LHCConstants.h

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// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
 
 
#ifndef ALICEO2_LHCCONSTANTS_H_
#define ALICEO2_LHCCONSTANTS_H_
 
namespace o2
{
namespace constants
{
namespace lhc
{
// LHC Beam1 and Beam2 definitions
enum BeamDirection : int { BeamA, // beamA = beam 0,
                           BeamC, // beamC = beam 1
                           NBeamDirections,
                           InteractingBC = -1 // as used in the BunchFilling class
};
constexpr int LHCMaxBunches = 3564;                              // max N bunches
constexpr double LHCRFFreq = 400.789e6;                          // LHC RF frequency in Hz
constexpr double LHCBunchSpacingNS = 10 * 1.e9 / LHCRFFreq;      // bunch spacing in ns (10 RFbuckets)
constexpr double LHCOrbitNS = LHCMaxBunches * LHCBunchSpacingNS; // orbit duration in ns
constexpr double LHCRevFreq = 1.e9 / LHCOrbitNS;                 // revolution frequency
constexpr double LHCBunchSpacingMUS = LHCBunchSpacingNS * 1e-3;  // bunch spacing in \mus (10 RFbuckets)
constexpr double LHCOrbitMUS = LHCOrbitNS * 1e-3;                // orbit duration in \mus
constexpr unsigned int MaxNOrbits = 0xffffffff;
 
// Offsets of A, C beam bunches at P2
constexpr int BunchOffsetsP2[2] = {344, 3017};
 
// convert LHC bunch ID to BC for 2 beam directions
constexpr int LHCBunch2P2BC(int bunch, BeamDirection dir)
{
  return (bunch + BunchOffsetsP2[int(dir)]) % LHCMaxBunches;
}
 
// convert BC at P2 to LHC bunch ID for 2 beam directions
constexpr int P2BC2LHCBunch(int bc, BeamDirection dir)
{
  int bunch = bc - BunchOffsetsP2[int(dir)];
  return bunch < 0 ? bunch + LHCMaxBunches : bunch;
}
 
} // namespace lhc
} // namespace constants
} // namespace o2
 
#endif