High-accuracy determination of the neutron flux at n_TOF
- 511 Downloads
The neutron flux of the n_TOF facility at CERN was measured, after installation of the new spallation target, with four different systems based on three neutron-converting reactions, which represent accepted cross sections standards in different energy regions. A careful comparison and combination of the different measurements allowed us to reach an unprecedented accuracy on the energy dependence of the neutron flux in the very wide range (thermal to 1 GeV) that characterizes the n_TOF neutron beam. This is a pre-requisite for the high accuracy of cross section measurements at n_TOF. An unexpected anomaly in the neutron-induced fission cross section of 235U is observed in the energy region between 10 and 30keV, hinting at a possible overestimation of this important cross section, well above currently assigned uncertainties.
- 5.OECD/NEA WPEC Subgroup 26 Final Report, Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations, http://www.nea.fr/html/science/wpec/volume26, NEA No. 6410 (2008).
- 9.International Atomic Energy Agency, International Evaluation of Neutron Cross-Section Standards (Vienna, 2007).Google Scholar
- 16.I. Giomataris, R. De Oliveira, Method for fabricating an amplification gap of an avalanche particle detector, Patent CEA-CERN, Application Number 09 290 825.0 (2009).Google Scholar
- 22.D. Tarrío, Neutron-induced fission fragment angular distribution at CERN n_TOF: The Th-232 case, PhD thesis (2012).Google Scholar
- 24.A. Ferrari, Fluka: A multi-particle transport code, Technical Report CERN-2005-010, INFN/TC_05/11, SLAC-R-773 (2005).Google Scholar