Sample-induced perturbations in neutron field

W., Mahmoud, Ateia; Elmaghraby, Elsayed K.; Solieman, A. H. M.; Salama, E.; Elghazaly, A.; El-Fiki, S.A.

doi:10.1063/5.0119940

Cited by 1 publication

(2 citation statements)

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“…The subscript (energy domain) is to be replaced by 'th' in case of thermal neutron energies below cadmium cutoff energy (∼0.5 eV) or by 'epi' for epi-thermal neutrons having energy domain greater than the cadmium cutoff energy. Here, we have used two notions of flux j o and j which stand for unperturbed neutron flux for which the material is diluted or absent [73] and the measured self-shielded neutron flux in the vicinity of the material, respectively.…”

Section: Probability Of the Neutron Interactionmentioning

confidence: 99%

“…Furthermore, the neutron's energy spectrum is varied, but ideally suited to research using the ideal Maxwellian distribution at room temperature, while the other distributions must be altered to match the reference nuclear reaction data [3,7,13]. Apart from that, neutrons are deeply employed in two significant geometries, including but not limited to: (1) beam geometry, where the neutron currents are assumed to travel in one direction, and (2) field geometry, where neutrons impact the sample from all directions, presuming the field is isotropic and has equal flux densities from all directions [14][15][16]. There is an important functional difference between these two geometries, i.e., the effect on the neutron flux itself.…”

Section: Introductionmentioning

confidence: 99%

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Mathematical formulae for neutron self-shielding properties of media in an isotropic neutron field

Elmaghraby,

Mahmoud,

Salama

et al. 2024

Phys. Scr.

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In the current study, an ab initio derivation of the neutron self-shielding factor to solve the complex neutron transport problem of the decrease of the neutron ﬂux as it penetrates into a material placed in an isotropic neutron ﬁeld. The theory of steady-state neutron transport was employed, starting from Stuart’s formula, to derive simple analytical formulae based on the integral cross-section parameters. The formulae could be adopted by the user according to various variables, such as the neutron ﬂux distribution and geometry of the simulation at hand. The concluded formulae of the self-shielding factors comprise an inverted sigmoid function normalized with a weight representing the ratio between the macroscopic total and scattering cross-sections of the medium. The general convex volume geometries are reduced to a set of chord lengths, while the neutron interaction probabilities within the volume are parameterized to the epithermal and thermal neutron energies. The arguments of the inverted-sigmoid function were derived from a simpliﬁed version of neutron transport formulation. The derived analytic formulae agreed greatly with the experimental observations for diﬀerent elements and geometries.

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Section: Probability Of the Neutron Interactionmentioning

confidence: 99%