A high performance neutron spectrometer for planetary hydrogen measurement

The elemental composition and its distribution on planetary surface provide important constraints on the origin and evolution of the planetary body. The nuclear spectrometer consisting of a neutron spectrometer and a gamma-ray spectrometer obtains elemental compositions by remote sensing. Especially, the neutron spectrometer is able to determine the hydrogen concentration, a piece of information that plays an important role in thermal history of the planets. In this work, numerical and experimental studies on the neutron spectrometer for micro-satellite application were conducted. It is found that background count rate of neutron produced from micro-satellite is very small, which enables to obtain successful results in short time observation. The neutron spectrometer combining a lithium-6 glass scintillator with a boron loaded plastic scintillator was used to be able to detect neutrons in different energy ranges. It was experimentally confirmed that the neutron signals from these scintillators were successfully discriminated by the difference of scintillation decay time between two detectors. The measurement of neutron count rates of two scintillators is found to determine hydrogen concentration on the planetary surfaces in the future missions.

[1]  Christopher T. Russell,et al.  Gamma-ray and neutron spectrometer for the Dawn mission to 1 Ceres and 4 Vesta , 2003 .

[2]  Eido Shibamura,et al.  Neutron Fluxes from Martian Satellites as a Function of Chemical Composition and Hydrogen Content , 2016 .

[3]  Martin P. Ward,et al.  The Mars Odyssey Gamma-Ray Spectrometer Instrument Suite , 2004 .

[4]  Joseph Cugnon,et al.  New potentialities of the Liege intranuclear cascade (INCL) model for reactions induced by nucleons and light charged particles , 2012, 1210.3498.

[5]  F. H. Fröhner.  Evaluation of 252Cf Prompt Fission Neutron Data from 0 to 20 MeV by Watt Spectrum Fit , 1990 .

[6]  Deepak Lal,et al.  Theoretically expected variations in the terrestrial cosmic-ray production rates of isotopes , 1988 .

[7]  Thomas H. Prettyman,et al.  The Lunar Prospector gamma ray and neutron spectrometers; overview of lunar global composition measurements , 1999 .

[8]  T. Yamagami,et al.  Measurements of 0.2–20 GeV/n cosmic-ray proton and helium spectra from 1997 through 2002 with the BESS spectrometer , 2006, astro-ph/0611388.

[9]  G. C. Barbarino,et al.  OBSERVATIONS OF THE 2006 DECEMBER 13 AND 14 SOLAR PARTICLE EVENTS IN THE 80 MeV n−1–3 GeV n−1 RANGE FROM SPACE WITH THE PAMELA DETECTOR , 2011, 1107.4519.

[10]  K. Shibata,et al.  JENDL-4.0: A New Library for Nuclear Science and Engineering , 2011 .

[11]  J. W. Boldeman,et al.  Measurements of the Prompt Fission Neutron Spectrum from the Spontaneous Fission of 252Cf , 1986 .

[12]  Richard P. Binzel,et al.  Phase II of the Small Main-Belt Asteroid Spectroscopic Survey: A Feature-Based Taxonomy , 2002 .

[13]  K. Niita,et al.  Relativistic nuclear collisions at 10A GeV energies from p+Be to Au+Au with the hadronic cascade model , 1999 .

[14]  Robert C. Reedy,et al.  Effects of bulk composition on nuclide production processes in meteorites , 1994 .

[15]  Olivier Forni,et al.  Elemental Mapping by Dawn Reveals Exogenic H in Vesta’s Regolith , 2012, Science.

[16]  Nobuyuki Hasebe,et al.  Neutron Spectrometer for Exploration of Near-Earth Asteroids , 2017 .

[17]  Thomas H. Prettyman,et al.  Improved modeling of Lunar Prospector neutron spectrometer data: Implications for hydrogen deposits at the lunar poles , 2006 .

[18]  D. J. Tholen,et al.  Asteroid taxonomic classifications , 1989 .

[19]  Hiroshi Nakashima,et al.  Particle and Heavy Ion Transport code System, PHITS, version 2.52 , 2013 .

[20]  S. Furihata,et al.  Statistical analysis of light fragment production from medium-energy proton induced reactions , 2000, nucl-th/0003036.

[21]  Takada,et al.  Analysis of the (N,xN') reactions by quantum molecular dynamics plus statistical decay model. , 1995, Physical review. C, Nuclear physics.

[22]  Kim Strohbehn,et al.  The MESSENGER Gamma-Ray and Neutron Spectrometer , 2007 .