Re: TCQUENCH parameters

From: Alberto Fasso' <fasso_at_slac.stanford.edu>
Date: Wed, 1 Apr 2009 11:57:56 -0700 (PDT)

Andrey,

as the manual says, the meaning of the WHAT(1) parameter in
TCQUENCH is that of a time cutoff. If a binning has been associated with
a certain value of WHAT(1), scoring in that binning will take place
only if the current particle age (the value of variable ATRACK in COMMON
TRACKR) is smaller than the time specified by WHAT(1).
Zero time is when a primary particle (defined by the BEAM command, or by
a SOURCE user routine) starts. Secondary particles inherit the age of
their parent at the time they are produced.
The reason you don't see the travel times you expect, is that in your
input you have not requested kinetic energy 10 MeV, but _momentum_
10 MeV/c, corresponding to a much lower speed (3.2E8 cm/s if I am not
wrong).
Try it again putting a minus sign -0.01 in the BEAM card.

Alberto

On Wed, 1 Apr 2009, Andrey Smolyakov wrote:

> RE: TCQUENCH parametersHello,
>
> Yes, I have noticed that attachment didn't find it's way to the
> discussion, but anyway...
> The trick is that I don't see protons with particular TCQUENCH
> parameters... with USRBIN without time cut-off I perfectly see these
> protons... and, increasing cut-off time by a few orders of magnitude I
> also can see them. And the situation is the same for 10 MeV protons.
>
> Anyway, I went to simplify my model even more, so it is now 10 MeV protons
> in vacuum with PRECISIO defaults. For 10-MeV protons I estimate their
> velocity to 4.3E+09 cm/s. Then I put two USRBIN's 0.1 cm and 100 cm away
> from the beam origin position on the beam axis. I expect to "see" protons
> in these beams in 2.3E-11s and 2.3E-8s respectively. In fact, I see my
> protons in both these bins after exactly 1.54932E-4s which suggests that I
> deal not with the beam travel time, but some other temporal parameter.
>
> So, my questions are:
> 1) What is the physical meaning of the WHAT(1) parameter in the TCQUENCH?
> What is the reference time from which the WHAT(1) seconds are counted?
> 2) If the reference is a beam particle origin time, then please help me to
> find what is going wrong (or what is made wrong) in my simulation?
>
> The input is included below. I run in the latest FLUKA2008 3b.0:
>
> TITLE
> Fluka TCQUENCH study. 1.04.2009. Andrey Smolyakov. ITEP.
> *
> *
> DEFAULTS PRECISIO
> *23456789 123456789 123456789 123456789 123456789 123456789 123456789
> 123456789
> *
> *
> BEAM 0.01 0.0 0.0 0.0 0.0 -1.0
> PROTON
> BEAMPOS 0.0 0.0 -0.1 0.0 0.0
> *
> PHYSICS 2.0 EVAPORAT
> EVENTYPE 0.0 0.0 2.0 0.0 0.0 0.0
> DPMJET
> *
> *23456789 123456789 123456789 123456789 123456789 123456789 123456789
> 123456789
> *
> *
> GEOBEGIN COMBINAT
> Target - thick
> XYP 001 0.0
> XYP 002 3.0
> *
> * GENERAL BODIES
> *
> SPH 003 0.0 0.0 0.0 50000.0
> SPH 004 0.0 0.0 0.0 49600.0
> SPH 005 0.0 0.0 0.0 49500.0
> END
> *23456789 123456789 123456789 123456789 123456789 123456789 123456789
> 123456789
> *
> * Vacuum volumes 1
> *
> VC1 5 +005
> *
> * Generic bodies 2,3
> *
> VAC 5 +004 -005
> BHL 5 +003 -004
> END
> *234 6789 123456 890123 567890 234567 901234 678901 345678 012345 789012x
> GEOEND
> *
> *23456789 123456789 123456789 123456789 123456789 123456789 123456789
> 123456789
> *
> *
> ASSIGNMA 2.0 1.0 2.0 1.0 0.0
> ASSIGNMA 1.0 3.0 3.0 0.0 0.0
> *
> *
> USRBIN 10.0 1.0 21.0 0.5 0.5 1.0
> TOF_0
> USRBIN -0.5 -0.5 0.0 1.0 1.0 1.0 &
>
> *
> USRBIN 10.0 1.0 22.0 0.5 0.5 101.0
> TOF_1
> USRBIN -0.5 -0.5 100.0 1.0 1.0 1.0 &
> *
> TCQUENCH 3.0E-11 0.0 0.0 1.0 1.0 0.0
> TCQUENCH 3.0E-08 0.0 0.0 2.0 2.0 0.0
> *23456789 123456789 123456789 123456789 123456789 123456789 123456789
> 123456789
> *
> USRBIN 10.0 1.0 98.0 0.5 0.5 101.0
> ETERNAL
> USRBIN -0.5 -0.5 100.0 1.0 1.0 1.0 &
> *
> *23456789 123456789 123456789 123456789 123456789 123456789 123456789
> 123456789
> RANDOMIZE 1.0 5364791.0
> START 1E+03
> *23456789 123456789 123456789 123456789 123456789 123456789 123456789
> 123456789
>
> ----- Original Message ----- From: Mario Santana Leitner
> To: Andrey Smolyakov ; fluka-discuss_at_fluka.org
> Sent: Wednesday, April 01, 2009 11:14 AM
> Subject: RE: TCQUENCH parameters
>
>
> Hi Andrey,
>
> I think that you forgot to attach the input file.
>
> Anyway, one of the reasons why you don't see a signal may well be the
> energy of your protons (~10 eV?), which is below the transport threshold
> for charged hadrons (1000 eV, please see
> http://www.fluka.org/fluka.php?id=man_onl&sub=3), which means that your
> protons are killed as soon as they are shot and they don't reach your
> detector.
>
> Mario
>
> -----Original Message-----
> From: owner-fluka-discuss_at_mi.infn.it on behalf of Andrey Smolyakov
> Sent: Tue 3/31/2009 4:29 PM
> To: fluka-discuss_at_fluka.org
> Subject: TCQUENCH parameters
>
> Hello,
>
> I'm somehow stuck with the TCQUENCH option in Fluka...
> Could you please explain what is exactly the reference time from which
> the WHAT(1) seconds are counted. Is it a time when primary particle
> originated, or a time when the binning in question scored it's first
> event? Or what?
>
> I need to simulate a TOF detector and I started with a simple model
> (attached is my input file), where non-relativistic proton beam (~10 eV)
> originates in vacuum and travels towards the area (100 cm away) where I
> score protons' track-lenght density with the USRBIN option. Since this
> is a non-relativistic case I use classical formulas to estimate time for
> my primary beam to reach the detector, but I can see nothing in the
> detector with these times. Increasing scoring time 3 orders of magnitude
> does help to score something, but still I'm not clear what is wrong.
> Well, it may be that I miss out something very simple but in any case I
> would really appreciate your help as I'm stuck with it %)
>
> Thanks in advance,
> Andrey.
>

-- 
Alberto Fasso`
SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
Phone: (1 650) 926 4762   Fax: (1 650) 926 3569
fasso_at_slac.stanford.edu
Received on Wed Apr 01 2009 - 22:42:42 CEST

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