RPCSensitiveDetector Class Reference

#include <RPCSensitiveDetector.h>

Inheritance diagram for RPCSensitiveDetector:

Collaboration diagram for RPCSensitiveDetector:

Public Member Functions
	RPCSensitiveDetector (const std::string &name, const std::string &hitCollectionName, unsigned int nGasGaps)
	construction/destruction More...
	~RPCSensitiveDetector ()=default
void	Initialize (G4HCofThisEvent *) override final
	member functions More...
G4bool	ProcessHits (G4Step *, G4TouchableHistory *) override final

Private Member Functions
	FRIEND_TEST (RPCSensitiveDetectortest, Initialize)
	FRIEND_TEST (RPCSensitiveDetectortest, ProcessHits)

Private Attributes
SG::WriteHandle< RPCSimHitCollection >	m_myRPCHitColl
	member data More...
const RpcHitIdHelper *	m_muonHelper {nullptr}

Detailed Description

Author

Andre.nosp@m.a.Di.nosp@m.Simon.nosp@m.e@ce.nosp@m.rn.ch

Class methods and properties

The method RPCSensitiveDetector::ProcessHits is executed by the G4 kernel each time a particle crosses one of the RPC gas gaps. Navigating with the touchableHistory method GetHistoryDepth() through the hierarchy of volumes crossed by the particle, the Sensitive Detector determines the correct set of Simulation Identifiers to associate to each hit. The RPC SimIDs are 32-bit unsigned integers, built using the MuonSimEvent/RpcHitIdHelper class which inherits from the MuonHitIdHelper base class.

We describe here how each field of the identifier is determined.

1) stationName, stationEta, stationPhi: when a volume is found in the hierarchy whose name contains the substring "station", the stationName is extracted from the volume's name. stationEta and stationPhi values are calculated starting from the volume's copy number.

2) doubletR: when a volume is found in the hierarchy whose name contains the substring "rpccomponent", its copy number is used to calulate the doubletR of the hit.

3) gasGap: the substring "layer" is searched through the names of the volumes in the hierarchy. When a the volume is found, its copy number is used, together with the sign of the copy number of the "rpccomponent" to decide what is the correct gasGap value.

4) doubletPhi: when the volume with the substring "gas volume" in its name is found, its copy number is enough to determine the doubletPhi of the hit if the hit is registered in a standard chamber. For special chambers (i.e. chambers with only one gas gap per layer readout by two strip panels per direction, or chambers in the ribs) some a special attribution is done using also the stationName.

5) doubletZ: "gazGap" is the required substring in the volume's name. doubletZ attribution is fairly complicated. For standard chambers it just uses the sign of the copy number of the "rpccomponent", but severa arrangements (based on the stationName and the technology name) are needed for special chambers.

6) the doubletPhi calculated as described above needs one further correction for some chambers to take into account chamber rotation before placement in the spectrometer. This is done just before creating the hit.

notes:

1) presently, chamber efficiency is assumed to be 100% at the level of the Sensitive Detector, i.e. two hits (one in eta and one in phi) are created each time the sensitive detector is created.

2) the hits created as described above contain information about their local position in the gas gap and the simulation identifier of the strip panel

3) the strip number is not assigned by the sensitive detector, and must be calculated by the digitization algorithm.

4) points 2 and 3 are due to the necessity of not introducing any dependency on the geometry description in the Sensitive Detector.

5) the present version of the Sensitive Detector produces hits which are different depending on whether hand coded G4 geometry or GeoModel is used for the geometrical description of the setup. When hand coded geometry is used, both GeoModel and the old MuonDetDescr can be used for digitization (using a proper tag of RPC_Digitization), while if GeoModel is used in the simulation, it must be used also in the digitization.

6) for each hit, the time of flight (the G4 globalTime), is recorded and associated to the hit.

7) the RPCHit object contains: the SimID, the globalTime, the hit local position and the track barcode.

Class methods and properties

The method RPCSensitiveDetector::ProcessHits is executed by the G4 kernel each time a particle crosses one of the RPC gas gaps. Navigating with the touchableHistory method GetHistoryDepth() through the hierarchy of volumes crossed by the particle, the Sensitive Detector determines the correct set of Simulation Identifiers to associate to each hit. The RPC SimIDs are 32-bit unsigned integers, built using the MuonSimEvent/RpcHitIdHelper class which inherits from the MuonHitIdHelper base class.

We describe here how each field of the identifier is determined.

1) stationName, stationEta, stationPhi: when a volume is found in the hierarchy whose name contains the substring "station", the stationName is extracted from the volume's name. stationEta and stationPhi values are calculated starting from the volume's copy number.

2) doubletR: when a volume is found in the hierarchy whose name contains the substring "rpccomponent", its copy number is used to calulate the doubletR of the hit.

3) gasGap: the substring "layer" is searched through the names of the volumes in the hierarchy. When a the volume is found, its copy number is used, together with the sign of the copy number of the "rpccomponent" to decide what is the correct gasGap value.

4) doubletPhi: when the volume with the substring "gas volume" in its name is found, its copy number is enough to determine the doubletPhi of the hit if the hit is registered in a standard chamber. For special chambers (i.e. chambers with only one gas gap per layer readout by two strip panels per direction, or chambers in the ribs) some a special attribution is done using also the stationName.

5) doubletZ: "gazGap" is the required substring in the volume's name. doubletZ attribution is fairly complicated. For standard chambers it just uses the sign of the copy number of the "rpccomponent", but severa arrangements (based on the stationName and the technology name) are needed for special chambers.

6) the doubletPhi calculated as described above needs one further correction for some chambers to take into account chamber rotation before placement in the spectrometer. This is done just before creating the hit.

notes:

1) presently, chamber efficiency is assumed to be 100% at the level of the Sensitive Detector, i.e. two hits (one in eta and one in phi) are created each time the sensitive detector is created.

2) the hits created as described above contain information about their local position in the gas gap and the simulation identifier of the strip panel

3) the strip number is not assigned by the sensitive detector, and must be calculated by the digitization algorithm.

4) points 2 and 3 are due to the necessity of not introducing any dependency on the geometry description in the Sensitive Detector.

5) the present version of the Sensitive Detector produces hits which are different depending on whether hand coded G4 geometry or GeoModel is used for the geometrical description of the setup. When hand coded geometry is used, both GeoModel and the old MuonDetDescr can be used for digitization (using a proper tag of RPC_Digitization), while if GeoModel is used in the simulation, it must be used also in the digitization.

6) for each hit, the time of flight (the G4 globalTime), is recorded and associated to the hit.

7) the RPCHit object contains: the SimID, the globalTime, the hit local position and the track barcode.

Definition at line 96 of file RPCSensitiveDetector.h.

Constructor & Destructor Documentation

RPCSensitiveDetector()

RPCSensitiveDetector::RPCSensitiveDetector	(	const std::string &	name,
		const std::string &	hitCollectionName,
		unsigned int	nGasGaps
	)

construction/destruction

Definition at line 22 of file RPCSensitiveDetector.cxx.

  : G4VSensitiveDetector( name )
  , m_myRPCHitColl( hitCollectionName )
{
  m_muonHelper = RpcHitIdHelper::GetHelper(nGasGaps);
}

~RPCSensitiveDetector()

RPCSensitiveDetector::~RPCSensitiveDetector ( )

default

Member Function Documentation

FRIEND_TEST() [1/2]

RPCSensitiveDetector::FRIEND_TEST ( RPCSensitiveDetectortest  , Initialize    )

private

FRIEND_TEST() [2/2]

RPCSensitiveDetector::FRIEND_TEST ( RPCSensitiveDetectortest  , ProcessHits    )

private

Initialize()

void RPCSensitiveDetector::Initialize ( G4HCofThisEvent *  )

finaloverride

member functions

Definition at line 29 of file RPCSensitiveDetector.cxx.

{
  if (!m_myRPCHitColl.isValid()) m_myRPCHitColl = std::make_unique<RPCSimHitCollection>();
  //FIXME probably only need to call this bit at start of the event
  //loop rather than the start of each G4Event.
  if (verboseLevel>5) G4cout << "Initializing SD"  << G4endl;
 
}

ProcessHits()

G4bool RPCSensitiveDetector::ProcessHits ( G4Step *  aStep, G4TouchableHistory *    )

finaloverride

RPCs sensitive to charged particle only

Reject hits that are parallel through the gas gap

Definition at line 38 of file RPCSensitiveDetector.cxx.

                                                                          {
 
  G4Track* track = aStep->GetTrack();
 
  if (track->GetDefinition()->GetPDGCharge() == 0.0) {
    if (track->GetDefinition()!=G4Geantino::GeantinoDefinition()) {
      return true;
    }
  }
 
  const G4TouchableHistory* touchHist = static_cast<const G4TouchableHistory*>(aStep->GetPreStepPoint()->GetTouchable());
  G4ThreeVector           position  = aStep->GetPreStepPoint()->GetPosition();
  G4ThreeVector           postPosition  = aStep->GetPostStepPoint()->GetPosition();
  const G4AffineTransform trans     = track->GetTouchable()->GetHistory()->GetTopTransform(); // from global to local
 
  // necessary to assign correct identifiers
  int rpcIsRotated      = 0;
  // int layer             = 0;
 
  std::string tech;
  // fields for the RPC identifier construction
  std::string stationName;
  int         stationEta= 0;
  int         stationPhi= 0;
  int         doubletR= 0;
  // int         doubletZ= 0;
  int         doubletPhi= 0;
  int         gasGap= 0;
  // int         eta_inversed=0;
  // int         phi_inversed=0;
  int         station_rotated=0; // tells us if the station was rotated before being positioned.
                                 // if =1 we have to correct some IDs
  int         zNeg_original=0; // tells if the station at z<0 was obtained duplicating a station at z>0
 
  // RPC hit information
  double     globalTime    = aStep->GetPreStepPoint()->GetGlobalTime();
  Amg::Vector3D localPosition = Amg::Hep3VectorToEigen( trans.TransformPoint(position) );
  Amg::Vector3D localPostPosition = Amg::Hep3VectorToEigen( trans.TransformPoint(postPosition) );
  {
    const Amg::Vector3D stepVector = localPostPosition - localPosition;
    if (stepVector.mag()>std::numeric_limits<float>::epsilon() &&
        std::abs(std::abs(Amg::angle(stepVector, Amg::Vector3D::UnitX()))
                 - 90.*Gaudi::Units::deg) < 0.0001* Gaudi::Units::deg) {
      return true;
    }
  }
  int mydbZ=0;
  int mydbPMod=0;
  int mydbP=0;
  bool isAssembly = false;
  // scan geometry tree to identify the hit channel
  for (int i=touchHist->GetHistoryDepth();i>=0;i--) {
 
    std::string::size_type npos;
    std::string volName = touchHist->GetVolume(i)->GetName();
    std::string num=volName.substr(3,2);
    if(num[0]==' ') num[0]=0;
 
    // check if this station is an assembly
    if ((npos = volName.find("av_")) != std::string::npos &&
        (npos = volName.find("impr_")) != std::string::npos)  isAssembly = true;
 
    // stationName, stationEta, stationPhi
    if ((npos = volName.find("station")) != std::string::npos  && (!isAssembly)) {
 
      stationName = volName.substr(0,npos-1);
 
      int volCopyNo = touchHist->GetVolume(i)->GetCopyNo();
 
      if(abs(volCopyNo/1000)==1){
        zNeg_original=1;
        volCopyNo=volCopyNo%1000;
      }
 
      stationEta = volCopyNo/100;
      stationPhi = abs(volCopyNo%100);
 
      if(stationEta<0&&!zNeg_original) station_rotated=1;
 
    // stationName, stationEta, stationPhi
    } else if ((npos = volName.find("RPC")) != std::string::npos && isAssembly) {
      // vol name for Assembly components are
      // av_WWW_impr_XXX_Muon::BMSxMDTxx_pv_ZZZ_NAME
      //         where WWW is ass. istance nr.
      //               XXX is comp. imprint nr.
      //               BMSxMDTxx is the name of the comp. log.Vol.
      //                  x station sub-type; xx technology subtype
      //               ZZZ is the comp. number of order
      //               NAME is the comp. tag (geoIdentifierTag)
      //                    for RPCs it is SwapdbPdbRdbZ[aaa]
      //                    with aaa = doubletZ + doubletR*100 + dbphi*1000;
      //                         aaa = -aaa if iswap == -1
      //                         dbphi = 1 always but for S1 or S2 at doubletPhi = 2
      // copy numbers for Ass.components are =
      //                CopyNoBase(= geoIdentifierTag of the assembly) + geoIdentifierTag of the component
      //                geoIdentifierTag of the component = Job
      //                geoIdentifierTag of the assembly = (sideC*10000 +
      //                             mirsign*1000 + abs(zi)*100 + fi+1)*100000;
      //                             mirsign = 1 if zi<0 and !mirrored; otherwise 0
      std::string::size_type loc1,loc2;
      if ((loc1 = volName.find("Muon::")) != std::string::npos) {
        stationName = volName.substr(loc1+6,4); //type and subtype
      }
 
      int volCopyNo = touchHist->GetVolume(i)->GetCopyNo();
      int copyNrBase = int(volCopyNo/100000);
      int sideC  = int(copyNrBase/10000);
      int zi     = int((copyNrBase%1000)/100);
      int mirfl  = int((copyNrBase%10000)/1000);
      int fi     = int(copyNrBase%100);
      if (sideC == 1) zi = -zi;
      stationEta    = zi;
      stationPhi    = fi;
      zNeg_original = mirfl;
 
      if(stationEta<0&&!zNeg_original) station_rotated=1;
 
      // doubletZ   = 1;
      tech=volName.substr(npos,5);
 
      // now get the geoIdentifierTag of the rpc components
      int gmID = 0;
      if ((loc1 = volName.find('[')) != std::string::npos) {
        if ((loc2 = volName.find(']', loc1+1)) != std::string::npos) {
          //G4cout << "first [ is at "<<loc1<<" first ] at "<<loc2 << G4endl;
          std::istringstream istrvar(volName.substr(loc1+1,loc2-loc1-1));
          istrvar>>gmID;
        }
      }
      int kk=gmID;
 
      if (kk < 0) rpcIsRotated=1;
 
      doubletR =(abs(kk)%1000)/100;
      mydbZ    = abs(int(kk%10));
      mydbPMod = abs(int(kk/1000));
    // doubleR, doubletZ
    } else if ((npos = volName.find("rpccomponent")) != std::string::npos && (!isAssembly)) {
 
      std::string::size_type loc1,loc2;
      tech=volName.substr(npos-5,5);
      int gmID = 0;
      if ((loc1 = volName.find('[')) != std::string::npos) {
        if ((loc2 = volName.find(']', loc1+1)) != std::string::npos) {
          std::istringstream istrvar(volName.substr(loc1+1,loc2-loc1-1));
          istrvar>>gmID;
        }
      }
      mydbZ    = abs(int(gmID%10));
      mydbPMod = abs(int(gmID/1000));
 
      int kk=touchHist->GetVolume(i)->GetCopyNo();
 
      if (kk < 0) rpcIsRotated=1;
 
      doubletR=(abs(kk)%1000)/100;
 
    } else if ((npos = volName.find("layer")) != std::string::npos) {
 
      int copyNo = touchHist->GetVolume(i)->GetCopyNo();
 
      if (copyNo == 1) {
        rpcIsRotated ? gasGap = 2 : gasGap = 1;
      } else if (copyNo ==2) {
        rpcIsRotated ? gasGap = 1 : gasGap = 2;
      } else if (copyNo ==3) {
        gasGap = 3;
      }
    } else if((npos = volName.find("gas volume")) != std::string::npos) {
 
      int copyNo = touchHist->GetVolume(i)->GetCopyNo();
      if (copyNo == 0) {
        doubletPhi = 1;
      } else if (copyNo == 10) {
        doubletPhi = 2;
      }
      mydbP = doubletPhi;
      int ngap_in_s=0;
      int nstrippanel_in_s=0;
      std::string::size_type loc1;
      if ((loc1 = volName.find("gg_in_s")) != std::string::npos) {
        std::istringstream istrvar(volName.substr(loc1-1,1));
        istrvar>>ngap_in_s;
      }
      if ((loc1 = volName.find("sp_in_s")) != std::string::npos) {
        std::istringstream istrvar(volName.substr(loc1-1,1));
        istrvar>>nstrippanel_in_s;
      }
      if (ngap_in_s == 1 && nstrippanel_in_s == 2) {
        if(localPosition.y()>0) mydbP=2;
        else mydbP=1;
      } else if (ngap_in_s == 1 && nstrippanel_in_s == 1) {
        mydbP = mydbPMod;
      }
    }
  }
 
  // correct wrong IDs due to station rotation. only doubletZ and doubletPhi are affected at this point
 
  if(station_rotated){
    // doubletPhi correction
    // note that this is correct also for ribs chambers
    mydbP++;
    if (mydbP>2) mydbP=1;
    //      G4cout << "Rcd PC - swap dbPhi because ch is MIRRORED "<<doubletPhi << G4endl;
 
    // strip numbering: if the station is rotated both eta and phi directions get inversed.
    // commented out for geomodel!
  }
 
 
  // now we have the position in the gas gap, with correct axis orientation, and the offlineIDs *of the strip panel*
  // nstrip is supposed to be calculated by RPC_Digitizer.
 
  // construct two (one in eta and one in phi) new RPC hits and store them in hit collection
 
  //construct the hit identifiers
  if (verboseLevel>5) {
    G4cout << "hit in station "<<stationName<< " on technology "<<tech << G4endl;
    G4cout << "constructing ids (stName, stEta, stPhi, dr, dZ, dPhi)= "<<stationName<< " "<< stationEta<<" " << stationPhi<< " "<<doubletR<< " "<< mydbZ<< " "<<mydbP << G4endl;
  }
 
  HitID RPCid_eta = m_muonHelper->BuildRpcHitId(stationName, stationPhi, stationEta,
                                              mydbZ, doubletR, gasGap, mydbP,0);
 
  HitID RPCid_phi = m_muonHelper->BuildRpcHitId(stationName, stationPhi, stationEta,
                                              mydbZ, doubletR, gasGap, mydbP,1);
 
  // retrieve track barcode
  TrackHelper trHelp(aStep->GetTrack());
 
  //construct new rpc hit
  m_myRPCHitColl->Emplace(RPCid_eta, globalTime,
                        localPosition, trHelp.GenerateParticleLink(), localPostPosition,
                        aStep->GetTotalEnergyDeposit(),
                        aStep->GetStepLength(),
                        track->GetDefinition()->GetPDGEncoding(),
                        aStep->GetPreStepPoint()->GetKineticEnergy());
  m_myRPCHitColl->Emplace(RPCid_phi, globalTime,
                        localPosition, trHelp.GenerateParticleLink(), localPostPosition,
                        aStep->GetTotalEnergyDeposit(),
                        aStep->GetStepLength(),
                        track->GetDefinition()->GetPDGEncoding(),
                        aStep->GetPreStepPoint()->GetKineticEnergy());
 
  return true;
}

Member Data Documentation

m_muonHelper

const RpcHitIdHelper* RPCSensitiveDetector::m_muonHelper {nullptr}

private

Definition at line 112 of file RPCSensitiveDetector.h.

m_myRPCHitColl

SG::WriteHandle<RPCSimHitCollection> RPCSensitiveDetector::m_myRPCHitColl

private

member data

Definition at line 111 of file RPCSensitiveDetector.h.

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The documentation for this class was generated from the following files:

• RPCSensitiveDetector.h
• RPCSensitiveDetector.cxx