Re: TCQUENCH parameters

Andrey,

the cutoffs, whether in energy or in time, are checked at the end of each
step. They cannot be checked "during" a step! How could that be done?
So, you do your tests starting protons in vacuum, and the program makes
a long step up the next boundary. Where is the next boundary? I suspect that
there is just a single step from the starting point to the blackhole.
Before reaching the end of the step, the "age" of the particle is
unchanged, it is updated only at the end of the step.
Try to introduce a number of fictitious boundaries (e.g. planes), so that
the step is forced to be truncated at each of them.

Also, I don't understand how you can know with such precision the time
at which the protons "show up" in a binning. In one of your previous
posts you wrote:
> 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.
How did you get that number with 6 significant figures??? A cutoff is seen
just as a yes/no (scored/not scored): how do you know the time at which
the two binnings do the scoring?

Alberto

On Fri, 3 Apr 2009, Andrey Smolyakov wrote:

> Hello all,
>
> So, while I'm still at complete loss concerning the apparent failure of
> TCQUENCH on my machine (and still I will be grateful for any help
> possible!), I came up with another problem, this time with TIME-CUT
> option.
>
> The same simulation -(TCQUENCH options) +(TIME-CUT for protons):
> TIME-CUT 1.5E-29 0.0 0.0 1.0 1.0 0.0
>
> I intentionally used small cut-off times, much smaller then cut-off times
> used in TCQUENCH so to make sure than my proton beam will be discarded
> before being scored in my USRBIN's. But the problem is that the beam IS
> scored whatever small time cut-off I input in the CUT-OFF option. I even
> tried to input 0.0 cut-off time, still I perfectly score my beam.
>
> It appears (after having fun with both TCQUENCH and TIME-CUT) that I have
> a problem with using timing parameters in my simulation. As far as I can
> understand basically there are three possibilities:
> 1) Some error in my simulation input (or some parameter missing) that
> prevent Fluka from correct processing of the simulation.
> 2) Some bug in my Fluka compilation, though I tried to compile and use
> both flukahp and flukadpm, no difference found. Also I tried to run my
> simulation on other Fluka installations (thanks to some of my colleagues
> around the world) and also there was no difference found.
> 3) Finally, some bug in the implementation of the time cut-offs in the
> Fluka itself. I tried both Fluka 2008.3.7 and Fluka 2008.3b-0 and have
> found no difference in respect to my problem.
>
> I'm looking forward for your feedback, :-)
> Andrey.
>
>
> ----- Original Message ----- From: "Andrey Smolyakov"
> <smolyakov_at_photo2000.ru>
> To: "Alberto Fasso'" <fasso_at_slac.stanford.edu>; <fluka-discuss_at_fluka.org>
> Cc: "Mario Santana Leitner" <Mario.Santana_at_cern.ch>
> Sent: Thursday, April 02, 2009 1:12 AM
> Subject: Re: TCQUENCH parameters
>
>
>> Alberto,
>>
>> Thank you for explanations, it is much more clear now. But still I miss
>> something...
>> I have changed momentum to energy, but it appears not to be the key. The
>> time expected (as I wrote before) for 100cm-away bin is 2.3E-8s yet I
>> got 1.13995E-5s.
>>
>> Another thing which is not clear to me: I have a bin 0.1cm away from the
>> beam origin position spanning 1cm along the beam axis. And I have
>> another bin 100.1cm away from the beam origin also spanning 1cm along
>> the beam axis. It is essential that I expect to see primary particles in
>> these bins at different moments of time. Yet I see primaries at
>> _exactly_ the same time in both binnings (say, at 1.13994E-5s both
>> binnings will see nothing), although their borders' distances from beam
>> origin differ by a factor of 100.
>>
>> I tried to move "closest" bin even closer to the beam origin, say to
>> 0.01 cm distance, and it allowed to see beam particles in the bins at
>> different times. But, summarizing all this experience, it feels, that it
>> takes the beam much more time to travel from the origin position to the
>> bin 1 (0.1 cm) than from the bin 1 to bin 2 (100 cm). Looks strange...
>>
>> I also simulated a beam of particles with Gaussian energy distibution.
>> Both bins produced a nice temporal pictures of the Gaussian, but once
>> again, completely similar pictures.
>>
>> So, making the long story short:
>> 1) I still get the times much greater than expected
>> 2) I get the similar times (and similar images of gaussian spectra) for
>> binnings placed at different distances from beam origin position.
>>
>> ----- Original Message ----- From: "Alberto Fasso'"
>> <fasso_at_slac.stanford.edu>
>> To: <fluka-discuss_at_fluka.org>
>> Cc: "Andrey Smolyakov" <Andrei.Smolyakov_at_itep.ru>; "Mario Santana
>> Leitner" <Mario.Santana_at_cern.ch>
>> Sent: Wednesday, April 01, 2009 10:57 PM
>> Subject: Re: TCQUENCH parameters
>>
>>
>>> 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
>>>
>>
>
>
>

-- 
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