Measurement of the spectral fluence rate of reference neutron sources with a liquid scintillation detector.
Reference neutron sources such as (241)AmBe(alpha,n) and (252)Cf are commonly used to calibrate neutron detectors for radiation protection purposes. The calibration factors of these detectors depend on the spectral distribution of the neutron fluence from the source. Differences between the spectral fluence of the neutron source and the ISO-recommended reference spectra might be caused by the properties of the individual source. The spectral neutron fluence rates of different reference neutron sources used at PTB were measured with a liquid scintillation detector (NE213), using maximum entropy unfolding and a new, experimentally determined detector response matrix. The detector response matrix was determined by means of the time-of-flight technique at a pulsed neutron source with a broad energy distribution realised at the PTB accelerator facility. The results of the measurements of the reference sources are compared with the ISO-recommended reference spectra. For the PTB (241)AmBe(alpha,n) reference source, the spectral neutron fluence was determined by means of a high-resolution (3)He semiconductor sandwich spectrometer in 1982. These measurements were the basis for the ISO recommendations. The current measurements confirm the high-energy part (E(n) > 2 MeV) of this spectrum and demonstrate the suitability of this new method for high-resolution spectrometry of broad neutron spectra.
Zimbal
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A
Physikalisch-Technische Bundesanstalt, D-38116 Braunschweig, Germany. andreas.zimbal@ptb.de
D004867:Equipment Design; D019544:Equipment Failure Analysis; D005858:Germany; D009502:Neutrons; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation / Q000592:standards; D011868:Radioisotopes / Q000032:analysis* / Q000592:standards*; D012016:Reference Values; D015203:Reproducibility of Results; D012588:Scintillation Counting / Q000295:instrumentation* / Q000592:standards*; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000592:standards*
D011868:Radioisotopes