPHY) 5, 74 (2011).
[4] M. Bansal, Study of Fusion Reactions Using Deformed and Oriented Nuclei, Ph.D. thesis, Panjab University, Chandigarh, 2012, Chapters 5 and 6 (Unpublished).
[5] S. K. Arun, R. Kumar, and R. K. Gupta, Fusion-evaporation cross-sections for the 64Ni+100Mo reaction using the dynamical cluster-decay model, J. Phys. G: Nucl. Part. Phys. 36, 085105 (2009).
[6] M. Bansal et al., Dynamical cluster-decay model using various formulations of a proximity potential for compact non-coplanar nuclei: Application to the 64Ni+100Mo reaction, Phys. Rev. C 86, 034604 (2012).
[7] S. Chopra et al., One neutron and noncompound-nucleus decay contributions in the 12C+93Nb reaction at energies near and below the fusion barrier, Phys. Rev. C 88, 014615 (2013).
[8] S. Chopra et al., Non-coplanar compact configurations of nuclei and non-compound-nucleus contribution in the fusion cross section of the 12C+93Nb, Phys. Rev. C 93, 024603 (2016).
[9] A. Kaur et al., Compound nucleus formation probability PCN determined within the dynamical cluster-decay model for various hot fusion reactions, Phys. Rev. C 90, 024619 (2014).
[10] S. Chopra et al., Determination of the compound nucleus survival probability Psurv for various hot fusion reactions based on the dynamical cluster-decay model, Phys. Rev. C 91, 034613 (2015).
[11] R. K. Gupta et al., Generalized proximity potential for deformed, oriented nuclei, Phys. Rev. C 70, 034608 (2004).
[12] M. Manhas and R. K. Gupta, Proximity potential for deformed, oriented nuclei:“Gentle” fusion and “hugging” fusion, Phys. Rev. C 72, 024606 (2005).
[13] R. K. Gupta et al., Optimum orientations of deformed nuclei for cold synthesis of superheavy elements and the role of higher multipole deformations, J. Phys. G: Nucl. Part. Phys. 31, 631 (2005).
[14] R. K. Gupta et al., Compactness of the 48Ca induced hot fusion reactions and the magnitudes of quadrupole and hexadecapole deformations, Phys. Rev. C 73, 054307 (2006).
[15] B. R. Behera et al., Entrance-channel effect in fusion fragment anisotropies from 11B+235U and 14N+232Th systems, Phys. Rev. C 64, 041602(R) (2001).
[16] B. R. Behera et al., Fission fragments angular distributions for the systems 14N+232Th and 11B+235U at near and sub-barrier energies, Phys. Rev. C 69, 064603 (2004).
[17] C. L. Jiang et al., Hindrance of heavy-ion fusion at extreme sub-barrier energies in open-shell colliding systems, Phys. Rev. C 71, 044613 (2005).
[18] T. Ahmad et al., Reaction Mechanisms in 12C+93Nb system: Excitation functions and recoil range distributions below 7 MeV/u, Int. J. Mod Phys. E 20, 645 (2011).