Alpha-Decay Systematics of the Heavy Elements

1948 ◽  
Vol 74 (11) ◽  
pp. 1730-1732 ◽  
Author(s):  
I. Perlman ◽  
A. Ghiorso ◽  
G. T. Seaborg
Keyword(s):  
Alpha Decay ◽  
Heavy Elements

Calculation of Q-value and half-life of alpha decay in super heavy elements using S-matrix theory

2020 ◽  
Vol 29 (07) ◽  
pp. 2050043
Author(s):  
R. Rahul ◽  
B. Nandana ◽  
S. Mahadevan
Keyword(s):  
Half Life ◽  
Matrix Theory ◽  
Scattering Problem ◽  
Alpha Decay ◽  
Heavy Elements ◽  
Nuclear Potential ◽  
Q Value ◽  
S Matrix ◽  
Double Folding ◽  
Heaviest Elements

The half-life and the [Formula: see text]-value of alpha decay in several super heavy elements are calculated. The nuclear potential is computed using the double-folding method. Using the S-matrix theory, the alpha decay is treated as a scattering problem between alpha particle and the daughter nucleus. Nuclear potential was approximated by the parameterized Woods–Saxon potential. This idea has also been extended to predict the half-life and the [Formula: see text]-value of the heaviest elements of few other alpha chains.

STUDY OF ALPHA DECAY OF SUPER HEAVY ELEMENTS USING S-MATRIX AND WKB METHODS

2008 ◽  
Vol 17 (04) ◽  
pp. 611-629 ◽  
Author(s):  
P. PREMA ◽  
S. MAHADEVAN ◽  
C. S. SHASTRY ◽  
A. BHAGWAT ◽  
Y. K. GAMBHIR
Keyword(s):  
Mean Field ◽  
Alpha Decay ◽  
Difficult Problem ◽  
Heavy Elements ◽  
Heavy Nuclei ◽  
Folding Model ◽  
Relativistic Mean Field ◽  
Double Folding Model ◽  
S Matrix ◽  
Double Folding

A comparative study of the S-matrix and the WKB methods for the calculation of the half widths of alpha decay of super heavy elements is presented. The extent of the reliability of the WKB methods is demonstrated through simple illustrative examples. Detailed calculations have been carried out using the microscopic alpha-daughter potentials generated in the framework of the double-folding model using densities obtained in the relativistic mean field theories. We consider alpha-nucleus systems appearing in the decay chains of super heavy parent elements having A = 277, Z = 112 and A = 269, Z = 110. For negative and small positive log τ1/2 values the results from both methods are similar even though the S-matrix results should be considered to be more accurate. However, when log τ1/2 values are large and positive, the width associated with such state is infinitesimally small and hence calculation of such width by the S-matrix pole search method becomes a numerically difficult problem. We find that overall, the WKB method is reliable for the calculation of half lives of alpha decay from heavy nuclei.

scholarly journals ANALYTIC RELATIONS FOR PARTIAL ALPHA DECAY HALF-LIVES AND BARRIER HEIGHTS AND POSITIONS

2011 ◽  
Vol 20 (04) ◽  
pp. 1030-1033 ◽  
Author(s):  
G. ROYER ◽  
C. SCHREIBER ◽  
H. SAULNIER
Keyword(s):  
Angular Momentum ◽  
Potential Barrier ◽  
Ground State ◽  
Alpha Decay ◽  
Heavy Elements ◽  
State Transitions ◽  
Heavy Nuclei ◽  
Data Set ◽  
Α Decay ◽  
Barrier Heights

From an adjustment on a recent selected data set of partial α-decay half-lives of 344 ground state to ground state transitions, analytic formulae are proposed depending on the angular momentum of the α particle. In particular, an expression allows to reproduce precisely the partial α-decay half-lives of even-even heavy nuclei and, then, to predict accurately the partial α-decay half-lives of other very heavy elements from the experimental or predicted Qα. Simple expressions are also provided to calculate the potential barrier radius and height.

Distribution of R- and S-Process Elements in the Galactic Halo

1988 ◽  
Vol 132 ◽  
pp. 501-506
Author(s):  
C. Sneden ◽  
C. A. Pilachowski ◽  
K. K. Gilroy ◽  
J. J. Cowan
Keyword(s):  
Heavy Element ◽  
Galactic Halo ◽  
Low Noise ◽  
Heavy Elements ◽  
Process Synthesis ◽  
Element Abundances ◽  
Halo Stars ◽  
Abundance Patterns ◽  
R Process ◽  
Process Elements

Current observational results for the abundances of the very heavy elements (Z>30) in Population II halo stars are reviewed. New high resolution, low noise spectra of many of these extremely metal-poor stars reveal general consistency in their overall abundance patterns. Below Galactic metallicities of [Fe/H] Ã −2, all of the very heavy elements were manufactured almost exclusively in r-process synthesis events. However, there is considerable star-to-star scatter in the overall level of very heavy element abundances, indicating the influence of local supernovas on element production in the very early, unmixed Galactic halo. The s-process appears to contribute substantially to stellar abundances only in stars more metal-rich than [Fe/H] Ã −2.

Scattering-angle dependence of signal/background ratio of inner-shell electron excitation loss in EELS

1983 ◽  
Vol 41 ◽  
pp. 390-391
Author(s):  
T. Oikawa ◽  
M. Inoue ◽  
T. Honda ◽  
Y. Kokubo
Keyword(s):  
Energy Loss ◽  
Electron Excitation ◽  
Heavy Elements ◽  
Background Intensity ◽  
Light Elements ◽  
Energy Analyzer ◽  
High Background ◽  
Scattering Angle ◽  
Angle Dependence ◽  
Shell Electron

EELS allows us to make analysis of light elements such as hydrogen to heavy elements of microareas on the specimen. In energy loss spectra, however, elemental signals ride on a high background; therefore, the signal/background (S/B) ratio is very low in EELS. A technique which collects the center beam axial-symmetrically in the scattering angle is generally used to obtain high total intensity. However, the technique collects high background intensity together with elemental signals; therefore, the technique does not improve the S/B ratio. This report presents the experimental results of the S/B ratio measured as a function of the scattering angle and shows the possibility of the S/B ratio being improved in the high scattering angle range.Energy loss spectra have been measured using a JEM-200CX TEM with an energy analyzer ASEA3 at 200 kV.Fig.l shows a typical K-shell electron excitation edge riding on background in an energy loss spectrum.

Long-period modulated superstructures in Pd-12.5 at.%Ce and Pd-15 at.%Ce alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 164-165
Author(s):  
Noriyuki Kuwano ◽  
Masaru Itakura ◽  
Kensuke Oki
Keyword(s):  
Electron Microscopy ◽  
Mean Value ◽  
Heavy Elements ◽  
Arc Furnace ◽  
X Ray ◽  
Long Period ◽  
Ultra High Purity ◽  
Heat Treated ◽  
Atomic Scattering ◽  
The Mean

Pd-Ce alloys exhibit various anomalies in physical properties due to mixed valences of Ce, and the anomalies are thought to be strongly related with the crystal structures. Since Pd and Ce are both heavy elements, relative magnitudes of (fcc-fpd) are so small compared with <f> that superlattice reflections, even if any, sometimes cannot be detected in conventional x-ray powder patterns, where fee and fpd are atomic scattering factors of Ce and Pd, and <f> the mean value in the crystal. However, superlattices in Pd-Ce alloys can be analyzed by electron microscopy, thanks to the high detectability of electron diffraction. In this work, we investigated modulated superstructures in alloys with 12.5 and 15.0 at.%Ce.Ingots of Pd-Ce alloys were prepared in an arc furnace under atmosphere of ultra high purity argon. The disc specimens cut out from the ingots were heat-treated in vacuum and electrothinned to electron transparency by a jet method.

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