d0/d7e/SmearMatrixDetector__0__2__B3T_8cxx_source.html

// Based on

// https://physdiv.jlab.org/DetectorMatrix/

// From November 21, 2020

//

// Tracking assumes a 3T field

//

// Important Notes:

// - Where ranges are given, the more conservative number is chosen.

// - Without available specifications, angular resolution is assumed to be perfect.

// - Momentum and energy acceptance specifications are NOT implemented

// -- a) "90% acceptance" is not specific enough to introduce efficiency

// -- b) It is not a priori clear whether cuts should apply to truth or smeared value

// --    A "looper" may not reach the detector.

// --    On the other hand, a calorimetry deposit may fluctuate above threshold

// - PID for pi/K/p is implemented with perfect PID in the acceptance (and momentum range)

// - Electron PID is not implemented. Very high purity is important and not handled well with the above approach


#include "eicsmear/erhic/VirtualParticle.h"

#include "eicsmear/smear/Acceptance.h"

#include "eicsmear/smear/Device.h"

#include "eicsmear/smear/Detector.h"

#include "eicsmear/smear/Smearer.h"

#include "eicsmear/smear/ParticleMCS.h"

#include "eicsmear/smear/PerfectID.h"

#include <eicsmear/smear/Smear.h>

#include <eicsmear/erhic/ParticleMC.h>

#include "Math/Vector4D.h"


// declare static --> local to this file, won't clash with others

static double ThetaFromEta( const double eta );


Smear::Detector BuildMatrixDetector_0_2_B3T() {

  gSystem->Load("libeicsmear");


  // Create the detector object to hold all devices

  Smear::Detector det;


  // The framework provides implementations of three kinematic calculation methods

  // from smeared values

  // NM - "Null method" uses the scattered lepton.

  // DA - Double Angle method

  // JB - Jacquet-Blondel method

  // Users should be mindful of the limitations and assumptions in

  // the calculation of smeared kinematics. Sophisticated calculations are best redone in user code

  // from the smeared particles directly.

  det.SetEventKinematicsCalculator("NM DA JB");


  // Perfect phi and theta for all particles

  // ---------------------------------------

  // total coverage of the handbook for tracker, ecal, and hcal is -3.5 < eta < 3.5

  Smear::Acceptance::Zone AngleZoneCommon(ThetaFromEta ( 3.5 ),ThetaFromEta ( -3.5 ));

  Smear::Device SmearThetaCommon(Smear::kTheta, "0.0");

  SmearThetaCommon.Accept.AddZone(AngleZoneCommon);

  SmearThetaCommon.Accept.SetGenre(Smear::kAll);

  det.AddDevice(SmearThetaCommon);


  Smear::Device SmearPhiCommon(Smear::kPhi, "0.0");

  SmearPhiCommon.Accept.AddZone(AngleZoneCommon);

  SmearPhiCommon.Accept.SetGenre(Smear::kAll);

  det.AddDevice(SmearPhiCommon);


  // Tracking  (B = 3 T)

  // --------

  // Note: Smear::kCharged checks pdg charge, so includes muons (good)

  // NOT implemented

  // Minimum pT for B = 3 T:

  // 150 MeV/c for -3.0 < eta < -2.5

  // 220 MeV/c for -2.5 < eta < -2.0

  // 160 MeV/c for -2.0 < eta < -1.5

  // 300 MeV/c for -1.5 < eta < -1.0


  // eta = -3.5 --  -2.5

  // sigma_p/p ~ 0.1% p + 2%

  Smear::Acceptance::Zone TrackBack1Zone(ThetaFromEta ( -2.5 ),ThetaFromEta ( -3.5 ));

  Smear::Device TrackBack1P(Smear::kP, "sqrt( pow ( 0.001*P*P, 2) + pow ( 0.02*P, 2) )");

  TrackBack1P.Accept.AddZone(TrackBack1Zone);

  TrackBack1P.Accept.SetCharge(Smear::kCharged);

  det.AddDevice(TrackBack1P);


  // eta = -2.5 --  -1

  // sigma_p/p ~ 0.02% p + 1%

  Smear::Acceptance::Zone TrackBack2Zone(ThetaFromEta ( -1 ),ThetaFromEta ( -2.5 ));

  Smear::Device TrackBack2P(Smear::kP, "sqrt( pow ( 0.0002*P*P, 2) + pow ( 0.01*P, 2) )");

  TrackBack2P.Accept.AddZone(TrackBack2Zone);

  TrackBack2P.Accept.SetCharge(Smear::kCharged);

  det.AddDevice(TrackBack2P);


  // eta = -1 -- +1

  // sigma_p/p ~ 0.02% p + 0.05%

  Smear::Acceptance::Zone TrackBarrelZone(ThetaFromEta ( 1 ),ThetaFromEta ( -1 ));

  Smear::Device TrackBarrelP(Smear::kP, "sqrt( pow ( 0.0002*P*P, 2) + pow ( 0.005*P, 2) )");

  TrackBarrelP.Accept.AddZone(TrackBarrelZone);

  TrackBarrelP.Accept.SetCharge(Smear::kCharged);

  det.AddDevice(TrackBarrelP);


  // eta = 1 -- 2.5

  // sigma_p/p ~ 0.02% p+1%

  Smear::Acceptance::Zone TrackFwd2Zone(ThetaFromEta ( 2.5 ),ThetaFromEta ( 1 ));

  Smear::Device TrackFwd2P(Smear::kP, "sqrt( pow ( 0.0002*P*P, 2) + pow ( 0.01*P, 2) )");

  TrackFwd2P.Accept.AddZone(TrackFwd2Zone);

  TrackFwd2P.Accept.SetCharge(Smear::kCharged);

  det.AddDevice(TrackFwd2P);


  // eta = 2.5 -- 3.5

  // sigma_p/p ~ 0.1% p+2%

  Smear::Acceptance::Zone TrackFwd1Zone(ThetaFromEta ( 3.5 ),ThetaFromEta ( 2.5 ));

  Smear::Device TrackFwd1P(Smear::kP, "sqrt( pow ( 0.001*P*P, 2) + pow ( 0.02*P, 2) )");

  TrackFwd1P.Accept.AddZone(TrackFwd1Zone);

  TrackFwd1P.Accept.SetCharge(Smear::kCharged);

  det.AddDevice(TrackFwd1P);


  // PID

  // ---

  // Perfect pi/K/P PID in the region indicating >3 sigma separation

  // Make sure to not cover more than is covered by the other detectors.

  // No minimum momentum is used.

  // Accept charged hadrons (excludes e, mu)


  // Back

  // eta = -3.5 -- -1

  // p < 10 GeV

  Smear::Acceptance::Zone PidBackZone(ThetaFromEta(-1),ThetaFromEta(-3.5),

              0., TMath::TwoPi(), // phi

              0., TMath::Infinity(), // E

              0., 10 ); // p

  Smear::PerfectID PidBack;

  PidBack.Accept.AddZone(PidBackZone);

  PidBack.Accept.SetCharge(Smear::kCharged);

  PidBack.Accept.SetGenre(Smear::kHadronic);

  det.AddDevice( PidBack );


  // Barrel

  // eta = -1 -- 1

  // p < 6 GeV

  Smear::Acceptance::Zone PidBarrelZone(ThetaFromEta(1),ThetaFromEta(-1),

              0., TMath::TwoPi(), // phi

              0., TMath::Infinity(), // E

              0., 6 ); // p

  Smear::PerfectID PidBarrel;

  PidBarrel.Accept.AddZone(PidBarrelZone);

  PidBarrel.Accept.SetCharge(Smear::kCharged);

  PidBarrel.Accept.SetGenre(Smear::kHadronic);

  det.AddDevice( PidBarrel );


  // Forward

  // eta = -1 -- 1

  // p < 50 GeV

  // not sure what to make of "(worse approaching 3.5)"

  Smear::Acceptance::Zone PidFwdZone(ThetaFromEta(3.5),ThetaFromEta(1),

              0., TMath::TwoPi(), // phi

              0., TMath::Infinity(), // E

              0., 50 ); // p

  Smear::PerfectID PidFwd;

  PidFwd.Accept.AddZone(PidFwdZone);

  PidFwd.Accept.SetCharge(Smear::kCharged);

  PidFwd.Accept.SetGenre(Smear::kHadronic);

  det.AddDevice( PidFwd );


  // EM Calorimeters

  // ---------------

  // Note: Smear::kElectromagnetic == gamma + e. Does not include muons (good)

  // Calorimeter resolution usually given as sigma_E/E = A% / E + B%/Sqrt{E} + C%

  // EIC Smear needs absolute sigma: sigma_E = Sqrt{A*A + B*B*E + C*C*E*E}


  // Back

  // eta = -3.5 -- -2

  // E> 20 MeV not used because it suppresses smeared-up particles

  // 1%/E + 2.5%/sqrtE + 1%

  // A       B           C

  Smear::Acceptance::Zone EmcalBackZone(ThetaFromEta ( -2 ),ThetaFromEta ( -3.5 ));

  Smear::Device EmcalBack(Smear::kE, "sqrt( pow ( 0.01,2 ) + pow( 0.025,2)*E + pow ( 0.01*E,2 ) )");

  EmcalBack.Accept.AddZone(EmcalBackZone);

  EmcalBack.Accept.SetGenre(Smear::kElectromagnetic);

  det.AddDevice(EmcalBack);


  // MidBack

  // eta = -2 -- -1

  // E> 50 MeV not used because it suppresses smeared-up particles

  // 2%/E   +  (4-8)%/sqrtE   + 2% (Upper limit achievable with 50 cm space. Better resolution requires ~65 cm   space allocated  )

  // A       B choose 8%        C

  Smear::Acceptance::Zone EmcalMidBackZone(ThetaFromEta ( -1 ),ThetaFromEta ( -2 ));

  Smear::Device EmcalMidBack(Smear::kE, "sqrt( pow ( 0.02,2 ) + pow( 0.08,2)*E + pow ( 0.02*E,2 ) )");

  EmcalMidBack.Accept.AddZone(EmcalMidBackZone);

  EmcalMidBack.Accept.SetGenre(Smear::kElectromagnetic);

  det.AddDevice(EmcalMidBack);


  // Barrel

  // eta = -1 -- 1

  // E > 100 MeV  (50 MeV if higher resolution)

  //  not used because it suppresses smeared-up particles

  // 2%/E⊕(12-14)%/√E⊕(2-3)% for 30 cm space

  // A better stochastic term can be achieved with more space:

  // 2.5% with crystals    35cm

  // 10% sampling          40cm

  // 4% SciGlass            65cm

  // (*Better resolution requires ~65 cm   space allocated  )"

  // choosing

  // 2%/E  + 14%/sqrtE + 3%

  // A       B           C

  Smear::Acceptance::Zone EmcalBarrelZone(ThetaFromEta ( 1 ),ThetaFromEta ( -1 ));

  Smear::Device EmcalBarrel(Smear::kE, "sqrt( pow ( 0.02,2 ) + pow( 0.14,2)*E + pow ( 0.03*E,2 ) )");

  EmcalBarrel.Accept.AddZone(EmcalBarrelZone);

  EmcalBarrel.Accept.SetGenre(Smear::kElectromagnetic);

  det.AddDevice(EmcalBarrel);


  // Forward

  // eta = 1 -- 3.5

  // E > 50 MeV not used because it suppresses smeared-up particles

  // "2%/E + (4*-12)%/sqrtE  + 2%  Upper limit achievable with 40cm space

  // *Better resolution requires ~65 cm   space allocated"

  // choosing

  // 2%/E  + 12%/sqrtE + 2%

  // A       B           C

  Smear::Acceptance::Zone EmcalFwdZone(ThetaFromEta ( 3.5 ),ThetaFromEta ( 1 )); // E

  Smear::Device EmcalFwd(Smear::kE, "sqrt( pow ( 0.02,2 ) + pow( 0.12,2)*E + pow ( 0.02*E,2 ) )");

  EmcalFwd.Accept.AddZone(EmcalFwdZone);

  EmcalFwd.Accept.SetGenre(Smear::kElectromagnetic);

  det.AddDevice(EmcalFwd);


  // Hadronic  Calorimeters

  // ----------------------

  // Note: kHadronic == |pdg|>110.


  // Back

  // eta = -3.5 -- -1

  // E>500 MeV  not used because it suppresses smeared-up particles

  // (Better resolution required more space and R&D)

  // stoch. = 50%, const = 10%

  Smear::Acceptance::Zone HcalBackZone(ThetaFromEta ( -1 ),ThetaFromEta ( -3.5 ) );

  Smear::Device HcalBack(Smear::kE, "sqrt(pow( 0.1*E, 2) + pow ( 0.5,2) *E)");

  HcalBack.Accept.AddZone(HcalBackZone);

  HcalBack.Accept.SetGenre(Smear::kHadronic);

  det.AddDevice(HcalBack);


  // Barrel

  // eta = -1 -- 1

  // E>500 MeV  not used because it suppresses smeared-up particles

  // stoch. = 100%, const = 10%

  Smear::Acceptance::Zone HcalBarrelZone(ThetaFromEta ( 1 ),ThetaFromEta ( -1 ) ); // E

  Smear::Device HcalBarrel(Smear::kE, "sqrt( pow( 0.1*E, 2) + pow( 1.0, 2)*E)");

  HcalBarrel.Accept.AddZone(HcalBarrelZone);

  HcalBarrel.Accept.SetGenre(Smear::kHadronic);

  det.AddDevice(HcalBarrel);


  // Forward

  // eta = 1 -- 3.5

  // E>500 MeV not used because it suppresses smeared-up particles

  // stoch. = 50%, const = 10%

  // "(35%/sqrtE not achievable)"

  Smear::Acceptance::Zone HcalFwdZone(ThetaFromEta ( 3.5 ),ThetaFromEta ( 1 ));

  Smear::Device HcalFwd(Smear::kE, "sqrt(pow( 0.1*E, 2) + pow ( 0.5,2) *E)");

  HcalFwd.Accept.AddZone(HcalFwdZone);

  HcalFwd.Accept.SetGenre(Smear::kHadronic);

  det.AddDevice(HcalFwd);


  // Not covered:

  // Tracker material budget X/X0 <~5%

  // Tracker pointing resolution

  // Low-Q^2 tagger: -6.9<eta<-5.8: Delta_theta/theta < 1.5%; 10^-6 < Q2 < 10^-2 GeV2

  // Proton spectrometer:  eta>6.2: sigma_intrinsic(|t|)/|t| < 1%; Acceptance: 0.2 < pT < 1.2 GeV/c

  // Barrel vertexing: sigma_xyz ~ 20 microns, d0(z) ~ d0(r phi) ~ (20 microns)/(pT [GeV])  + 5 microns

  // Central muon detection


  return det;

}


// -------------------------------------------------------------------

double ThetaFromEta( const double eta ) {

  if ( !std::isnan(eta) && !std::isinf(eta)   ) {

    return 2.0 * atan( exp( -eta ));

  }

  throw std::runtime_error("ThetaFromEta called with NaN or Inf");

  return -1;

}