5
$\begingroup$

In space radiation shielding-related literature, equivalent BFO doses are sometimes provided in terms of sphere thickness (g/cm^2). For example in Fig. 1 of [Ref 1] (the figure is attached below), the radiation dose is calculated in the annual blood forming organs (BFO) with the radiation data from 1977 and 1990. I find them expressed as shield thickness (g/cm^2) for the equivalent BFO doses in many other studies (for example in this book by Wilson et al., page 490 [Ref 2]).

It seems to be a bit confusing for me to find the difference between these two parameters. For shield thickness, we can divide it by density and get the thickness in cm unit. Then we can also measure the volume of the added protective layer by considering its shape (e. g. a cylinder) for a certain thickness. From the unit's perspective, I can do the same with sphere thickness too. Will it be correct? How these two kinds of thicknesses (shield and sphere) are different?

The estimated impact of the shielding using different materials (aluminum, polyethylene, hydrogen nanofibers, or liquid hydrogen) on the annual dose equivalent.

$\endgroup$
4
  • 1
    $\begingroup$ Hello @uhoh, I have added a short explanation along with an image from the Semantic scholar. $\endgroup$
    – Ankan
    Jul 25 at 6:58
  • 1
    $\begingroup$ Sorry for the confusion, @Fred. It is g/cm^2. Thank you. $\endgroup$
    – Ankan
    Jul 25 at 6:59
  • 1
    $\begingroup$ Section 3 of this open-access paper can be helpful to have a view of radiation doses: agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009SW000533. $\endgroup$
    – Ankan
    Jul 25 at 7:09
  • $\begingroup$ looks great, thanks! $\endgroup$
    – uhoh
    Jul 25 at 11:23
3
$\begingroup$

The oldest standard simulation codes (CREAM and SPENVIS) that are used to calculate exposure are written assuming shielding is arranged in a spherical geometry to make calculation easier. The more modern calculators can handle rectangular boxes where you can specify the shielding thickness of each side. So I strongly suspect that "shield" in ref 2 was still assuming the shielding is arranged in a sphere, so these two references you mention really do mean the same thing, just use different terms. References after ~ 2000 may mean different things with the term "shielding" but if they do they should talk about the specific conditions they mean.

$\endgroup$
1
  • $\begingroup$ Thank you! I have this confusion because in the figure of Ref 1, for zero sphere thickness, the value is approximately 75 cSv. Whereas in Ref 2, the value for zero shield thickness is 60 cSv. These values are for the same material. Is this due to any other considerations? If it is possible for you to share any relevant resources/literature, that will be helpful too. Thanks again! $\endgroup$
    – Ankan
    Jul 26 at 5:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.