Re: question about AUXSCORE card + dose

From: Mr. Bhushankumar Jagnnath Patil. <bjp_at_physics.unipune.ernet.in>
Date: Sat, 11 Jul 2009 15:09:16 +0530 (IST)

Dear sir,
     Very much thankful to the nice explanation on dose deposition by
particles. I want to discuss few points regarding this

1. Dr Andrea suggest me to use two AUXSCORE with SDUM =AMB74 for
dose-equivalent and without SDUM for dose calculation . But the default
setting is AMB74 for SDUM in auxscore card. That gives the same results as
it was before.

2. As I am passing 15MeV electron on Tungsten. I have made Pcut in 15MeV
in water phantom. And this gives me the maximum dose deposited by photon.
But as all the photons are get deposited in few milimeters of water. So
there is no photons in forward direction.

3. Actually I want to caluate the depth dose curve in water. How can I
calculate?

4. We have measure the dose of the system by ionization chamber and it is
giving 6000Rad/min at 1 meter. I want to check this with fluka. I have
converted the fluence spectra to dose and it is giving me near about same
answer. I am trying, Is it possible to get the same using dose (228)
option of the fluka ? so that I dont have to convert it.

Shall I consider the all particle dose to find out the depth dose curve in
water phantom and the dose calculation ?

Sir I have one more question can you write something on How the
dose-equivalent is calculated in fluka? or if it is written somewhere
point it out to me.

 Thanking you.

> Probably you will judge me pedantic, but I would like to add a
> clarification.
> What Andrea said is exact, concerning the way the dose is technically
scored
> by FLUKA. But be careful: what happens in the real physical world is
different.
> In the real world photons don't ever deposit ANY dose: they are
indirectly
> ionizing and the ionization is all done by electrons and positrons
liberated or produced by photons.
> In FLUKA, energy is "deposited by photons" when the photon energy
becomes
> lower than the photon transport threshold: that energy is then deposited on
> the spot. See value of Pcut on your *.out file (search for the string
> "Correspondence of regions and EMF-FLUKA material numbers and
names").
> You can change that threshold using command EMFCUT
> Probably there are also a few other rare cases, for example when
fluorescence/Auger has not been requested and the corresponding energy
is deposited on the spot.
> In any case, it must be clear that the amount of "photon dose" is
strictly
> related to user choices: if you change the cutoff energy, you get a
different result. And the "photon dose", being only the energy of
photons
> below threshold, is obviously always smaller than the "electron dose".
>
> And, despite the popular success among the users of the possibility to
filter dose deposition with AUXSCORE, getting "neutron dose", "proton
dose", etc., it must be remembered that nearly ALL dose is electron
dose. "Proton dose" is energy transferred by protons to electrons with
energies lower than the delta-ray threshold (again, dependent on a user
choice). "Neutron dose" in FLUKA is kerma, which in the real world would
be ionizing charged recoils, and they too would ionize by transferring
energy to electrons.
> The only exception of NIEL=Non Ionizing Energy Loss, which will
> be introduced soon into FLUKA, and which refers to kinetic energy
transferred to nuclei without ionization. But I am not sure that it must
be considered part of the dose, and anyway it is always many orders of
magnitude smaller than dose from ionization.
>
> So, to summarize: if FLUKA allows you to calculate dose not due to
electrons, it is only a technical artifact, with results depending on
your threshold settings (transport thresholds or delta-ray production
thresholds). In the real world there is only electron dose.
>
> Alberto
>
> On Thu, 9 Jul 2009, Andrea.Mairani_at_mi.infn.it wrote:
>
>> Dear user,
>> about
>> "If I want to measure the DOSE deposited by only photon and only
electron how can I measure it with USRBIN card ?"
>> See the information written in the manual for the AUXSCORE card: Examples:
>> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
USRBIN 10.0 208.0 -50.0 10.0 10.0
10.0Ene.p
>> USRBIN -10.0 -10.0 -10.0 100.0 100.0 100.0&
AUXSCORE 2.0 1.0 1.0
>> * The above AUXSCORE card will filter the energy scoring of the *
      USRBIN card to only the energy that is deposited by protons In
your input you've used:
>> USRBIN 10.0 228.0 -86.0 35.0 35.0
>> 133.0ElectronB
>> USRBIN -35.0 -35.0 98.0 70.0 70.0 70.0

>> &
>> USRBIN 10.0 240.0 -87.0 35.0 35.0
>> 133.0ElectronB
>> USRBIN -35.0 -35.0 98.0 70.0 70.0 70.0

>> &
>> AUXSCORE 2.00 3.0 6.0 7.0 AMB74
>> I think that you've to change the:
>> AUXSCORE 2.00 3.0 6.0 7.0 AMB74
>> in:
>> AUXSCORE 2.00 3.0 6.0 AUXSCORE
>> 2.00 3.0 7.0 AMB74
>> In this way, you've the dose due to electrons in ***fort.86 and the
equivalent dose due to elctrons in ***fort.87.
>> Ciao
>> Andrea
>
> --
> Alberto Fasso`
> SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
> Phone: (1 650) 926 4762 Fax: (1 650) 926 3569
> fasso_at_slac.stanford.edu
>

Mr. Bhushankumar Jagnnath Patil.
Microtron Accelerator Lab.
Department of Physics,
University of Pune,
Ganeshkhind, Pune 411007
Ph. No. Off. 020-25692678 Ext. 421
Mob. 9823968377
Webpage http://physics.unipune.ernet.in/~bjp
Alternate e-mail amolbhushan_at_gmail.com
Received on Sat Jul 11 2009 - 12:56:47 CEST

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