Lunar EVA Dosimetry: Microdosimeter-Dosimeter Instrument

NOTE: Former PI Vincent Pisacane retired as of 9/30/2011; James Ziegler is new PI effective 10/1/2011 and project continues, per NSBRI. See Pisacane for FY2011 and earlier reports (Ed., 2/29/2012) The overall objective of this research project is to design, develop, and test a prototype solid-state microdosimeter (SSMD) by September 2013, suitable for use in the new NASA spacesuit and robotic operation on rovers, tool boxes, and spacecraft. The benchtop instrument continues to be used to develop and investigate improvements to the state-of-the-art of SSMDs. This past year the focus has been on development of improved ultra-low noise preamplifiers and new sensors. Radiation sources available at the U.S. Naval Academy (USNA) have been used to carry out the test protocols. The benchtop system has been expanded to obtain and analyze microdosimetric spectra for incident NASA Space Radiation Laboratory (NSRL) beams of both protons and heavy ions with identification of particle types in the beam, their energies, and their mass-to-charge ratios and those produced by intervening materials. We carried out tests of our bench-top system with a neutron beam generated in the Nucleonics Laboratory at the USNA with favorable results. An improved version of the flight engineering model, MIDN-III, has been designed and is nearing completion. It has a reduced footprint and mass and expanded remote command capability. We processed data sets obtained at the NSRL/BNL from our benchtop system, flight engineering model MIDN-II, and two Far West HAWK tissue equivalent proportional counters. Inter-comparisons of the observations agreed well and also agreed with Stopping and Range of Ions in Matter (SRIM) and Geant4 simulations. These spectra have been added to our past data sets to update our extensive library of microdosimetric spectra. We continued development our unique optical calibration system for a SSMD that permits continual end-to-end system test and calibration while the instrument is operational deployed. This is an alternative to using a radiation source that is problematic in a personal dosimeter and eliminates handling and shipping restrictions and personnel and facility certifications required by international, federal, and local regulations. Our provisional patent application was superseded by a patent application. We have tested our second generation microdosimeter sensors with our bench-top and flight engineering instruments and compared our results favorably with those obtained at the University of Wollongong. We have completed testing new MIDN-III detectors, built with an SOI technology that reduces sensor noise over 10x. These sensors will allow accurate monitoring of protons of low energies, such as occur in a solar flare event. We completed an initial conceptual design of our instrument to fit within a NanoRacks configuration for deployment on the International Space Station through the auspices of the DoD Space Test Program. The NanoRacks configuration is modeled after the design of a cubesat. Our configuration would be 10 cm X 10 cm x 15 cm with the majority of the volume dedicated to a rechargeable battery power supply.