RE: [fluka-discuss]: magnetic field in vacuum

From: REDDELL, BRANDON D. (JSC-EV511) <"REDDELL,>
Date: Mon, 24 Feb 2014 14:50:10 +0000

Hello,

Is it reasonable to expect a larger *.err file when using the magnetic field in FLUKA. I have a lot of statements such as below. Region 3 is where the magnetic field is. All (or most) particle trajectories pass through this region and then into region 4. I'm not sure if these error statements are because of my choice in stepsize.


 Geomtr: Particle in region 3 (cell # 0) in position -4.545250219E+01 3.974091972E+02 -9.581085993E+02
  is now causing trouble, requesting a step of 3.561574808E-04 cm
  to direction 1.281491000E-01 -9.914775958E-01 -2.345176459E-02, error count: 5
  R2: 4.000000000E+02 R3: 1.038254347E+03 cm
  X*U (2D): -3.998470127E+02 X*U (3D): -3.773776753E+02 cm
  X*UOLD(2D): -3.178127075E+02 X*UOLD(3D): -2.953433702E+02 cm
  Kloop: 747826, error code: -3 Nfrom: 3 Ntrack: 6
  old direction 6.931231389E-01 -7.204375955E-01 -2.345176459E-02, lagain, lstnew, lsense F F F
  Particle index 1 total energy 1.049244169E+00 GeV
 Try again to establish the current region moving the particle of a 8.035041212E-06 long step
 We succeeded in saving the particle: current region is n. 4 (cell # 0)


I've listed my geometry and magnetic field statements in other emails, but have listed them here again.

.
.
.
MGNFIELD 20.0 0.2 0.10 0.0 0.0 10.0
STEPSIZE 0.5 0.0 VAC2 0.0 0.0 0.0
EMF EMF-OFF
*---o---- ----o---- ----o---- ----o---- ----o---- ----o---- ----o---- ----o----
GEOBEGIN COMBNAME
    0 0 Targets
SPH BLKH 0.0 0.0 0.0 5.D4
SPH SPCE 0.0 0.0 0.0 2.5D4
* BField Region
RCC B1 0.0 0.0 -1000.0 0.0 0.0 2000.0 1030.0
RCC B2 0.0 0.0 -1000.0 0.0 0.0 2000.0 400.0
* cylinder for materials (vacuum for now)
RCC HAB1 0.0 0.0 -500.0 0.0 0.0 1000.0 300.0
RCC HAB2 0.0 0.0 -496.0 0.0 0.0 992.0 296.0
* spherical surface to measure flux
SPH D01a 0.0 0.0 0.0 28.2095
SPH D01b 0.0 0.0 0.0 27.2095
.
.
.
END
BH 5 +BLKH -SPCE
VAC1 5 +SPCE -B1
VAC2 5 +B1 -B2
VAC3 5 +B2 -HAB1
.
.
.
END
GEOEND
*---o---- ----o---- ----o---- ----o---- ----o---- ----o---- ----o---- ----o----
.
.
ASSIGNMA BLCKHOLE BH
ASSIGNMA VACUUM VAC1
ASSIGNMA VACUUM VAC2 1.0
ASSIGNMA VACUUM VAC3

________________________________________
From: Santana, Mario [msantana_at_slac.stanford.edu]
Sent: Tuesday, February 18, 2014 2:43 PM
To: Mina Nozar; Francesco Cerutti
Cc: Dr. Vittorio Boccone; REDDELL, BRANDON D. (JSC-EV511); FLUKA discussion
Subject: Re: [fluka-discuss]: magnetic field in vacuum

No, you always need to set the appropriate flag in ASSIGNMAT, regardless
whether you use a simple field (MAGNFIELD only) or a programmed one
(magfld.f) .


On 2/18/14 11:17 AM, "Mina Nozar" <nozarm_at_triumf.ca> wrote:

>Dear Francesco,
>
>So do I understand correctly that if one needs to assign/associate a
>magnetic field to a region of interest in the ASSIGNMAT card, if one
>uses the MAGNFIELD card for a simple magnetic field setting but NOT if
>one uses the magfld.f to set and assign the magnetic field to a given
>region.
>
>Thanks and best wishes,
>Mina
>
>On 14-02-14 12:57 PM, Francesco Cerutti wrote:
>>
>> Dear Mina,
>>
>> first of all we just saw with Brandon that, if you are fine with a
>> constant field, you do not need to write a magfld.f routine but it is
>> enough to define it in the MGNFIELD card. Then ASSIGNMAT is essential
>> to tell the code in which regions that field should be applied.
>>
>> Furthermore and more important, you definitely do not want to ask the
>> code to go always through the magnetic tracking algorithm - by far
>> more complex than a straight step - despite the fact that no magnetic
>> field is present in your region, and to call the magfld.f routine at
>> each substep to get back a humiliating zero.
>>
>> Ciao
>>
>> Francesco
>>
>> **************************************************
>> Francesco Cerutti
>> CERN-EN/STI
>> CH-1211 Geneva 23
>> Switzerland
>> tel. ++41 22 7678962
>> fax ++41 22 7668854
>>
>> On Fri, 14 Feb 2014, Mina Nozar wrote:
>>
>>> Hello Francesco and everyone else.
>>>
>>> Just trying to understand the flow/logic of assigning magnetic fields
>>> in a region.
>>>
>>> Here is my understanding and a question where I lack understanding...
>>>
>>> 1) MGNFIELD card activates calling the subroutine MAGFLD defined in
>>> mgfld.f
>>> 2) In subroutine MAGFLD, one defines the intensity and direction of
>>> the magnetic field(s) and assigns it to a given region(s).
>>> 3) Set Field to Magfiled in the ASSINMAT card for the region(s) with
>>> magnetic field.
>>>
>>> What I don't understand is why do we need to turn on magnetic field
>>> in the ASSIGNMAT card? Is this not already set via MAGFLD?
>>>
>>> Best wishes,
>>> Mina
>>>
>>> On 14-02-14 01:57 AM, Francesco Cerutti wrote:
>>>>
>>>> Hallo,
>>>>
>>>> actually, in case of constant magnetic field in all magnetic
>>>> regions, the
>>>> MGNFIELD card is enough (as stated in the manual). It will
>>>> automatically
>>>> feed the default magfld routine (the one provided in usermvax,
>>>> where in
>>>> fact the comment
>>>> * 2 Tesla uniform field along +z:
>>>> does not apply) and you do NOT need to link the latter into a
>>>> customized
>>>> executable, unless you want to modify it, since it is already in the
>>>> standard FLUKA library and linked in the standard executable.
>>>>
>>>> Cheers
>>>>
>>>> Francesco
>>>>
>>>> **************************************************
>>>> Francesco Cerutti
>>>> CERN-EN/STI
>>>> CH-1211 Geneva 23
>>>> Switzerland
>>>> tel. ++41 22 7678962
>>>> fax ++41 22 7668854
>>>>
>>>> On Thu, 13 Feb 2014, Dr. Vittorio Boccone wrote:
>>>>
>>>> > No you should still include and link the default magfld routine
>>>> which is
>>>> > configured for a uniform magnetic field, as explained in the
>>>> lecture and > the
>>>> > tutorial.
>>>> > Best
>>>> > V.
>>>> > Sent from my iPad
>>>> > > On 13/feb/2014, at 22:42, "REDDELL, BRANDON D. (JSC-EV511)"
>>>> > <brandon.d.reddell_at_nasa.gov> wrote:
>>>> > > Thanks Vittorio.
>>>> > > So in my simple problem, I am not using the magfld.f
>>>> routine,
>>>> > just only the MGNFIELD card. So, could you confirm if these
>>>> > cards should work:
>>>> > > MGNFIELD 20.0 0.2 0.10 0.0
>>>> > 0.0 1.0
>>>> > STEPSIZE 0.5 0.0 VAC2 0.0
>>>> > 0.0 0.0
>>>> > EMF
>>>> > EMF-OFF
>>>> > .
>>>> > .
>>>> > .
>>>> > ASSIGNMA VACUUM VAC2 1.0
>>>> > (the 1 here is at WHAT(5)
>>>> > > Thanks.
>>>> > > Brandon
>>>> > > > >
>>>>
>>>>_______________________________________________________________________
>>>>_____
>>>> > > From: Vittorio Boccone [dr.vittorio.boccone_at_ieee.org]
>>>> > Sent: Thursday, February 13, 2014 2:47 PM
>>>> > To: REDDELL, BRANDON D. (JSC-EV511); fluka-discuss_at_fluka.org
>>>> > Subject: Re: [fluka-discuss]: magnetic field in vacuum
>>>> > > Sure, check out the magnetic field exercise (solution) on the
>>>> advanced
>>>> > course:
>>>> >
>>>>
>>>>http://www.fluka.org/fluka.php?id=course&sub=program&navig=2&which=triu
>>>>mf20
>>>> > > 12
>>>> > Best
>>>> > V.
>>>> > > On 2/13/2014 8:47 PM, REDDELL, BRANDON D. (JSC-EV511) wrote:
>>>> > > FLUKA Users/Experts,
>>>> > > > > Do the magnetic field settings in a region (using
>>>> MGNFIELD
>>>> > card along with WHAT card 5 in ASSIGNMA Card) work if the
>>>> > region of the B field is a vacuum?
>>>> > > > > Brandon
>>>> > > > >
>>>
>>>
>>
>
Received on Mon Feb 24 2014 - 16:52:22 CET

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