The Number and Reaction Multiplicities of GCR Nuclei and Delta-rays Passing through a Cell Nucleus on a Mars Mission

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The Number and Reaction Multiplicities of GCR
Nuclei and Delta-rays Passing through a Cell
Nucleus on a Mars Mission

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• Xiaodong Hu1, Premkumar Saganti2, Francis A.
  Cucinotta3,
• 1U.S.R.A., Houston TX, 2Lockheed Martin, Houston
  TX and 3NASA Lyndon
• Johnson Space Center Houston TX, 77058.

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Fig. 1. Results of calculations of the integral
number of particle tracks per cell per Year from
GCR exposures in free space at solar minimum as a
function of ion charge Behind 5 g/cm2 Aluminum
using cell areas of 100 um2 , the upper curve is
with Delta- rays and lower curve is without
Delta-rays.
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Multiplicities of GCR Reaction Events

• Nuclear reactions produced by GCR as they
  traverse tissue are quite frequent.
• Reaction lead to high-multiplicity events with a
  large number of ions produced in a small volume
  (lt1 cm)
• The reaction products are distributed between
• Target like (highly ionizing from tissue
  constituents)
• Projectile like including projectile fragment and
  like particles
• Intermediate rapidity fragments
• For Biological damage, the highly ionizing target
  fragments are most important and can lead to a
  high doses in small volumes (gt1 Gy)
• The Quantum multiple scattering model of nuclear
  fragmentation (QMSFRG) is used to model
  multiplicities and combined with the HZETRN code
  to project the number and types of
  high-multiplicity events in tissue from GCR.

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La La Collision showing high multiplicity event
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Fig. 2a. The probability of a nuclear reaction
per cm of tissue traversed versus energy for
several ions prominent in the GCR.
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Fig. 2b. Comparisons of the elemental fluence of
GCR ions near solar minimum to the number of
nuclear interactions that occur per cm of tissue
traversed by each charge GCR group. Calculations
are made behind 5 cm of tissue.
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