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fixes the background bug reported in MUSR-299

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This commit is contained in:
suter_a
2014-08-12 18:33:12 +02:00
parent da6fa2f544
commit 3d7324e91e
1 changed files with 22 additions and 10 deletions
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32
src/classes/PRunAsymmetry.cpp
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@ -736,7 +736,7 @@ Bool_t PRunAsymmetry::PrepareData()
// subtract background from histogramms ------------------------------------------ // subtract background from histogramms ------------------------------------------
if (fRunInfo->GetBkgFix(0) == PMUSR_UNDEFINED) { // no fixed background given if (fRunInfo->GetBkgFix(0) == PMUSR_UNDEFINED) { // no fixed background given
if (fRunInfo->GetBkgRange(0) >= 0) { if (fRunInfo->GetBkgRange(0) >= 0) { // background range given
if (!SubtractEstimatedBkg()) if (!SubtractEstimatedBkg())
return false; return false;
} else { // no background given to do the job, try to estimate it } else { // no background given to do the job, try to estimate it
@ -788,8 +788,8 @@ Bool_t PRunAsymmetry::PrepareData()
//-------------------------------------------------------------------------- //--------------------------------------------------------------------------
/** /**
* <p>Subtracts a fixed background from the raw data. The background is given * <p>Subtracts a fixed background from the raw data. The background is given
* in units of (1/ns). The error propagation * in units of (1/bin); for the Asymmetry representation (1/ns) doesn't make too much sense.
* is done the following way: it is assumed that the error of the background * The error propagation is done the following way: it is assumed that the error of the background
* is Poisson like, i.e. \f$\Delta\mathrm{bkg} = \sqrt{\mathrm{bkg}}\f$. * is Poisson like, i.e. \f$\Delta\mathrm{bkg} = \sqrt{\mathrm{bkg}}\f$.
* *
* Error propagation: * Error propagation:
@ -806,18 +806,21 @@ Bool_t PRunAsymmetry::SubtractFixBkg()
{ {
Double_t dval; Double_t dval;
for (UInt_t i=0; i<fForward.size(); i++) { for (UInt_t i=0; i<fForward.size(); i++) {
// keep the error, and make sure that the bin is NOT empty
if (fForward[i] != 0.0) if (fForward[i] != 0.0)
dval = TMath::Sqrt(fForward[i]); dval = TMath::Sqrt(fForward[i]);
else else
dval = 1.0; dval = 1.0;
fForwardErr.push_back(dval); fForwardErr.push_back(dval);
fForward[i] -= fRunInfo->GetBkgFix(0) * fTimeResolution * 1.0e3; // bkg per ns -> bkg per bin; 1.0e3: us -> ns fForward[i] -= fRunInfo->GetBkgFix(0);
// keep the error, and make sure that the bin is NOT empty
if (fBackward[i] != 0.0) if (fBackward[i] != 0.0)
dval = TMath::Sqrt(fBackward[i]); dval = TMath::Sqrt(fBackward[i]);
else else
dval = 1.0; dval = 1.0;
fBackwardErr.push_back(dval); fBackwardErr.push_back(dval);
fBackward[i] -= fRunInfo->GetBkgFix(1) * fTimeResolution * 1.0e3; // bkg per ns -> bkg per bin; 1.0e3: us -> ns fBackward[i] -= fRunInfo->GetBkgFix(1);
} }
return true; return true;
@ -905,23 +908,32 @@ Bool_t PRunAsymmetry::SubtractEstimatedBkg()
Double_t errBkg[2] = {0.0, 0.0}; Double_t errBkg[2] = {0.0, 0.0};
// forward // forward
for (UInt_t i=start[0]; i<end[0]; i++) for (UInt_t i=start[0]; i<=end[0]; i++)
bkg[0] += fForward[i]; bkg[0] += fForward[i];
errBkg[0] = TMath::Sqrt(bkg[0])/(end[0] - start[0] + 1); errBkg[0] = TMath::Sqrt(bkg[0])/(end[0] - start[0] + 1);
bkg[0] /= static_cast<Double_t>(end[0] - start[0] + 1); bkg[0] /= static_cast<Double_t>(end[0] - start[0] + 1);
cout << endl << ">> estimated forward histo background: " << bkg[0]; cout << endl << ">> estimated forward histo background: " << bkg[0];
// backward // backward
for (UInt_t i=start[1]; i<end[1]; i++) for (UInt_t i=start[1]; i<=end[1]; i++)
bkg[1] += fBackward[i]; bkg[1] += fBackward[i];
errBkg[1] = TMath::Sqrt(bkg[1])/(end[0] - start[0] + 1); errBkg[1] = TMath::Sqrt(bkg[1])/(end[1] - start[1] + 1);
bkg[1] /= static_cast<Double_t>(end[1] - start[1] + 1); bkg[1] /= static_cast<Double_t>(end[1] - start[1] + 1);
cout << endl << ">> estimated backward histo background: " << bkg[1] << endl; cout << endl << ">> estimated backward histo background: " << bkg[1] << endl;
// correct error for forward, backward // correct error for forward, backward
Double_t errVal = 0.0;
for (UInt_t i=0; i<fForward.size(); i++) { for (UInt_t i=0; i<fForward.size(); i++) {
fForwardErr.push_back(TMath::Sqrt(fForward[i]+errBkg[0]*errBkg[0])); if (fForward[i] > 0.0)
fBackwardErr.push_back(TMath::Sqrt(fBackward[i]+errBkg[1]*errBkg[1])); errVal = TMath::Sqrt(fForward[i]+errBkg[0]*errBkg[0]);
else
errVal = 1.0;
fForwardErr.push_back(errVal);
if (fBackward[i] > 0.0)
errVal = TMath::Sqrt(fBackward[i]+errBkg[1]*errBkg[1]);
else
errVal = 1.0;
fBackwardErr.push_back(errVal);
} }
// subtract background from data // subtract background from data