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The Design of the mini-Neutron Spectrometer for the Lunar Hydrogen Mapper

Author: 
Erik Johnson
Topic: 
Radiation
Delivered As: 
Oral
Abstract Text: 

A key tool used in the exploration of water equivalent hydrogen is a neutron detector. A new scintillation material call CLYC is able to replace the standard neutron detector, the helium-3 tube. CLYC is a scintillation material that provides a unique signature for the type of incident radiation, be it a neutron or gamma ray. The method for stopping neutrons is the lithium-6 capture reaction, where the produced alpha and tritons generate a light flash in the material. A photodetector, such as a photomultiplier tube, converts the light flash into an electrical signal. The density of Li-6 in CLYC is very high (95% Li-6 to 5% Li-7), requiring only a couple centimeters of material to provide an equivalent efficiency to helium-3 tube based detectors used for other planetary science missions. Epi-thermal neutrons are discriminated from thermal neutrons by covering one-half of the detector volume with cadmium. A detector is being design to fly on the LunaH-Map 6U cubesat mission, where epi-thermal and thermal neutron counts will provide a measure of the spatial and depth information of water equivalent hydrogen in the permanently shadowed regions of the moon. The performance characteristics of CLYC and the design of the mini-Neutron Spectrometer will be presented.

Co-Authors: 
T. D. Glotch, and P. G. Lucey
SSERVI Identifier: 
NESF2016-073

About SSERVI
Recognizing that science and human exploration are mutually enabling, NASA created the Solar System Exploration Research Virtual Institute (SSERVI) to address basic and applied scientific questions fundamental to understanding the Moon, Near Earth Asteroids, the Martian moons Phobos and Deimos, and the near space environments of these target bodies. As a virtual institute, SSERVI funds investigators at a broad range of domestic institutions, bringing them together along with international partners via virtual technology to enable new scientific efforts."