CRaTER: The Cosmic Ray Telescope for the Effects of Radiation Experiment on the Lunar Reconnaissance Orbiter Mission

Spence, H. E.; Case, A. W.; Golightly, M. J.; Heine, Thomas; Larsen, B.; Blake, J. B.; Caranza, P.; Crain, William R.; George, Jimin; Lalić, M.V.; Lin, Albert Y.; Looper, M. D.; Mazur, J. E.; Salvaggio, D.; Kasper, J. C.; Stubbs, T. J.; Doucette, M.; Ford, P. G.; Foster, R.F.; Goeke, R.; Gordon, D. D.; Klatt, B. W.; O'Connor, J. R.; Smith, Matthew W.; Onsager, T. G.; Zeitlin, C.; Townsend, Lawrence W.; Charara, Y

doi:10.1007/978-1-4419-6391-8_11

Cited by 15 publications

(29 citation statements)

References 33 publications

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“…TEP consists of a mixture of hydrogen, carbon, nitrogen, oxygen, fluorine, and calcium. TEP is used as a human tissue surrogate to determine effects of body self-shielding by human tissue overlaying the blood-forming organs [Spence et al, 2010]. Prior to launching LRO, CRaTER was calibrated using radioactive sources and a variety of charged particle beams at three different laboratories [Spence et al, 2010].…”

Section: Cratermentioning

confidence: 99%

“…One of these objectives is to characterize the lunar radiation environment for future manned missions. To accomplish this objective, the LRO carries the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument [Spence et al, 2010]. The CRaTER telescope consists of three pairs of thin and thick silicon detectors separated by two segments of tissue equivalent plastic (TEP), all in an aluminum casing.…”

Section: Introductionmentioning

confidence: 99%

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Radiation environment at the Moon: Comparisons of transport code modeling and measurements from the CRaTER instrument

et al. 2014

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The Cosmic Ray Telescope for the Effects of Radiation (CRaTER), an instrument carried on the Lunar Reconnaissance Orbiter spacecraft, directly measures the energy depositions by solar and galactic cosmic radiations in its silicon wafer detectors. These energy depositions are converted to linear energy transfer (LET) spectra. High LET particles, which are mainly high-energy heavy ions found in the incident cosmic ray spectrum, or target fragments and recoils produced by protons and heavier ions, are of particular importance because of their potential to cause significant damage to human tissue and electronic components. Aside from providing LET data useful for space radiation risk analyses for lunar missions, the observed LET spectra can also be used to help validate space radiation transport codes, used for shielding design and risk assessment applications, which is a major thrust of this work. In this work the Monte Carlo transport code HETC-HEDS (High-Energy Transport Code-Human Exploration and Development in Space) is used to estimate LET contributions from the incident primary ions and their charged secondaries produced by nuclear collisions as they pass through the three pairs of silicon detectors. Also in this work, the contributions to the LET of the primary ions and their charged secondaries are analyzed and compared with estimates obtained using the deterministic space radiation code HZETRN 2010, developed at NASA Langley Research Center. LET estimates obtained from the two transport codes are compared with measurements of LET from the CRaTER instrument during the mission. Overall, a comparison of the LET predictions of the HETC-HEDS code to the predictions of the HZETRN code displays good agreement. The code predictions are also in good agreement with the CRaTER LET measurements above 15 keV/μm but differ from the measurements for smaller values of LET. A possible reason for this disagreement between measured and calculated spectra below 15 keV/μm is an inadequate representation of the light ion spectra in HETC-HEDS and HZETRN code calculations. It is also clear from the results of this work that Vavilov distributions need to be incorporated into the HETC-HJEDS code before it will be able to recreate the observed LET spectra measured by the CRaTER instrument.

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Section: Cratermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Radiation environment at the Moon: Comparisons of transport code modeling and measurements from the CRaTER instrument

et al. 2014

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“…[3] For heavy ions and protons, there are considerable advantages of providing direct measurements of the energy deposition spectra both behind shielding material and with no shielding. The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) [Spence et al, 2010] is designed for this purpose. Lineal energy transfer (LET) is the basis of risk assessment in a mixed radiation field; it is the mean energy absorbed (ΔE) locally per unit path length (Δx) when a charged particle traverses material.…”

mentioning

confidence: 99%

“…Case et al, 2013]. Here D1/D2, D3/D4, and D5/D6 refer to the three thin (~150 μm)/thick (~1000 μm) silicon detector pairs with each detector pair separated by tissue equivalent plastic [Spence et al, 2010]. The LET shown here is separated between "thick" detector LET measurements (< 50 keV/μm) and "thin" detector LET measurements (>50 keV/μm).…”

mentioning

confidence: 99%

“…LET measurements by DoSEN provide fast, active readout of dose, dose rate, dose equivalent rate, and organ dose rate from galactic cosmic rays, solar energetic particles, and secondary charged particles with sufficient energy to penetrate the housing (>10 MeV p+). tissue equivalent plastic (TEP) [Spence et al, 2010]. Coincidence provides not only suppression of backgrounds but also separation between energetic particle sources from beyond the Moon and albedo sources from the Moon itself [Wilson et al, 2012].…”

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confidence: 99%

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Dose spectra from energetic particles and neutrons

et al. 2013

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[1] Dose spectra from energetic particles and neutrons (DoSEN) are an early-stage space technology research project that combines two advanced complementary radiation detection concepts with fundamental advantages over traditional dosimetry. DoSEN measures not only the energy but also the charge distribution (including neutrons) of energetic particles that affect human (and robotic) health in a way not presently possible with current dosimeters. For heavy ions and protons, DoSEN provides a direct measurement of the lineal energy transfer (LET) spectra behind shielding material. For LET measurements, DoSEN contains stacks of thin-thick Si detectors similar in design to those used for the Cosmic Ray Telescope for the Effects of Radiation. With LET spectra, we can now directly break down the observed spectrum of radiation into its constituent heavy-ion components and through biologically based quality factors that provide not only doses and dose rates but also dose equivalents, associated rates, and even organ doses. DoSEN also measures neutrons from 10 to 100 MeV, which requires enough sensitive mass to fully absorb recoil particles that the neutrons produce. DoSEN develops the new concept of combining these independent measurements and using the coincidence of LET measurements and neutron detection to significantly reduce backgrounds in each measurement. The background suppression through the use of coincidence allows for significant reductions in size, mass, and power needed to provide measurements of dose, neutron dose, dose equivalents, LET spectra, and organ doses. Thus, we introduce the DoSEN concept: a promising low-mass instrument that detects the full spectrum of energetic particles, heavy ions, and neutrons to determine biological impact of radiation in space.

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Relative contributions of galactic cosmic rays and lunar proton “albedo” to dose and dose rates near the Moon

et al. 2013

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[1] We use validated radiation transport models of the Cosmic Ray Telescope for the Effects of Radiation instrument and its response to both primary galactic cosmic rays (GCR) and secondary radiation, including lunar protons released through nuclear evaporation, to estimate their relative contributions to total dose rate in silicon (372 μGy/d) and dose equivalent rate at the skin (2.88 mSv/d). Near the Moon, we show that GCR accounts for~91.4% of the total absorbed dose, with GCR protons accounting for~42.8%, GCR alpha particles for~18.5%, and GCR heavy ions for~30.1%. The remaining~8.6% of the dose at Lunar Reconnaissance Orbiter altitudes (~50 km) arises from secondary lunar species, primarily "albedo" protons (3.1%) and electrons (2.2%). Other lunar nuclear evaporation species contributing to the dose rate are positrons (1.5%), gammas (1.1%), and neutrons (0.7%). Relative contributions of these same species to the total dose equivalent rate in skin, a quantity of more direct biological relevance, favor those with comparatively high quality factors. Consequently, the primary GCR heavy ion components dominate the estimated effective skin dose. Finally, we note that when considering the lunar radiation environment, although the Moon blocks approximately half of the sky, thus essentially halving the absorbed dose rate near the Moon relative to deep space, the secondary radiation created by the presence of the Moon adds back a small, but measurable, absorbed dose (~8%) that can and should be now accounted for quantitatively in radiation risk assessments at the Moon and other similar exploration targets.

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CRaTER: The Cosmic Ray Telescope for the Effects of Radiation Experiment on the Lunar Reconnaissance Orbiter Mission

Cited by 15 publications

References 33 publications

Radiation environment at the Moon: Comparisons of transport code modeling and measurements from the CRaTER instrument

Radiation environment at the Moon: Comparisons of transport code modeling and measurements from the CRaTER instrument

Dose spectra from energetic particles and neutrons

Relative contributions of galactic cosmic rays and lunar proton “albedo” to dose and dose rates near the Moon

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