Charge propagation through- and neutron sensitivity of- reticulated vitreous carbon foam

Several potential neutron conversion materials have been studied over the past several years due to the ³He shortage. One candidate neutron conversion material is reticulated vitreous carbon (RVC) foam which can function as a coated substrate and is also suitable for high temperate environments. However, one concern with the material is the charge carrier propagation characteristics through the bulk of RVC foam. Electron propagation through the bulk of RVC foam samples was studied by comparing the resulting count rates and peak channel locations, with and without a sample present, for samples with linear pore densities ranging from 5-100 pores per linear inch (PPI). Count rates and pulse-height spectra from charge carriers generated by collimated 5.48 MeV ²⁴¹Am alpha particles were studied and are reported here. The observed count rate and pulse height peak locations indicate that some electrons are able to drift through the 5 PPI sample. The peak channel locations with and without the 5 PPI sample were 230 and 360, respectively. However, all other linear pore density samples tested yielded much lower pulse heights, indicating loss of induced charge. Additionally, the intrinsic thermal neutron detection efficiency of a ¹⁰B₄C-coated 45 PPI RVC foam sample was 3.23 ± 0.05%, indicating that the ¹⁰B₄C-coated sample essentially functioned similar to a thin-film-coated device. Finally, the coating thickness of the ¹⁰B₄C coating layer was measured using a SEM to be 1.29 ± 0.47 μm.