CachedShowerRegeneratorOG/LogGaussSmearing.h

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#ifndef _CachedShowerRegeneratorOG_LogGaussSmearing_h_
#define _CachedShowerRegeneratorOG_LogGaussSmearing_h_

#include <CLHEP/Random/RandGauss.h>

#include <utl/Point.h>
#include <utl/Vector.h>
#include <utl/CoordinateSystemPtr.h>
#include <utl/TimeStamp.h>
#include <utl/TimeInterval.h>
#include <utl/RandomEngine.h>


namespace CachedShowerRegeneratorOG {

  class LogGaussSmearing {
  public:
    LogGaussSmearing(const double width, utl::RandomEngine::RandomEngineType* const engine)
      : fWidth(width), fRandomEngine(engine) { }

    double
    GetSmearedTime(const double planeFrontTime, const double particleTime)
      const
    {
      if (particleTime > planeFrontTime) {
        // particle is trailling the plane front, smear between the two
        const double fact = exp(fWidth * CLHEP::RandGauss::shoot(fRandomEngine));
        return planeFrontTime * (1 - fact) + particleTime * fact;
      }
      return particleTime;
    }

  private:
    const double fWidth;
    utl::RandomEngine::RandomEngineType* const fRandomEngine;
  };

}


#endif