KVParticle.cpp

/***************************************************************************
$Id: KVParticle.cpp,v 1.50 2009/04/28 08:59:05 franklan Exp $
                          kvparticle.cpp  -  description
                             -------------------
    begin                : Sun May 19 2002
    copyright            : (C) 2002 by J.D. Frankland
    email                : frankland@ganil.fr
 ***************************************************************************/
 
/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
#include "TMath.h"
#include "Riostream.h"
#include "KVPosition.h"
#include "KVParticle.h"
#include "KVList.h"
#include "TRotation.h"
#include "TLorentzRotation.h"
#include "TObjString.h"
#include "TClass.h"
#include "KVKinematicalFrame.h"
 
Double_t KVParticle::kSpeedOfLight = TMath::C() * 1.e-07;
 
using namespace std;
 
ClassImp(KVParticle)
 
 
 
 
 
KVParticle::KVParticle() : fParameters("ParticleParameters", "Parameters associated with a particle in an event")
{
   init();
}
 
 
 
 
void KVParticle::init()
{
   //default initialisation
   fE0 = nullptr;
   SetFrameName("");
   fGroups.SetOwner(kTRUE);
}
 
 
 
 
KVParticle::KVParticle(const KVParticle& obj) : TLorentzVector()
{
   //copy ctor
   init();
#if ROOT_VERSION_CODE >= ROOT_VERSION(3,4,0)
   obj.Copy(*this);
#else
   ((KVParticle&) obj).Copy(*this);
#endif
}
 
 
 
 
KVParticle::KVParticle(Double_t m, const TVector3& p) : fParameters("ParticleParameters", "Parameters associated with a particle in an event")
{
   //create particle with given mass and momentum vector
   init();
   SetMass(m);
   SetMomentum(p);
}
 
 
 
 
KVParticle::KVParticle(Double_t m, Double_t px, Double_t py, Double_t pz) : fParameters("ParticleParameters", "Parameters associated with a particle in an event")
{
   //create particle with given mass and momentum vector
   init();
   SetMass(m);
   SetMomentum(px, py, pz);
}
 
 
 
 
KVParticle::~KVParticle()
{
   //Info("~KVParticle","%p",this);
   Clear();
}
 
 
 
 
Double_t KVParticle::C()
{
   //Static function.
   //Returns speed of light in cm/ns units.
   return kSpeedOfLight;
}
 
 
 
 
void KVParticle::SetRandomMomentum(Double_t T, Double_t thmin,
                                   Double_t thmax, Double_t phmin,
                                   Double_t phmax, Option_t* opt)
{
   //Give randomly directed momentum to particle with kinetic energy T
   //Direction will be between (thmin,thmax) [degrees] limits in polar angle,
   //and (phmin,phmax) [degrees] limits in azimuthal angle.
   //
   //If opt = "" or "isotropic" (default) : direction is isotropically distributed over the solid angle
   //If opt = "random"                    : direction is randomly distributed over solid angle
   //
   //Based on KVPosition::GetRandomDirection().
 
   Double_t p = (T + M()) * (T + M()) - M2();
   if (p > 0.)
      p = (TMath::Sqrt(p));     // calculate momentum
   else
      p = 0.;
 
   TVector3 dir;
   KVPosition pos(thmin, thmax, phmin, phmax);
   dir = pos.GetRandomDirection(opt);   // get isotropic unit vector dir
   if (p && dir.Mag())
      dir.SetMag(p);            // set magnitude of vector to momentum required
   SetMomentum(dir);            // set momentum 4-vector
}
 
 
 
 
void KVParticle::SetMomentum(Double_t T, const TVector3& dir)
{
   //set momentum with kinetic energy t and unit direction vector d
   //(d is normalised first in case it is not a unit vector)
 
   Double_t p = (T + M()) * (T + M()) - M2();
   TVector3 pdir;
   TVector3 unit_dir = dir.Unit();
   if (p > 0.) {
      p = (TMath::Sqrt(p));
      pdir = p * unit_dir;
   }
   SetMomentum(pdir);
};
 
 
 
 
void KVParticle::print_frames(TString fmt) const
{
   // recursive print out of all defined kinematical frames
 
   fmt += "\t";
   if (fBoosted.GetEntries()) {
      TIter next(&fBoosted);
      KVKinematicalFrame* frame;
      while ((frame = (KVKinematicalFrame*)next())) {
         cout << fmt << " " << frame->GetName() << ": ";
         KVParticle* part = frame->GetParticle();
         cout << " Theta=" << part->GetTheta() << " Phi=" << part->GetPhi()
              << " KE=" << part->GetKE() << " Vpar=" << part->GetVpar() << endl;
         part->print_frames(fmt);
      }
   }
}
 
 
 
 
void KVParticle::Print(Option_t*) const
{
   // print out characteristics of particle
 
   cout << "KVParticle mass=" << M() <<
        " Theta=" << GetTheta() << " Phi=" << GetPhi()
        << " KE=" << GetKE() << " Vpar=" << GetVpar() << endl;
   print_frames();
   GetParameters()->Print();
}
 
 
 
 
void KVParticle::SetKE(Double_t ecin)
{
   //Change particle KE, keeping momentum direction constant
   //If momentum is zero (i.e. no direction defined) the particle will be given
   //a velocity in the positive z-direction
 
   if (ecin > 0.) {
      Double_t et = M() + ecin; // new total energy = KE + m
      Double_t pmod = 0;
      if (et * et > M2()) {
         pmod = TMath::Sqrt(et * et - M2());    // p**2 = E**2 - m**2
         TVector3 newp(Px(), Py(), Pz());
         if (pmod && newp.Mag()) {
            newp.SetMag(pmod);
         }
         else {
            newp.SetXYZ(0, 0, 1);
            newp.SetMag(pmod);
         }
         SetMomentum(newp);
      }
      else {
         SetMomentum(0., 0., 0.);
      }
   }
   else
      SetMomentum(0., 0., 0.);
}
 
 
#if ROOT_VERSION_CODE >= ROOT_VERSION(3,4,0)
 
 
void KVParticle::Copy(TObject& obj) const
#else
void KVParticle::Copy(TObject& obj)
#endif
{
   // Copy this to obj
   // Particle kinematics are copied using operator=(const KVParticle&)
   // List of particle's groups is copied
   // The particle's name is copied
   // The list of parameters associated with the particle is copied
 
   ((KVParticle&) obj) = *this;
   if (!fFrameCopyOnly) {
      // do not make a full copy if particle is just a new kinematical frame
      ((KVParticle&) obj).SetGroups(GetGroups());
      ((KVParticle&) obj).SetName(GetName());
      fParameters.Copy(((KVParticle&) obj).fParameters);
   }
}
 
 
 
 
 
void KVParticle::Clear(Option_t*)
{
   //Reset particle properties i.e. before creating/reading a new event
 
   SetXYZM(0., 0., 0., 0.);
   if (fE0) {
      delete fE0;
      fE0 = 0;
   }
   ResetIsOK();                 //in case IsOK() status was set "by hand" in previous event
   GetOriginal()->ResetBit(kIsDetected);
   fParameters.Clear();
   fGroups.Clear();
   fBoosted.Delete();
}
 
 
 
 
Bool_t KVParticle::IsOK() const
{
   //Determine whether this particle is considered "good" or not for analysis,
   //depending on a previous call to SetIsOK(Bool_t flag).
   //If SetIsOK has not been called, IsOK returns kTRUE by default.
 
   if (GetOriginal()->TestBit(kIsOKSet)) {     //status set by SetIsOK()
      return TestBit(kIsOK);
   }
   //Default if SetIsOK not used: accept particle
   return kTRUE;
}
 
 
 
 
 
void KVParticle::SetIsOK(Bool_t flag)
{
   //Set acceptation/rejection status for the particle.
   //
   //In order to 'forget' this status (accept all particles) use ResetIsOK()
 
   GetOriginal()->SetBit(kIsOK, flag);
   GetOriginal()->SetBit(kIsOKSet);
}
 
 
 
 
void KVParticle::ls(Option_t* option) const
{
   std::cout << option << GetName() << ":" << GetFrameName() << ":" << this << "\n";
   if (fBoosted.GetEntries()) {
      TString nopt = option;
      nopt += "   ";
      TIter next(&fBoosted);
      KVKinematicalFrame* p;
      while ((p = (KVKinematicalFrame*)next())) p->GetParticle()->ls(nopt.Data());
   }
}
 
 
 
 
 
KVParticle& KVParticle::operator=(const KVParticle& rhs)
{
   //KVParticle assignment operator.
 
   if (this != &rhs) {
      TLorentzVector::operator=((TLorentzVector&) rhs);
      if (rhs.GetPInitial()) SetE0(rhs.GetPInitial());
   }
   return *this;
}
 
 
 
 
 
void KVParticle::ResetEnergy()
{
   //Used for simulated particles after passage through some absorber/detector.
   //The passage of a particle through the different absorbers modifies its
   //kinetic energies, indeed the particle may be stopped in the detector.
   //Calling this method will reset the particle's momentum to its
   //initial value i.e. before it entered the first absorber.
   //Particles which have not encountered any absorbers/detectors are left as they are.
 
   if (IsDetected())
      SetMomentum(GetPInitial());
}
 
 
 
 
 
void KVParticle::SetName(const Char_t* nom)
{
   //Set Name of the particle
   GetOriginal()->fName.Form("%s", nom);
}
 
 
 
 
const Char_t* KVParticle::GetName() const
{
   // return the field fName
   return GetOriginal()->fName.Data();
}
 
 
 
 
void KVParticle::AddGroup(const Char_t* groupname, const Char_t* from) const
{
   // Associate this particle with the given named group.
   // Optional argument "from" allows to put a condition on the already stored
   // group list, is set to "" by default
 
   TString sfrom(from);
   sfrom.ToUpper();
   TString sgroupname(groupname);
   sgroupname.ToUpper();
 
   if (BelongsToGroup(sfrom.Data()) && !BelongsToGroup(sgroupname.Data())) {
      GetGroups()->Add(new TObjString(sgroupname.Data()));
   }
}
 
 
 
 
void KVParticle::SetGroups(KVUniqueNameList* un)
{
   //Define for the particle a new list of groups
   GetGroups()->Clear();
   AddGroups(un);
}
 
 
 
 
void KVParticle::AddGroups(KVUniqueNameList* un)
{
   //list of groups added to the current one
   TObjString* os = 0;
   TIter no(un);
   while ((os = (TObjString*)no.Next())) {
      AddGroup(os->GetName());
   }
 
}
 
 
 
 
Int_t KVParticle::_GetNumberOfDefinedFrames() const
{
   // \returns the number of kinematical frames defined by transformations of this frame
   //
   // \note this is always at least equal to one (we count the present frame of the particle)
 
   TIter it(GetListOfFrames());
   KVKinematicalFrame* p;
   Int_t nf = 1; // start with the current actual frame
   while ((p = (KVKinematicalFrame*)it())) {
      nf += p->GetParticle()->_GetNumberOfDefinedFrames();
   }
   return nf;
}
 
 
 
 
Bool_t KVParticle::BelongsToGroup(const Char_t* groupname) const
{
   //Check if particle belong to a given group
   //return kTRUE if groupname="".
   //return kFALSE if no group has be defined
 
   TString sgroupname(groupname);
   sgroupname.ToUpper();
   //Important for KVEvent::GetNextParticle()
   if (sgroupname.IsNull()) return kTRUE;
   //retourne kFALSE si aucun groupe n'est defini
   if (!GetNumberOfDefinedGroups()) return kFALSE;
   if (GetGroups()->FindObject(sgroupname.Data())) return kTRUE;
   return kFALSE;
}
 
 
 
 
void KVParticle::RemoveGroup(const Char_t* groupname)
{
   // Remove group from list of groups
   if (!GetGroups()->GetEntries()) return;
   TString sgroupname(groupname);
   sgroupname.ToUpper();
 
   TObjString* os = 0;
   if ((os = (TObjString*)GetGroups()->FindObject(sgroupname.Data()))) delete  GetGroups()->Remove(os);
}
 
 
 
 
void KVParticle::RemoveAllGroups()
{
   //Remove all groups
   GetGroups()->Clear();
}
 
 
 
 
 
void KVParticle::ListGroups(void) const
{
   //List all stored groups
   if (GetGroups()->GetEntries()) {
      cout << "Particle belongs to no groups" << endl;
      return;
   }
   else {
      cout << "----------------------------------------" << endl;
      cout << "List of groups this particle belongs to:" << endl;
      cout << "----------------------------------------" << endl;
   }
   TObjString* os = 0;
   TIter no(GetGroups());
   while ((os = (TObjString*)no.Next())) cout << "\t" << os->GetName() << endl;
   cout << "----------------------------------------" << endl;
}
 
 
 
 
KVParticle KVParticle::InFrame(const KVFrameTransform& t)
{
   // Use this method to obtain 'on-the-fly' some information on particle kinematics
   // in a different reference frame. The default kinematics of the particle are unchanged.
 
   KVParticle p;
   p.Set4Mom(*this);
   KVKinematicalFrame(&p, t);
   return p;
}
 
 
 
 
void KVParticle::ChangeFrame(const KVFrameTransform& t, const KVString& name)
{
   // Permanently modify kinematics of particle according to the given transformation.
   // You can optionally set the name of this new default kinematics.
   // NB the current kinematics will be lost. If you want to keep it after changing the
   // default kinematics, define the new frame with SetFrame and then use ChangeDefaultFrame.
 
   KVKinematicalFrame(this, t);
   if (name != "") SetFrameName(name);
}
 
 
 
 
void KVParticle::ChangeDefaultFrame(const Char_t* newdef, const Char_t* defname)
{
   // Make existing reference frame 'newdef' the new default frame for particle kinematics.
   // The current default frame will then be accessible from the list of frames
   // using its name (if set with SetFrameName).
   //
   // You can change/set the name of the previous default frame with 'defname'.
   // If no name was set and none given, it will be renamed "default" by default.
 
   if (!fFrameName.CompareTo(newdef, TString::kIgnoreCase)) return;//newdef is already the default frame, do nothing
 
   TString _defname(defname);
   if (_defname == "") _defname = GetFrameName();
   if (_defname == "") _defname = "default";
   // get list of all parents of new default
   TList parents;
   TString ff = newdef;
   KVKinematicalFrame* f;
   do {
      f = get_parent_frame(ff);
      if (f) {
         parents.Add(f);
         ff = f->GetName();
      }
   }
   while (f);
   // modify tree structure
   TIter it(&parents);
   KVKinematicalFrame* newdframe = get_frame(newdef);
   KVKinematicalFrame* save_newdef = newdframe;
   KVFrameTransform trans, next_trans = newdframe->GetTransform();
   while ((f = (KVKinematicalFrame*)it())) {
      f->GetParticle()->GetListOfFrames()->Remove(newdframe);
      trans = next_trans;
      next_trans = f->GetTransform();
      newdframe->GetParticle()->GetListOfFrames()->Add(f);
      f->SetTransform(trans.Inverse());
      newdframe = f;
   }
   GetListOfFrames()->Remove(newdframe);
   // copy current default kinematics particle momentum/energy
   TLorentzVector old_def_p(*this);
   // set momentum/energy of new default kinematics
   Set4Mom(*(save_newdef->GetParticle()));
   save_newdef->GetParticle()->Set4Mom(old_def_p);
   save_newdef->SetTransform(next_trans.Inverse());
   save_newdef->SetName(_defname);
   save_newdef->GetParticle()->SetFrameName(_defname);
   newdframe->GetParticle()->GetListOfFrames()->Add(save_newdef);
   // copy frame list from new default frame
   TList frame_list;
   frame_list.AddAll(save_newdef->GetParticle()->GetListOfFrames());
   save_newdef->GetParticle()->GetListOfFrames()->Clear("nodelete");
   save_newdef->GetParticle()->GetListOfFrames()->AddAll(&fBoosted);
   fBoosted.Clear("nodelete");
   fBoosted.AddAll(&frame_list);
   SetFrameName(newdef);
}
 
 
 
 
void KVParticle::SetFrame(const Char_t* frame, const KVFrameTransform& ft)
{
   //Define a Lorentz-boosted and/or rotated frame in which to calculate this particle's momentum and energy.
   //
   //The new frame will have the name given in the string "frame", which can then be used to
   //access the kinematics of the particle in different frames using GetFrame() (frame names are case-insensitive).
   //Calling this method with the name of an existing frame will update the kinematics of the particle
   //in that frame using the given transform (note that kinematics in all frames defined as 'subframes' of
   //this frame will also be updated).
   //
   //USING BOOSTS
   //The boost velocity vector is that of the boosted frame with respect to the original frame of the particles in the event.
   //The velocity vector can be given either in cm/ns units (default) or in units of 'c' (beta=kTRUE).
   //
   //E.g. to define a frame moving at 0.1c in the +ve z-direction with respect to the original
   //event frame:
   //
   //      (...supposing a valid pointer KVParticle* my_part...)
   //      TVector3 vframe(0,0,0.1);
   //      my_part->SetFrame("my_frame", KVFrameTransform(vframe, kTRUE));
   //
   //or with velocity in cm/ns units (default):
   //      TVector3 vframe(0,0,3);
   //      my_part->SetFrame("my_frame", KVFrameTransform(vframe));
   // OR   my_part->SetFrame("my_frame", vframe);
   //
   //USING ROTATIONS
   //According to the conventions adopted for the TRotation and TLorentzRotation classes,
   //we actually use the inverse of the TLorentzRotation to make the transformation,
   //to get the coordinates corresponding to a rotated coordinate system, not the coordinates
   //of a rotated vector in the same coordinate system
   //=> you do not need to invert the transformation matrix
   //
   //E.g. if you want to define a new frame whose coordinate axes are rotated with respect
   //to the original axes, you can set up a TRotation like so:
   //
   //      TRotation rot;
   //      TVector3 newX, newY, newZ; // the new coordinate axes
   //      rot.RotateAxes(newX, newY, newZ);
   //
   //If you are using one of the two global variables which calculate the event tensor
   //(KVTensP and KVTensPCM) you can obtain the transformation to the tensor frame
   //using:
   //
   //      TRotation rot;
   //      KVTensP* tens_gv;// pointer to tensor global variable
   //      tens_gv->GetTensor()->GetRotation(rot);// see KVTenseur3::GetRotation
   //
   //Then the new frame can be defined by
   //      my_part->SetFrame("my_frame", KVFrameTransform(rot));
   //  OR  my_part->SetFrame("my_frame", rot);
   //
   //USING COMBINED BOOST AND ROTATION
   //You can define a frame using both a boost and a rotation like so:
   //      my_part->SetFrame("my_frame", KVFrameTransform(vframe,rot,kTRUE));
   //
   //ACCESSING KINEMATICS IN NEW FRAMES
   //In order to access the kinematics of the particle in the new frame:
   //
   //      my_part->GetFrame("my_frame")->GetTransverseEnergy();// transverse energy in "my_frame"
 
   if (!strcmp(frame, "")) return;
 
   if (!fFrameName.CompareTo(frame, TString::kIgnoreCase)) {
      // 'frame' is name of current default kinematics, therefore we do not want to add a new frame
      // (which would have the same name as the current default, and the two would coexist),
      // we want to change the kinematics of the current frame
      ChangeFrame(ft);
      return;
   }
 
   KVKinematicalFrame* tmp = GetTopmostParentFrame()->get_frame(frame);
   if (!tmp) {
      //if this frame has not already been defined, create a new one
      tmp = new KVKinematicalFrame(frame, this, ft);
      fBoosted.Add(tmp);
      tmp->GetParticle()->SetOriginal(GetOriginal());
   }
   else
      tmp->ApplyTransform(this, ft);
}
 
 
 
 
KVParticle const* KVParticle::GetFrame(const Char_t* frame, Bool_t warn_and_return_null_if_unknown) const
{
   // Return the momentum of the particle in the Lorentz-boosted frame corresponding to the name
   // "frame" given as argument (see SetFrame() for definition of different frames).
   // If the default frame name has been set (see KVEvent::SetFrameName) and 'frame' is the
   // name of this default frame (KVParticle::fFrameName), we return the address of the particle
   // itself.
   //
   // This frame may have been defined by a direct transformation of the original kinematics of the
   // particle (using SetFrame(newframe,...)) or by a transformation of the kinematics in another
   // user-defined frame (using SetFrame(newframe,oldframe,...)).
   //
   // Note that frames are not "dynamic": if any changes are made to the original particle's kinematics
   // after definition of a frame, if you want these changes to affect also the other frames you
   // need to update them by hand by calling KVParticle::UpdateAllFrames().
   //
   // Frame names are case insensitive: "CM" or "cm" or "Cm" are all good...
   //
   // By default, if no frame with the given name is found, we return nullptr and print a warning.
   // If `warn_and_return_null_if_unknown=kFALSE`, we return the address of the particle itself,
   // i.e. the original/default kinematics.
   // [Note that this is an inversion of the previous default behaviour]
   //
   // Note that the properties of the particle returned by this method can not be modified:
   //    this is deliberate, as any modifications e.g. to kinematics will have no effect
   //    in any other frames.
   //
   // The returned pointer corresponds to a "pseudoparticle" in the desired frame,
   // therefore you can use any KVParticle method in order to access the kinematics of the
   // particle in the boosted frame, e.g.
   //
   //~~~~~~~~~~~~~~~~~~~~
   //      (...supposing a valid pointer KVParticle* my_part...)
   //      my_part->GetFrame("cm_frame")->GetVpar();// //el velocity in "cm_frame"
   //      my_part->GetFrame("QP_frame")->GetTheta();// polar angle in "QP_frame"
   //      etc. etc.
   //~~~~~~~~~~~~~~~~~~~~
   //
 
   if (!fFrameName.CompareTo(frame, TString::kIgnoreCase)) return (KVParticle const*)this;
   KVKinematicalFrame* f = GetTopmostParentFrame()->get_frame(frame);
   return f ? (KVParticle const*)f->GetParticle() :
          (warn_and_return_null_if_unknown ?
           Warning("GetFrame(const Char_t*)", "No frame \"%s\" defined for particle. 0x0 returned.",
#ifndef WITH_CPP11
                   frame), (KVParticle*)nullptr
#else
                   frame), nullptr
#endif
           : this);
}
 
 
 
 
void KVParticle::UpdateAllFrames()
{
   // Call this method to update particle kinematics in all defined frames if you change
   // the kinematics of the particle in its original/default frame.
 
   if (fBoosted.GetEntries()) {
      TIter it(&fBoosted);
      KVKinematicalFrame* f;
      while ((f = (KVKinematicalFrame*)it())) {
         f->ReapplyTransform(this);
         // recursively apply to all subframes
         f->GetParticle()->UpdateAllFrames();
      }
   }
}
 
 
 
 
KVKinematicalFrame* KVParticle::get_frame(const Char_t* frame) const
{
   // \param[in] frame name of a kinematical frame
   // \returns pointer to the kinematical frame if previously defined, nullptr otherwise
   //
   // \note PRIVATE method for internal use only. This method allows to modify the returned frame, i.e. in order to define new frames in SetFrame()
 
   if (!fBoosted.GetEntries() || !strcmp(frame, "")) {
      // no frames defined or no frame name given
      return nullptr;
   }
   TString _frame(frame);
   TIter it(&fBoosted);
   KVKinematicalFrame* p(nullptr), *f(nullptr);
   while ((p = f = (KVKinematicalFrame*)it())) {
      if (!_frame.CompareTo(p->GetName(), TString::kIgnoreCase)) break;
      // look for subframe
      if ((f = p->GetParticle()->get_frame(_frame))) break;
   }
   return f;
}
 
 
 
 
KVKinematicalFrame* KVParticle::get_parent_frame(const Char_t* f, KVKinematicalFrame* F) const
{
   // PRIVATE method for internal use only
   // Returns pointer to parent frame of 'f'
   if (!fBoosted.GetEntries() || !strcmp(f, "")) {
      // no frames defined or no frame name given
      return nullptr;
   }
   TString _frame(f);
   TIter it(&fBoosted);
   KVKinematicalFrame* p(nullptr), *r(nullptr);
   while ((p = (KVKinematicalFrame*)it())) {
      if (!_frame.CompareTo(p->GetName(), TString::kIgnoreCase)) return F;
      // look for subframe
      if ((r = p->GetParticle()->get_parent_frame(_frame, p))) return r;
   }
   return nullptr;
}
 
 
 
 
 
 
void KVParticle::SetFrame(const Char_t* newframe, const Char_t* oldframe, const KVFrameTransform& ft)
{
   // Define new kinematical frame by transformation from existing frame
   // See SetFrame(const Char_t*,const KVFrameTransform&) for details on
   // defining kinematically-transformed frames.
 
   if (!fFrameName.CompareTo(oldframe, TString::kIgnoreCase)) {
      // 'oldframe' is name of current default kinematics, therefore this is same as
      // calling SetFrame(newframe,ft)
      SetFrame(newframe, ft);
      return;
   }
 
   KVKinematicalFrame* f = GetTopmostParentFrame()->get_frame(oldframe);
   if (!f) {
      Error("SetFrame(newframe,oldframe)", "oldframe=%s does not exist!", oldframe);
      return;
   }
   f->GetParticle()->SetFrame(newframe, ft);
}
 
 
 
 
 
TVector3 KVParticle::GetVelocity() const
{
   //returns velocity vector in cm/ns units
   TVector3 beta;
   if (E()) {
      beta = GetMomentum() * (1. / E());
   }
   else {
      beta.SetXYZ(0, 0, 0);
   }
   return (kSpeedOfLight * beta);
}
 
 
 
 
 
Double_t KVParticle::GetVperp() const
{
   //returns transverse velocity in cm/ns units
   //sign is +ve if py>=0, -ve if py<0
   return (GetV().y() >= 0.0 ? GetV().Perp() : -(GetV().Perp()));
}
 
 
 
 
 
void KVParticle::SetMomentum(Double_t px, Double_t py, Double_t pz,
                             Option_t* opt)
{
   // Set Momentum components (in MeV/c)
   // if option is "cart" or "cartesian" we give cartesian components (x,y,z)
   // if option is "spher" or "spherical" we give components (rho,theta,phi) in spherical system
   //   with theta, phi in DEGREES
   if (!strcmp("spher", opt) || !strcmp("spherical", opt)) {
      TVector3 pvec(0., 0., 1.);
      pvec.SetMag(px);
      pvec.SetTheta(TMath::Pi() * py / 180.);
      pvec.SetPhi(TMath::Pi() * pz / 180.);
      SetVectM(pvec, M());
   }
   else {
      if (strcmp("cart", opt) && strcmp("cartesian", opt)) {
         Warning("SetMomentum(Double_t,Double_t,Double_t,Option_t*)",
                 "Unkown coordinate system\n known system are :\n\t\"cartesian\" or \"cart\" (default)\n\t\"spherical\" or \"spher\"");
         Warning("SetMomentum(Double_t,Double_t,Double_t,Option_t*)",
                 "default used.");
      }
      TVector3 pvec(px, py, pz);
      SetVectM(pvec, M());
   }
}
 
 
 
 
void KVParticle::SetVelocity(const TVector3& vel)
{
   // Set velocity of particle (in cm/ns units)
   Double_t gamma = 1. / kSpeedOfLight / sqrt(1 - (vel.Mag2() / pow(kSpeedOfLight, 2)));
   TVector3 p = GetMass() * gamma * vel;
   SetMomentum(p);
}
 
 
 
 
void KVParticle::Streamer(TBuffer& R__b)
{
   // Stream an object of class KVParticle.
   // When reading: If parameter "frameName" is set, use it to set non-persistent
   // fFrameName member (used by GetFrame)
 
   if (R__b.IsReading()) {
      R__b.ReadClassBuffer(KVParticle::Class(), this);
      if (GetParameters()->HasStringParameter("frameName")) fFrameName = GetParameters()->GetStringValue("frameName");
   }
   else {
      R__b.WriteClassBuffer(KVParticle::Class(), this);
   }
}
 
 
 
 
void KVParticle::FrameList::Add(TObject* f)
{
   // When a kinematical frame is added, this particle becomes the parent frame
   dynamic_cast<KVKinematicalFrame*>(f)->GetParticle()->SetParentFrame(parent);
   KVList::Add(f);
}
 
 
 
 
TObject* KVParticle::FrameList::Remove(TObject* f)
{
   // When a kinematical frame is removed, this particle is no longer the parent frame
   if (KVList::Remove(f) == f) {
      auto _f = dynamic_cast<KVKinematicalFrame*>(f);
      if (_f->GetParticle()->GetParentFrame() == parent) {
         _f->GetParticle()->SetParentFrame(nullptr);
      }
      return f;
   }
   return nullptr;
}
 
 
 
 
void KVParticle::FrameList::Clear(Option_t* opt)
{
   // When the frame list is cleared, this particle is no longer the parent of any frames in the list
   TIter it(this);
   KVKinematicalFrame* f;
   while ((f = (KVKinematicalFrame*)it())) {
      if (f->GetParticle()->GetParentFrame() == parent) {
         f->GetParticle()->SetParentFrame(nullptr);
      }
   }
   KVList::Clear(opt);
}
 
 
 
 
void KVParticle::FrameList::AddAll(const TCollection* l)
{
   // When all frames in a list are added to this one, this particle becomes the parent of all frames in the list
   TIter it(l);
   KVKinematicalFrame* f;
   while ((f = (KVKinematicalFrame*)it())) {
      f->GetParticle()->SetParentFrame(parent);
   }
   KVList::AddAll(l);
}