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Data from manganese bath measurements of the neutron emission rates from commercial 252Cf sources over a period of 40 years have been used to derive an accurate value for the 252Cf half-life. Particular care was taken to account for the presence of other californium and curium isotopes in the sources, and the resulting value has an uncertainty of 0.05%. The present value has been compared with earlier measurements in a review of this important half-life. [ABSTRACT FROM AUTHOR]

Abstract: In order to develop reference low-energy monoenergetic neutron fields, the 45Sc(p,n) reaction is being studied within the framework of a scientific cooperation between NPL, PTB, IRMM and IRSN. The first study is dedicated to the selection of the most suitable backing material for scandium targets. It must be able to sustain high proton beam currents to compensate for the low cross section of the 45Sc(p,n) reaction. Targets with backings made of Mo, Al, W, Ag, Pt and Ta were irradiated during several hours at a few tens of μA at the NPL neutron reference facility. Target thickness and composition were analysed with the RBS method at the AIFIRA facility before and after NPL irradiations leading to the selection of tantalum as the best choice for backing material. [ABSTRACT FROM AUTHOR]

Abstract: The reasons for measuring neutron spectra, and the locations where these measurements need to be made, are identified, and the underlying techniques used for making spectrometry measurements are discussed together with examples of various instruments. [ABSTRACT FROM AUTHOR]

Abstract: A EURAMET comparison exercise (#936) was hosted at NPL in 2008 with measurements being made by IRSN, NPL and PTB. The three laboratories have between them 3 types of long counter, two near identical commercial instruments, and two home-made instruments. Measurements were made using accelerator-produced monoenergetic fields of the following energies: 144 keV, 565 keV, 1.2 MeV, 5 MeV, and 17 MeV; and with the following radionuclide sources: 252Cf, 241Am-Be, 241Am-Li, 241Am-B, and 241Am-F. [ABSTRACT FROM AUTHOR]

Abstract: NPL, PTB, IRMM and IRSN are involved, within a scientific cooperation, in a comprehensive study aimed at developing reference low-energy monoenergetic neutron fields. This paper will explain the importance of such developments, highlighted by the over response of neutron survey meters in the keV energy range, and also describe the main difficulties encountered. The variation of the neutron yield with ion beam energy from the neutron threshold up to about 50 keV has been measured at IRSN AMANDE facility for the 45Sc(p,n), 65Cu(p,n), 51V(p,n), 57Fe(p,n) and 37Cl(p,n) reactions. [ABSTRACT FROM AUTHOR]