Re: Understanding EMF-CUT and residual dose rate

From: Mina Nozar <>
Date: Tue, 13 Mar 2012 11:58:12 -0700

I just realized I attached the wrong file with this message. Here is the correct plot showing residual dose rates for
six targets (separate runs and fluka setups) as a function of time in a cylindrical detector a meter away from the beam
line. When comparing does rates for a given target at a given cooling time (1.2 years after EOB), we are seeing a
factor of 2 less in dose rates from FLUKA than those measured at the same time. I am still trying to figure out why
this is.

I have tested few other runs where I don't include an EMFCUT card. The results are the same as the time when I did not
specify a region for the 20 keV transport card. Confirming this by looking at the echoed input in the output files,
this means the default behaviour as stated in the manual is not correct:

       WHAT(4) = lower bound (or corresponding name) of the region indices with
                 electron cutoff equal to |WHAT(1)| and/or photon cutoff equal
                 to WHAT(2) and/or leading particle biasing
                 ("From region WHAT(4)...")
                 Default: = 2.0.

i.e. not defining any lower and upper bound regions for transport energy cut-offs in the EMFCUT card, does not set the
lower and upper bound regions to the 2nd region in the drop down menu (on the list of Regions) and the EMFCUT is simply
not applied.

What I still do not understand are:
1) How are the default decay and prompt transport energy cut-offs determined if one does not use an EMFCUT card. My
results show that the default energy cut-off does not come from PART-THRES (10 MeV) in NEW-DEFA.
2) Do the decay and prompt cuts in RADDECAY card use the transport cut as defined in the EMFCUT card?

I would appreciate if one of the FLUKA gurus could shed some light on this.

Thanks again,

On 12-03-09 05:49 PM, Mina Nozar wrote:
> Hello everyone,
> I have just finished simulating a few of our ISAC targets that have already been used and assayed after they have been
> taken off-line. The targets themselves range from Ta, SiCGr (Silicon Carbide & Graphite compound), and Nb with
> different heat shield assemblies. It took me a while to add all the components to the geometry where for the main
> components I used design drawing information and for minor components (Stainless Steel screws for instance) I just used
> the volume information for modelling the bodies in fluka.
> Beam: 480 MeV protons
> Beam intensities range between 40 and 80 uA (depending on the target). One target per FLUKA setup of course.
> As usual, I used RADDECAY and IRRPROF cards for scoring residual nuclei and defining Irradiation time and beam
> intensity. I have six regions of interest where I score gamma dose rates for a few ramp-up and cool-down times, using
> times defined in DCYTIMES. I score DOSE-EQ using USRTRACK with DCYSCORE and AMB74 conversion factors in AUXSCORE cards.
> for regions of interest to look at gamma dose rates at a cylindrical detector (10 cm thick * 1 m radius) 1 m away from
> the center of the beam.
> At the end, I plot dose rates summed up over all energies and plot them as a function of time (attached figure).
> Since we have assay results for few targets, I compare FLUKA results with assay results and see that FLUKA is off by a
> factor of 2, giving lower dose rates than the measured.
> Initially thought this might be due to the transport cut for e+,e-, and gamma set in the EMFCUT card. I use the
> NEW-DEFA with EMFCUT of 20 keV for e+,e-, and gammas.
> Here are my questions.
> 1) What are the thresholds set for e+,e-, and gammas if one does not specify a transport energy cut-off through the
> EMF-CUT card? Is it 10 MeV as set in PART-THR?
> 2) If I don't specify a region for transport cut-off energy (i.e. leaving "Reg" and "to Reg" blank, is the cut still
> applied?
> 3) I set 10 for "decay cut" and 99999 for "prompt cut" in RADDECAY card.
> Does this mean 1 * the transport energy cut defined in the EMFCUT? i.e. 1*20 keV for e+,e-,and g decay radiation?
> I set the "prompt cut" to 999999 to kill the electromagnetic cascade in the prompt part.
> 4) In the USRTRACK estimator card, I use 0.0001 and 0.1 GeV as the min and max bins respectively, with 60 bins but when
> I look at the lis files, I see a bunch of zeros printed, then there are values starting from energy bin
> 3.1622799E-04 (min) 3.4145513E-04 (max). I don't know why this is.
> Thank you in advance for your help. I can provide other plots and output info.
> Best wishes,
> Mina

Received on Wed Mar 14 2012 - 10:27:57 CET

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