Re: MGDRAW Directional Cosines

From: John Clem <>
Date: Tue, 24 Jan 2012 18:53:20 -0500


Thanks for your quick response.

It is not clear all required quantities are available through TRACKR
common. But before going forward with this issue, I have another
related question with MGDRAW. Perhaps a bug?? "NTRACK+1" returns the
number of track segments while "MTRACK" are the number of energy
deposition events along the track, but it is ambiguous as to which track
segment where the deposition occurs.. Based on my experience with
MGDRAW, "MTRACK" is either "0" or "1" and never higher, while "NTRACK"
varies from "0" to values observed as high as "10". So the question, in
the situation when NTRACK is greater than 1 and MTRACK=1, which NTRACK
segment corresponds to the MTRACK segment??

The list of the quantities needed in vector potential integration (RF
yield) are again pasted below with an additional description. Items 1
and 5 are available through TRACKR, however items 2-4 are problematic.

1) *X, Y, Z values at each track segment start and end-point* /(XTRACK,

2)*Velocity vector values at each track segment start and end points *
/TRACKR gives the directional cosines only for the end point not the
start point. Not clear which track segment
end-point is associated with Cxtrck,Cytrck,Cztrck
3) *Particle Time/Age at each track segment start and end points*
/TRACKR gives the Time (ATRACK) only for the end point, not the start
point. Also not clear which track segment
end-point is associated with this time stamp. /

4)*Curved path between each track segment*
/Not clear which track segment is associated with CTRACK /

5) *Electric charge of the particle *"/ICHRGE(JTRACK)/"

Thanks, John

On 1/24/2012 12:10 PM, Anna Ferrari wrote:
> Hi John,
> if I have well understood your problem, you need to compute with FLUKA the
> set of kinematic parameters you wrote, to be given in input to your RF
> Yield function.
> You already know that MGDRAW is the right user routine to intercept the
> tracking and you already know very well the list of the parameters in the
> (TRACKR) common that correspond to your needs.
> In order to "extract these values" you need only to save them somewhere,
> for example creating a customized ntuple.
> To do this (and in particular in order to know which other user routines
> you need) I would suggest to look at this simple example:
> In addition, you can give a look at:
> where this example is interesting for you in case you want to have your
> output in the form of a ROOT file.
> Hope this helps,
> regards,
> Anna
> -----------------------------
> Anna Ferrari
> HZDR Dresden-Rossendorf
> D - 01314 Dresden (Germany)
>> Vasilis et al., the ultimate goal is to use FLUKA to characterize
>> synchrotron and ck radiation in the radio frequency regime for EM energy
>> showers in different materials and magnetic fields. It was my hope the
>> necessary kinematic parameters could be extracted from MGDRAW as input
>> to a RF Yield function (the Lienard--Wiechart potentials) such that each
>> track segment could be transform to an E-field element at given location
>> relative to the shower. Summing all the track segment contributions
>> should produce the expected E-field pulse in the time domain of course.
>> The list of parameters needed to do this:
>> 1) X, Y, Z values at each track segment end-point (XTRACK, YTRACK, ZTRACK)
>> 2) Velocity vector at each track end-point
>> 3) Particle Time/Age at each track end-point (ATRACK for each end-point)
>> 4) Curved path between each track segment end-point (CTRCK for each
>> segment)
>> 5) Electric charge of the particle "ICHRGE(JTRACK)"
>> Is there a way to extract these values ?? I realize this can be done
>> within GEANT, but for comparison purposes, I would like to perform this
>> calculation in FLUKA if possible. Any help would be appreciated.
>> Thanks, John
>> On 1/12/2012 10:35 AM, Vasilis Vlachoudis wrote:
>>> Hi John,
>>> you could do something like this (of course it would require a loop for
>>> j=NTRACK to 1 by -1),
>>> but you will not get the desired incoming direction, but the one
>>> actually
>>> performed due to the MCS.
>>> Which I would assume would be almost-equal with first sub-step direction
>>> DX = Xtrack(1) - Xtrack(0)
>>> DY = Ytrack(1) - Ytrack(0)
>>> DZ = Ztrack(1) - Ztrack(0)
>>> and then get dx/sqrt(dx^2 + dy^2 + dz^2), ...
>>> The correct incoming direction you will have it from the previous
>>> C[XYZ]TRCK variables,
>>> which you have to save somewhere.
>>> Vasilis Vlachoudis
>>> Dep EN, CERN
>>> CH-1211 GENEVA 23
>>> Phone: +41-22 767 9851
>>> GSM: +41-76 487 4378
>>> Fax: +41-22 766 9644
>> --
>>>> John Clem
>>>> Research Associate Professor
>>>> Bartol Research Institute
>>>> Department of Physics and Astronomy
>>>> 217 Sharp Lab
>>>> University of Delaware
>>>> Newark, DE 19716
>>>> off 302-831-4354
>>>> cell 302-388-1218
Received on Wed Jan 25 2012 - 09:20:19 CET

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