Dear Riya Dey,
If the transport cutoff of electron is set at 1 MeV, it will stop all electrons being generated due to 1 MeV photons. Ideally, the cut-off for photons should be at 1 KeV. This is how KERMA is also defined. It will ofcourse not stop the secondary photons generated due to these 1 MeV Photons. You can see the details at the paper mentioned below:
Davis, S. D., Ross, C. K., Mobit, P. N., Van der Zwan, L., Chase, W. J. and Shortt, K. R. The response of LiF thermoluminescence dosimeters to photon beams in the energy range from 30 kV X rays to 60Co gamma rays. Radiat. Prot. Dosim 106, 33–43 (2003).
Hope this helps.
with regards,
डॉ. सुजय चटर्जी/Dr. Sujoy Chatterjee
प्रभारी अधिकारी/Officer In Charge
टी एल डी यूनिट, वी ई सी सी/TLD Unit, VECC
भाभा परमाणु अनुसंधान केंद्र/Bhabha Atomic Research Centre
1/ए एफ विधान नगर/1/AF-Bidhannagar,
कोलकाता - 700064/Kolkata - 700064
फ़ोन/Ph: +91-33-23184343/23214399
फैक्स/Fax:+91-33-23346871
Alt. Email: sujoy_at_barc.gov.in
-----owner-fluka-discuss_at_mi.infn.it wrote: -----
To: <paola.sala_at_mi.infn.it>, <fluka-discuss_at_fluka.org>
From: "riya dey"
Sent by: owner-fluka-discuss_at_mi.infn.it
Date: 07/16/2018 12:03PM
Subject: RE: [fluka-discuss]: TRANSPORT CUTOFF VALUES FOR ESTIMATION OF AIR KERMA
Dear Expert,
I want to estimate air kerma. Now suppose for 1 MeV source photon, the
transport cutoff for electrons is chosen 1 MeV and the gamma cut off is
chosen as low as possible ( 10 keV let's say ) . Now energy is scored in
USRBIN . Now if we divide the energy with the mass of the detector , we will
get the value of air kerma. Is it correct way to estimate air kerma in FLUKA
?
My concern is since for high energy photons, although some highly energetic
secondary electrons and X-rays escape the region of interest before
depositing their energy, their escaping energy is counted in kerma according
to the theory. But if I score energy in USRBIN, is that escaping energy
counted or not ?
With regards,
Riya dey
-----Original Message-----
From: owner-fluka-discuss_at_mi.infn.it [mailto:owner-fluka-discuss_at_mi.infn.it]
On Behalf Of Paola Sala
Sent: 14 July 2018 22:01
To: riya dey <riyadey_at_barc.gov.in>
Cc: fluka-discuss_at_fluka.org
Subject: Re: [fluka-discuss]: TRANSPORT CUTOFF VALUES FOR ESTIMATION OF AIR
KERMA
Dear Riya Day
I am not sure that I understand, do you want to score kerma or dose?
Foe kerma, threshold should be as high as possible, just below the energy of
your primary photon.
For dose..as low as possible
Scoring can be done with USRBIN in energy Regards Paola
> Dear FLUKA Experts,
>
>
>
> What transport cutoff values should be used to determine air kerma ??
> Also, what should be scored in USRBIN ??
>
> For low-energy photons, kerma is numerically approximately the same as
> absorbed dose. For higher-energy photons, kerma is larger than
> absorbed dose because some highly energetic secondary electrons and
> X-rays escape the region of interest before depositing their energy.
> The escaping energy is counted in kerma, but not in absorbed dose.
>
>
>
>
>
> With regards,
>
> Riya Dey
>
>
>
>
>
>
Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
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Received on Mon Jul 16 2018 - 15:14:32 CEST