SEDL / STP / STP1228-EB / STP15124S

Neutron Fluence Determination at Reactor Filters by ³He Proportional Counters: Comparison of Unfolding Algorithms

Matzke, M
Senior scientists, Physikalisch-Technische Bundesanstalt (PTB), Braunschweig,

Alberts, WG
Senior scientists, Physikalisch-Technische Bundesanstalt (PTB), Braunschweig,

Dietz, E
Senior scientists, Physikalisch-Technische Bundesanstalt (PTB), Braunschweig,

Pages: 10    Published: Jan 1994

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Abstract

Multichannel pulse height measurements with a cylindrical ³He proportional counter obtained at a reactor filter of natural iron are taken to investigate the properties of three algorithms for neutron spectrum unfolding. For a systematic application of uncertainty propagation the covariance matrix of previously determined ³He response functions is evaluated. The calculated filter transmission function together with a covariance matrix estimated from cross-section uncertainties of the filter material is used as fluence pre-information. The results obtained from algorithms with and without pre-information differ in shape and uncertainties for single group fluence values, but there is sufficient agreement when evaluating integrals over neutron energy intervals.