The multinucleon transfer reaction 238U + 248Cm is studied at incident energies <math altimg='si1.svg'><msub><mrow><mi>E</mi></mrow><mrow><mi mathvariant='normal'>c</mi><mo>.</mo><mi mathvariant='normal'>m</mi><mo>.</mo></mrow></msub></math> = 898 and 800 MeV using the Isospin-dependent Quantum Molecular Dynamics model. In this work, we investigate the angular distribution of products and their correlations with incident energy, charge distribution fluctuations, and kinetic energy. At 898 MeV, the angular distribution of heavy actinide products peaks near the grazing angle, whereas at 800 MeV, it shifts near <math altimg='si2.svg'><msup><mrow><mn>0</mn></mrow><mrow><mo>&#8728;</mo></mrow></msup></math>. Moreover, at 800 MeV, the proportion of isotopes emitted at forward angles increases with atomic number. These results suggest that current gas-filled recoil separators and velocity filters, which are highly effective for small-angle fusion-evaporation products, could be adapted for low-energy multinucleon transfer reactions. Given the challenges in the separation and identification of transfer products, the results of this study provide valuable guidance for future experimental investigations.

China

Yu Yang

Long Zhu

Zehong Liao

Zepeng Gao

Yueping Fang

Jun Su

Zhong Liu

Hong Kong

Dongsheng Hou

Hao Huang

Cheng Li

Fengshou Zhang

Production of actinide isotopes near <italic>&#952;</italic> <inf><italic>lab</italic></inf>&#8239;=&#8239;0 &#8728; in multinucleon transfer reaction 238U + 248Cm

To improve the theoretical prediction power for synthesizing superheavy elements beyond Og, a Bayesian uncertainty quantification method is employed to evaluate the uncertainty of the calculated evaporation residue cross sections (ERCS) for the first time. The key parameters of the dinuclear system model (DNS-sysu), such as the diffusion parameter a, the damping factor <math><msub><mrow><mi>E</mi></mrow><mrow><mi>d</mi></mrow></msub></math>, and the level-density parameter ratio <math><msub><mrow><mi>a</mi></mrow><mrow><mi>f</mi></mrow></msub><mo>/</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>n</mi></mrow></msub></math> are systematically constrained by the Bayesian analysis of recent ERCS data. One intriguing behaviour is shown that the optimal incident energies (OIE) corresponding to the largest ERCS weakly depend on the fission process. We also find that these parameters are strongly correlated and the uncertainty propagation considering the parameters independently is not reasonable. The 2σ confidence level of posterior distributions for <math><mi>a</mi><mo>=</mo><msubsup><mrow><mn>0.586</mn></mrow><mrow><mo>−</mo><mn>0.002</mn></mrow><mrow><mo>+</mo><mn>0.002</mn></mrow></msubsup></math> fm, <math><msub><mrow><mi>E</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>=</mo><msubsup><mrow><mn>25.65</mn></mrow><mrow><mo>−</mo><mn>3.41</mn></mrow><mrow><mo>+</mo><mn>3.43</mn></mrow></msubsup></math> MeV, and <math><msub><mrow><mi>a</mi></mrow><mrow><mi>f</mi></mrow></msub><mo>/</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>=</mo><msubsup><mrow><mn>1.081</mn></mrow><mrow><mo>−</mo><mn>0.021</mn></mrow><mrow><mo>+</mo><mn>0.021</mn></mrow></msubsup></math> are obtained. Furthermore, the confidence levels of the ERCS and OIE for synthesizing Z = 119 via the reactions <math><mmultiscripts><mrow><mi>Cr</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>54</mn></mrow></mmultiscripts><mo>+</mo><msup><mrow></mrow><mrow><mn>243</mn></mrow></msup><mrow><mi>Am</mi></mrow></math>, <math><mmultiscripts><mrow><mi>Ti</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>50</mn></mrow></mmultiscripts><mo>+</mo><msup><mrow></mrow><mrow><mn>249</mn></mrow></msup><mrow><mi>Bk</mi></mrow></math>, and <math><mmultiscripts><mrow><mi>V</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>51</mn></mrow></mmultiscripts><mo>+</mo><msup><mrow></mrow><mrow><mn>248</mn></mrow></msup><mrow><mi>Cm</mi></mrow></math> are predicted. This work sets the stage for future analyses to explore the OIE and reaction systems for the synthesis of superheavy elements.

Yinu Zhang

Bayesian uncertainty quantification for synthesizing superheavy elements