i have re-done the monte carlo analysis for the momentum lost by protons
and deuterons in making their way from the target cell to the exit plane
of the outermost wire chamber. since energy loss has not yet been
explicitly added to the reconstruction, a monte carlo model is the
best that we can do right now.
i checked the momentum loss dependence on all four kinematic parameters
(i.e. p, theta, phi, and z). only p and theta showed non-negligible
dependence (see the attached plots).
for those of you who would like to take momentum loss into account in
your analysis, i have written two macros (one for protons, one for
deuterons) to do so. they are both listed below. the macros are short,
easy to read, and ready to be directly put into your analysis codes
without any further modification whatsoever.
aaron
Float_t ProtonMomentumLoss(Float_t p,Float_t theta){
//*********************************************************************
//* Returns the momentum lost (in [GeV]) by a proton in passing from *
//* the target cell to the exit plane of the outer-most wire chamber *
//* *
//* Arguments: *
//* p : reconstructed proton momentum in [GeV] *
//* theta : polar angle of reconstructed proton momentum in the *
//* BLAST coordinate system in [deg] *
//*********************************************************************
const Float_t PLOW=0.135;
const Float_t PUPP=1.000;
const Int_t NUMDIVSTHETA=7;
const Float_t THETALOW=15.0;
const Float_t THETAUPP=85.0;
const Float_t C[NUMDIVSTHETA][9]=
{{+2.525887e-01,-2.463591e+00,+1.109465e+01,-2.902014e+01,+4.737158e+01,
-4.889279e+01,+3.092569e+01,-1.088934e+01,+1.622587e+00},
{+2.467519e-01,-2.586977e+00,+1.255536e+01,-3.550835e+01,+6.294246e+01,
-7.098161e+01,+4.949543e+01,-1.946127e+01,+3.299227e+00},
{+2.470371e-01,-2.782622e+00,+1.457769e+01,-4.467991e+01,+8.609354e+01,
-1.057935e+02,+8.054456e+01,-3.464091e+01,+6.435032e+00},
{+2.377869e-01,-2.742439e+00,+1.467808e+01,-4.586923e+01,+8.994726e+01,
-1.122878e+02,+8.671446e+01,-3.777704e+01,+7.099781e+00},
{+2.250083e-01,-2.584070e+00,+1.372053e+01,-4.242290e+01,+8.215929e+01,
-1.011799e+02,+7.703141e+01,-3.307514e+01,+6.126511e+00},
{+2.226852e-01,-2.578033e+00,+1.379630e+01,-4.299399e+01,+8.392735e+01,
-1.041823e+02,+7.994897e+01,-3.459866e+01,+6.458445e+00},
{+2.219288e-01,-2.600811e+00,+1.412805e+01,-4.477074e+01,+8.894891e+01,
-1.124014e+02,+8.778393e+01,-3.864007e+01,+7.330892e+00}};
Int_t thetaIndice=
Int_t(NUMDIVSTHETA*(theta-THETALOW)/((THETAUPP-THETALOW)));
if(p<PLOW) p=PLOW;
else if(p>PUPP) p=PUPP;
if(thetaIndice<0) thetaIndice=0;
else if(thetaIndice>=NUMDIVSTHETA) thetaIndice=NUMDIVSTHETA-1;
return(C[thetaIndice][0]+C[thetaIndice][1]*p+C[thetaIndice][2]*p*p
+C[thetaIndice][3]*p*p*p+C[thetaIndice][4]*p*p*p*p
+C[thetaIndice][5]*p*p*p*p*p+C[thetaIndice][6]*p*p*p*p*p*p
+C[thetaIndice][7]*p*p*p*p*p*p*p+C[thetaIndice][8]*p*p*p*p*p*p*p*p);
}
Float_t DeuteronMomentumLoss(Float_t p,Float_t theta){
//*********************************************************************
//* Returns the momentum lost (in [GeV]) by a deuteron in passing *
//* from the target cell to the exit plane of the outer-most wire *
//* chamber *
//* *
//* Arguments: *
//* p : reconstructed proton momentum in [GeV] *
//* theta : polar angle of reconstructed proton momentum in the *
//* BLAST coordinate system in [deg] *
//*********************************************************************
const Float_t PLOW=0.195;
const Float_t PUPP=1.000;
const Int_t NUMDIVSTHETA=7;
const Float_t THETALOW=15.0;
const Float_t THETAUPP=85.0;
const Float_t C[NUMDIVSTHETA][9]=
{{-1.809151e-01,+6.310025e+00,-4.794185e+01,+1.786171e+02,-3.884445e+02,
+5.186335e+02,-4.198597e+02,+1.895051e+02,-3.663460e+01},
{+4.858613e-01,-3.317892e+00,+9.801995e+00,-1.313674e+01,-2.502832e-01,
+2.650557e+01,-3.757053e+01,+2.288091e+01,-5.395364e+00},
{+7.957955e-01,-8.346428e+00,+4.296252e+01,-1.331760e+02,+2.630077e+02,
-3.329085e+02,+2.613282e+02,-1.157758e+02,+2.211583e+01},
{+2.973238e-01,-1.308478e+00,-1.976850e-01,+1.517645e+01,-4.863401e+01,
+7.664054e+01,-6.768753e+01,+3.210503e+01,-6.388907e+00},
{+1.227123e-01,+1.082067e+00,-1.457410e+01,+6.379820e+01,-1.492508e+02,
+2.069895e+02,-1.709908e+02,+7.794567e+01,-1.511996e+01},
{+2.906743e-01,-1.360304e+00,+3.116820e-01,+1.351816e+01,-4.580120e+01,
+7.386021e+01,-6.613844e+01,+3.166455e+01,-6.342882e+00},
{+2.983323e-01,-1.480130e+00,+9.941900e-01,+1.149800e+01,-4.235965e+01,
+7.045492e+01,-6.431991e+01,+3.126104e+01,-6.344395e+00}};
Int_t thetaIndice=
Int_t(NUMDIVSTHETA*(theta-THETALOW)/((THETAUPP-THETALOW)));
if(p<PLOW) p=PLOW;
else if(p>PUPP) p=PUPP;
if(thetaIndice<0) thetaIndice=0;
else if(thetaIndice>=NUMDIVSTHETA) thetaIndice=NUMDIVSTHETA-1;
return(C[thetaIndice][0]+C[thetaIndice][1]*p+C[thetaIndice][2]*p*p
+C[thetaIndice][3]*p*p*p+C[thetaIndice][4]*p*p*p*p
+C[thetaIndice][5]*p*p*p*p*p+C[thetaIndice][6]*p*p*p*p*p*p
+C[thetaIndice][7]*p*p*p*p*p*p*p+C[thetaIndice][8]*p*p*p*p*p*p*p*p);
}
This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:32 EST