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

Abstract

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 $V_{\rm in}$ shows a linear trend with the product of projectile-target proton numbers, with neutron-rich systems exhibiting lower $V_{\rm in}$. Some reactions with $V_{\rm in} < V_{\rm S}$ 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.