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Nuclear Theory·nucl-th

Wednesday·May 1, 2024

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    [Submitted on 30 Apr 2024]

    Statistical Theory of Neutron-Induced Nuclear Fission and of Heavy-Ion Fusion

    Hans A. Weidenmüller

    For both reactions we use an approach similar to that of compound-nucleus reaction theory. For neutron-induced fission, we describe the compound system generated by absorption of the neutron and the nuclear system near the scission point as two statistically independent systems governed by random-matrix theory. The systems are connected either by a barrier penetration factor or by a set of transition states above the barrier. Each system is coupled to a different set of channels. An analogous model is used for heavy-ion fusion. Assuming that (seen from the entrance channel) the system on the other side of the barrier is in the regime of strongly overlapping resonances, we obtain for fixed spin and parity closed-form analytical expressions for the total probability for fission and for fusion. Parts of these expressions can be calculated reliably within existing compound-nucleus reaction theory. The remaining parts are the probabilities for passage through or over the barrier. These may be determined theoretically from the liquid-drop model or experimentally from total fission or fusion cross sections.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2404.19355 [pdf]
    PRC(2024)·2 citations
  2. 02

    [Submitted on 30 Apr 2024]

    Exploring the potential of synthesizing unknown superheavy isotopes via cold-fusion reactions based on the dinuclear system model

    Hao Wu · Peng-Hui Chen · Fei Niu · Zu-Xing Yang · Xiang-Hua Zeng · Zhao-Qing Feng

    To assess the potential of cold-fusion for synthesizing superheavy nuclei (SHN) with proton numbers 104-113, we systematically calculated 145 naturally occurring projectile-target combinations within the DNS model. Reactions predominantly show maximum cross-sections in the 1n to 2n channels, peaking near the Coulomb barrier with a sum of barrier and Q-value within 30 MeV. The maximum cross-section occurs below the Bass barrier, suggesting either the Bass model's limitation or significant deformation reducing the effective Coulomb barrier. Our calculations align well with experimental data, revealing that more neutron-rich projectiles slightly enhance fusion, though the effect is minor. For fixed targets (Pb, Bi), evaporation residue cross-sections decrease linearly with increasing projectile proton number, attributed to reduced fusion probability and lower fission barriers in heavier SHN. The touching potential shows a linear trend with the product of projectile-target proton numbers, with neutron-rich systems exhibiting lower . Some reactions with may involve nucleon transfer before capture. Based on the DNS model, we identified optimal combinations and collision energies for synthesizing SHN with significant cross-sections. Collectively, our findings indicate that cold fusion is a promising avenue for creating proton-rich SHN around the drip line in the Z=104-113 region, offering distinct advantages over alternative mechanisms.

    Comments:
    10 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2404.19446 [pdf]
    PRC(2025)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE