CSCDriftParam.cc

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#include "SimMuon/CSCDigitizer/src/CSCDriftSim.h"
#include <cmath>

// the following functions were all generated by f2c.
// vin tried to optimize them...
//     with no sizeble effect....

double CSCDriftSim::avgDrift() const{
    /* Initialized data */

    static const double coeff[6] = { -.08618265,-.0020471805,-7.7771331e-4,
            -.0058433565,-5.0241491e-4,.0010223353 };


/* ! Parameterization of Lorentz drift in CSCs */
/* ***********************************************************************
 * DOC MC_ALL_BDFT                                                       *
 *                                                                       *
 * DOC  Function    : Parameterization of the Lorentz drift of electrons *
 * DOC                in the muon endcap CSCs.                           *
 *                                                                       *
 * DOC  References  : None                                               *
 *                                                                       *
 * DOC  Arguments   : BZ  - z componant of the local magnetic            *
 *                         field in kgauss                               *
 * DOC                ZCELL - distance from the anode wire in the wire   *
 *                           plane coordinate normalized to one          *
 * DOC  Errors      : None                                               *
 *                                                                       *
 * DOC  Returns     : Drift distance along the anode wire                *
 *                                                                       *
 * DOC  Created     : 15-OCT-1996   Author : Jeff Rowe                   *
 * ***********************************************************************
 */




    const double x10 = 1.;
    const double x11 = bz / 40.;
    const double x12 = x11 * 2. * x11 - x10;
    const double x13 = x11 * 2. * x12 - x11;
    const double x14 = x11 * 2. * x13 - x12;
    const double x15 = x11 * 2. * x14 - x13;
    const double x16 = x11 * 2. * x15 - x14;
    const double x17 = x11 * 2. * x16 - x15;
    const double x18 = x11 * 2. * x17 - x16;
    const double x19 = x11 * 2. * x18 - x17;
    const double x20 = 1.;
    const double x21 = zcell;
    const double x22 = x21 * 2. * x21 - x20;
    const double x23 = x21 * 2. * x22 - x21;
    const double x24 = x21 * 2. * x23 - x22;
    const double x25 = x21 * 2. * x24 - x23;
    const double x26 = x21 * 2. * x25 - x24;
    const double x27 = x21 * 2. * x26 - x25;

  // not sure why we need a minus sign for avgDrift, but we think the
  // parametrization has a wrong sign.  For the +z endcap, bz should
  // be negative in local coord, so it should drift to the right
  // if drifting up (neg zcell), and to the left if it drifts down.  It doesn't.
  // the first-order term here is -0.08 * bz/40 * zcell

    return -1 * (coeff[0] * x11 * x21 + coeff[1] * x17 * x21 + coeff[2] * x21 +
            coeff[3] * x11 * x27 + coeff[4] * x22 + coeff[5] * x19);
}


double CSCDriftSim::driftSigma() const {
    // Initialized data 

    static const double coeff[3] = { .01069525,.010364504,.0021662697 };


/* ! Parameterization of Lorentz drift error in CSCs */
/*************************************************************************
 * DOC MC_ALL_BSIG                                                       *
 *                                                                       *
 * DOC  Function    : Parameterization of the dispersion in Lorentz Drift*
 * DOC                in the muon endcap CSCs.                           *
 *                                                                       *
 * DOC  References  : None                                               *
 *                                                                       *
 * DOC  Arguments   : BZ  - z componant of the local magnetic            *
 * DOC                ZCELL - distance from the anode wire in the wire   *
 *                           plane coordinate normalized to 1            *
 * DOC  Errors      : None                                               *
 *                                                                       *
 * DOC  Returns     : Dispersion in Lorentz drift along anode wire       *
 *                                                                       *
 * DOC  Created     : 15-OCT-1996   Author : Jeff Rowe                   *
 * ***********************************************************************
 */


    const double x11 = bz / 40.;
    const double x20 = 1.;
    const double x21 = zcell;
    const double x22 = x21 * 2. * x21 - x20;

    return coeff[0] + coeff[1] * x11 * x21 + coeff[2] * x22;
}