Initial exciton configuration in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>n</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math>pre-equilibrium emission reactions

Elmaghraby, Elsayed K.

doi:10.1103/physrevc.78.014601

Cited by 11 publications

(4 citation statements)

References 44 publications

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“…The summation is taken over all possible neutrino flavors. Here, N(t) is the number of nuclei at time t, K(Q) is the factor representing the modification of nucleon properties in the nuclear medium, which can be investigated by nucleon induced nuclear reactions [13,14]; K(Q) depends on the Q-value of the reaction and the state of the nucleus upon interaction. The in-medium neutrino cross section σ ν can replace K(Q) σ νn .…”

Section: Model For Analysismentioning

confidence: 99%

Configuration mixing in particle decay and reaction

Elmaghraby¹

2022

Preprint

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Background: Decay constants of unstable nuclei and particles are quantum constants. Recent controversy on the existence (versus non-existence) of variability in the observation of decay rate can be settled by considering mixing in decay configuration.Purpose: Variability in decay rate was investigated based on the available information of beta decay rate data, solar neutrino flux, and energy distribution.Method: Full systematic analysis of the oscillatory behavior was carried out. Based on the zero threshold energy for neutrino absorption in beta emitters, a model for configuration mixing between two distinct beta disintegration modes β ν -disintegration (electron from neutrino interaction) and the β − -disintegration (electron from natural decay) was proposed.Results: The phenomenon of variability in beta decay rate was related to the possible exothermic neutrino absorption by unstable nuclei which, in principle, should include the whole range of flux energies involving flux with energy below the 71 Ga threshold at 0.23 MeV. These two disintegration modes occur independently and model for their apparent mixing rate was proposed. Conclusions:The configuration mixing between the two modes cause depletion of radioactive nuclei which is subject to change with seasonal solar neutrino variability. Ability to detect this variability was found to be dependent on the Q-value of the β ν disintegration and detection instrument setup. Value of neutrino cross section weighted by the ratio between β ν and β − detection efficiencies was found to be in the range 10 −44 to 10 −36 cm 2 . For experiments that uses the end point to determine the neutrino mass, interference due to mixing should be taken into account.

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Section: Model For Analysismentioning

confidence: 99%

Configuration mixing in particle decay and reaction

Elmaghraby¹

2022

Preprint

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“…Nuclear reactions on nuclei proceed through different processes in which the majority of them possess full thermodynamic equilibrium before decay (compound nucleus reaction) with minor contribution in pre-equilibrium decay stages [6,7]. Neutron capture, on the other hand, is a pure compound process, especially in the thermal and epi-thermal energies.…”

Section: Introductionmentioning

confidence: 99%

Role of isomeric state formation on the measurement of thermal neutron cross section and resonance integral

Elmaghraby¹,

Salem²,

Yousef³

et al. 2018

Phys. Scr.

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The isomeric thermal neutron cross section and isomeric resonance integral of 109 Ag(n, γ) 110m Ag, 133 Cs(n, γ) 134m Cs and 134g Cs, and 136 Ba(n, γ) 137m Ba reactions were investigated together with 115 In(n, γ) 116m In monitor reaction. These residual nuclei have broad half-life time scale suitable for our investigation. Moderated neutrons from steady AmBe source were used for activation of samples with natural abundances. Field was monitored and mapped using gold and indium activation. The formulae used for neutron activation analysis were derived with emphasizing the different interpenetrations of cadmium transmission factor and self-shielding factors. The k 0 -factor for γ-rays in the residual nuclei were measured. The isomeric thermal neutron cross section and resonance integral for 115 In(n, γ) 116m In were evaluated to be 162.6 b and 2585 b. These data were used to measure the k 0 -factors; and compared to reported values to confirm the procedure. The thermal neutron cross section and resonance integral for 133 Cs(n, γ) 134m Cs were found to be 2.64±0.11 b and 42±1.7 b, respectively; while those of the 109 Ag(n, γ) 110m Ag reaction were 4.09±0.35 b and 68±6 b. Thermal neutron cross section for 136 Ba(n, γ) 137m Ba was identified as 0.032±0.003 b, while the resonance integral could not be evaluated as a result of interfering reactions. Model calculations were done using EMPIRE code to simulate isomeric ratio and compared with the experimental results. The feeding of isomeric state from neutron reaction is more sensitive to the variation of neutron flux distribution than the nucleus formation. Steady neutron field could be retained with isotopic neutron source with moderation setup and geometry of suitable homogeneity and isotropy.

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“…Energy distribution among limited number of particles with finite degeneracy was a confusing issue when dealing with nuclear reaction/interaction. It is of the interest in pre-equilibrium reaction [1,2] in which low degeneracy states are occupied by finite number of excitons that exist together for very short time compared to the total reaction time; very long as compared to the nucleonnucleon interaction time. As a matter of quantum nature of physical system, non-degenerate and low degeneracy systems are considered finite; which means that systems from nuclei to nanoparticle are finite and their properties may be comparable.…”

Section: Introductionmentioning

confidence: 99%

“…Credibility in the formulations for the asymptotic Maxwell-Boltzmann (MB), Fermi-Dirac (FD) and Bose-Einstein (BE) distribution functions guided the physicists through a century to great findings. However, modern science needs more precise expressions for these distributions [3][4][5][6]. In general, the current statistical description of the physical ensemble needs adjustment in order to follow proper justification of the definition of number and equivalence (or even non-equivalence) of a priori probabilities.…”

Section: Introductionmentioning

confidence: 99%

On the Quantum Statistical Distributions Describing Finite Fermions and Bosons Systems

Elmaghraby¹

2011

JMP

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A century old methodology for deriving statistical distribution using approximate Stirling’s formulation of the factorial becomes questionable. By avoiding the use of exaggerated approximations, a new picture of the energy distribution of fermions and bosons are presented. Energy distribution among fermions (or bosons) in systems with finite degeneracy are found to be degeneracy dependent. The presented point of view explains, successfully, presence of degeneracy pressure in ultra-cooled Fermi gas and predicts the minimum accessible temperature for finite degeneracy fermions system

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Initial exciton configuration in(p,n)pre-equilibrium emission reactions

Cited by 11 publications

References 44 publications

Configuration mixing in particle decay and reaction

Configuration mixing in particle decay and reaction

Role of isomeric state formation on the measurement of thermal neutron cross section and resonance integral

On the Quantum Statistical Distributions Describing Finite Fermions and Bosons Systems

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