Re: Role of DCYTIMES in finding time evolution of dose eq rate

From: Francesco Cerutti <Francesco.Cerutti_at_cern.ch>
Date: Tue, 24 Jul 2012 15:07:45 +0200

Dear Mina

let me reaffirm some fundamental beliefs:

i. putting in a card a wrong (misspelled) name of a region leads the run
to abort. Putting in RESNUCLE a name of a wrong (not desired) region has
no effect on other detectors. (I understand that you did not mean the
opposite, but it's just to prevent any misinterpretation of your message).

ii. residual dose values at a given cooling time depend on the irradiation
profile and on the selected cooling time, and not on other cooling times

Now, in your two cases (Ta26_Wrong and Ta26), you have always 13 cooling
times, with identical subsequences #1-2 and #5-13, whereas
#3[Ta26_Wrong]=#4[Ta26]. So, for negative and zero cooling times (up to #5
included) your results look perfectly consistent (and your table is wrong,
since a "*" is put on the wrong row - 2 instead of 4 - and you compare in
rows 3-4 values referring to different cooling times).
As for the discrepancies at positive cooling times, would you be so kind
as to send the two input files in order to investigate them?

Ciao

Francesco

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854

On Tue, 24 Jul 2012, Mina Nozar wrote:

> Hello everyone,
>
> I have come across a feature that is puzzling to me.
>
> A bit of context:
> While summarizing the results of the time evolution of activities in different regions and DoseEq. rate at a detector
> placed a meter away from various targets, and comparing the results with measurements, I found a bug in my input files
> where I had accidentally set the region in one of the RESNUCLEi cards wrong. After correcting this mistake and
> rerunning, I noticed that the values for DoseEq rate in my detector had also changed. This should not have happened.
> So upon further investigation and many sets of runs, ruling out any differences between the first set of runs few months
> ago and the recent run (including different versions of FLUKA), through the process of elimination, I have come to the
> conclusion that the difference in the DoseEq values has to do with the difference in two intermediate ramp up times as
> defined in my DCYTIMES cards!! This would have been the last culprit I would have thought as the source of the
> difference.
>
> Dose Eq. (uSv/h) Delta
> # Time(s) Ta26_Wrong-DCYTIMES Ta26 ((Ta26_Wrong-DCYTIMES - Ta26) /Ta26) * 100 %
> #
> 1 1h_SOB 3.6000e+03 2.635534e+05 2.635534e+05 0.00
> 2 1d_SOB 8.6400e+04 1.405412e+06* 1.405412e+06 0.00
> 3 3d_SOB 2.5920e+05 1.677836e+06* 1.631715e+06 2.75
> 4 10d_SOB 8.6400e+05 1.685668e+06 1.677836e+06 0.46
> 5 0s_EOB 2.1600e+06 1.697290e+06 1.697290e+06 0.00
> 6 1h_EOB 2.1636e+06 1.450112e+06 1.448546e+06 0.11
> 7 1d_EOB 2.2464e+06 2.875528e+05 2.859396e+05 0.56
> 8 10d_EOB 3.0240e+06 2.326512e+04 2.173031e+04 6.60
> 9 40d_EOB 5.6160e+06 8.896961e+03 7.884914e+03 11.38
> 10 1y_EOB 3.3696e+07 1.709451e+03 1.289858e+03 24.55
> 11 2y_EOB 6.5232e+07 1.063496e+03 7.738430e+02 27.24
> 12 3y_EOB 9.6768e+07 7.320424e+02 5.321056e+02 27.31
> 13 5y_EOB 1.5984e+08 3.542361e+02 2.589828e+02 26.89
>
>
> NOTE: 1.405412e+06 is dose rate at 10 days after SOB (Start Of rBeam) and 1.677836e+06 at 14 days after SOB as opposed
> to 1 and 3 days after SOB in the case for Ta26, respectively. The last column shows the fractional differences between
> the dose rates in the two sets of runs. The difference increases to around 27% while the errors in each case are on
> the order of 0.3%!
>
>
> The IRRPROFI and DCYTIMES cards for the original run (Ta26_Wrong-DCYTIMES):
>
> IRRPROFI 2.16E6 4.994E14
> * Ramp up (grown in) times -- negative times for times before EOB
> * 1 hour after SOB ===> 2.16e6 - 3600 = -2.156e6 s
> * 1 day after SOB ===> 2.16e6 - 24*3600 = -2.074e6 s
> * 10 days after SOB ===> 2.16e6 - 3*24*3600 = -1.901e6 s
> * 14 days after SOB ===> 2.16e6 - 10*24*3600 = -1.296e6 s
> DCYTIMES -2.156E6 -2.074E6 -1.296E6 -9.36E5 <========
> * Cool down times
> * 0 sec after EOB ===> 0 s
> * 1 hour after EOB ===> 3600 s
> * 1 day after EOB ===> 24*3600 = 86400 s
> * 10 days after EOB ===> 10*24*3600 = 864000 s
> * 40 days after EOB ===> 40*24*3600 = 3.456e6 s
> * 1 year after EOB ===> 365*24*3600 = 3.154e7 s
> DCYTIMES 0. 3600. 86400. 864000. 3.456E6 3.154E7
> * 2 years after EOB ===> 2*365*24*3600 = 6.307e7 s
> * 3 years after EOB ===> 3*365*24*3600 = 9.461e7 s
> * 5 years after EOB ===> 5*365*24*3600 = 1.577e8 s
> DCYTIMES 6.307E7 9.461E7 1.577E8
>
>
> For the recent run (Ta26):
> IRRPROFI 2.16E6 4.994E14
> DCYTIMES -2.156E6 -2.074E6 -1.901E6 -1.296E6 <=======
> DCYTIMES 0. 3600. 86400. 864000. 3.456E6 3.154E7
> DCYTIMES 6.307E7 9.461E7 1.577E8
>
>
> There are no other differences between the two input files. My question is this... How could the dose rates, say 3
> years after EOB be different if one or two of the intermediate ramp-up or cool-down times are different??? What am I
> missing?
>
>
> Thank you in advance,
> Mina
>
>
Received on Tue Jul 24 2012 - 22:41:30 CEST

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