Energy Loss

Graduate School of Science, Tohoku UniversityToshi Gogami22/May/2013

GEANT4 Simulation

Energy Loss• 12C 100mg/cm2

• 208Pb 100mg/cm2

Angular distributions

Setup (1)Simulation code : POSI

Generate4500 MeV/c electrons at the center of target

Target Virtual Detector

e

( 200,000 events )

Setup(1)

Simple estimations

• 12C 100 mg/cm2 target , X0 = 42700 mg/cm2

ΔE = ( 1.0 – exp(-x/X0) ) * 4500 = 5.3 MeV

• 208Pb 100 mg/cm2 target , X0 = 6370 mg/cm2

ΔE = ( 1.0 – exp(-x/X0) ) * 2344 = 35.2 MeV

NOTE:Effective thickness 100.0 / 2.0 [ mg/cm2 ]

Setup(1)

Simulation Results (12C)

Mean : 5.5 MeV(Estimation:5.3MeV)

Energy Loss

Most probable energy loss ～ 70 keV

N(<0.5 MeV) : N(>0.5 MeV)= 1 : 0.023

Setup(1)

Simulation Results (208Pb)

Mean : 37.0 MeV(Estimation:35.2MeV)

Energy Loss

Most probable energy loss ～ 50 keV

N(<0.5 MeV) : N(>0.5 MeV)= 1 : 0.093

Setup(1)

Setup (2)Simulation code : POSI

Generate4500 MeV/c electrons at moving generation point within the target

Target Virtual Detector

e

( 200,000 events )

Randomly moved

Setup(2)

Simulation Results (12C)

Mean : 5.6 MeV(Setup(1) : 5.5MeV)

Energy Loss

N(<0.5 MeV) : N(>0.5 MeV)= 1 : 0.024

Setup(2)

Simulation Results (208Pb)

Mean : 36.6 MeV(Setup(1):37.0MeV)

Energy Loss

N(<0.5 MeV) : N(>0.5 MeV)= 1 : 0.092

Setup(2)

Angular distributions of electrons

Setup (3)

Simulation code : POSI(Default HKS setting)

Generate2344 MeV/c electrons at the center of target

TargetVirtual Detector

17 degrees

e

Setup(3)

Theta distributions for 12C target

Setup (3)Incident electrons with 2344 MeV

MEAN : 0.2 mrad

MEAN : 0.1 mrad

Setup (1)Incident electrons with 4500 MeV

Setup(3) Setup(1)

Theta distributions for 208Pb target

Setup (3)Incident electrons with 2344 MeV

MEAN : 0.6 mrad

MEAN : 0.3 mrad

Setup (1)Incident electrons with 4500 MeV

Setup(3) Setup(1)

Theta distributions for 12C target

Setup (2)Incident electrons with 4500 MeV

MEAN : 0.1 mrad

MEAN : 0.1 mrad

Setup (1)Incident electrons with 4500 MeV

Moving Generation point

Setup(1)Setup(2)

Theta distributions for 208Pb target

Setup (2)Incident electrons with 4500 MeV

MEAN : 0.3 mrad

MEAN : 0.3 mrad

Setup (1)Incident electrons with 4500 MeV

Moving Generation point

Setup(1)Setup(2)

Summary

• Energy losses for 12C and 208Pb (Ee = 4500 MeV)– There are long tails which increase the mean values

of energy loss largely.

• Angular distributions of ( scattered ) electrons– More forward distributions for Ee=4500 MeV than

that for Ee=2344 MeV– No big difference between the Setup(1) and

Setup(2) for the estimations of angular distributionsThe difference between setup(1) and setup(2) is just only the behaviors of generation points.

Backup

Setup (4)

Simulation code : POSI(Default HKS setting)

Generate2344 MeV/c electrons at moving generation point within the target

TargetVirtual Detector

17 degrees

e

Setup(4)

( 200,000 events ) Randomly moved

Simulation Results (52Cr 154mg/cm2)

Mean : 13.3 MeV(Estimation : 11.9MeV)

Energy Loss

N(<0.5 MeV) : N(>0.5 MeV)= 1 : 0.074

Setup(3)Most probable energy loss ～ 85 keV

Simulation Results (52Cr 154mg/cm2)

Mean : 13.2 MeV(Setup(3) : 13.3MeV)

Energy Loss

N(<0.5 MeV) : N(>0.5 MeV)= 1 : 0.075

Setup(4)

energyloss.cc

//----- Histogram Options ------- // histopt(h1); histopt(h2); // ========== Draw Histograms ============== TCanvas* c1 = new TCanvas("c1","c1"); c1->Divide(1,2); c1->cd(1); gPad->SetGridx();gPad->SetGridy(); gPad->SetLogy(1); h1->Draw(); c1->cd(2); gPad->SetGridx();gPad->SetGridy(); gPad->SetLogy(1); h2->Draw(); // ===== Number of events ================ double n1,n2; double ratio12; n1 = h1->Integral(0,100); // total n2 = h2->Integral(0,100); // < 5 MeV cout << n1 << " " << n2 << endl; n1 = n1 - n2; // > 5 MeV ratio12 = n1/n2; cout << " 1 : " << ratio12 << endl;

// ======== Print ======================= //c1->Print("Pb208_100mg_4.5_center_energyloss.eps","eps"); //c1->Print("Pb208_100mg_4.5_center_energyloss.png","png"); c1->Print("C12_100mg_4.5_center_energyloss.eps","eps"); c1->Print("C12_100mg_4.5_center_energyloss.png","png"); }

/* energyloss.cc Toshi Gogami , 22/May/2013*/

void histopt(TH1F*h){ h->GetXaxis()->SetTitle(" [ MeV ] "); h->GetYaxis()->SetTitle(" Counts "); h->SetFillStyle(3005); h->SetFillColor(9); h->GetXaxis()->SetLabelSize(0.05); h->GetXaxis()->SetTitleSize(0.05); h->GetYaxis()->SetLabelSize(0.05); h->GetYaxis()->SetTitleSize(0.05);}

void energyloss(char* file){ // ========== General Conditions ============== gROOT->SetStyle("Plain"); //gStyle->SetOptStat(0); // ========== Open ROOT File =============== TFile* f = new TFile(file); TTree* t = (TTree*)f->Get("tree");

// ========== Cut Conditions =============== TCut cut = "eleflag && !eIoni"; // ========== Create Histograms =========== //TH1F*h1 = new TH1F( "h1" , "" , 100 , 0.0 , 2400.0 ); TH1F*h1 = new TH1F( "h1" , "" , 100 , 0.0 , 4600.0 ); TH1F*h2 = new TH1F( "h2" , "" , 100 , 0.0 , 0.5 ); t->Project("h1",

"sqrt(pBeam*pBeam+0.511+0.511)-sqrt(pVD*pVD+0.511*0.511)", cut);

t->Project("h2", "sqrt(pBeam*pBeam+0.511+0.511)-sqrt(pVD*pVD+0.511*0.511)", cut);

angle.cc/* angle.cc Toshi Gogami , 22/May/2013*/

void histopt(TH1F*h){ h->GetXaxis()->SetTitle(" [ mrad ] "); h->GetYaxis()->SetTitle(" Counts "); h->SetFillStyle(3005); h->SetFillColor(9); h->GetXaxis()->SetLabelSize(0.05); h->GetXaxis()->SetTitleSize(0.05); h->GetYaxis()->SetLabelSize(0.05); h->GetYaxis()->SetTitleSize(0.05);}

void angle(char* file){ // ========== General Conditions ============== gROOT->SetStyle("Plain"); //gStyle->SetOptStat(0); // ========== Open ROOT File =============== TFile* f = new TFile(file); TTree* t = (TTree*)f->Get("tree"); // ========== Cut Conditions =============== TCut cut = "eleflag && !eIoni && theta<0.03"; // ========== Create Histograms =========== //TH1F* h = new TH1F( "h" , "" , 100 , 0.0 , 10.0 ); TH1F* h = new TH1F( "h" , "" , 100 , 0.0 , 30.0 ); t->Project("h","theta*1.0e3",cut); histopt(h); // ========== Draw Histograms =========== TCanvas*c1 = new TCanvas("c1","c1"); gPad->SetLogy(1); gPad->SetGridx();gPad->SetGridy(); h->Draw();}