///////////////////////////////////////////////////////////////////////////////
// //
// Time Projection Chamber version 2 -- detailed TPC and slow simulation //
// //
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/*
*/
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// //
// //
///////////////////////////////////////////////////////////////////////////////
#include
#include "AliTPCv2.h"
#include "AliTPCD.h"
#include "AliRun.h"
#include "AliConst.h"
ClassImp(AliTPCv2)
//_____________________________________________________________________________
AliTPCv2::AliTPCv2(const char *name, const char *title) :
AliTPC(name, title)
{
//
// Standard constructor for Time Projection Chamber version 2
//
fIdSens1=0;
fIdSens2=0;
SetBufferSize(128000);
}
//_____________________________________________________________________________
void AliTPCv2::CreateGeometry()
{
//
// Create the geometry of Time Projection Chamber version 2
//
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/*
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AliMC* pMC = AliMC::GetMC();
Int_t *idtmed = fIdtmed->GetArray()-399;
AliTPCParam * fTPCParam = &(fDigParam->GetParam());
Float_t tana;
Int_t isll;
Float_t rlsl, wlsl, rssl, rlsu, wssl, wlsu, rssu, wssu;
Int_t i;
Float_t alpha, x, y, z, sec_thick;
Float_t r1, r2, x1, z0, z1, x2, theta1, theta2, theta3, dm[21];
Int_t il, iu;
Float_t z_side, zz;
Int_t idrotm[100];
Float_t x0l, x0u;
Int_t idr;
Float_t thl, opl;
Int_t ils, iss;
Float_t thu, opu;
Int_t ifl1 = 0, ifl2 = 0;
Float_t phi1, phi2, phi3;
// ---------------------------------------------------
// sector specification check
// ---------------------------------------------------
if (fSecAL >= 0) {
ifl1 = 0;
for (i = 0; i < 6; ++i) {
if (fSecLows[i] > 0 && fSecLows[i] <25) {
ifl1 = 1;
printf("*** SECTOR %d selected\n",fSecLows[i]);
}
}
} else {
printf("*** ALL LOWER SECTORS SELECTED ***\n");
ifl1 = 1;
}
if (fSecAU >= 0) {
ifl2 = 0;
for (i = 0; i < 12; ++i) {
if (fSecUps[i] > 24 && fSecUps[i] < 73) {
ifl2 = 1;
printf("*** SECTOR %d selected\n",fSecUps[i]);
}
}
} else {
printf("*** ALL UPPER SECTORS SELECTED ***\n");
ifl1 = 1;
}
if (ifl1 == 0 && ifl2 == 0) {
printf("*** ERROR: AT LEAST ONE SECTOR MUST BE SPECIFIED ***\n");
printf("!!! PROGRAM STOPPED !!!\n");
exit(1);
}
if ((fSecAL < 0 || fSecAU < 0) && fSens >= 0) {
printf("** ERROR: STRIPS CANNOT BE SPECIFIED FOR ALL SECTORS **\n");
printf("!!! PROGRAM STOPPED !!!\n");
exit(1);
}
// ----------------------------------------------------
// FIELD CAGE WITH ENDCAPS - CARBON FIBER
// THIS IS ALSO A TPC MOTHER VOLUME
// ----------------------------------------------------
dm[0] = 76.;
dm[1] = 278.;
dm[2] = 275.;
pMC->Gsvolu("TPC ", "TUBE", idtmed[407], dm, 3);
// -------------------------------------------------------
// drift gas Ne/CO2 (90/10 volume) - nonsensitive
// field cage thickness = 0.52% X0
// ----------------------------------------------------
dm[0] = 76.+0.09776;
dm[1] = 257.;
dm[2] = 250.;
pMC->Gsvolu("TGAS", "TUBE", idtmed[402], dm, 3);
// ------------------------------------------------------
// "side" gas volume (the same as drift gas),
// here the readout chambers are positioned
// ------------------------------------------------------
dm[2] = 0.5*(275.-250.);
z_side = dm[2];
pMC->Gsvolu("TPSG", "TUBE", idtmed[401], dm, 3);
// ------------------------------------------------------
// HV midplane - 20 microns of mylar
// -----------------------------------------------------
dm[2] = .001;
pMC->Gsvolu("TPHV", "TUBE", idtmed[405], dm, 3);
// ====================================================
// lower and upper readout chambers
// ====================================================
// sectros opening angles in degrees
// ---------------------------------------------------
opl = 30.;
opu = 15.;
thl = TMath::Tan(opl * .5 * kDegrad);
thu = TMath::Tan(opu * .5 * kDegrad);
// ---------------------------------------------------
// S and L-sectors radii
// ---------------------------------------------------
rssl = 88.;
rssu = 136.;
rlsl = 142.;
rlsu = 250.;
// --------------------------------------------------
// Sectors widths
// --------------------------------------------------
wssl = 46.5;
wssu = 72.2;
wlsl = 37.;
wlsu = 65.4;
// ---------------------------------------------------
// Sector thickness 25% of X0 (Al)
// ---------------------------------------------------
sec_thick = 2.225;
// ---------------------------------------------------
// S-sectors (lower sectors)
// ---------------------------------------------------
dm[0] = wssl * .5;
dm[1] = wssu * .5;
dm[2] = sec_thick * .5;
dm[3] = (rssu - rssl) * .5;
x0l = rssl + dm[3];
pMC->Gsvolu("TRCS", "TRD1", idtmed[399], dm, 4);
// -----------------------------------------------------
// S-sectors --> "gas sectors" - sensitive
// -----------------------------------------------------
dm[2] = (250.-0.001)/2.;
pMC->Gsvolu("TSGA", "TRD1", idtmed[403], dm, 4);
// -------------------------------------------------------------
// Only for the debugging purpose and resolution calculation
// Sensitive strips at the pad-row center
// -------------------------------------------------------------
if (fSens >= 0) {
pMC->Gsvolu("TSST", "TRD1", idtmed[403], dm, 0);
dm[3] = .005;
z0 = rssl + (rssu - rssl) * .5;
for (iss = 0; iss < fTPCParam->GetNRowLow(); ++iss) {
r1 = fTPCParam->GetPadRowRadiiLow(iss);
r2 = r1 + dm[3] * 2.;
dm[0] = r1 * thl - 2.63;
dm[1] = r2 * thl - 2.63;
zz = -z0 + r1 +dm[3];
pMC->Gsposp("TSST", iss+1, "TSGA", 0, 0, zz, 0, "ONLY", dm, 4);
}
pMC->Gsord("TSGA", 3);
}
// ---------------------------------------------------
// L-sectors (upper sectors)
// ---------------------------------------------------
dm[0] = wlsl * .5;
dm[1] = wlsu * .5;
dm[2] = sec_thick * .5;
dm[3] = (rlsu - rlsl) * .5;
x0u = rlsl + dm[3];
pMC->Gsvolu("TRCL", "TRD1", idtmed[399], dm, 4);
// -----------------------------------------------------
// L-sectors - "gas sectors" - sensitive!
// -----------------------------------------------------
dm[2] = (250.-0.001)/2.;
pMC->Gsvolu("TLGA", "TRD1", idtmed[403], dm, 4);
// -------------------------------------------------------------
// Only for the debugging purpose and resolution calculation
// Sensitive strips at the pad-row center
// -------------------------------------------------------------
if (fSens >= 0) {
pMC->Gsvolu("TLST", "TRD1", idtmed[403], dm, 0);
dm[3] = .005;
z0 = rlsl+ (rlsu - rlsl) * .5;
for (ils = 0; ils GetNRowUp(); ++ils) {
r1 = fTPCParam->GetPadRowRadiiUp(ils);
r2 = r1 + dm[3] * 2.;
dm[0] = r1 * thu - 2.63;
dm[1] = r2 * thu - 2.63;
zz = -z0 + r1 +dm[3];
pMC->Gsposp("TLST", ils+1, "TLGA", 0, 0, zz, 0, "ONLY", dm, 4);
}
pMC->Gsord("TLGA", 3);
}
// ******************************************************
// ------------------------------------------------
// positioning of lower sectors (1-12)*2
// rotation matrices 1-12
// the isec_al flag allows to select all (<0) or
// only a few (up to 6) sectors
// ------------------------------------------------
z = (250.+0.001)/2.;
z1 = -z_side + sec_thick * .5;
for (il = 1; il <= 12; ++il) {
phi1 = (il - 1) * opl + 270.;
if (phi1 > 360.) {
phi1 += -360.;
}
theta1 = 90.;
phi2 = 90.;
theta2 = 180.;
phi3 = (il - 1) * opl;
theta3 = 90.;
idr = il;
AliMatrix(idrotm[idr], theta1, phi1, theta2, phi2, theta3, phi3);
alpha = (il - 1) * opl * kDegrad;
x = x0l * TMath::Cos(alpha);
y = x0l * TMath::Sin(alpha);
if (fSecAL < 0) {
// -----------------------------------------------------------
// position ALL lower sectors
// -----------------------------------------------------------
pMC->Gspos("TSGA", il, "TGAS", x, y, z, idrotm[idr], "ONLY");
pMC->Gspos("TSGA",il+12 , "TGAS", x, y, -z, idrotm[idr], "ONLY");
} else {
// -----------------------------------------------------------
// position selected lower sectors
// -----------------------------------------------------------
for (isll = 1; isll <= 6; ++isll) {
if (fSecLows[isll - 1] == il) {
pMC->Gspos("TSGA", il, "TGAS", x, y, z, idrotm[idr], "ONLY");
} else if (fSecLows[isll - 1] == il + 12) {
pMC->Gspos("TSGA",il+12 , "TGAS", x, y, -z, idrotm[idr],"ONLY");
}
}
}
pMC->Gspos("TRCS", il, "TPSG", x, y, z1, idrotm[idr], "ONLY");
}
// ----------------------------------------------------
// positioning of upper sectors (1-24)*2
// rotation matrices 13-36
// the isec_au flag allows to select all (<0) or
// only a few (up to 12) sectors
// ----------------------------------------------------
for (iu = 1; iu <= 24; ++iu) {
phi1 = (iu - 1) * opu + 270.;
if (phi1 > 360.) {
phi1 += -360.;
}
theta1 = 90.;
phi2 = 90.;
theta2 = 180.;
phi3 = (iu - 1) * opu;
theta3 = 90.;
idr = iu + 12;
AliMatrix(idrotm[idr], theta1, phi1, theta2, phi2, theta3, phi3);
alpha = (iu - 1) * opu * kDegrad;
x = x0u * TMath::Cos(alpha);
y = x0u * TMath::Sin(alpha);
if (fSecAU < 0) {
// -------------------------------------------------------------
// position ALL upper sectors
// -------------------------------------------------------------
pMC->Gspos("TLGA", iu, "TGAS", x, y, z, idrotm[idr], "ONLY");
pMC->Gspos("TLGA",iu+24 , "TGAS", x, y, -z, idrotm[idr], "ONLY");
} else {
// -------------------------------------------------------------
// position selected upper sectors
// -------------------------------------------------------------
for (isll = 1; isll <= 12; ++isll) {
if (fSecUps[isll - 1] == iu + 24) {
pMC->Gspos("TLGA", iu, "TGAS", x, y, z, idrotm[idr], "ONLY");
} else if (fSecUps[isll - 1] == iu + 48) {
pMC->Gspos("TLGA",iu+24 , "TGAS", x, y, -z, idrotm[idr],"ONLY");
}
}
}
pMC->Gspos("TRCL", iu, "TPSG", x, y, z1, idrotm[idr], "ONLY");
}
// --------------------------------------------------------
// Spoke wheel structures
// --------------------------------------------------------
pMC->Gsvolu("TSWS", "TUBE", idtmed[399], dm, 0);
z0 = -z_side + 2.;
dm[0] = 82.;
dm[1] = 86.;
dm[2] = 1.;
pMC->Gsposp("TSWS", 1, "TPSG", 0, 0, z0, 0, "ONLY", dm, 3);
dm[0] = 253.;
dm[1] = 257.;
pMC->Gsposp("TSWS", 2, "TPSG", 0, 0, z0, 0, "ONLY", dm, 3);
dm[0] = 140.9;
dm[1] = 141.9;
pMC->Gsposp("TSWS", 3, "TPSG", 0, 0, z0, 0, "ONLY", dm, 3);
// -------------------------------------------------------
// this volumes are to avoid overlaping
// -------------------------------------------------------
z0 = 253.;
dm[0] = 76.;
dm[1] = 76.+0.09776;
pMC->Gsposp("TSWS", 4, "TPC ", 0, 0, z0, 0, "ONLY", dm, 3);
pMC->Gsposp("TSWS", 5, "TPC ", 0, 0, -z0, 0, "ONLY", dm, 3);
z0 += 21.;
pMC->Gsposp("TSWS", 6, "TPC ", 0, 0, z0, 0, "ONLY", dm, 3);
pMC->Gsposp("TSWS", 7, "TPC ", 0, 0, -z0, 0, "ONLY", dm, 3);
dm[0] = 257.;
dm[1] = 257.+0.09776;
dm[2] = 11.5;
z0 = 263.5;
pMC->Gsposp("TSWS", 8, "TPC ", 0, 0, z0, 0, "ONLY", dm, 3);
pMC->Gsposp("TSWS", 9, "TPC ", 0, 0, -z0, 0, "ONLY", dm, 3);
// ==========================================================
// wheels
// ==========================================================
// ----------------------------------------------------------
// Large wheel -> positioned in the TPC
// ----------------------------------------------------------
dm[0] = 257.+0.09776;
dm[1] = 278.;
dm[2] = 11.5;
pMC->Gsvolu("TPW1", "TUBE", idtmed[399], dm, 3);
dm[0] = 259.;
dm[1] = 278.;
dm[2] = 9.5;
pMC->Gsvolu("TPW2", "TUBE", idtmed[498], dm, 3);
pMC->Gspos("TPW2", 1, "TPW1", 0, 0, 0, 0, "ONLY");
pMC->Gspos("TPW1", 1, "TPC ", 0, 0, z0, 0, "ONLY");
pMC->Gspos("TPW1", 2, "TPC ", 0, 0, -z0, 0, "ONLY");
// -----------------------------------------------------------
// Small wheel -> positioned in the TPSG
// -----------------------------------------------------------
dm[0] = 76.+0.09776;
dm[1] = 82.;
dm[2] = 11.5;
pMC->Gsvolu("TPW3", "TUBE", idtmed[399], dm, 3);
dm[0] = 76.+0.09776;
dm[1] = 80.;
dm[2] = 9.5;
pMC->Gsvolu("TPW4", "TUBE", idtmed[401], dm, 3);
pMC->Gspos("TPW4", 1, "TPW3", 0, 0, 0, 0, "ONLY");
z0 = 1.;
pMC->Gspos("TPW3", 1, "TPSG", 0, 0, z0, 0, "ONLY");
// ---------------------------------------------------------
// spokes, inner and outer, also the inner ring
// ---------------------------------------------------------
dm[0] = 0.5*(135.9-82.1);
dm[1] = 3.;
dm[2] = 2.;
x1 = dm[0] + 82.;
pMC->Gsvolu("TSPI", "BOX ", idtmed[399], dm, 3);
dm[1] = 2.;
dm[2] = 1.;
pMC->Gsvolu("TSP1", "BOX ", idtmed[498], dm, 3);
pMC->Gspos("TSP1", 1, "TSPI", 0, 0, 0, 0, "ONLY");
dm[0] = 0.5*(256.9-142.1);
dm[1] = 3.;
dm[2] = 2.;
x2 = dm[0] + 142.;
pMC->Gsvolu("TSPO", "BOX ", idtmed[399], dm, 3);
dm[1] = 2.;
dm[2] = 1.;
pMC->Gsvolu("TSP2", "BOX ", idtmed[498], dm, 3);
pMC->Gspos("TSP2", 1, "TSPO", 0, 0, 0, 0, "ONLY");
// --------------------------------------------------------
dm[0] = 136.;
dm[1] = 142.;
dm[2] = 2.;
pMC->Gsvolu("TSWH", "TUBE", idtmed[399], dm, 3);
dm[0] = 137.;
dm[1] = 141.;
dm[2] = 1.;
pMC->Gsvolu("TSW1", "TUBE", idtmed[498], dm, 3);
pMC->Gspos("TSW1", 1, "TSWH", 0, 0, 0, 0, "ONLY");
z0 = z_side - .16168 - 2.;
// --------------------------------------------------------
pMC->Gspos("TSWH", 1, "TPSG", 0, 0, z0, 0, "ONLY");
// -------------------------------------------------------
// posiioning of the inner spokes
// -------------------------------------------------------
for (il = 1; il <= 6; ++il) {
phi1 = opl * .5 + (il - 1) * 2. * opl;
theta1 = 90.;
phi2 = opl * .5 + 90. + (il - 1) * 2. * opl;
if (phi2 > 360.) {
phi2 += -360.;
}
theta2 = 90.;
phi3 = 0.;
theta3 = 0.;
alpha = phi1 * kDegrad;
x = x1 * TMath::Cos(alpha);
y = x1 * TMath::Sin(alpha);
idr = il + 36;
AliMatrix(idrotm[idr], theta1, phi1, theta2, phi2, theta3, phi3);
pMC->Gspos("TSPI", il, "TPSG", x, y, z0, idrotm[idr], "ONLY");
}
for (iu = 1; iu <= 12; ++iu) {
phi1 = opu * .5 + (iu - 1) * 2. * opu;
theta1 = 90.;
phi2 = opu * .5 + 90. + (iu - 1) * 2. * opu;
if (phi2 > 360.) {
phi2 += -360.;
}
theta2 = 90.;
phi3 = 0.;
theta3 = 0.;
alpha = phi1 * kDegrad;
x = x2 * TMath::Cos(alpha);
y = x2 * TMath::Sin(alpha);
idr = iu + 42;
AliMatrix(idrotm[idr], theta1, phi1, theta2, phi2, theta3, phi3);
pMC->Gspos("TSPO", iu, "TPSG", x, y, z0, idrotm[idr], "ONLY");
}
// --------------------------------------------------------
// endcap cover (C, 0.86% X0)
// --------------------------------------------------------
dm[0] = 76.+0.09776;
dm[1] = 257.;
dm[2] = 0.16168*0.5;
pMC->Gsvolu("TCOV", "TUBE", idtmed[407], dm, 3);
z0 = z_side - dm[2];
pMC->Gspos("TCOV", 1, "TPSG", 0, 0, z0, 0, "ONLY");
// --------------------------------------------------------
// put the readout chambers into the TPC
// --------------------------------------------------------
theta1 = 90.;
phi1 = 0.;
theta2 = 90.;
phi2 = 270.;
theta3 = 180.;
phi3 = 0.;
AliMatrix(idrotm[55], theta1, phi1, theta2, phi2, theta3, phi3);
z0 = z_side + 250.;
pMC->Gspos("TPSG", 1, "TPC ", 0, 0, z0, 0, "ONLY");
pMC->Gspos("TPSG", 2, "TPC ", 0, 0, -z0, idrotm[55], "ONLY");
// ---------------------------------------------------------
// outer gas insulation (CO2)
// ---------------------------------------------------------
dm[0] = 257.+0.09776;
dm[1] = 278.-0.25004;
dm[2] = 275.-23.;
pMC->Gsvolu("TPOI", "TUBE", idtmed[406], dm, 3);
pMC->Gspos("TPHV", 1, "TGAS", 0, 0, 0, 0, "ONLY");
pMC->Gspos("TGAS", 1, "TPC ", 0, 0, 0, 0, "ONLY");
pMC->Gspos("TPOI", 1, "TPC ", 0, 0, 0, 0, "ONLY");
pMC->Gspos("TPC ", 1, "ALIC", 0, 0, 0, 0, "ONLY");
// ======================================================
// all volumes below are positioned in ALIC
// ======================================================
// ------------------------------------------------------
// the last parts of the smaller wheel (TSWS)
// ------------------------------------------------------
dm[0] = 74.;
dm[1] = 76.;
dm[2] = 1.;
z0 = 253.;
pMC->Gsposp("TSWS", 10, "TPC ", 0, 0, z0, 0, "ONLY", dm, 3);
pMC->Gsposp("TSWS", 11, "TPC ", 0, 0, -z0, 0, "ONLY", dm, 3);
dm[0] = 70.;
z0 += 21.;
pMC->Gsposp("TSWS", 12, "TPC ", 0, 0, z0, 0, "ONLY", dm, 3);
pMC->Gsposp("TSWS", 13, "TPC ", 0, 0, -z0, 0, "ONLY", dm, 3);
// ----------------------------------------------------
// Inner vessel (PCON)
// This volume is to be positioned directly in ALIC
// ----------------------------------------------------
dm[0] = 0.;
dm[1] = 360.;
dm[2] = 4.;
dm[3] = -250.;
dm[4] = 75.;
dm[5] = 76.;
dm[6] = -64.5;
dm[7] = 50.;
dm[8] = 76.;
dm[9] = 64.5;
dm[10] = 50.;
dm[11] = 76.;
dm[12] = 250.;
dm[13] = 75.;
dm[14] = 76.;
pMC->Gsvolu("TPIV", "PCON", idtmed[407], dm, 15);
// --------------------------------------------------------
// fill the inner vessel with CO2, (HV kDegrader)
// cone parts have different thickness
// than the central barrel, according to the TP
// --------------------------------------------------------
tana = 75./185.5;
dm[0] = 0.;
dm[1] = 360.;
dm[2] = 6.;
dm[3] = -(250.-0.2162);
dm[4] = (185.5-0.2126)*tana+0.2126;
dm[5] = 76-0.001;
dm[6] = -64.5;
dm[7] = 50.+0.2162;
dm[8] = 76-0.001;
dm[9] = -64.5;
dm[10] = 50+0.05076;
dm[11] = 76-0.001;
dm[12] = 64.5;
dm[13] = 50+0.05076;
dm[14] = 76-0.001;
dm[15] = 64.5;
dm[16] = 50.+0.2162;
dm[17] = 76-0.001;
dm[18] = (250.-0.2162);
dm[19] = (185.5-0.2126)*tana+0.2126;
dm[20] = 76-0.001;
pMC->Gsvolu("TPVD", "PCON", idtmed[406], dm, 21);
pMC->Gspos("TPVD", 1, "TPIV", 0, 0, 0, 0, "ONLY");
pMC->Gspos("TPIV", 1, "ALIC", 0, 0, 0, 0, "ONLY");
// ---------------------------------------------------
// volumes ordering
// ---------------------------------------------------
pMC->Gsord("TGAS", 6);
pMC->Gsord("TPSG", 6);
}
//_____________________________________________________________________________
void AliTPCv2::DrawDetector()
{
//
// Draw a shaded view of the Time Projection Chamber version 1
//
AliMC* pMC = AliMC::GetMC();
// Set everything unseen
pMC->Gsatt("*", "seen", -1);
//
// Set ALIC mother transparent
pMC->Gsatt("ALIC","SEEN",0);
//
// Set the volumes visible
pMC->Gsatt("TPC","SEEN",0);
pMC->Gsatt("TGAS","SEEN",0);
pMC->Gsatt("TPSG","SEEN",0);
pMC->Gsatt("TPHV","SEEN",1);
pMC->Gsatt("TRCS","SEEN",1);
pMC->Gsatt("TRCL","SEEN",1);
pMC->Gsatt("TSWS","SEEN",1);
pMC->Gsatt("TPW1","SEEN",1);
pMC->Gsatt("TPW3","SEEN",1);
pMC->Gsatt("TSPI","SEEN",1);
pMC->Gsatt("TSPO","SEEN",1);
pMC->Gsatt("TSWH","SEEN",1);
pMC->Gsatt("TPOI","SEEN",1);
pMC->Gsatt("TPIV","SEEN",1);
pMC->Gsatt("TPVD","SEEN",1);
//
pMC->Gdopt("hide", "on");
pMC->Gdopt("shad", "on");
pMC->Gsatt("*", "fill", 7);
pMC->SetClipBox(".");
pMC->SetClipBox("*", 0, 1000, -1000, 1000, -1000, 1000);
pMC->DefaultRange();
pMC->Gdraw("alic", 40, 30, 0, 12, 9.5, .025, .025);
pMC->Gdhead(1111, "Time Projection Chamber");
pMC->Gdman(18, 4, "MAN");
pMC->Gdopt("hide","off");
}
//_____________________________________________________________________________
void AliTPCv2::CreateMaterials()
{
//
// Define materials for version 2 of the Time Projection Chamber
//
AliMC* pMC = AliMC::GetMC();
//
// Increase maximum number of steps
pMC->SetMaxNStep(30000);
//
AliTPC::CreateMaterials();
}
//_____________________________________________________________________________
void AliTPCv2::Init()
{
//
// Initialises version 2 of the TPC after that it has been built
//
AliMC* pMC=AliMC::GetMC();
Int_t *idtmed = fIdtmed->GetArray()-399;
AliTPC::Init();
fIdSens1=pMC->VolId("TLGA"); // L-sector
fIdSens2=pMC->VolId("TSGA"); // S-sector
fIdSens3=pMC->VolId("TSST"); // strip - S-sector (not always used)
fIdSens4=pMC->VolId("TLST"); // strip - S-sector (not always used)
pMC->SetMaxNStep(30000); // max. number of steps increased
pMC->Gstpar(idtmed[403],"LOSS",5);
printf("*** TPC version 2 initialized ***\n");
printf("Maximum number of steps = %d\n",pMC->GetMaxNStep());
//
}
//_____________________________________________________________________________
void AliTPCv2::StepManager()
{
//
// Called for every step in the Time Projection Chamber
//
//
// parameters used for the energy loss calculations
//
const Float_t prim = 14.35; // number of primary collisions per 1 cm
const Float_t poti = 20.77e-9; // first ionization potential for Ne/CO2
const Float_t w_ion = 35.97e-9; // energy for the ion-electron pair creation
const Float_t big = 1.e10;
Int_t id,copy;
Float_t hits[4];
Int_t vol[2];
TClonesArray &lhits = *fHits;
AliMC* pMC=AliMC::GetMC();
vol[1]=0;
//
pMC->SetMaxStep(big);
if(!pMC->TrackAlive()) return; // particle has disappeared
Float_t charge = pMC->TrackCharge();
if(TMath::Abs(charge)<=0.) return; // take only charged particles
id=pMC->CurrentVol(0, copy);
// Check the sensitive volume
if(id == fIdSens1)
{
vol[0] = copy + 24; // L-sector number
}
else if(id == fIdSens2)
{
vol[0] = copy; // S-sector number
}
else if(id == fIdSens3 && pMC->TrackEntering())
{
vol[1] = copy; // row number
id = pMC->CurrentVolOff(1,0,copy);
vol[0] = copy; // sector number (S-sector)
pMC->TrackPosition(hits);
hits[3]=0.; // this hit has no energy loss
new(lhits[fNhits++]) AliTPChit(fIshunt,gAlice->CurrentTrack(),vol,hits);
}
else if(id == fIdSens4 && pMC->TrackEntering())
{
vol[1] = copy; // row number
id = pMC->CurrentVolOff(1,0,copy);
vol[0] = copy+24; // sector number (L-sector)
pMC->TrackPosition(hits);
hits[3]=0.; // this hit has no energy loss
new(lhits[fNhits++]) AliTPChit(fIshunt,gAlice->CurrentTrack(),vol,hits);
}
else return;
//
// charged particle is in the sensitive volume
//
if(pMC->TrackStep() > 0) {
Int_t nel = (Int_t)(((pMC->Edep())-poti)/w_ion) + 1;
nel=TMath::Min(nel,300); // 300 electrons corresponds to 10 keV
pMC->TrackPosition(hits);
hits[3]=(Float_t)nel;
// Add this hit
new(lhits[fNhits++]) AliTPChit(fIshunt,gAlice->CurrentTrack(),vol,hits);
}
// Stemax calculation for the next step
Float_t pp;
Float_t vect[4];
pMC->TrackMomentum(vect);
Float_t ptot = vect[3];
Float_t beta_gamma = ptot/(pMC->TrackMass());
if(pMC->TrackPid() <= 3 && ptot > 0.002)
{
pp = prim*1.58; // electrons above 20 MeV/c are on the plateau!
}
else
{
pp=prim*BetheBloch(beta_gamma);
if(TMath::Abs(charge) > 1.) pp *= (charge*charge);
}
Float_t random[1];
pMC->Rndm(random,1); // good, old GRNDM from Geant3
Double_t rnd = (Double_t)random[0];
pMC->SetMaxStep(-TMath::Log(rnd)/pp);
}
//_____________________________________________________________________________
Float_t AliTPCv2::BetheBloch(Float_t bg)
{
//
// Bethe-Bloch energy loss formula
//
const Double_t p1=0.76176e-1;
const Double_t p2=10.632;
const Double_t p3=0.13279e-4;
const Double_t p4=1.8631;
const Double_t p5=1.9479;
Double_t dbg = (Double_t) bg;
Double_t beta = dbg/TMath::Sqrt(1.+dbg*dbg);
Double_t aa = TMath::Power(beta,p4);
Double_t bb = TMath::Power(1./dbg,p5);
bb=TMath::Log(p3+bb);
return ((Float_t)((p2-aa-bb)*p1/aa));
}