exampleDc.cpp File Reference

Example drift chamber application. More...

#include <time.h>
#include "exampleDc.h"
#include "GblTrajectory.h"

Go to the source code of this file.

Namespaces
namespace	gbl
	Namespace for the general broken lines package.

Functions
void	exampleDc ()
	Drift chamber example. More...
GblDetectorLayer	gbl::CreateLayerDc (const std::string aName, unsigned int layer, double xPos, double yPos, double zPos, double thickness, double xzAngle, double stereoAngle, double uRes)
	Create a drift chamber layer with 1D measurement. More...

Detailed Description

Example drift chamber application.

Author

Claus Kleinwort, DESY, 2018 (Claus.nosp@m..Kle.nosp@m.inwor.nosp@m.t@de.nosp@m.sy.de)

Copyright

Copyright (c) 2018-2024 Deutsches Elektronen-Synchroton, Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details.

You should have received a copy of the GNU Library General Public License along with this program (see the file COPYING.LIB for more details); if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

Definition in file exampleDc.cpp.

Function Documentation

exampleDc()

void exampleDc

(

)

Drift chamber example.

Simulate and reconstruct helical tracks in a sector of (forward) drift chambers.

Create points on initial trajectory, create trajectory from points, fit and write trajectory to MP-II binary file (for rigid body alignment).

Setup:

• Beam forward (+Z) direction
• Constant magnetic field in Z direction
• Planar drift chambers with normal in XZ plane, center at Y=0, 1D measurement from (azimuthal) wires, cell size 2 cm.
• Multiple scattering in detectors (gas, wires, walls) (air in between ignored)
• Curvilinear system (T,U,V) as local coordinate system and (q/p, slopes, offsets) as local track parameters

Alignment with MP-II:

• The alignables are the objects to be aligned. This can be single detector elements (with a 1D or 2D measurement) or sets of those with similar or different orientations.
• MP-II determines only alignment corrections. For the absolute detector position and orientation an external reference is needed or the appropriate number of degrees of freedom have to be fixed (in the alignment as internal reference).

Local systems. Up to three (different) local coordinate systems can be defined at each point:

• Track model linearization (propagation, fitting), e.g. curvilinear system
• Measurement, defined by two (optionally non-orthogonal) measurement directions, normal to detector plane and detector position (offset)
• Alignment, defined by two orthogonal directions in detector plane, normal to that and detector position (offset). If different from measurement system for alignables with a single 1D measurements the unmeasured component has to be fixed by a linear equality constraint for MP-II.

Remarks

To exercise (mis)alignment different sets of layers (with different geometry) for simulation and reconstruction can be used.

Example steering file for Millepede-II (B=0, chamber alignment):

Cfiles
milleBinaryISN.dat
 
method inversion 3 0.1
chiscut 30. 6.
printcounts
! fix first chamber as reference
parameter
1001  0.  -1.
1002  0.  -1.
1003  0.  -1.
1004  0.  -1.
1005  0.  -1.
1006  0.  -1.
end

Definition at line 90 of file exampleDc.cpp.

References gbl::GblPoint::addGlobals(), gbl::GblPoint::addMeasurement(), gbl::GblPoint::addScatterer(), gbl::CreateLayerDc(), gbl::GblTrajectory::fit(), gbl::gblMultipleScatteringError(), gbl::gblSimpleJacobian(), gbl::GblHelixPrediction::getArcLength(), gbl::GblHelixPrediction::getCosIncidence(), gbl::GblHelixPrediction::getCurvilinearDirs(), gbl::GblHelixPrediction::getDirection(), gbl::GblHelixPrediction::getMeasPred(), gbl::GblDetectorLayer::getMeasSystemDirs(), gbl::GblHelixPrediction::getPosition(), gbl::GblDetectorLayer::getPrecision(), gbl::GblDetectorLayer::getRadiationLength(), gbl::GblDetectorLayer::getRigidBodyDerGlobal(), gbl::GblDetectorLayer::getRigidBodyGlobalLabel(), gbl::GblDetectorLayer::intersectWithHelix(), gbl::GblTrajectory::milleOut(), gbl::GblSimpleHelix::moveToXY(), gbl::unif(), and gbl::unrm().