Exploring active-target microcalorimeter detectors for neutronics measurements

Neutron scattering cross section uncertainties in high-mass nuclei drive large parts of the uncertainty budget of critical assembly experiments and limit future advanced reactor designs. While a breadth of experiments exists at LANSCE and worldwide to measure neutron-induced reactions, a long list of key reactions remain unmeasured.

Many of these reactions can potentially be measured using an active-target microcalorimeter (uCal) detector, though the possibility for this groundbreaking measurement capability has never been developed or proven for in-beam nuclear data measurements. Such a detector measures reactions of interest not by looking for secondary particles in external detectors, but by measuring the nuclear recoil and other small-energy depositions from a neutron-induced reaction in situ, in the presence of large-energy deposition backgrounds. This capability will enable experiments for nuclear applications, astrophysics, and open the possibility of neutrino physics experiments in the actinides 241Pu and 243Cm. We will present on a new project at LANL that seeks to demonstrate the world’s first active-target uCal detector to be installed on a neutron beamline.