SEQUENTIAL BINARY DECAY OF HIGHLY EXCITED NUCLEI

2008 ◽  
Vol 17 (08) ◽  
pp. 1541-1556 ◽  
Author(s):  
N. G. NICOLIS
Keyword(s):  
Rate Equations ◽  
Stage Theory ◽  
Mass Distributions ◽  
Model Code ◽  
Decay Products ◽  
Final Mass ◽  
Initial Excitation ◽  
Nucleon Emission ◽  
Excited Nuclei ◽  
Complete Dissociation

The decay of highly excited nuclei is described as a sequence of binary processes involving emission of fragments in their ground, excited-bound and unbound states. Primary together with secondary decay products lead to the final mass distributions. Asymmetric mass splittings involving nucleon emission up to symmetric binary ones are treated according to a generalized Weisskopf evaporation formalism. This procedure is implemented in the Monte-Carlo multi-step statistical model code MECO (Multisequential Evaporation COde). We examine the evolution of the calculated final mass distributions in the decay of a light compound nucleus, as the initial excitation energy increases towards the limits of complete dissociation. Comparisons are made with the predictions of the transition-stage theory, as well as a consistent Weisskopf treatment in which the decay process is described by rate equations for the generation of different fragment species.

scholarly journals Sequential binary decay of highly excited 40Ar*

2019 ◽  
Vol 14 ◽  
pp. 53
Author(s):  
N. G. Nicolis
Keyword(s):  
Decay Process ◽  
Rate Equations ◽  
Final States ◽  
Intermediate Mass ◽  
Mass Distributions ◽  
Model Code ◽  
Alternative Description ◽  
Unbound States ◽  
Initial Excitation ◽  
Nucleon Emission

The sequential statistical binary decay of the highly excited compound nucleus 40Ar* is described with an extended evaporation formalism implemented in a Monte-Carlo multi-step statistical model code. Asymmetric mass splittings involving nucleon emission up to symmetric binary ones are treated within the evaporation formalism, in a unified manner. Emission of heavy fragments in their ground and excited (particle-bound or unbound) states is considered. The evolution of the final mass distributions from 40Ar* is studied as a function of the initial excitation energy, in the range from 45 up to 405 MeV. The population of final states originating from the decay of intermediate mass fragments in particle-bound and particle-unbound states (side-feeding) is discussed. Results are compared with an alternative description in which the time-dependent decay process is described by rate equations for the generation of different fragment species.

scholarly journals Sequential binary decay of light nuclear systems: An assessment of statistical model codes

2020 ◽  
Vol 15 ◽  
pp. 83
Author(s):  
N. G. Nicolis
Keyword(s):  
Monte Carlo ◽  
Statistical Model ◽  
Sequential Decay ◽  
Model Code ◽  
Charge Distributions ◽  
Final Mass ◽  
Nuclear Systems ◽  
Nucleon Emission ◽  
Excited Nuclei ◽  
Complete Dissociation

The sequential decay of excited nuclei is described as a succession of binary processes involving fragments in their ground, excited-bound and unbound states. Primary together with secondary decays lead to the final mass and charge distributions. Asymmetric mass splittings involving nucleon emission up to symmetric binary ones are treated within the Weisskopf evaporation formalism, in a unified manner. This procedure was imple- mented in the Monte-Carlo multi-step statistical model code MECO (Multisequential Evaporation COde). We study the evolution of the calculated final mass and charge distributions from 40Ar* as a function of the excitation energy, up to complete dissociation. Our results are compared with the predictions of statistical evaporation codes based on different assumptions for the compound nucleus decay.

scholarly journals POSSIBILITY OF SYNTHESIZING SUPERHEAVY ELEMENTS IN NUCLEAR EXPLOSIONS

2010 ◽  
Vol 19 (10) ◽  
pp. 2063-2075 ◽  
Author(s):  
ALEXANDER BOTVINA ◽  
IGOR MISHUSTIN ◽  
VALERY ZAGREBAEV ◽  
WALTER GREINER
Keyword(s):  
Kinetic Model ◽  
Neutron Capture ◽  
Superheavy Elements ◽  
Heavy Nuclei ◽  
Β Decay ◽  
Mass Distributions ◽  
Nuclear Explosions ◽  
Simple Kinetic Model ◽  
Excited Nuclei ◽  
Calculated Average

The possibility to produce superheavy elements in the course of low-yield nuclear explosions is analyzed within a simple kinetic model which includes neutron capture, γ-emission, fission and particle evaporation from excited nuclei. We have calculated average numbers of absorbed neutrons as well as mass distributions of U and Cm nuclei exposed to an impulsive neutron flux as functions of its duration. It is demonstrated that detectable amounts of heavy nuclei absorbing from 20 to 60 neutrons may be produced in this process. According to an optimistic scenario, after multiple β-decay such nuclei may reach the long-living elements of the predicted "island of stability".

Mass distributions of fission fragments emitted by highly excited nuclei

1983 ◽  
Vol 310 (4) ◽  
pp. 347-348 ◽  
Author(s):  
L. N. Andronenko ◽  
A. A. Kotov ◽  
M. M. Nesterov ◽  
W. Neubert ◽  
N. A. Tarasov ◽  
...  
Keyword(s):  
Mass Distributions ◽  
Fission Fragments ◽  
Excited Nuclei

Langevin description of mass distributions of fragments originating from the fission of excited nuclei

2000 ◽  
Vol 63 (11) ◽  
pp. 1865-1873 ◽  
Author(s):  
D. V. Vanin ◽  
P. N. Nadtochy ◽  
G. I. Kosenko ◽  
G. D. Adeev
Keyword(s):  
Mass Distributions ◽  
Excited Nuclei

Dielectronic Recombination in the Average-Atom Model

1988 ◽  
Vol 102 ◽  
pp. 215
Author(s):  
R.M. More ◽  
G.B. Zimmerman ◽  
Z. Zinamon
Keyword(s):  
Detailed Balance ◽  
Systematic Errors ◽  
Dielectronic Recombination ◽  
Rate Equations ◽  
Strong Correlations ◽  
Dense Plasmas ◽  
Atom Model ◽  
New Feature ◽  
Average Atom Model ◽  
Attachment Process

Autoionization and dielectronic attachment are usually omitted from rate equations for the non–LTE average–atom model, causing systematic errors in predicted ionization states and electronic populations for atoms in hot dense plasmas produced by laser irradiation of solid targets. We formulate a method by which dielectronic recombination can be included in average–atom calculations without conflict with the principle of detailed balance. The essential new feature in this extended average atom model is a treatment of strong correlations of electron populations induced by the dielectronic attachment process.

On the interpretation of dislocation-loop growth during in-situ high-voltage Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 532-533
Author(s):  
E. Holzäpfel ◽  
F. Phillipp ◽  
M. Wilkens
Keyword(s):  
Point Defect ◽  
Rate Equations ◽  
Rate Theory ◽  
Dislocation Loops ◽  
High Voltage Electron Microscopy ◽  
Vacancy Migration ◽  
Voltage Electron ◽  
Reaction Rate Theory ◽  
Defect Reactions

During in-situ radiation damage experiments aiming on the investigation of vacancy-migration properties interstitial-type dislocation loops are used as probes monitoring the development of the point defect concentrations. The temperature dependence of the loop-growth rate v is analyzed in terms of reaction-rate theory yielding information on the vacancy migration enthalpy. The relation between v and the point-defect production rate P provides a critical test of such a treatment since it is sensitive to the defect reactions which are dominant. If mutual recombination of vacancies and interstitials is the dominant reaction, vαP0.5 holds. If, however, annihilation of the defects at unsaturable sinks determines the concentrations, a linear relationship vαP is expected.Detailed studies in pure bcc-metals yielded vαPx with 0.7≾×≾1.0 showing that besides recombination of vacancies and interstitials annihilation at sinks plays an important role in the concentration development which has properly to be incorporated into the rate equations.

Label-free, mass-sensitive single-molecule imaging using interferometric scattering microscopy

2020 ◽  
Author(s):  
Nikolas Hundt
Keyword(s):  
Single Molecule ◽  
Cellular Systems ◽  
Single Molecule Imaging ◽  
Label Free ◽  
Measurement Sensitivity ◽  
Mass Distributions ◽  
Quantitative Measurements ◽  
Contrast Mechanism ◽  
Cellular Components ◽  
Scattering Signal

Abstract Single-molecule imaging has mostly been restricted to the use of fluorescence labelling as a contrast mechanism due to its superior ability to visualise molecules of interest on top of an overwhelming background of other molecules. Recently, interferometric scattering (iSCAT) microscopy has demonstrated the detection and imaging of single biomolecules based on light scattering without the need for fluorescent labels. Significant improvements in measurement sensitivity combined with a dependence of scattering signal on object size have led to the development of mass photometry, a technique that measures the mass of individual molecules and thereby determines mass distributions of biomolecule samples in solution. The experimental simplicity of mass photometry makes it a powerful tool to analyse biomolecular equilibria quantitatively with low sample consumption within minutes. When used for label-free imaging of reconstituted or cellular systems, the strict size-dependence of the iSCAT signal enables quantitative measurements of processes at size scales reaching from single-molecule observations during complex assembly up to mesoscopic dynamics of cellular components and extracellular protrusions. In this review, I would like to introduce the principles of this emerging imaging technology and discuss examples that show how mass-sensitive iSCAT can be used as a strong complement to other routine techniques in biochemistry.

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