Time - resolved Gamma Ray spectral analysis of planetary neutron and Gamma Ray instrumentation

Abstract

The current gamma ray/neutron instrumentation development effort at NASA Goddard Space Flight Center¿s Astrochemistry Laboratory aims to extend the use of neutron interrogation techniques, using a 14 MeV Pulsed Neutron Generator (PNG) combined with neutron and gamma ray detectors, to probe the surface and subsurface of planetary bodies in situ without the need to drill. One aspect of the current work includes the development of taking timed tagged event-byevent data using our custom designed software with the Canberra Lynx Digital Signal Analyzer to provide a unique three-dimensional master data set with channel/energy, time, and intensity information. Since the master data set is not limited to predetermined coincidence timing gates set for a specific nuclear process, the user is allowed the flexibility to slice the data cube in a multitude of ways without loss of information or experimental time due to the need for additional acquisition windows. Time tagged event-by-event data allows the user to isolate a particular energy line from the spectrum over a specific window in time with respect to the PNG pulse, analyze a gamma ray spectrum resulting from either neutron capture, between the burst, or inelastic scattering events, during the neutron burst, and extract data for engineering purposes to optimize timing windows to look at specific elements in different environments. In this paper, we will present the results of our experimental data using the time tagged event-by-event data analysis technique compared with non-time-gated data taken at the test facility at NASA Goddard Space Flight Center. Comparison of these data will show the advantages and validity of this method to obtain more precise, sensitive, and accurate elemental composition measurements.