Determination of important nuclear fragmentation processes for human space radiation protection

We present a semianalytical method to determine which partial cross sections of nuclear fragmentations most affect the shielded dose equivalent due to exposure to galactic cosmic rays. The cross sections thus determined will require more theoretical and/or experimental studies for us to better predict, reduce, and mitigate the radiation exposure in human space explorations.

Figure 1

Matrix elements for the sensitivity of dose equivalent in water shielding to a given change in each partial cross section ${\sigma }_{\mathit{kj}}$ for the 1977 solar minimum GCR environment in the thin-shielding limit.

Figure 2

Matrix elements for the sensitivity of dose equivalent in water shielding to a given relative change in each partial cross section ($\delta {\sigma }_{\mathit{kj}}/{\sigma }_{\mathit{kj}}$) for the 1977 solar minimum GCR environment in the thin-shielding limit.

Figure 3

Fragment (a) and projectile (b) distributions for the sensitivity of dose equivalent to a given relative change in the partial cross sections.

Figure 4

Matrix elements for the sensitivity of dose equivalent at 20 g/cm${}^2$ in water shielding to a given relative change in each partial cross section.

Figure 5

Fragment (a) and projectile (b) distributions for the sensitivity of dose equivalent at 20 g/cm${}^2$ in water shielding to a given relative change in the partial cross sections.

Figure 6

Projectile distributions for the sensitivity of dose equivalent at 0, 5, 10, and 20 g/cm${}^2$ in water shielding to a given relative change in the partial cross sections.

Figure 7

Matrix elements, without imposing the unitarity constraint, for the sensitivity of dose equivalent to a given relative change in each partial cross section.

Figure 8

Correlated matrix elements for the sensitivity of dose equivalent to a given relative change in each partial cross section ${\sigma }_{\mathit{kj}}$, with the unitarity constraint of Eq. (9) being satisfied by fixing ${\sigma }_j$ and changing all other partial cross sections by the same fraction.

Figure 9

Correlated matrix elements for the sensitivity of dose equivalent to a given relative change in each partial cross section ${\sigma }_{\mathit{kj}}$, with the unitarity constraint of Eq. (9) being satisfied by fixing ${\sigma }_j$ and changing ${\sigma }_{k-1,j}$.

Figure 10

Fragment (a) and projectile (b) distributions for the sensitivity of dose equivalent to a given relative change in the partial cross sections for the 1989 solar maximum GCR environment.