Re: [fluka-discuss]: How to determine the fraction of deposited energy going into ith scintillation photon emission in the "OPT-PROD" card?

From: Anna Ferrari <a.ferrari_at_hzdr.de>
Date: Mon, 04 Nov 2013 21:44:30 +0100

Dear Joe,

I completely agree that this is a slippery terrain. But it is also clear that
when we (we users) input an experimental value (N_ph/MeV in this case) we have
to know how this value has been measured and the effects included in the
measurement, in order to avoid possible double-counting. Then I'm afraid that
the balance of most of the issues you mention is responsability of the user.
Maybe the authors of this part of the code can add their comments...

Concerning the Birks corrections: since the effect of the quenching is one of
the ingredients that determine the fraction of deposited energy going in
light,
and since on the other hand we give in input the experimental value of this
fraction (no matter how it's calculated), I think that these corrections have
not to be considered here (they are at the contrary essential when we use
directly the information of the deposited energy).

As I said, maybe somebody wants to comment more.

Kind regards,
Anna

Am Mon, 04 Nov 2013 10:54:30 -0700 schrieb Joseph Comfort
<Joseph.Comfort_at_asu.edu>:
> Dear Anna,
>
> The input for optical photons is overall confusing, and often some
>information about the properties of materials is unknown or not available.
> The fraction of the deposited energy one of the most confusing parameters.
>
> It seems to me that using the experimental observed N_ph/MeV may not be
>correct. This number would include the effects of absorption in the
>materials, incomplete collection of the light, loss through cookies, etc. At
>least some of these would be included in the Fluka calculations, leading to
>possible double-counting the effects. There is also an issue with mixed
>scintillation/Cherenkov radiation.
>
> How are all of these issues, as well as things such as Birk's corrections,
>balanced with each other?
>
> Thank you,
> Joe Comfort
>
> On 11/03/2013 06:37 AM, Anna Ferrari wrote:
>> Dear Xiaokun Zhao,
>>
>> I think you can find already the answer in my previous email, in any
>> case I repeat here explicitly.
>>
>> When you chose OPT-PROD card with sdum=SCINT-WV this means that in
>> what(1) you have to provide the wavelength of the (first) scintillating
>> photons emitted. In the example that you cite this is 1.280E-05 cm. From
>> this you can calculate the energy of the scintillating photons:
>>
>> E=hc/lambda=9.686 eV
>>
>> If the experimental data tells yo that the light yield is N_ph photons
>> per MeV of deposited energy (with N_ph/MeV = 2 x 10^4 in the example),
>> then the fraction of deposited energy that must go in scintillating
>> photons is:
>>
>> 9.686 eV x N_ph/10^6 eV = 2 x 9.686 10^-2
>>
>> Except the factor 2, this is the value you find in the example
>> (now I don't know where this factor 2 comes from -maybe because only
>> half energy is supposed to produce the first scintillating line?- but I
>> don't think this is really relevant for you: the important thing is the
>> procedure. Somebody can correct me if I'm wrong!).
>>
>> Hope it helps,
>> kind regards
>> Anna
>>
>>
>>
>>
>> Am Fri, 1 Nov 2013 20:28:42 +0800 (CST) schrieb 赵晓坤
>> <zhaoxk_at_mail.ustc.edu.cn>:
>>>
>>>
>>> Dear FLUKA experts,
>>> Hello!
>>> Now,I want to use the "OPT-PROD" card to set some optical
>>> properties of specified materials. When the SDUM is set to "SCINT-WV"
>>> ,we can set the "fraction of deposited energy going into ith
>>> scintillation photon emission". I see an example in the chapter12,it
>>> gives us the light yield(20000 photons/MeV),but set the "fraction of
>>> deposited energy going into ith scintillation photon emission" to
>>> 9.686E-02. Why?
>>> What I want to know is if know the the light yield(like 20000
>>> photons/MeV), how can I determine the "fraction of deposited energy
>>> going into ith scintillation photon emission"?
>>> Best regards!
>>> Xiaokun Zhao
>>>
>>>
>>
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Dr. Anna Ferrari
>> Institute of Radiation Physics
>> Helmholtz-Zentrum Dresden-Rossendorf e.V.
>> Bautzner Landstraße 400
>> D - 01328 Dresden (Germany)
>> Tel. +49 351 260 2872
>>
>>
>

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Anna Ferrari
Institute of Radiation Physics
Helmholtz-Zentrum Dresden-Rossendorf e.V.
Bautzner Landstraße 400
D - 01328 Dresden (Germany)
Tel. +49 351 260 2872
Received on Mon Nov 04 2013 - 22:41:14 CET