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[3.14] HOLDEN, N.E., “Neutron scattering and absorption properties (revised 2003)”, CRC Handbook of Chemistry and Physics, 84th edn (LIDE, D.R., Ed.), CRC Press, Boca Raton, FL (2003) 198–213. [3.15] MUGHABGHAB, S.F., Brookhaven Natl Lab., Upton, NY, personal communication, 2003. 29
4. RESPONSE OF ACTIVATION REACTIONS IN THE NEUTRON FIELD OF CALIFORNIUM-252 SPONTANEOUS FISSION W. Mannhart The response of evaluated cross-section data for neutron activation reactions in the reference neutron field of 252 Cf spontaneous fission has been calculated. The bulk of the investigated cross-section data stems from the previous version of the IRDF (IRDF-90.2) [4.1], the JENDL <strong>Dosimetry</strong> <strong>File</strong> (JENDL/D-99) [4.2] and RRDF-98 [4.3, 4.4]. A few selected data sets of the ENDF/B-VI and JEFF-3.0 libraries were also used. The neutron field of 252 Cf spontaneous fission is the only neutron field for which the available data meet all the criteria of a reference field with a well established and accurate spectral distribution, valid up to 20 MeV, together with a complete description of the uncertainty. The spectral distribution N(E) of the fission neutrons of 252 Cf is the result of an evaluation based on modern time of flight measurements of this neutron spectrum [4.5]. The numerical values and the associated covariance matrix are given in Ref. [4.6]. Calculated spectrum averaged cross-sections of Ú s ( E) N( E) d E/ N( E) dE Ú were determined for the various σ(E) data. Associated uncertainties were obtained from the propagated uncertainties of σ(E) and N(E). The calculated data were compared with experimental data to derive C/E values, and the experimental data were obtained from a detailed evaluation of the available integral experiments [4.7, 4.8]. The results are summarized in Table 4.1. Column 1 lists the neutron reactions that were investigated, in order of increasing energy response ranges. Column 2 quantifies the mean neutron energy E(50%) of the integrated response of each neutron reaction in the specified fission neutron field. The experimental data of spectrum averaged cross-sections and the uncertainties are given in columns 3 and 4; data in square brackets are from single experiments that were not included in the evaluation. These data can be found in Ref. [4.9], and in a few cases more recent data from the EXFOR database were used. The C/E values in columns 5–7 were obtained with the IRDF-90.2, JENDL/D-99 and RRDF-98 libraries, as indicated. With the exception of the 24 Mg(n,p) 24 Na and 93 Nb(n,2n) 92 Nb m reactions, the original σ(E) data of the RRDF-98 library were replaced by recent updates [4.3, 4.4]. 30
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