14C Cluster Research Articles

Possible Alpha and 14C Cluster Emission From Hyper Radium Nuclei in The Mass Region A = 202-235

The possibilities for the emission of 4He and 14C clusters from hyper 202-235ΛRa are studied using our Coulomb and proximity potential model (CPPM) by including the lambda-nucleus potential. The predicted half lives show that hyper 202-231ΛRa nuclei are unstable against 4He emission and 14Cemission from 217- 229ΛRa are favorable for measurement. Our study also show that hyper Λ202235-Ra are stable against hyper Λ4He and Λ14C emission. The role of neutron shell closure (N = 126) in 213 ΛRn daughter and role of proton and neutron shell closure (Z = 82, N = 126) in Λ209Pb daughter are also revealed. As hyper nuclei decays to normal nuclei by mesonic/non-mesonic decay and since most of the predicted half lives for 4He and 14C emission from normal Ra nuclei are favorable for measurement, we presume that alpha and 14C cluster emission from hyper Ra nuclei can be detected in laboratory in a cascade (two-step) process.

Internal bremsstrahlung of strongly interacting charged particles

A universal theoretical model intended for calculating internal-bremsstrahlung spectra is proposed. In this model, which can be applied to describing nuclear decays of various type (such as alpha decay, cluster decay, and proton emission), use is made of realistic nucleus–nucleus potentials. Theoretical internal-bremsstrahlung spectra were obtained for the alpha decay of the 214Po nucleus, as well as for the decay of the 222Ra nucleus via the emission of a 14C cluster and for the decay of the 113Cs nucleus via proton emission, and the properties of these spectra were studied. The contributions of various regions (internal, subbarrier, and external) to the internal-bremsstrahlung amplitude were analyzed in detail. It is shown that the contribution of the internal region to the amplitude for internal bremsstrahlung generated in nuclear decay via proton emission is quite large, but that this is not so for alpha decay and decay via cluster emission. Thus, a process in which strong interaction of nuclear particles affects the internal-bremsstrahlung spectrum if found.

Probable alpha and 14C cluster emission from hyper Ac nuclei

A systematic study on the probability for the emission of 4^He and 14^C cluster from hyper ${207-234}^$Ac and non-strange normal ${207-234}^$Ac nuclei are performed for the first time using our fission model, the Coulomb and proximity potential model (CPPM). The predicted half lives show that hyper ${207-234}^$Ac nuclei are unstable against 4^He emission and 14^C emission from hyper ${217-228}^$Ac are favorable for measurement. Our study also show that hyper ${207-234}^$Ac are stable against hyper 4^He and 14^C emission. The role of neutron shell closure (N=126) in hyper 214^Fr daughter and role of proton/ neutron shell closure (Z =82, N =126) in hyper 210^Bi daughter are also revealed. As hyper-nuclei decays to normal nuclei by mesonic/non-mesonic decay and since most of the predicted half lives for 4^He and 14^C emission from normal Ac nuclei are favourable for measurement, we presume that alpha and 14^C cluster emission from hyper Ac nuclei can be detected in laboratory in a cascade (two-step) process.

Fine structure in the cluster decay of radium isotopes

Half-life times for 14C cluster emission from various radium isotopes are computed taking interacting potential as the sum of Coulomb and proximity potentials. The half-life time values are compared with experimental data and with the values reported by Poenaru et al using the analytical super-asymmetric fission model (ASAFM). The lowest half-life time for 222Ra stresses the role of the doubly magic 208Pb daughter in the exotic decay process. It is found that neutron excess in the parent nucleus slows down the exotic decay process. The high hindrance factor (HF) of the 14C branch to the ground state (9/2+) and the low HF to the first excited state (11/2+) of the 209Pb daughter are in good agreement with the experimental result. The fine structure from 223Ra gives direct evidence of the presence of a spherical component in the deformed parent nucleus.

Fine structure in 14C cluster emission from 225Ac

A fine structure in the 14C decay of 225Ac is predicted quantitatively by accounting dynamical aspects during the disintegration process. Transitions to the excited states of the daughter nucleus are considered to be mainly directed by the Landau–Zener promotion mechanism in the region of avoided crossing levels. The level scheme is evaluated with the superasymmetric two–center shell model. The half–lives are computed considering the cluster decay as a superasymmetric fission process.

Cluster model investigation of the structure of 223Ra

We extend our previous exotic cluster treatment of heavy even-even nuclei by modelling 223Ra as a 208Pb + 14C + n system. The neutron occupies 1 g 9 2 , 0i 11 2 , 0j 15 2 , 2d 5 2 , 3s 1 2 , 1g 7 2 and 2d 3 2 states with energies taken from the known spectrum of 209Pb, while the 14C cluster occupies 0 +, 2 +, 4 +, … or 1 −, 3 −, 5 −, … states whose energies are taken from the known levels of 222Ra. The 14C-n interaction mixes together the various combinations of neutron and 14C orbital motion states coupled to total angular momentum I. Diagonalization of the Hamiltonian matrices for each I-state then yields energies and eigenvectors for comparison with experimental data. Once the Pauli principle has been satisfied by excluding the odd neutron from orbitals already occupied by neutrons in the 14C cluster we generate low-lying bands with K π values (in order of increasing energy) 3 2 + , 3 2 + , 5 2 + , 5 2 + , 1 2 + and 1 2 + . We calculate strong E2 transitions (∼100 W.u.) within a given band, and much weaker ones (≲1 W.u.) between different K-bands. We give a good account of the relatively strong E1 transitions between bands of equal K but opposite parity (≲0.001 W.u.) and the much weaker ones (<10 −4 W.u.) between opposite parity bands with different values of K. Our description of in-band M1 transitions is in good accord with the data, and we predict equally strong cross-band transitions. Our calculation indicates that the ground state of 223Ra is constructed principally from a 0i 11 2 neutron coupled to the 208Pb 14C relative motion, in qualitative agreement with the observation that the exotic decay of 223Ra goes preferentially to the first excited state of 209Pb with spin 11 2 + .

Exotic clustering in 222,224,226Ra

We describe the J π = 0 +, 2 +, 4 +, … ground state bands of 222,224,226Ra, using a model in which these bands are treated as a 14C cluster orbiting the appropriate Pb core. For each isotope, we obtain good agreement with the measured half-life for the 14C decay of the 0 + ground state, as well as with the excitation energies and in-band E2 decays of other states of the ground state band. We also propose extensions of the model to deal with the observed low-lying J π = 1 −, 3 −, 5 −, … bands, their in-band E2 decays, and the E1 and E3 transitions connecting to the ground state bands.

14C cluster emission: a tool for the study of nuclear structures

14C cluster emission: a tool for the study of nuclear structures

Cluster preformation probabilities and fine-structure effects in heavy-cluster decays using folding potentials

For the double-folding model, the role of effective NN interaction and decay-product densities is studied for the exotic cluster decays. Fixing the density parameters, the 14C cluster preformation probability is approximately 10-7-10-8 for the Michigan 3 Yukawa (M3Y) interaction, whereas it is 0.1-0.5 for the Dirac delta interaction. This difference in preformation probabilities is related to the differences in the predicted barriers. The parameters of the decay product densities are also shown to affect the cluster preformation probabilities by a factor of approximately 10-4. The M3Y interaction is further used to predict the fine-structure effects for 14C decays of some odd-even nuclei to the excited states of their daughters.

PRODUCTION, STRUCTURE AND DECAY OF HYPERNUCLEI

PRODUCTION, STRUCTURE AND DECAY OF HYPERNUCLEI