Cluster Radioactivity Decay Research Articles

Neutron Surveying as First Applied in a Complex of Geoelectrochemical Methods on Reference Pipes of the Zimneberezhnyi Diamond-Bearing Area

The method of registration of free neutrons in a complex with geoelectrochemical methods has been applied for the first time to a case study in the Arkhangelsk diamondiferous province. Its application is based on the newly developed concept about formation of diamonds in the deep chamber, shielded by dense rocks. The high density of energy in such an excited environment leads to dissociation of nuclei, cluster radioactive decay, and low-energy transmutation of elements. The cluster radioactive decay and the low-energy transmutation of nuclei that occur during the formation of a kimberlite pipe produce electromagnetic radiation with a quantum energy of tens and hundreds of keV. This concept was confirmed by research and development on the reference Pionerskaya and Verkhnetovskaya pipes; an exploration technique based on this geological model is proposed.

Experience of application of neutron shooting in the complex with geoelectrochemical methods on reference tybes of the Zimmeberezhny diamondiferous area

The method of registration of free neutrons applied in a complex with geoelectrochemical methods is for the first time tested in the Arkhangelsk diamondiferous province. The basis on its application is the concept developed now about formation of diamonds in the deep center, screened dense breeds. As a result density of energy of the excited environment increases that leads to course of nuclear dissociation of nuclear kernels, cluster radioactive decay and a low-energy transmutation of elements. At formation of a kimberlite tube in the course of cluster radioactive decay and a low-energy transmutation of nuclear kernels there is an electromagnetic radiation with energy of quantum about tens and hundreds kiloelectronvolt. By results of the carried-out skilled and methodical works on the reference blocked tubes Pioneer and Verkhnetovsky confirmation of this concept is received and the search technique leaning on this geological model is offered.

Role of 208Pb daughter nucleus and nuclear shell effects in trans‐lead cluster radioactivity by emission of neon clusters from 218–236U isotopes

AbstractIn the present work, the cluster radioactivity of even A uranium isotopes (218–236U) with the emission of both alpha‐like and non‐alpha‐like neon clusters (20,22,24,26,28Ne) was studied. The decimal logarithm of half‐lives (expressed in seconds) were calculated by three different approaches based on (i) the single line of Universal curve (UNIV) for alpha and cluster radioactive decay, (ii) the Universal Decay law (UDL) and (iii) by considering a fission‐like model in which the interacting nuclear potential barrier was taken to be the sum of Coulomb and proximity potentials (CPPM) respectively. Based on the half‐lives calculated by using the three different approaches mentioned above, significance of the role of 208Pb nucleus (doubly magic nucleus) and nuclear shell effects in trans‐lead cluster radioactivity were investigated. The calculated half‐lives have also been compared with available experimental results. It was observed that cluster decay modes leading to the formation of 208Pb daughter nucleus have the lowest half‐lives. This implies that there is a shell closure at proton number (Z) = 82 and neutron number (N) = 126. Hence, it confirms the existence of nuclear shell effect and stresses the significance of role of 208Pb daughter nucleus in the trans‐lead cluster radioactivity. It can be noticed that the calculated half‐lives for several cluster decay modes are well within the present experimental upper limit for measurements (T1/2 < 1030S). These results may be useful for future experiments.

Optical potential obtained from relativistic-mean-field theory-based microscopic nucleon–nucleon interaction: applied to cluster radioactive decays

A microscopic nucleon–nucleon (NN) interaction is derived from the popular relativistic-mean-field (RMF) theory Lagrangian and used to obtain the optical potential by folding it with the RMF densities of cluster and daughter nuclei. The NN-interaction is remarkably related to the inbuilt fundamental parameters of RMF theory, and the results of the application of the so obtained optical potential, made to exotic cluster radioactive decays and α+α scattering, are found comparable to that for the well-known, phenomenological M3Y effective NN-interaction. The RMF-based NN-interaction can also be used to calculate a number of other nuclear observables.

HALF-LIVES OF CLUSTER DECAY OF NEUTRON RICH NUCLEI IN TRANS-TIN REGION

In this work, the logarithmic half-life [ log 10(T1/2)] values have been reported for the exotic decay of some neutron rich even–even parent nuclei (56≤Z≤64) accompanied by the emission of alpha-like and non-alpha-like clusters in the trans-tin region. These values were calculated by using the single line of universal curve (UNIV) for alpha and cluster radioactive decay as well as the universal decay law (UDL). The half-life values were also separately calculated by considering the interacting nuclear potential barrier as the sum of Coulomb and proximity potentials. The half-life values based on the three calculations mentioned above, were found to agree with one another within a few orders of magnitude. Possible conclusions are drawn based on the present study.

Cluster radioactive decay within the preformed cluster model using relativistic mean-field theory densities

We have studied the (ground-state) cluster radioactive decays within the preformed cluster model (PCM) of Gupta and collaborators [R. K. Gupta, in Proceedings of the 5th International Conference on Nuclear Reaction Mechanisms, Varenna, edited by E. Gadioli (Ricerca Scientifica ed Educazione Permanente, Milano, 1988), p. 416; S. S. Malik and R. K. Gupta, Phys. Rev. C 39, 1992 (1989)]. The relativistic mean-field (RMF) theory is used to obtain the nuclear matter densities for the double folding procedure used to construct the cluster-daughter potential with M3Y nucleon-nucleon interaction including exchange effects. Following the PCM approach, we have deduced empirically the preformation probability ${{P}_{0}}^{\mathrm{emp}}$ from the experimental data on both the $\ensuremath{\alpha}$- and exotic cluster-decays, specifically of parents in the trans-lead region having doubly magic $^{208}\mathrm{Pb}$ or its neighboring nuclei as daughters. Interestingly, the RMF-densities-based nuclear potential supports the concept of preformation for both the $\ensuremath{\alpha}$ and heavier clusters in radioactive nuclei. ${{P}_{0}}^{\ensuremath{\alpha}(\mathrm{emp})}$ for $\ensuremath{\alpha}$ decays is almost constant ($~$${10}^{\ensuremath{-}2}$--${10}^{\ensuremath{-}3}$) for all the parent nuclei considered here, and ${{P}_{0}}^{c(\mathrm{emp})}$ for cluster decays of the same parents decrease with the size of clusters emitted from different parents. The results obtained for ${{P}_{0}}^{c(\mathrm{emp})}$ are reasonable and are within two to three orders of magnitude of the well-accepted phenomenological model of Blendowske-Walliser for light clusters.

The relation between ternary fission and cluster decay

It was found that the main ternary fission products, such as 4He, 14C, 20O, 24Ne and 28Mg, are also the main clusters in cluster radioactivity decay. This similarity suggests that ternary fission can be described as a cluster decay of the fissioning nucleus in the last phase of the scission process.

Systematic behaviour in cluster radioactivity

Based on observations of cluster radioactivity, it was found that nuclei that decay by cluster radioactivity have either a daughter that is magic ( N = 126 or Z = 82) or a light emitted cluster with the highest binding energy (BE) per cluster. Nuclei that obey both conditions (magic and highest BE per cluster for the emitted cluster) have shorter half-lives. Thus, the most likely mode of cluster radioactive decay is when the light cluster has the highest BE per cluster and the daughter product is the double magic nucleus 208Pb.

Fine structure of cluster decays.

Within the one level R-matrix approach, expressions are derived for the hindrance factors of cluster radioactive decays in which y the shell model with effective residual interactions [e.g.,thelar in the Michigan State University version for nearly spherical nuclei, or the enlarged superfluid model (ESM) recently proposed for deformed nuclei]. The exterior wave functions are calculated from a cluster-nucleus double-folding model potential obtained with the M3Y interaction. As examples of the cluster decay fine structure we analyzed the particular cases of \ensuremath{\alpha} decay of $^{241}\mathrm{Am}$ and $^{243}\mathrm{Cm}$, $^{14}\mathrm{C}$ decay of $^{223}\mathrm{Ra}$, and $^{34}\mathrm{Si}$ decay of $^{243}\mathrm{Cm}$. Good agreement with the experimental data is obtained.

Search for cluster radioactivity of 237Np.

The few odd-{ital A} nuclides known to exhibit cluster radioactivity decay at rates hindered with respect to their even-even neighbors. For {sup 237}Np, the most likely clusters are predicted to be {sup 30}Mg and {sup 32}Si. We have completed a rigorous search for cluster emission from {sup 237}Np, with a null result. Our 90% confidence limit on the branching ratio with respect to alpha emission, {ital B} (cluster/{alpha}) {lt}1.8{times}10{sup {minus}14}, is a factor 4.3 lower than the limit obtained by Tretyakova {ital et} {ital al}. The two experiments together place an upper limit of 1.5{times}10{sup {minus}14} on the branching ratio for emission of clusters with 10{le}{ital Z}{le}14 from {sup 237}Np.

Theory of cluster radioactive decay and of cluster formation in nuclei.

A new model is proposed for the mechanism of cluster formation and then penetration of the confining nuclear interaction barrier in radioactive nuclei. The cluster formation is treated as a quantum-mechanical fragmentation process and the WKB penetrability is found analytically. Applications of the model are made to $^{14}\mathrm{C}$ decay of $^{222\mathrm{\ensuremath{-}}224}\mathrm{Ra}$ and $^{24}\mathrm{Ne}$ decay of $^{232}\mathrm{U}$. The branching ratio for $^{14}\mathrm{C}$ decay of $^{232}\mathrm{U}$ is also calculated and is found to be incredibly small as compared to that for its $^{24}\mathrm{Ne}$ decay.