Heavy particle radioactivity of superheavy nuclei.

We investigated different decay modes such as heavy particle radioactivity (HPR), spontaneous fission (SF), alpha decay and beta-decay in superheavy (SH) region 104 ≤ Z ≤ 126. In HPR, different emissions from Zmin = 28 to maximum heavy particle (HP) emission up to Zmax = Z - 82 were considered. In the evaluation of Q-values, mass excess Weizsäcker-Skyrme 4+radial basis function (WS4+RBF) values were taken into account. The half-lives of cluster decay determined using modified generalised liquid drop model (MGLDM) and Coulomb and proximity potential model (CPPM) were in close agreement with the experimental results. The MGLDM produce less deviation compared with CPPM. The role of asymmetry effect, relative neutron excess, pairing effect and Coulomb effect on half-lives were studied. A band of neutron numbers from 193 to 200 shows extra stability against HPR. The HPR of 86Kr, 94Zr, 91Y and 96Mo is observed in the superheavy elements Z = 118, 122-124 and 126. The dominant decay mode identified is compared with SF, alpha and beta± decay, the majority of decay chains end with the lead nuclei, which is also evident in supernova and galaxy spectrum. This study could be useful in nuclear astrophysics.

An investigation on polymers for shielding of cosmic radiation for lunar exploration.

In outer space, we find many types of radiations that are due to solar flares, radiation belt, cosmic rays, etc. We are fortunate enough to be protected from these radiations on the surface of the Earth, whereas in other celestial objects such as planets and satellites, without a protecting atmosphere, penetration of radiation that may be ionising or non-ionising is inevitable. Hence, studying radiation environment and its effect on such celestial objects is very important for establishing facilities such as satellites, payloads, vehicles and human exploration. For such cases, manufacturing the products with lightweight, thermally stable, flexible, mechanically durable materials is essential and needs to be studied for the radiation effect. Hence, in the present work, we have made an attempt to calculate the rate of absorbed dose in case of polymers such as Polyvinyl Chloride (PVC), polytetrafluoroethylene, Mylar, polystyrene and Zylon for the lunar radiation environment. From the literature, it is found that ions up to iron has a lion share in the ionic radiation in space. The simulations were carried out for ions from hydrogen to iron using the SRIM software with various energies. It is observed that the absorbed dose rate in the polymers increases with the increase in ion mass. Further, the study can be extended to get the information of various flexible materials for these ions from which a suitable material can be chosen for the different space applications.

An innovative approach for estimating energy absorption buildup factors (EABF) with HVL and TVL.

The current study proposes an empirical formula for absorption buildup factors as a function of target thickness. The present formula produces absorption buildup factors of compounds and mixtures with simple inputs of linear attenuation coefficient (µ), tenth value layer (TVL) and half value layer (HVL) of interacting target for the atomic number region 29 < Z < 92 for the energies 0.2 MeV < E < 1.5 MeV. This method is used to compute the energy absorption buildup factors using HVL and TVL.