scholarly journals Spontaneous double alpha decay: First experimental limit and prospects of investigation

2021 ◽  
Vol 22 (2) ◽  
pp. 121-126
Author(s):  
V.I. Tretyak ◽  
Keyword(s):  
Isotopic Composition ◽  
Experimental Observation ◽  
Half Life ◽  
Alpha Decay ◽  
Alpha Particles ◽  
Experimental Limit ◽  
Natural Isotopic Composition ◽  
Simultaneous Emission

Nuclear decays with simultaneous emission of two alpha particles are energetically possible for a number of nuclides. Prospects of searching for such kind of decay for nuclides present in the natural isotopic composition of elements are discussed here. The first experimental limit on half-life for 2α decay is set for 209Bi as T1/2 > 2.9·1020 y at 90 % C.L., using the data of work [P. de Marcillac et al. Nature 422 (2003) 876]. Theoretical T1/2 estimations for the process are also given. Using these values, which are on the level of 1033 y or more, one can conclude that the prospects of experimental observation of 2α decay are very pessimistic.

scholarly journals Unearthing radial independence for prediction of alpha-decay half-lives

2018 ◽  
Vol 27 (06) ◽  
pp. 1850048
Author(s):  
Swagatika Bhoi ◽  
Basudeb Sahu
Keyword(s):  
Closed Form ◽  
Effective Potential ◽  
Half Life ◽  
Radial Distance ◽  
Alpha Decay ◽  
Bound State ◽  
Alpha Particles ◽  
Closed Form Expression ◽  
Form Expression ◽  
Scattering State

Nuclear radial distance is a prerequisite for generating any alpha-decay half-life formula by taking a suitable effective potential. We study the emission process of alpha particles from an isolated quasi-bound state generated by an effective potential to a scattering state. The effective potential is expressed in terms of Frahn form of potential which is exactly solvable and an analytical expression for half-life is obtained in terms of Coulomb function, wave function and the potential. We then derive a closed-form expression for the decay half-life in terms of the parameters of the potential, Q-value of the system, mass and proton numbers of the nuclei valid for alpha-decay as well as proton-decay. From the nature of variations of half-life as a function of radial distance, we trace the radial independence region where decay time is almost constant. Finally, by overviewing our results and picking that particular radial distance, we predict the half-lives of a series of nuclei by using the closed-form expression. We also predict the half-lives of isotopes of nuclei with [Formula: see text] and 120.

The electrical resistivity of lithium-6

1961 ◽  
Vol 263 (1314) ◽  
pp. 407-419 ◽  
Keyword(s):  
Electrical Resistivity ◽  
Isotopic Composition ◽  
Specific Heat ◽  
Room Temperature ◽  
Natural Isotopic Composition ◽  
Square Roots ◽  
Conduction Electrons ◽  
Ionic Mass ◽  
Theoretical Predictions ◽  
Electrical Resistivities

The electrical resistivities of lithium -6 and lithium of natural isotopic composition have been studied between 4°K and room temperature. In addition, their absolute resistivities have been carefully compared at room temperature. These measurements show that the effect of ionic mass on electrical resistivity agrees with simple theoretical predictions, namely, that the properties of the conduction electrons in lithium do not depend on the mass of the ions, and that the characteristic lattice frequencies for the two pure isotopes are in the inverse ratio of the square roots of their ionic masses. A comparison with the specific heat results of Martin (1959, 1960), where the simple theory is found not to hold, indicates the possibility that anharmonic effects are present which affect the specific heat but not the electrical resistivity.

ALPHA DECAY AND FISSION OF ALIGNED NUCLEI

1960 ◽  
Vol 38 (2) ◽  
pp. 290-314 ◽  
Author(s):  
N. R. Steenberg ◽  
R. C. Sharma
Keyword(s):  
Angular Distribution ◽  
High Temperature ◽  
Experimental Work ◽  
Low Temperatures ◽  
Alpha Decay ◽  
Alpha Particles ◽  
Nuclear Shape ◽  
Fission Fragments ◽  
Partial Waves ◽  
High Temperature Approximation

The theory of the angular distribution of alpha particles and of fission fragments from nuclei aligned at low temperatures is presented. Very explicit results are obtained in the high temperature approximation. These are directly dependent upon the branching which takes place to the various allowed partial waves. This branching is influenced by the nuclear shape, but it is shown that for this problem the effect of penetrating a spheroidal barrier is not critical. An application is made to the experimental work so far available and the result is reasonably satisfactory.

scholarly journals Magnetic properties of the natural and isotope-modified diamond and silicon carbide

2018 ◽  
Vol 185 ◽  
pp. 04007 ◽  
Author(s):  
A.N. Taldenkov ◽  
A.V. Inyushkin ◽  
E.A. Chistotina ◽  
V.G. Ralchenko ◽  
A.P. Bolshakov ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Magnetic Properties ◽  
Isotopic Composition ◽  
Single Crystals ◽  
High Purity ◽  
Diamagnetic Susceptibility ◽  
Synthetic Diamond ◽  
Paramagnetic Centers ◽  
Natural Isotopic Composition ◽  
Ferromagnetic Component

The magnetic properties of single crystals of synthetic diamond and crystals of silicon carbide were studied. High-purity samples of diamonds synthesized with HPHT and CVD technologies were used. The crystals of silicon carbide were grown by sublimation and industrial technology. Along with samples with a natural isotopic composition, monoisotopic crystals of diamond (99.96% 12C and 99.96% 13C) and silicon carbide (99.993% of 28Si) were studied. On the basis of the data obtained, the diamagnetic susceptibility was determined and the concentration of paramagnetic centers and the content of the ferromagnetic component were evaluated. The results are discussed.

Research of Radon Transportation Model to Investigate Buried Fault

2010 ◽  
Author(s):  
Lei Wang ◽  
Xianguo Tuo ◽  
Chunlai Liu
Keyword(s):  
Half Life ◽  
Southwest China ◽  
Sampling Period ◽  
Alpha Particles ◽  
Initial Concentration ◽  
Gas Sampling ◽  
Actual Measure ◽  
Buried Fault ◽  
Soil Gas Sampling ◽  
Buried Faults

How to get the position, direction and width of buried fault effectively is still very difficult when finding buried faults by measuring 222Rn radioactivity. In this paper we established a technique to carry out buried fault investigation. It was based on Fick’s fist law, Darcy’s law and theory of clusters to analyze radon transportation and simulate 222Rn transportation in ideal conditions. The feasibility indicates that measuring or investigating the concentration of radon to find abnormal region can help people find buried faults. 218Po and 214Po, daughter products of 222Rn, are generally considered to be proportional to initial concentration of 222Rn. 218Po and 214Po have short half-life of 3.05 min and 164us respectively which is very suitable for actual measure work. So in order to accumulate alpha particles effectively, soil gas sampling period is set about twice half-life of 218Po. The established model is applied to analyze two buried fault areas in Southwest China and the results are really much better.

scholarly journals Theoretical Study on the Formation of 1-neutron and 2-neutron Halo Nuclei via Decay of Elements in Super-Heavy Region

2020 ◽  
Vol 8 (1) ◽  
pp. 11-24
Author(s):  
R.K. Biju ◽  
K. Prathapan ◽  
K.P. Anjali
Keyword(s):  
Half Life ◽  
Neutron Number ◽  
Halo Nuclei ◽  
Neutron Halo ◽  
Experimental Limit ◽  
Proximity Potential ◽  
Deformed Nuclei ◽  
Halo Structure ◽  
Frame Work ◽  
Neutron Shell Closure

The possibility for the existence of 1-neutron and 2-neutron halo nuclei through the decay of even-even nuclei 270-316116, 272-318118 and 278-320120 in the super-heavy region is studied within the frame work of the Coulomb and Proximity Potential Model (CPPM). Halo structure in neutron rich nuclei with Z<=20  is identified by calculating the neutron separation energies and on the basis of potential energy considerations. The 1n + core configuration of proposed 1-neutron halo nuclei between z=10  and Z=20 is found shifted to 2n + core configuration in higher angular momentum states. The calculation of half-life of decay is performed by considering the proposed halo nuclei as spherical cluster and as deformed nuclei with a rms radius. Except for 15C, the half-life of decay is found decreased when the rms radius is considered. Only the 1-neutron halo nuclei 26F and 55Ca showed half-lives of decay which are less than the experimental limit. None of the proposed 2-neutron halo nuclei have shown a half-life of decay lower than the experimental limit. Also, the probability for the emission of neutron halo nuclei is found to be less in super-heavy region when compared with the clusters of same isotope family. Further, neutron shell closure at neutron numbers 150, 164 and 184 is identified form the plot of  log10 T1/2 verses the neutron number of parents. The plots of Q-1/2 verses log10 T1/2 and -ln P verses log10 T1/2 for various halo nuclei emitted from the super-heavy elements are found to be linear showing that Geiger-Nuttall law is applicable to the emission of neutron halo also.

Study of the dependence of alpha decay half-life on the surface symmetry energy

2020 ◽  
Vol 29 (09) ◽  
pp. 2050070
Author(s):  
S. Nejati ◽  
O. N. Ghodsi
Keyword(s):  
Symmetry Energy ◽  
Half Life ◽  
Surface Region ◽  
Alpha Decay ◽  
Proton Density ◽  
Skin Thickness ◽  
Neutron Skin ◽  
Mother And Daughter ◽  
Energy Coefficient ◽  
Finite Nuclei

In this study, the effect of the surface symmetry energy on the neutron skin thickness and division of it into the bulk and surface parts are investigated by determination of the symmetry energy coefficient [Formula: see text] of finite nuclei. We demonstrate the importance of the isospin asymmetry distribution in the symmetry energy coefficient of finite nuclei at the surface region. We attempt to find out how different surface symmetry energies may affect alpha decay half-life. The Skyrme interactions are used to describe the neutron and proton density distributions and to calculate the symmetry energy coefficient [Formula: see text] of four nuclei and the surface symmetry energy. The chosen Skyrme interactions can produce the binding energy and root-mean-square charge radii of both mother and daughter nuclei. We single out the spherical isotones of [Formula: see text] named [Formula: see text]Pb, [Formula: see text]Po, [Formula: see text]Rn and [Formula: see text]Ra for daughter nuclei and explore the dependence of the bulk and surface contributions on the surface symmetry energy. The half-life of mother nuclei, i.e., [Formula: see text]Po, [Formula: see text]Rn, [Formula: see text]Ra and [Formula: see text]Th, is employed to investigate the extent to which it is affected by different surface symmetry energies. The calculated half-lives show a downward tendency for different surface symmetry energies which can be caused by various neutron skin thicknesses.

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