1. Vanadium-based neutron Beam Monitor
- Author
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N. Mauritzson, Thomas Wilpert, Robin Woracek, V. Maulerova, Kevin Fissum, F. Issa, Kalliopi Kanaki, Richard Hall-Wilton, A. Laloni, and P. M. Kadletz
- Subjects
Nuclear and High Energy Physics ,Materials science ,Physics - Instrumentation and Detectors ,Physics and Astronomy (miscellaneous) ,Physics::Instrumentation and Detectors ,FOS: Physical sciences ,Large scale facilities for research with photons neutrons and ions ,Neutron scattering ,01 natural sciences ,Optics ,Neutron flux ,0103 physical sciences ,Calibration ,Spallation ,Neutron ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,010306 general physics ,010308 nuclear & particles physics ,business.industry ,Surfaces and Interfaces ,Instrumentation and Detectors (physics.ins-det) ,Neutron radiation ,Neutron temperature ,lcsh:QC770-798 ,Physics::Accelerator Physics ,business ,Beam (structure) - Abstract
A prototype quasi-parasitic thermal neutron beam monitor based on isotropic neutron scattering from a thin natural vanadium foil and standard $^3$He proportional counters is conceptualized, designed, simulated, calibrated, and commissioned. The European Spallation Source designed to deliver the highest integrated neutron flux originating from a pulsed source is currently under construction in Lund, Sweden. The effort to investigate a vanadium-based neutron beam monitor was triggered by a list of requirements for Beam Monitors permanently placed in the ESS neutron beams in order to provide reliable monitoring at complex beamlines: low attenuation, linear response over a wide range of neutron fluxes, near to constant efficiency for neutron wavelengths in a range of 0.6-10 \r{A}, calibration stability and the possibility to place the system in vacuum are all desirable characteristics. The scattering-based prototype, employing a natural vanadium foil and standard $^3$He proportional counters, was investigated at the V17 and V20 neutron beamlines of the Helmholtz-Zentrum in Berlin, Germany, in several different geometrical configurations of the $^3$He proportional counters around the foil. Response linearity is successfully demonstrated for foil thicknesses ranging from 0.04 mm to 3.15 mm. Attenuation lower than 1% for thermal neutrons is demonstrated for the 0.04 mm and 0.125 mm foils. The geometries used for the experiment were simulated allowing for absolute flux calibration and establishing the possible range of efficiencies for various designs of the prototype. The operational flux limits for the beam monitor prototype were established as a dependency of the background radiation and prototype geometry. The herein demonstrated prototype monitors can be employed for neutron fluxes ranging from $10^3-10^{10}$ n/s/cm$^2$.
- Published
- 2020
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