Uniformity of response of Uranium fission chambers used as neutron beam monitors

TL;DR

This study evaluates the uniformity of uranium fission chambers used as neutron beam monitors, focusing on their detection efficiency and transparency variations across the active area in a neutron research setting.

Contribution

The paper provides experimental characterization of uranium fission chambers' efficiency and transparency, highlighting their spatial uniformity for neutron beam monitoring applications.

Findings

Monitor transparency varies from 90% to 96%.

Detection efficiency varies by up to 50% across the active area.

Results inform better design and calibration of neutron monitors.

Abstract

Uranium fission chambers are commonly used for neutron beam monitoring in neutron research facilities. The challenges brought with the renewing or commissioning of new neutron facilities encourage to minimize the interaction between the monitor and the neutron beam. In order to characterize both their detection efficiency and transmission factor, several fission chambers, have been scanned on the CT1 monochromatic beam line of the ILL. Results show that the monitor transparency, measured at the center of the monitor, varies from 90% to 96%, and that the detection efficiency varies by as much as 50% over the active area.