Preliminary analysis of gain measurements at the HFBR liquid hydrogen moderator

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The High Flux Beam Reactor (HFBR) is a 60 MW steady state neutron source. As part of the facility a cold neutron source is included in one of the beam tubes (H-9). The arrangement of this source is shown in Figure 1, which shows the reactor core, beam tube H-9, and the cold source with its attached helium cooling lines and hydrogen feed lines. The liquid hydrogen chamber is in the shape of an oblate spheroid and has a volume of 1.466 liters, and an aspect ratio of 1:3. Aluminum is used as the material of construction. The wall thickness ... continued below

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9 p.

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Ludewig, H.; Aronson, A.; Todosow, M.; Passell, L. & Wildgruber, U. May 1, 1998.

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Description

The High Flux Beam Reactor (HFBR) is a 60 MW steady state neutron source. As part of the facility a cold neutron source is included in one of the beam tubes (H-9). The arrangement of this source is shown in Figure 1, which shows the reactor core, beam tube H-9, and the cold source with its attached helium cooling lines and hydrogen feed lines. The liquid hydrogen chamber is in the shape of an oblate spheroid and has a volume of 1.466 liters, and an aspect ratio of 1:3. Aluminum is used as the material of construction. The wall thickness of the chamber varies, with the thinnest value being on the flatter parts of the oblate spheroid. This design minimizes the amount of metal in the direction of the neutron beam of interest. Gain is defined as the ratio of the flux at a specific wave length leaking from the front face of the cold source, with and without the liquid hydrogen present. Measurements of the gain were made at several wavelength for the HFBR cold source. The change in the neutron spectrum at a particular wave length is a strong function of the scattering kernel of the moderator. Thus, these measurements can be used as integral data to validate calculational models and scattering kernel data for liquid hydrogen, and shed light on the actual mixture of ortho/para hydrogen in the cold source. Two scattering kernels for each of the states of liquid hydrogen (ortho and para) were available at the beginning of the study. The total scattering cross section for each of these are shown. The two ortho kernels are seen to be quite similar. However, in the case of para-hydrogen there is seen to be a significant difference between the two cross sections at lower energies or longer wavelengths. This difference implies a similar difference in the scattering kernel. In the following analysis both para-hydrogen kernels and only one ortho-hydrogen kernel will be used. In addition, a free proton gas kernel (no molecular binding) will be used for comparison purposes.

Physical Description

9 p.

Notes

INIS; OSTI as DE98005759

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  • International workshop on cold moderation for pulsed neutron sources, Chicago, IL (United States), 29 Sep - 2 Oct 1997

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  • Other: DE98005759
  • Report No.: BNL--65525
  • Report No.: CONF-9709256--
  • Grant Number: AC02-98CH10886
  • Office of Scientific & Technical Information Report Number: 654198
  • Archival Resource Key: ark:/67531/metadc705721

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  • May 1, 1998

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  • Sept. 12, 2015, 6:31 a.m.

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  • Nov. 5, 2015, 2:36 p.m.

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Ludewig, H.; Aronson, A.; Todosow, M.; Passell, L. & Wildgruber, U. Preliminary analysis of gain measurements at the HFBR liquid hydrogen moderator, article, May 1, 1998; United States. (digital.library.unt.edu/ark:/67531/metadc705721/: accessed August 24, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.