Energy spectra of the pneumatically positioned neutron sources at LLNL's Hazards control standards and calibration facility

Technical Report · Mon Jun 15 00:00:00 EDT 1987

DOI:https://doi.org/10.2172/6350690· OSTI ID:6350690

Thorngate, J H

The Hazards Control Department of Lawrence Livermore National Laboratory maintains a Standards and Calibration Laboratory that includes three neutron sources (two /sup 252/Cf and one /sup 238/PuBe that can be positioned pneumatically for irradiations. Ten moderators exist to modify the neutron energy spectra produced by these sources. The thicknesses and materials of these moderators are: 25-cm water; 5-, 10-, 15-, and 25-cm heavy water; 20-cm aluminum; and 2-, 5-, 10-, and 15-cm polyethylene. We used a multisphere spectrometer to measure the neutron spectra at 2 m from both the PuBe source and the smaller Cf source, with the sources bare, and in all of the moderators. These data were reduced in 25 energy groups ranging from 0.25 eV to 16 MeV. Except for the 15-m polyethylene moderator, we also made measurements using a liquid-scintillator fast-neutron spectrometer. These data were reduced in 0.1-MeV increments from 0.5 to 12.5 MeV. Spectra from the measurements and from independent calculations are presented in tabular and graphic form. Dosimetric values, calculated from both the measured and calculated spectra, are also presented.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6350690
• Report Number(s): UCID-21035; ON: DE87013573
• Resource Relation: Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
• Country of Publication: United States
• Language: English

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