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#include <CSCFindPeakTime.h>
Public Member Functions | |
| float | averageTime (int tmax, const float *adc) |
| Weighted average of time bins. | |
| CSCFindPeakTime (const edm::ParameterSet &ps) | |
| void | fivePoleFitCharge (int tmax, const float *adc, const float &t_zero, const float &t_peak, std::vector< float > &adcsFit) |
| float | fivePoleFitTime (int tmax, const float *adc, float t_peak) |
| float | parabolaFitTime (int tmax, const float *adc) |
| Parabolic fit to three time bins centered on maximum. | |
| float | peakTime (int tmax, const float *adc, float t_peak) |
| Basic result of this class. | |
| ~CSCFindPeakTime () | |
Private Attributes | |
| bool | useAverageTime |
| bool | useFivePoleFit |
| bool | useParabolaFit |
This is CSCFindPeakTime
Used to provide improved estimate of SCA peak time.
Definition at line 13 of file CSCFindPeakTime.h.
| CSCFindPeakTime::CSCFindPeakTime | ( | const edm::ParameterSet & | ps | ) | [explicit] |
Definition at line 8 of file CSCFindPeakTime.cc.
References edm::ParameterSet::getParameter(), LogTrace, useAverageTime, useFivePoleFit, and useParabolaFit.
: useAverageTime(false), useParabolaFit(false), useFivePoleFit(false) { useAverageTime = ps.getParameter<bool>("UseAverageTime"); useParabolaFit = ps.getParameter<bool>("UseParabolaFit"); useFivePoleFit = ps.getParameter<bool>("UseFivePoleFit"); LogTrace("CSCRecHit|CSCFindPeakTime") << "CSCFindPeakTime: useAverageTime=" << useAverageTime << ", useParabolaFit=" << useParabolaFit << ", useFivePoleFit=" << useFivePoleFit; }
| CSCFindPeakTime::~CSCFindPeakTime | ( | ) | [inline] |
Definition at line 19 of file CSCFindPeakTime.h.
{};
| float CSCFindPeakTime::averageTime | ( | int | tmax, |
| const float * | adc | ||
| ) |
Weighted average of time bins.
Definition at line 34 of file CSCFindPeakTime.cc.
References i.
Referenced by peakTime().
| void CSCFindPeakTime::fivePoleFitCharge | ( | int | tmax, |
| const float * | adc, | ||
| const float & | t_zero, | ||
| const float & | t_peak, | ||
| std::vector< float > & | adcsFit | ||
| ) |
Integrated charge after fivePoleFitTime
Definition at line 153 of file CSCFindPeakTime.cc.
References funct::exp(), i, j, MultiGaussianStateTransform::N, matplotRender::t, x, and detailsBasic3DVector::y.
{
//@@ This code can certainly be replaced by fivePoleFitTime above, but I haven't time to do that now (Tim).
float p0 = 4./t_peak;
float tt0 = t_zero;
int n_fit = 4;
if ( tmax == 6 ) n_fit=3;
float tb[4], y[4];
for ( int t = 0; t < 4; ++t ){
tb[t] = (tmax + t - 1) * 50.;
y[t] = adc[t];
}
// Find the normalization factor for the function
float x[4];
float sx2 = 0.;
float sxy = 0.;
for ( int j=0; j < n_fit; ++j ) {
float t = tb[j];
x[j] = (t-tt0)*(t-tt0)*(t-tt0)*(t-tt0) * exp( -p0 * (t-tt0) );
sx2 = sx2 + x[j] * x[j];
sxy = sxy + x[j] * y[j];
}
float N = sxy / sx2;
// Now compute charge for a given t --> only need charges at: t_peak-50, t_peak and t_peak+50
for ( int i = 0; i < 3; ++i ) {
float t = t_peak + (i - 1) * 50.;
float q_fitted = N * (t-tt0)*(t-tt0)*(t-tt0)*(t-tt0) * exp( -p0 * (t-tt0) );
adcsFit.push_back(q_fitted);
}
return;
}
| float CSCFindPeakTime::fivePoleFitTime | ( | int | tmax, |
| const float * | adc, | ||
| float | t_peak | ||
| ) |
Based on RecoLocalMuon/CSCStandAlone/interface/PulseTime.h by S. Durkin, and ported by D. Fortin. Comments updated by Tim Cox Apr 2009.
The SCA pulse shape should be representable by a function
N*(p0^2/256/exp(-4)) * (t-t0)^4 * exp( -p0*(t-t0) )
Rather than do a full fit with varying peak time too, assume the peak time is fixed to 133 nsec w.r.t. start time, t0, and fit for t0. The fit uses a binary search in t0, and at each step calculates the overall normalization factor between the function and the SCA pulse height as a least-squares fit over the 4 time bins tmax -1, tmax, tmax+1, tmax+2
Note: t0peak =4/p0 = 133 nsec, and adc[0] is arbitrarily defined a time of 0.0 nsec.
Definition at line 68 of file CSCFindPeakTime.cc.
References funct::exp(), j, cond::rpcobgas::time, and x.
Referenced by peakTime().
{
// Input is
// tmax = bin# 0-7 containing max SCA pulse height
// adc = 4-dim array containing SCA pulse heights in bins tmax-1 to tmax+2
// t_peak = input estimate for SCA peak time
// Returned value is improved (we hope) estimate for SCA peak time
// Algorithm is to fit five-pole Semi-Gaussian function for start time of SCA pulse, t0
// (The SCA peak is assumed to be 133 ns from t0.)
// Note that t^4 in time domain corresponds to 1/t^5 in frequency domain (that's the 5 poles).
// Initialize parameters to sensible (?) values
float fpNorm = adc[1]; // this is tmax bin
float t0 = 0.;
float t0peak = 133.; // this is offset of peak from start time t0
float p0 = 4./t0peak;
// Require that tmax is in range 2-6 of bins the eight SCA time bins 0-7
// (Bins 0, 1 used for dynamic ped)
if ( tmax < 2 || tmax > 6 ) return t_peak; //@@ Just return the input value
// Set up time bins to match adc[4] input
float tb[4];
for ( int time=0; time<4; ++time ){
tb[time] = (tmax + time -1) * 50.;
}
// How many time bins are we fitting?
int n_fit = 4;
if ( tmax == 6 ) n_fit = 3;
float chi_min = 1.e10;
float chi_last = 1.e10;
float tt0 = 0.;
float chi2 = 0.;
float del_t = 100.;
float x[4];
float sx2 = 0.;
float sxy = 0.;
float fN = 0.;
while ( del_t > 1. ) {
sx2 = 0.;
sxy = 0.;
for ( int j=0; j < n_fit; ++j ) {
float tdif = tb[j] - tt0;
x[j] = tdif * tdif * tdif * tdif * exp( -p0 * tdif );
sx2 += x[j] * x[j];
sxy += x[j] * adc[j];
}
fN = sxy / sx2; // least squares fit over time bins i to adc[i] = fN * fivePoleFunction[i]
// Compute chi^2
chi2 = 0.0;
for (int j=0; j < n_fit; ++j) chi2 += (adc[j] - fN * x[j]) * (adc[j] - fN * x[j]);
// Test on chi^2 to decide what to do
if ( chi_last > chi2 ) {
if (chi2 < chi_min ){
t0 = tt0;
fpNorm = fN;
}
chi_last = chi2;
tt0 = tt0 + del_t;
} else {
tt0 = tt0 - 2. * del_t;
del_t = del_t / 2.;
tt0 = tt0 + del_t;
chi_last = 1.0e10;
}
}
return t0 + t0peak;
}
| float CSCFindPeakTime::parabolaFitTime | ( | int | tmax, |
| const float * | adc | ||
| ) |
Parabolic fit to three time bins centered on maximum.
Definition at line 45 of file CSCFindPeakTime.cc.
References LogTrace, and tmax.
Referenced by peakTime().
{
// 3-point parabolic fit, from Andy Kubik
// We calculate offset to tmax by finding the peak of a parabola through three points
float tpeak = tmax;
float tcorr = 0;
// By construction, input array adc is for bins tmax-1 to tmax+2
float y1 = adc[0];
float y2 = adc[1];
float y3 = adc[2];
// Checked and simplified... Tim Cox 08-Apr-2009
// Denominator is not zero unless we fed in nonsense values with y2 not the peak!
if ( (y1+y3) < 2.*y2 ) tcorr = 0.5 * ( y1 - y3 ) / ( y1 - 2.*y2 + y3 );
tpeak += tcorr;
LogTrace("CSCRecHit|CSCFindPeakTime") << "CSCFindPeakTime: tmax=" << tmax
<< ", parabolic peak time is tmax+" << tcorr <<" bins, or " << tpeak*50. << " ns";
return tpeak * 50.; // convert to ns.
}
| float CSCFindPeakTime::peakTime | ( | int | tmax, |
| const float * | adc, | ||
| float | t_peak | ||
| ) |
Basic result of this class.
Definition at line 18 of file CSCFindPeakTime.cc.
References averageTime(), fivePoleFitTime(), parabolaFitTime(), useAverageTime, useFivePoleFit, and useParabolaFit.
{
if ( useAverageTime ) {
return averageTime( tmax, adc );
}
else if ( useParabolaFit ) {
return parabolaFitTime( tmax, adc );
}
else if ( useFivePoleFit ) {
return fivePoleFitTime( tmax, adc, t_peak);
}
else {
// return something, anyway.. may as well be average
return averageTime( tmax, adc );
}
}
bool CSCFindPeakTime::useAverageTime [private] |
Definition at line 56 of file CSCFindPeakTime.h.
Referenced by CSCFindPeakTime(), and peakTime().
bool CSCFindPeakTime::useFivePoleFit [private] |
Definition at line 58 of file CSCFindPeakTime.h.
Referenced by CSCFindPeakTime(), and peakTime().
bool CSCFindPeakTime::useParabolaFit [private] |
Definition at line 57 of file CSCFindPeakTime.h.
Referenced by CSCFindPeakTime(), and peakTime().
1.7.3