Delayed neutrons measurement at the MEGAPIE target

TL;DR

This paper reports on the measurement of delayed neutron flux at the MEGAPIE target's top, aiming to improve radioprotection and validate models, with preliminary decay spectrum results presented.

Contribution

First measurement of delayed neutron flux at the MEGAPIE target, providing experimental data to validate and improve neutron activity models.

Findings

Delayed neutron flux comparable to prompt neutron flux at the target top

Preliminary decay spectra obtained and analyzed

Measurement supports radioprotection and modeling efforts

Abstract

In the framework of the Neutronic and Nuclear Assessment Task Group of the MEGAPIE experiment we measured the delayed neutron (DN) flux at the top of the target. The measurement was proposed mainly for radioprotection purposes since the DN flux at the top of the target has been estimated to be of the same order of magnitude as the prompt neutron flux. Given the strong model-dependence of DN predictions, the measurement of DN contribution to the total neutron activity at the top of the target was thus desired. Moreover, this measurement is complementary to the DN experiments performed at PNPI (Gatchina) on solid lead and bismuth targets. The DN measurement at MEGAPIE was performed during the start-up phase of the target. In this paper we present a detailed description of the experimental setup and some preliminary results on decay spectra.