Re: FLUKA: escaping energy
Hi Dominik,
I think you should give us a little more information on your input
(why don't you send it too, together with your water.peg file?)
>From what you have said (electron beam), it looks that you have a pure
electromagnetic problem (unless you had PHOTONUC on).
If this is true, you should have no muons and no neutrinos, and
(un)DISCARDing them should have no effect.
Other things you haven't said: what are your cutoffs? Are you
doing any kind of biasing?
I have done a quick test with the geometry you have described,
adding also one USRBDX from vacuum to blackhole. I had very low
cutoffs for photons and electrons (1 keV)
Result:
1. USRBDX (one-way current estim. from reg. 1 to reg. 2)
for FLUKA particle 208. I have obtained:
E1 = 1.8099 GeV
2. USRBDX (one-way current estim. from reg. 2 to reg. 3)
for FLUKA particle 208. I have obtained:
E1 = 1.8099 GeV
3. SCORE option for particle 208.
In reg. 3 (blackhole) I find:
E3 = 1.8104 GeV
And in the final balance I find:
2.500E+02 GEV (100.%) DEPOSITED PER BEAM PARTICLE OUT OF WHICH
0.000E+00 GEV ( 0.0%) BY IONISATION,
2.482E+02 GEV (99.3%) BY EM-CASCADE,
0.000E+00 GEV ( 0.0%) BY NUCLEAR RECOILS AND HEAVY FRAGMENTS,
0.000E+00 GEV ( 0.0%) BY PARTICLES BELOW THRESHOLD,
0.000E+00 GEV ( 0.0%) BY RESIDUAL EXCITATION ENERGY,
0.000E+00 GEV ( 0.0%) BY LOW ENERGY NEUTRONS,
1.810E+00 GEV ( 0.7%) ESCAPING THE SYSTEM, <======
0.000E+00 GEV ( 0.0%) DISCARDED, <======
0.000E+00 GEV ( 0.0%) OUT OF TIME LIMIT AND
2.950E-11 GEV ( 0.0%) MISSING.
My numbers seem to agree all within 0.03%, which is acceptable since
I got them from formatted output with 5 significant figures.
On the other hand, my numbers are smaller than yours by 40%.
Therefore, I suspect that your input has some special feature that
you have forgotten to tell us about.
Cheers,
Alberto
On Thu, 1 Feb 2001, Dominik Dworak wrote:
> Hi,
> I have as simply geometry as it is possible:
> region 1 = water filled cylinder (r=60 cm, l=10 m)
> region 2 = an external vacuum surrounding this cylinder
> region 3 = blackhole surrounding vacuum.
> Water in the cylinder is irradiated by 250 GeV, pencil like
> electron beam.
> I look for the total energy escaping out from the cylinder.
> To do it I used two ways:
>
> 1. USRBDX (one-way current estim. from reg. 1 to reg. 2)
> for FLUKA particle 208. I have obtained:
>
> E1 = 2.543 GeV
>
> 2. SCORE option for particle 208.
> Looking at reg. 3 (blackhole) I found:
>
> E2 = 2.483 GeV
>
> The same value E2 is printed out in FLUKA output as the
> energy escaping the system. Right.
>
> The difference E1 - E2 = +60 MeV and it means that more energy
> escapes from the cylinder than from the whole system.
> It means, some of energy is "deposed" in vacuum. Strange.
> Of course, the difference is not big in comparison to the beam
> energy but it is much too much to be caused by rounding errors.
>
> I thought, "maybe a reason were neutrinos:
> particles like muons can escape the cylinder (their energy is
> stored by USRBDX) but afterwards they decay in fly in vacuum
> and neutrinos from this decay are not visible in blackhole
> region as in my job all neutrinos are DISCARDed by default".
>
> So, I "unDISCARD" all neutrinos and made the same job.
> I have received:
> E1 = 2.635 GeV
> E2 = 2.685 GeV
>
> This time we have opposite situation:
>
> E1 - E2 = -50 MeV
>
> and it means that some of energy is "created" in the external vacuum.
>
> What is going on and which values are true ?
> Regards, Dominik Dworak, Cracow, Poland
>
>
>
--
Alberto Fasso'
Stanford Linear Accelerator Center
Radiation Physics Dept. ms 48, 2575 Sand Hill Road, Menlo Park, CA 94025
Tel. +1 650 926 4062 Fax: +1 650 926 3569
fasso@slac.stanford.edu
>From March 1st, 2001:
CERN-EP
CH-1211 Geneve 23 (Switzerland)
Alberto.Fasso@cern.ch
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