The Measurement Of ⁵⁵Mn+¹⁵⁹Tb Reaction And The Systematic Analysis Of The α-decay Reduced Width

Exploring the limits of nuclei’s charge and mass,as well as synthesizing superheavy elements,is an important frontier issue in nuclear physics research.This work is based on experimental studies of heavy-ion-induced fusion evaporation reactions,specifically⁵⁵Mn+¹⁵⁹Tb,using the new gas-filled recoil separator SHANS2.The experimental results were systematically analyzed to investigate theα-decay reduced widths in the heavy nuclear region.The present work consists of two main parts.The first part involves experimental measurements of the heavy-ion-induced complete fusion reaction of⁵⁵Mn+¹⁵⁹Tb.With the support of the China Accelerator Facility for Superheavy Elements（CAFE2）in Lanzhou,the relevant information on the evaporation residues of the⁵⁵Mn+¹⁵⁹Tb reaction was measured at the gas-filled recoil（ERs）sepa-rator known as the Spectrometer for Heavy Atoms and Nuclear Structure-2（SHANS2）.Nineteen ER-α₁-α₂decay chains from²¹⁰Th produced from the 4n evaporation channel were observed.Theα-particle energy and half-life of²¹⁰Th were respectively determined to be 7922（14）ke V and 14（4）ms.In addition,the decay properties of E_α=7788（14）ke V and T_1/2=36_-8⁺¹⁵ms were obtained for²¹¹Th.The measuredα-decay properties of²¹⁰Th and²¹¹Th were consistent with the literature data.The cross sections were measured to be 0.59_-0⁺⁰..₂₃²⁵nb and 0.19_-0⁺⁰..₀₉¹²nb for²¹⁰Th and²¹¹Th,respectively.The equilibrium charge state of the recoiled nucleus²¹⁰Th was determined to be 10.45 e experimentally.The new data are helpful for the estimation of the equilibrium charge states of the elements119 and 120,which could be respectively produced via the²⁴⁰Pu(⁵⁵Mn,3n)²⁹²119 and²⁴³Am(⁵⁵Mn,3n)²⁹⁵120 reactions.The second part,by systematically analyzing theα-decay reduced widths（δ²）in the heavy nuclear region,we studied the nuclear structural properties of the superheavy nuclei region.Theα-decay reduced widths contain information about nuclear structure and can indicate shell evolution.Through the analysis ofα-decay reduced widths as a function of neutron number and the systematic study of theα-decay reduced widths by the N_pN_nmethod,it is found that in the region with N<152,theα-cluster preformation probability is enhanced from Th to Rf as the strength of the interaction between valence protons and valence neutrons increases,it shows that the effect of the shell effect of N=152 is gradually weakening.