CSCTriggerPrimitives/src/CSCGEMMatcher.cc

0001 #include "L1Trigger/CSCTriggerPrimitives/interface/CSCGEMMatcher.h"
0002 #include "L1Trigger/CSCTriggerPrimitives/interface/GEMInternalCluster.h"
0003 #include "DataFormats/CSCDigi/interface/CSCConstants.h"
0004 #include "DataFormats/CSCDigi/interface/CSCALCTDigi.h"
0005 #include "DataFormats/CSCDigi/interface/CSCCLCTDigi.h"
0006 #include "FWCore/MessageLogger/interface/MessageLogger.h"
0007
0008 #include <algorithm>
0009 #include <cmath>
0010
0011 CSCGEMMatcher::CSCGEMMatcher(
0012     int endcap, unsigned station, unsigned chamber, const edm::ParameterSet& tmbParams, const edm::ParameterSet& conf)
0013     : endcap_(endcap), station_(station), chamber_(chamber) {
0014   isEven_ = (chamber_ % 2 == 0);
0015
0016   enable_match_gem_me1a_ = tmbParams.getParameter<bool>("enableMatchGEMandME1a");
0017   enable_match_gem_me1b_ = tmbParams.getParameter<bool>("enableMatchGEMandME1b");
0018
0019   maxDeltaWG_ = tmbParams.getParameter<unsigned>("maxDeltaWG");
0020   maxDeltaHsEven_ = tmbParams.getParameter<unsigned>("maxDeltaHsEven");
0021   maxDeltaHsOdd_ = tmbParams.getParameter<unsigned>("maxDeltaHsOdd");
0022
0023   matchCLCTpropagation_ = tmbParams.getParameter<bool>("matchCLCTpropagation");
0024
0025   mitigateSlopeByCosi_ = tmbParams.getParameter<bool>("mitigateSlopeByCosi");
0026   assign_gem_csc_bending_ = tmbParams.getParameter<bool>("assignGEMCSCBending");
0027 }
0028
0029 void CSCGEMMatcher::setESLookupTables(const CSCL1TPLookupTableME11ILT* conf) { lookupTableME11ILT_ = conf; }
0030
0031 void CSCGEMMatcher::setESLookupTables(const CSCL1TPLookupTableME21ILT* conf) { lookupTableME21ILT_ = conf; }
0032
0033 //##############################################################
0034 //                Best clusters by location
0035 //##############################################################
0036
0037 void CSCGEMMatcher::bestClusterLoc(const CSCALCTDigi& alct,
0038                                    const GEMInternalClusters& clusters,
0039                                    GEMInternalCluster& best) const {
0040   if (!alct.isValid() or clusters.empty())
0041     return;
0042
0043   // match spatially
0044   GEMInternalClusters clustersLoc;
0045   matchingClustersLoc(alct, clusters, clustersLoc);
0046
0047   // simply pick the first matching one
0048   if (!clustersLoc.empty())
0049     best = clustersLoc[0];
0050 }
0051
0052 void CSCGEMMatcher::bestClusterLoc(const CSCCLCTDigi& clct,
0053                                    const GEMInternalClusters& clusters,
0054                                    GEMInternalCluster& best) const {
0055   if (!clct.isValid() or clusters.empty())
0056     return;
0057
0058   // match spatially
0059   bool ignoreALCTGEMmatch = true;
0060   GEMInternalClusters clustersLoc;
0061   matchingClustersLoc(clct, clusters, clustersLoc, ignoreALCTGEMmatch);
0062
0063   // the first matching one is also the closest in phi distance (to expected position, if extrapolating), by ordered list in CLCT matching
0064   if (!clustersLoc.empty())
0065     best = clustersLoc[0];
0066 }
0067
0068 void CSCGEMMatcher::bestClusterLoc(const CSCALCTDigi& alct,
0069                                    const CSCCLCTDigi& clct,
0070                                    const GEMInternalClusters& clusters,
0071                                    GEMInternalCluster& best) const {
0072   if (!alct.isValid() or !clct.isValid() or clusters.empty())
0073     return;
0074
0075   // match spatially
0076   GEMInternalClusters clustersLoc;
0077   matchingClustersLoc(alct, clct, clusters, clustersLoc);
0078
0079   // the first matching one is also the closest in phi distance (to expected position, if extrapolating), by ordered list in CLCT matching
0080   if (!clustersLoc.empty()) {
0081     best = clustersLoc[0];
0082     if (best.isCoincidence() and !best.isMatchingLayer1() and best.isMatchingLayer2())
0083       best.set_coincidence(false);
0084     // std::cout << "\nGEM selected: " << best << "\n" << std::endl;
0085   }
0086 }
0087
0088 //##############################################################
0089 //                  Matching by locations
0090 //##############################################################
0091
0092 // match an ALCT to GEMInternalCluster by location
0093 void CSCGEMMatcher::matchingClustersLoc(const CSCALCTDigi& alct,
0094                                         const GEMInternalClusters& clusters,
0095                                         GEMInternalClusters& output) const {
0096   if (!alct.isValid() or clusters.empty())
0097     return;
0098
0099   int number_of_wg = 0;
0100   if (station_ == 1)
0101     number_of_wg = CSCConstants::NUM_WIREGROUPS_ME11;
0102   else if (station_ == 2)
0103     number_of_wg = CSCConstants::NUM_WIREGROUPS_ME21;
0104
0105   // select clusters matched in wiregroup
0106
0107   for (const auto& cl : clusters) {
0108     // std::cout << "GEM cluster: " << cl << std::endl;
0109     bool isMatchedLayer1 = false;
0110     bool isMatchedLayer2 = false;
0111
0112     if (cl.id1().layer() == 1) {  // cluster has valid layer 1
0113       int min_wg = std::max(0, int(cl.layer1_min_wg() - maxDeltaWG_));
0114       int max_wg = std::min(number_of_wg - 1, int(cl.layer1_max_wg() + maxDeltaWG_));
0115       if (min_wg <= alct.getKeyWG() and alct.getKeyWG() <= max_wg)
0116         isMatchedLayer1 = true;
0117     }
0118     if (cl.id2().layer() == 2) {  // cluster has valid layer 2
0119       int min_wg = std::max(0, int(cl.layer2_min_wg() - maxDeltaWG_));
0120       int max_wg = std::min(number_of_wg - 1, int(cl.layer2_max_wg() + maxDeltaWG_));
0121       if (min_wg <= alct.getKeyWG() and alct.getKeyWG() <= max_wg)
0122         isMatchedLayer2 = true;
0123     }
0124
0125     // std::cout << "ALCT-GEM matching L1-L2: " << isMatchedLayer1 << " " << isMatchedLayer2 << std::endl;
0126
0127     if (isMatchedLayer1 or isMatchedLayer2) {
0128       output.push_back(cl);
0129       if (isMatchedLayer1)
0130         output.back().set_matchingLayer1(true);
0131       if (isMatchedLayer2)
0132         output.back().set_matchingLayer2(true);
0133     }
0134   }
0135 }
0136
0137 // match a CLCT to GEMInternalCluster by location
0138 void CSCGEMMatcher::matchingClustersLoc(const CSCCLCTDigi& clct,
0139                                         const GEMInternalClusters& clusters,
0140                                         GEMInternalClusters& output,
0141                                         bool ignoreALCTGEMmatch) const {
0142   if (!clct.isValid() or clusters.empty())
0143     return;
0144
0145   if (station_ == 1 and !enable_match_gem_me1a_ and !enable_match_gem_me1b_)
0146     return;
0147
0148   const bool isME1a(station_ == 1 and clct.getKeyStrip() > CSCConstants::MAX_HALF_STRIP_ME1B);
0149
0150   //determine window size
0151   unsigned eighthStripCut = isEven_ ? 4 * maxDeltaHsEven_ : 4 * maxDeltaHsOdd_;  // Cut in 1/8 = 4 * cut in 1/2
0152
0153   for (const auto& cl : clusters) {
0154     // std::cout << "GEM cluster: " << cl << std::endl;
0155     // if (!ignoreALCTGEMmatch) std::cout << "IN CLCT-GEM => ALCT-GEM matching L1-L2: " << cl.isMatchingLayer1() << " " << cl.isMatchingLayer2() << std::endl;
0156
0157     bool isMatchedLayer1 = false;
0158     bool isMatchedLayer2 = false;
0159
0160     if (cl.id1().layer() == 1) {  // cluster has valid layer 1
0161       if ((station_ == 1 and enable_match_gem_me1a_ and
0162            ((isME1a and cl.roll1() == 8) or (!isME1a and cl.roll1() < 8))) or
0163           (station_ == 1 and !enable_match_gem_me1a_ and !isME1a) or (station_ == 2)) {
0164         constexpr bool isLayer2 = false;
0165         unsigned distanceES = abs(matchedClusterDistES(clct, cl, isLayer2, false));
0166         if (distanceES <= eighthStripCut)
0167           isMatchedLayer1 = true;
0168       }
0169     }
0170     if (cl.id2().layer() == 2) {  // cluster has valid layer 2
0171       if ((station_ == 1 and enable_match_gem_me1a_ and
0172            ((isME1a and cl.roll2() == 8) or (!isME1a and cl.roll2() < 8))) or
0173           (station_ == 1 and !enable_match_gem_me1a_ and !isME1a) or (station_ == 2)) {
0174         constexpr bool isLayer2 = true;
0175         unsigned distanceES = abs(matchedClusterDistES(clct, cl, isLayer2, false));
0176         if (distanceES <= eighthStripCut)
0177           isMatchedLayer2 = true;
0178       }
0179     }
0180
0181     // std::cout << "CLCT-GEM matching L1-L2: " << isMatchedLayer1 << " " << isMatchedLayer2 << std::endl;
0182
0183     if (((ignoreALCTGEMmatch or cl.isMatchingLayer1()) and isMatchedLayer1) or
0184         ((ignoreALCTGEMmatch or cl.isMatchingLayer2()) and isMatchedLayer2)) {
0185       output.push_back(cl);
0186       output.back().set_matchingLayer1(false);
0187       output.back().set_matchingLayer2(false);
0188       if ((ignoreALCTGEMmatch or cl.isMatchingLayer1()) and isMatchedLayer1)
0189         output.back().set_matchingLayer1(true);
0190       if ((ignoreALCTGEMmatch or cl.isMatchingLayer2()) and isMatchedLayer2)
0191         output.back().set_matchingLayer2(true);
0192     }
0193   }
0194
0195   // Sorting of matching cluster prefers copads and ordering by smallest relative distance
0196   std::sort(
0197       output.begin(), output.end(), [clct, this](const GEMInternalCluster cl1, const GEMInternalCluster cl2) -> bool {
0198         if (cl1.isCoincidence() and !cl2.isCoincidence())
0199           return cl1.isCoincidence();
0200         else if ((cl1.isCoincidence() and cl2.isCoincidence()) or (!cl1.isCoincidence() and !cl2.isCoincidence())) {
0201           bool cl1_isLayer2 = !cl1.isMatchingLayer1() and cl1.isMatchingLayer2();
0202           bool cl2_isLayer2 = !cl2.isMatchingLayer1() and cl2.isMatchingLayer2();
0203           unsigned cl1_distanceES = abs(matchedClusterDistES(clct, cl1, cl1_isLayer2, false));
0204           unsigned cl2_distanceES = abs(matchedClusterDistES(clct, cl2, cl2_isLayer2, false));
0205           return cl1_distanceES < cl2_distanceES;
0206         } else
0207           return false;
0208       });
0209 }
0210
0211 void CSCGEMMatcher::matchingClustersLoc(const CSCALCTDigi& alct,
0212                                         const CSCCLCTDigi& clct,
0213                                         const GEMInternalClusters& clusters,
0214                                         GEMInternalClusters& output) const {
0215   // both need to be valid
0216   if (!alct.isValid() or !clct.isValid() or clusters.empty())
0217     return;
0218
0219   // get the single matches
0220   bool ignoreALCTGEMmatch = false;
0221   GEMInternalClusters alctClusters;
0222   matchingClustersLoc(alct, clusters, alctClusters);
0223   matchingClustersLoc(clct, alctClusters, output, ignoreALCTGEMmatch);
0224 }
0225
0226 //##############################################################
0227 //  Ancillary functions: CLCT to GEM distance in eighth strips
0228 //##############################################################
0229
0230 // calculate distance in eighth-strip units between CLCT and GEM, switch ForceTotal on to calculate total distance without slope extrapolation
0231 int CSCGEMMatcher::matchedClusterDistES(const CSCCLCTDigi& clct,
0232                                         const GEMInternalCluster& cl,
0233                                         const bool isLayer2,
0234                                         const bool ForceTotal) const {
0235   const bool isME1a(station_ == 1 and clct.getKeyStrip() > CSCConstants::MAX_HALF_STRIP_ME1B);
0236
0237   int cl_es = isME1a ? cl.getKeyStripME1a(8, isLayer2) : cl.getKeyStrip(8, isLayer2);
0238
0239   int eighthStripDiff = cl_es - clct.getKeyStrip(8);
0240
0241   if (matchCLCTpropagation_ and !ForceTotal) {  //modification of DeltaStrip by CLCT slope
0242     int SlopeShift = 0;
0243     uint16_t baseSlope = -1;
0244     baseSlope = mitigateSlopeByCosi_ ? mitigatedSlopeByConsistency(clct) : clct.getSlope();
0245
0246     int clctSlope = pow(-1, clct.getBend()) * baseSlope;
0247
0248     SlopeShift = CSCGEMSlopeCorrector(isME1a, clctSlope, isLayer2);
0249     eighthStripDiff -= SlopeShift;
0250   }
0251
0252   return eighthStripDiff;
0253 }
0254
0255 //##############################################################
0256 //  Ancillary functions: CLCT COSI
0257 //##############################################################
0258
0259 // function to determine CLCT consistency of slope indicator (COSI) and use it to mitigate slope according to LUT
0260 uint16_t CSCGEMMatcher::mitigatedSlopeByConsistency(const CSCCLCTDigi& clct) const {
0261   const bool isME1a(station_ == 1 and clct.getKeyStrip() > CSCConstants::MAX_HALF_STRIP_ME1B);
0262
0263   // extract hit values from CLCT hit matrix
0264   std::vector<std::vector<uint16_t>> CLCTHitMatrix = clct.getHits();
0265   int CLCTHits[6] = {-1, -1, -1, -1, -1, -1};
0266
0267   for (unsigned layer = 0; layer < CLCTHitMatrix.size(); ++layer) {
0268     for (unsigned position = 0; position < CLCTHitMatrix.at(layer).size(); ++position) {
0269       const uint16_t value = CLCTHitMatrix.at(layer).at(position);
0270       if (value != 0 && value != 65535) {
0271         CLCTHits[layer] = (int)value;
0272         break;
0273       }
0274     }
0275   }
0276
0277   //Debugging
0278   //std::cout<<"CLCT Hits = "<<CLCTHits[0]<<", "<<CLCTHits[1]<<", "<<CLCTHits[2]<<", "<<CLCTHits[3]<<", "<<CLCTHits[4]<<", "<<CLCTHits[5]<<std::endl;
0279
0280   //calculate slope consistency
0281   float MinMaxPairDifferences[2] = {999., -999.};
0282   for (unsigned First = 0; First < 5; ++First) {
0283     //skip empty layers
0284     if (CLCTHits[First] == -1)
0285       continue;
0286     for (unsigned Second = First + 1; Second < 6; ++Second) {
0287       //skip empty layers
0288       if (CLCTHits[Second] == -1)
0289         continue;
0290       float PairDifference = (CLCTHits[First] - CLCTHits[Second]) / (float)(Second - First);
0291       if (PairDifference < MinMaxPairDifferences[0])
0292         MinMaxPairDifferences[0] = PairDifference;
0293       if (PairDifference > MinMaxPairDifferences[1])
0294         MinMaxPairDifferences[1] = PairDifference;
0295     }
0296   }
0297
0298   //calculate consistency of slope indicator: cosi
0299   uint16_t cosi = std::ceil(std::abs(MinMaxPairDifferences[1] - MinMaxPairDifferences[0]));
0300   //Debugging
0301   //std::cout<<"COSI = "<<cosi<<std::endl;
0302
0303   //disambiguate cosi cases
0304
0305   //extremely inconsistent track, deprecate slope
0306   if (cosi > 3)
0307     return 0;
0308   //consistent slope, do not change
0309   else if (cosi < 2)
0310     return clct.getSlope();
0311   //need to look up in table 2->1
0312   else if (cosi == 2) {
0313     if (station_ == 1) {
0314       if (isME1a) {
0315         if (chamber_ % 2 == 0)
0316           return lookupTableME11ILT_->CSC_slope_cosi_2to1_L1_ME11a_even(clct.getSlope());
0317         else
0318           return lookupTableME11ILT_->CSC_slope_cosi_2to1_L1_ME11a_odd(clct.getSlope());
0319       } else {
0320         if (chamber_ % 2 == 0)
0321           return lookupTableME11ILT_->CSC_slope_cosi_2to1_L1_ME11b_even(clct.getSlope());
0322         else
0323           return lookupTableME11ILT_->CSC_slope_cosi_2to1_L1_ME11b_odd(clct.getSlope());
0324       }
0325     } else {
0326       if (chamber_ % 2 == 0)
0327         return lookupTableME21ILT_->CSC_slope_cosi_2to1_L1_ME21_even(clct.getSlope());
0328       else
0329         return lookupTableME21ILT_->CSC_slope_cosi_2to1_L1_ME21_odd(clct.getSlope());
0330     }
0331   }
0332   //need to look up in table 3->1
0333   else if (cosi == 3) {
0334     if (station_ == 1) {
0335       if (isME1a) {
0336         if (chamber_ % 2 == 0)
0337           return lookupTableME11ILT_->CSC_slope_cosi_3to1_L1_ME11a_even(clct.getSlope());
0338         else
0339           return lookupTableME11ILT_->CSC_slope_cosi_3to1_L1_ME11a_odd(clct.getSlope());
0340       } else {
0341         if (chamber_ % 2 == 0)
0342           return lookupTableME11ILT_->CSC_slope_cosi_3to1_L1_ME11b_even(clct.getSlope());
0343         else
0344           return lookupTableME11ILT_->CSC_slope_cosi_3to1_L1_ME11b_odd(clct.getSlope());
0345       }
0346     } else {
0347       if (chamber_ % 2 == 0)
0348         return lookupTableME21ILT_->CSC_slope_cosi_3to1_L1_ME21_even(clct.getSlope());
0349       else
0350         return lookupTableME21ILT_->CSC_slope_cosi_3to1_L1_ME21_odd(clct.getSlope());
0351     }
0352   }
0353   //just to avoid compiler errors an error code
0354   else {
0355     return 999;
0356   }
0357 }
0358
0359 //##############################################################
0360 //  Ancillary functions: CLCT extrapolation towards GEM
0361 //##############################################################
0362
0363 //function to correct expected GEM position in phi by CSC slope measurement
0364 int CSCGEMMatcher::CSCGEMSlopeCorrector(bool isME1a, int cscSlope, bool isLayer2) const {
0365   int SlopeShift = 0;
0366   int SlopeSign = pow(-1, std::signbit(cscSlope));
0367
0368   //account for slope mitigation by cosi, if opted-in
0369   if (mitigateSlopeByCosi_) {
0370     if (station_ == 1) {
0371       if (chamber_ % 2 == 0)
0372         SlopeShift = isME1a ? lookupTableME11ILT_->CSC_slope_cosi_corr_L1_ME11a_even(std::abs(cscSlope))
0373                             : lookupTableME11ILT_->CSC_slope_cosi_corr_L1_ME11b_even(std::abs(cscSlope));
0374       else
0375         SlopeShift = isME1a ? lookupTableME11ILT_->CSC_slope_cosi_corr_L1_ME11a_odd(std::abs(cscSlope))
0376                             : lookupTableME11ILT_->CSC_slope_cosi_corr_L1_ME11b_odd(std::abs(cscSlope));
0377     } else if (station_ == 2) {
0378       if (chamber_ % 2 == 0)
0379         SlopeShift = lookupTableME21ILT_->CSC_slope_cosi_corr_L1_ME21_even(std::abs(cscSlope));
0380       else
0381         SlopeShift = lookupTableME21ILT_->CSC_slope_cosi_corr_L1_ME21_odd(std::abs(cscSlope));
0382     }
0383   } else {  //account for slope without mitigation, if opted out
0384     if (station_ == 1) {
0385       if (!isLayer2) {
0386         if (chamber_ % 2 == 0)
0387           SlopeShift = isME1a ? lookupTableME11ILT_->CSC_slope_corr_L1_ME11a_even(std::abs(cscSlope))
0388                               : lookupTableME11ILT_->CSC_slope_corr_L1_ME11b_even(std::abs(cscSlope));
0389         else
0390           SlopeShift = isME1a ? lookupTableME11ILT_->CSC_slope_corr_L1_ME11a_odd(std::abs(cscSlope))
0391                               : lookupTableME11ILT_->CSC_slope_corr_L1_ME11b_odd(std::abs(cscSlope));
0392       } else {
0393         if (chamber_ % 2 == 0)
0394           SlopeShift = isME1a ? lookupTableME11ILT_->CSC_slope_corr_L2_ME11a_even(std::abs(cscSlope))
0395                               : lookupTableME11ILT_->CSC_slope_corr_L2_ME11b_even(std::abs(cscSlope));
0396         else
0397           SlopeShift = isME1a ? lookupTableME11ILT_->CSC_slope_corr_L2_ME11a_odd(std::abs(cscSlope))
0398                               : lookupTableME11ILT_->CSC_slope_corr_L2_ME11b_odd(std::abs(cscSlope));
0399       }
0400     } else if (station_ == 2) {
0401       if (!isLayer2) {
0402         if (chamber_ % 2 == 0)
0403           SlopeShift = lookupTableME21ILT_->CSC_slope_corr_L1_ME21_even(std::abs(cscSlope));
0404         else
0405           SlopeShift = lookupTableME21ILT_->CSC_slope_corr_L1_ME21_odd(std::abs(cscSlope));
0406       } else {
0407         if (chamber_ % 2 == 0)
0408           SlopeShift = lookupTableME21ILT_->CSC_slope_corr_L2_ME21_even(std::abs(cscSlope));
0409         else
0410           SlopeShift = lookupTableME21ILT_->CSC_slope_corr_L2_ME21_odd(std::abs(cscSlope));
0411       }
0412     }
0413   }
0414   return std::round(SlopeShift * SlopeSign);
0415 }
0416
0417 //##############################################################
0418 //  Ancillary functions: computation of slope corrected by GEM
0419 //##############################################################
0420
0421 //function to replace the CLCT slope by the slope indicated by the strip difference between the CLCT and its matching GEM internal cluster
0422 int CSCGEMMatcher::calculateGEMCSCBending(const CSCCLCTDigi& clct, const GEMInternalCluster& cluster) const {
0423   const bool isME1a(station_ == 1 and clct.getKeyStrip() > CSCConstants::MAX_HALF_STRIP_ME1B);
0424
0425   bool isLayer2 = false;
0426   if (!cluster.isMatchingLayer1() and cluster.isMatchingLayer2())
0427     isLayer2 = true;
0428
0429   //ME1a necessitates a different treatment because of a different strip numbering scheme and strip width
0430   const int SignedEighthStripDiff = matchedClusterDistES(clct, cluster, isLayer2, true);
0431   const unsigned eighthStripDiff = abs(SignedEighthStripDiff);  //LUTs consider only absolute change
0432
0433   //use LUTs to determine absolute slope, default 0
0434   int slopeShift = 0;
0435   if (station_ == 2) {
0436     if (!isLayer2) {
0437       if (isEven_)
0438         slopeShift = lookupTableME21ILT_->es_diff_slope_L1_ME21_even(eighthStripDiff);
0439       else
0440         slopeShift = lookupTableME21ILT_->es_diff_slope_L1_ME21_odd(eighthStripDiff);
0441     } else {
0442       if (isEven_)
0443         slopeShift = lookupTableME21ILT_->es_diff_slope_L2_ME21_even(eighthStripDiff);
0444       else
0445         slopeShift = lookupTableME21ILT_->es_diff_slope_L2_ME21_odd(eighthStripDiff);
0446     }
0447   } else if (station_ == 1) {
0448     if (isME1a) {  //is in ME1a
0449       if (!isLayer2) {
0450         if (isEven_)
0451           slopeShift = lookupTableME11ILT_->es_diff_slope_L1_ME11a_even(eighthStripDiff);
0452         else
0453           slopeShift = lookupTableME11ILT_->es_diff_slope_L1_ME11a_odd(eighthStripDiff);
0454       } else {
0455         if (isEven_)
0456           slopeShift = lookupTableME11ILT_->es_diff_slope_L2_ME11a_even(eighthStripDiff);
0457         else
0458           slopeShift = lookupTableME11ILT_->es_diff_slope_L2_ME11a_odd(eighthStripDiff);
0459       }
0460     } else {
0461       if (!isLayer2) {
0462         if (isEven_)
0463           slopeShift = lookupTableME11ILT_->es_diff_slope_L1_ME11b_even(eighthStripDiff);
0464         else
0465           slopeShift = lookupTableME11ILT_->es_diff_slope_L1_ME11b_odd(eighthStripDiff);
0466       } else {
0467         if (isEven_)
0468           slopeShift = lookupTableME11ILT_->es_diff_slope_L2_ME11b_even(eighthStripDiff);
0469         else
0470           slopeShift = lookupTableME11ILT_->es_diff_slope_L2_ME11b_odd(eighthStripDiff);
0471       }
0472     }
0473   }
0474
0475   //account for the sign of the difference
0476   slopeShift *= pow(-1, std::signbit(SignedEighthStripDiff));
0477
0478   return slopeShift;
0479 }