RE: [fluka-discuss]: Cobalt source

From: Joachim Vollaire <joachim.vollaire_at_cern.ch>
Date: Tue, 17 May 2016 08:24:15 +0000

Dear Leila

What I suggest to convince yourself on the quantity you are scoring (and be sure you did not forget a card) is to use the built-in source to test your detector. I understand you have 8 cylindrical sources. In practice you could run 8 different batches of calculations changing each time the location of the emission points (use CYLI-VOL and BEAMAXES to change the source frame as regards to the geometry frame if needed).
Then you can just add the contribution of the 8 calculations weighted by the activity of each “pencil”. From a CPU point of view, it is equivalent to the source routine, but this way you even have the possibility to have the individual contribution of each pencil and change the contribution of each later….

Otherwise the normalization you are suggesting is appropriate, did you use a DCYSCORE card (with WHAT(1) = -1) which absence could explain the zero contribution ?

Greetings
Joachim



From: leila.ounalli_at_cnstn.rnrt.tn [mailto:leila.ounalli_at_cnstn.rnrt.tn]
Sent: 13 May 2016 16:04
To: Joachim Vollaire <joachim.vollaire_at_cern.ch>
Subject: RE: [fluka-discuss]: Cobalt source

Dear Joachim,
Thanks a lot for the answer

The Cobalt-60 source is made by 8 cylindrical pencils with almost equal emission probability (Activity), so that's way I was in need to sample the source from the subroutine source.f, Which will serve us for the uniformity study and dose distribution around the source.

Meanwhile, I used the BEAM with ISOTOPE and RADDECAY in simi-analog mode with DCYSCORE in simi-analog mode too (which is a must from my perception) connected to USRBIN. The USRBIN card is used to calculate DOSE returned in [GeV/g/decay] with region's binning (detectors). My normalization factor is (Activity * 1.602E-7* 60 = #[Gy/min]).
The result was so far from the experimental one (1000 times higher). I was expecting that the cooling time was the issue, i tried also to use TCQUENCH card with one of two cloned USRBIN. But with TCQUENCH, the results are with 100% statistical error!

Ultimately:
1. Should I proceed with TCQUENCH till i get a reliable data (increase the number of histories)
or
2. There is an other way to define cooling time in my source.f
or
3. As i understand from your reply that the cooling time and beam intensity are meaningless in case the BEAM is used with ISOTOPE followed by HI-PROPE card (Co-60 only). Then there must be something wrong with my source.f modeling!

Regards



Le 2016-05-13 12:23, Joachim Vollaire a écrit :
Dear Leila

Maybe you could tell a little more on your application.

If you are using ISOTOPE in the BEAM card it means that you are interested in the transport of decay originating from a single isotope (selected with HI-PROPE card) . So I am not sure about the meaning of an irradiation profile and a decay time in that case ?
If you use the semi-analogue mode then your results just need to be scaled to your activity at the time of interest (which may depend on the decay since your source was purchased of fabricated but this you should determine analytically yourself and is considered in the post-processing of the results…)

Concerning the use of the source card to specify the spatial distribution, note that there are already some cases (cylindrical/spherical/Cartesian layers) which are pre-defined in case it could be meaningful for your case.

Greetings
Joachim


From: owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi.infn.it> [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of leila.ounalli_at_cnstn.rnrt.tn<mailto:leila.ounalli_at_cnstn.rnrt.tn>
Sent: 13 May 2016 12:09
To: fluka-discuss_at_fluka.org<mailto:fluka-discuss_at_fluka.org>
Subject: [fluka-discuss]: Cobalt source

Dear Fluka experts:

I am defining the BEAM with SDUM = ISOTOPE combined with source.f user routine for the spatial distribution. At the end of the road, i need to score dose rate. Then i should allocate scoring card with different cooling time and beam intensity, But I faced these constrain:

1. The Fluka manual said: "If the BEAM defined by SDUM = ISOTOPE then the RADDECAY MUST be in simi-analog mode"

2. If RADDECAY is in a simi-analog mode, then IRRPROFI is ignored and DCYSCORE MUST be also in simi-analog mode which means i cant use DCYTIMES!

Combining 1. and 2. it seams no way to defining cooling time for scoring and BEAM intensity?

Regards
[X]





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Received on Tue May 17 2016 - 12:12:37 CEST

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