[Brahms-dev-l] BRAG update request

Dear dev'ils, in particular the fortran/BRAG-knowledgeable of you:

I have a request for an update that would make acceptance generation a lot
easier: Could someone, in guxint.F, add a kine definition that finds the
front planes of D1 and D5 (i.e. the front magnet volumes) and throws a
flat, random distribution in this square area?

This is identical to what Peters acceptance software does, but since all
the geometry informaion can be input to BRAG through Flemmings
generatebraggeometry program it would be very useful to do this
automatically rather than having to through the database one more time.
All the values are present, so it should be an easy fix for someone who
knows the ins and outs of brag a bit better than I do.

To be specific, what I want is to be able to simply issue the following
command:
kine 13 <pmin> <pmax> <spec_id> <pid>
BRAG then determines the position and angle of the front plane of D1
(if spec_id==0) or D5 (if spec_id==1), and uses the max and min vertex
z position defined through control/spot to find the max and min theta and
phi angles that can hit this plane. The distribution should just be a
flat, random dist. between these values and between PMIN and PMAX.

Could someone look at this? (If noone volunteers in a day or two I'll look
at it myself, but since I'm lousy at fortran this is not the most time
efficient way to get it done ;-)

Regards
--Bjorn

PS: For reference, here's the math that Peter uses in his generate code:
//___________________________________________________________________________
void GetAngleRange(BrVector3D vtx1,
                   BrVector3D vtx2,
                   BrMagnetVolume* magnet,
                   Float_t* theta,
                   Float_t* phi,
                   Bool_t isMrs)
{
  // --- get theta and phi ranges

  Float_t* size = magnet->GetSize();
  BrVector3D *frontRight = new BrVector3D(-size[0]/2.0, -size[1]/2.0,
-size[2]/2.0);
  BrVector3D *frontLeft  = new BrVector3D(size[0]/2.0, size[1]/2.0,
-size[2]/2.0);

  magnet->LocalToGlobal(*frontRight, *frontRight, 0);
  magnet->LocalToGlobal(*frontLeft,  *frontLeft,  0);

  *frontLeft  -= vtx1;
  *frontRight -= vtx2;

  // --- theta
  const Float_t radtodeg = 180.0/TMath::Pi();

  // --- phi
  if (isMrs) {
    theta[0] = radtodeg * frontRight->Theta();
    theta[1] = radtodeg * frontLeft->Theta();
    phi[0]   = -radtodeg * TMath::Abs(frontRight->Phi());
    phi[1]   = radtodeg * TMath::Abs(frontRight->Phi());
  }
  else {
    theta[0] = radtodeg * frontLeft->Theta();
    theta[1] = radtodeg * frontRight->Theta();
    phi[0]   = radtodeg * TMath::Abs(frontRight->Phi());
    phi[1]   = 360-radtodeg * TMath::Abs(frontRight->Phi());
  }
}




--
Bjorn H. Samset                           Phone: 22856465/92051998
PhD student, heavy ion physics            Adr:   Schouterrassen 6
Inst. of Physics, University of Oslo             0573 Oslo
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