Re: Transport of decay particles

From: Mina Nozar <>
Date: Fri, 03 Aug 2012 12:53:11 -0700

Dear Francesco,

Thank you. I still don't have a clear picture of what is happening.

On 12-08-03 02:20 AM, Francesco Cerutti wrote:
> Hallo
> you are referring to decay in the activation study mode (associated to a
> cooling times list), not to the semi-analogue mode.

Yes, correct. I am referring to the radioactive decays activated for requested cooling times (analogue mode).

> In that case, at the end of each primary history, the produced
> radioisotopes are let decay (by default three times each, as in WHAT(3) of
> RADDECAY) down to the end of their decay chain.

But the manual says:

WHAT(3) : number of "replicas" of the decay of each individual residual
= 0.0: ignored
< 0.0: reset to default

Default = 1.0 for analogue decays, 3.0 otherwise

Doesn't this mean by default, individual residuals are decayed only once in the analogue mode?

> All the so generated electromagnetic particles are transported (with materials in the geometry
> transformed into vacuum or blackhole on request), irrespective of the input cooling times.

Just to clarify... The generate e+,e-, gammas, as well as neutrons are transported through the decay material which by
default are set to the same material during the irradiation time and only through vacuum or blackhole if requested by
the user. Correct?

Also, as I understand, dose rates are calculated from the fluence of a given decay particle in a given volume (and not
from the activities) at a given cooling time. How is this done?

> At scoring, an analytical weight accounting for the activity of the emitting radionuclide (the one emitting the gamma/beta
> particles under consideration, not necessarily the original one first in the chain) at the requested cooling time, is applied.
> Best
> Francesco

Sorry but I need more detail.
Thank you very much,

> On Fri, 3 Aug 2012, Mina Nozar wrote:
>> Hello everyone,
>> I am trying to understand how tracking is done for decay particles. Can someone please explain/clarify the following
>> statement (Note 4 under section 7.10 (DCYSCORE) in the manual? Perhaps with an example?
>> "
>> The scoring of decay radiation is different from all the rest: decay particles are transported once, and a factor
>> is applied at scoring time depending on the decay time associated to each detector. This factor accounts for
>> the buildup and decay of the parent nucleus at the specied decay time. This factor is not available in user
>> routines such as fluscw and comscw
>> "
>> Thank you very much,
>> Mina
Received on Sat Aug 04 2012 - 13:45:57 CEST

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