Narrow Results

Based on a modified di-nuclear system model in which the nucleon transfer is coupled with the dissipation of energy and angular momentum, the isotopic dependence and the orientation (between the target and the projectile) effects on the evaporation residue cross section for synthesizing super-heavy nuclei are investigated. The calculated results indicate that the cross sections shows an odd-even effect and does not change much with increasing neutron number of the target. The influences of deformation and relative orientation of the projectile and target are also discussed. Our results show that the waist to waist orientation is in favor of the formation of super-heavy compound nuclei.

The macroscopic–microscopic model with the Lublin–Strasbourg Drop, the Yukawa–folded single-particle potential and a monopole pairing force is used together with the cranking model to describe rotational bands in even–even actinide (Ra–Cn) isotopes. The pairing strength is adjusted for every nucleus to reproduce the experimentally known energy of the rotational 2⁺ state. The average pairing strength obtained in this way is used to predict the rotational states in superheavy No–Cn nuclei. A simple mechanism which takes into account a dynamical coupling of rotation with the pairing field is explained in detail.

We have performed a systematic calculation on the alpha decay half-lives of heavy mass nuclei with 106 $\le Z\le$ 118, within the universal decay law (UDL) and modified universal decay law (MUDL). The calculated half-life values are found to be in agreement with the experimental data. The standard deviations of the logarithm of half-lives are found to be the least for MUDL in all cases of even–even, even–odd, odd–even and odd–odd, so the MUDL formula is better than UDL formula for alpha decay studies. We have predicted half-lives of some superheavy nuclei (SHN) in the region $Z=110$–118 that are not yet experimentally detected. The decay energies are computed using three different mass models. We hope this study will help future measurements on alpha decay half-lives of SHN.

One of the substantial successes achieved in nuclear physics in the last two decades was the synthesis of dozens of isotopes of new elements up to ${}_{118}$Og, which closed the seventh row of the periodic table and inspired the ambition of adding more elements. This work aims to study extensively the ground state structure and decay properties of proposed $Z=120$ isotopes. We employed Macroscopic–microscopic scheme based on the Skyrme energy density functional, the Woods–Saxon single-particle potential and Strutinsky’s method to find the structure properties, in a multidimensional deformation space. The same nucleon–nucleon potential is used to find the $\alpha$-decay half-life, within the Preformed Cluster Model. For 45 ${}^{270-314}$120 isotopes, the total energy surfaces, ground state masses, binding energy, deformations and fissionability are determined. The $Q$-values of the different competing decays and $\alpha$-decay half-lives are investigated based on the obtained structure. The results indicate the ${}^{294-300}$120 isotopes to be the most bound among the studied isotopes. The smallest fission barriers are indicated for the ${}^{285-294,296,313}$120 isotopes. The ${}^{294-304}$120 isotopes showed the longer half-lives against $\alpha$-decay, with an order of $\mu \mathrm{\text{s}}$. The longest half-lives are estimated for the ${}^{301}$120 ($3.7\pm 3.6\mu \mathrm{\text{s}})$ and ${}^{304}$120 ($1.1\pm 1.0\mu \mathrm{\text{s}})$ isotopes. The longest full decay chain ending with the stable ${}^{207}$Pb nucleus is anticipated for the ${}^{295}$120 isotope. The shortest decay chain of ${}^{296}$120 terminates after three $\alpha$-decays by the spontaneous fission of ${}^{284}$Fl.

Radioactive ion beams (RIBs) offer a way to obtain moderately excited nuclei with atomic numbers Z≥100 produced in the multi-nucleon transfer reactions. The choice of suitable RIBs available from the ACCULINNA-2 fragment separator, coupled with the U-400 cyclotron, and possible results of relevant experiments are discussed.

Based on a modified di-nuclear system model in which the nucleon transfer is coupled with dissipation of energy and angular momentum, the evaporation residue cross sections of some cold and hot fusion reactions to synthesize super-heavy nuclei are calculated. The influences of deformation and relative orientation of projectile and target are discussed. Our results show that the waist to waist orientation is in favor of the formation of super-heavy compound nuclei. The isotopic dependence of the maximal evaporation residue cross section is also investigated. The calculated results show that the cross sections do not change much with increasing neutron number of the target.

Results are presented and discussed from an experiment searching for element 120. The reaction ⁵⁴Cr + ²⁴⁸Cm → ³⁰²120* was investigated at the velocity filter SHIP at GSI in Darmstadt. In a complementary study, α-decay chains of isotopes of known even elements were reviewed in order to prepare a comprehensive basis for comparison of experimental data among each other and with results of model calculations. Model dependent shell-correction energies and related heights of fission barriers were deduced from measured Q_α values and compared with results of macroscopic-microscopic models. The consequences for calculations of cross-sections are discussed.

After a successful production of isotopes of element 116 in the reaction ⁴⁸Ca + ²⁴⁸Cm, the reaction ⁵⁴Cr + ²⁴⁸Cm → ³⁰²120* was investigated at the velocity filter SHIP at GSI, Darmstadt, aiming to search for isotopes of element 120. One chain of events was observed, which is not created by chance with high probability. Parts of the chain agree with model predictions and measured data from a decay chain which could start at the isotope ²⁹⁹120. In a complementary study, model dependent shell-correction energies and related heights of fission barriers were deduced from measured Q_α values. The results are compared with predictions of macroscopic-microscopic models. The consequences for calculations of crosssections are discussed.

Based on a semi-empirical nuclear mass formula, the super-heavy stability island is investigated. From the calculated shell corrections of super-heavy nuclei, the region N = 172-178, Z = 116-120 with shell corrections about -6 MeV roughly gives the position of the super-heavy stability island. The probability to synthesize nuclei with Z = 126 may be much smaller than that of produced super-heavy nuclei already, according to the obtained shell corrections and the proton drip line.

Two-step model is adopted to analyze the fusion process of heavy ion reactions ⁴⁸Ca+²⁵²Es. Based on this model, the fusion is divided into two consecutive steps, i.e., the sticking step and the formation step, and corresponding sticking probability and formation probability are calculated. Combining the statistical evaporation model for the evaporation stage, the maximum residue cross section is 0.23 pb at 3_n, E_lab=252.4 MeV.

In recent years, nuclear-physics investigations into the laws of the microscopic world have contributed to extend significantly our knowledge of phenomena occurring in the macroscopic world (the Universe) and made a formidable contribution to the development of astrophysical and cosmological theories. First of all, this concerns the expanding-universe model, the evolution of stars, and the abundances of elements, as well as the properties of various stars and cosmic objects, including “cold” and neutron stars, black holes, and pulsars. Without claiming to give a full account of all cosmological problems, we will dwell upon those of them that, in my opinion, have much in common with nuclear-matter properties manifesting themselves in nuclear interactions.