Neutron Wave Analysis in Finite Media

Nishina, Kojiro; Akcasu, A. Ziya

doi:10.13182/nse70-a21197

Cited by 20 publications

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“…With use made of Eqs. ( 6) and 155 ( 7 ), of the relations between a± and b±, B=(v) and A(±v), and of the same procedure as in the one-velocity case< 20 \ we find…”

Section: -Tz-jimentioning

confidence: 63%

Reflection and Transmission of Thermal Neutrons in Polycrystalline Slab

Yamagishi

Deguchi

Sekiya

1976

J. Nucl. Sci. Technol.

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Solutions of the neutron transport equation with a one-term degenerate scattering kernel for a polycrystalline plane slab with finite thickness are derived with use made of the eigenfunction expansion method. The effect brought upon the energy spectrum of reflected and of transmitted neutrons by changes in temperature are examined by numerical calculations. No discontinuous change occurs in the spectra upon passage the critical temperature, below which the discrete eigenvalue vanishes, despite the abrupt change undergone at this point by the analytical solution. The spectra of the reflected and the transmitted neutrons differ entirely from each other, particularly below the Bragg energy. The discrepancy between these spectra increases with lowering temperature and widening slab thickness. A sharp peak occurring in the energy spectrum for transmitted neutrons is found to grow significantly with decreasing temperature.

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“…With use made of Eqs. ( 6) and 155 ( 7 ), of the relations between a± and b±, B=(v) and A(±v), and of the same procedure as in the one-velocity case< 20 \ we find…”

Section: -Tz-jimentioning

confidence: 63%

Reflection and Transmission of Thermal Neutrons in Polycrystalline Slab

Yamagishi

Deguchi

Sekiya

1976

J. Nucl. Sci. Technol.

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“…This explains the wide discrepancy between the observed values of the dip distance at the same frequency in assemblies of comparable transverse dimensions. Nishina and Ackasu (1970) have studied the continuum spectrum using an energydependent diffusion theory with a modified one-term degenerate kernel. Their analysis indicated the difficulties in measuring meaningful wave parameters in graphite assemblies even in large assemblies.…”

Section: Discussionmentioning

confidence: 99%

“…In crystalline moderators such as graphite, the behaviour of neutrons of energies below the so-called Bragg cut-off is quite different from that of thermal neutrons. Recent theoretical studies (Utsuro et al 1968, Nishina and Ackasu 1970, Wood and Lawrence 1971, Yamagishi 1972, 1974, Takahashi 1972, Kumar et al 1973 of the propagation of neutron pulses have shown that the contribution from the sub-Bragg neutrons (hereafter referred to as cold neutrons) exhibits 'quasi-discrete' properties away from the source, and that it interfered with the discrete mode to cause a dip in the total amplitude versus frequency curve. This phenomenon had already been observed by Utsuro et al (1968) and confirmed by Takahashi and Sumita (1968).…”

Section: Introductionmentioning

confidence: 99%

Effect of cold neutrons on pulse propagation in graphite

Hanna

1977

J. Phys. D: Appl. Phys.

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A pulsed neutron beam from the thermal column of a reactor has been used to study neutron pulse propagation in graphite. A peculiar irregularity (an anomalous peak occurring rather earlier than the main peak) has been observed in the shape of the propagating pulse. The anomalous peak fist appears at long distances from the source and its relative magnitude increases quickly with distance. This phenomenon does not appear to have been reported elsewhere. Observations of the effect on the anomaly of changes in source conditions, source separation, and transverse buckling suggest that it is attributable to interference between sub-Bragg and thermal neutron waves in the frequency range around 2500 rad s-1, and not to direct penetration by cold neutrons. The observed phenomenon is very sensitive to source conditions and experimental configuration.

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Neutron wave interference effects in beryllium oxide

Wow

Lawrence

1971

Journal of Nuclear Energy

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Neutron Wave Analysis in Finite Media

Cited by 20 publications

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Reflection and Transmission of Thermal Neutrons in Polycrystalline Slab

Reflection and Transmission of Thermal Neutrons in Polycrystalline Slab

Effect of cold neutrons on pulse propagation in graphite

Neutron wave interference effects in beryllium oxide

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