Dear Bo Yang,
"thick target bremsstrahlung" has no precise physical meaning. Its
definition is arbitrary: everybody can give a different definition,
depending on the application.
For instance, Ervin B. Podgorsak, in his book "Radiation Physics for
Medical Physicists" gives still another definition (on p. 164):
"Thick x-ray targets have thicknesses of the order of the range of
electrons R in the target material. In practice, typical thicknesses are
equal to about 1.1 R to satisfy two opposite conditions:
1. To ensure that no electrons that strike the target can traverse the
target
2. To minimize the attenuation of the bremsstrahlung beam in the target"
Since your application is radiation protection, you should adopt the most
conservative definition, which seems to be that of IAEA188.
Alberto
On Wed, 18 Mar 2015, 杨博 wrote:
>
> Dear Fluka user
>
> Rencently ,I have been working on radiation protection of X-ray
> generated by high-intensity laser facility. The source term is high-energy
> electrons following Maxwell distribution whose averaged energy is from a few
> MeV to Hundreds of MeV for different laser intensities . I would like
> to calculated the bremsstrahlung yield generated by these high-energy
> electrons hiting high-z thick target and evaluate this kind of ionizing
> hazard to compare with that of conventional electron
> accelerator. But I found a disagreement about the discription of
> thick-target bremsstrahlung between IAEA188 and NCRP 144. IAEA188 define the
> thick-target bremsstrahlung as a target of thickness corresponding to the
> maximum radiation called “optimum target”,But NCRP144 define
> the thick-target bremsstrahlung as a target that is sufficiently thick to
> allow full development of the electro-magnetic cascade. I believe that these
> two kind of targets are not the same one and the bremsstrahlung yield from
> the former is much larger than that from the later.
>
> So I am very confused about the thick-target bremsstrahlung yield and tenth
> values in different materials from IAEA188 and lately adopted by NCRP 144.
>
> I don"t know why the definition of thick-target bremsstrahlung is
> different，but the results can be shared by IAEA and NCRP and how should I
> define the thick target in the simulation in terms of conservative
> practice.I hope you could help me to solve it.
>
> Thanks in advance
>
> Best regard
>
> Bo Yang
>
>
>
>
>
>
__________________________________________________________________________
You can manage unsubscription from this mailing list at
https://www.fluka.org/fluka.php?id=acc_info
Received on Wed Mar 18 2015 - 12:39:56 CET