3.6 DSSD Multiplicity Event Analysis¶

Purpose：¶

  • Based on the x-y correlation, classify events: determine the number of incident particles, their corresponding positions, and energies.
In [1]:
//%jsroot on
TFile *ipf = new TFile("./data/cal_16C.root");
TTree *tree = (TTree*)ipf->Get("tree");
TCanvas *c1=new TCanvas("c1","c1");

Event Structure¶

Int_t  x1hit;      //multiplicity
Int_t  x1[x1hit];  //Strip 
double  x1e[x1hit]; //energy

Int_t  y1hit;
Int_t  y1[y1hit];
Int_t  y1e[y1hit];

double x1es,y1es; //total energy of x,y side.
int x1m,y1m;      //multiplicity, adjacent tracks are counted as one.
...

offset correction¶

In [2]:
int off[3] = {25, 25, 30};
//DSSD1
for(int id=1; id<=3; id++){
    for(int i=0; i<3; i++){
        tree->SetAlias(Form("x%da%d",id,i),Form("x%de[%d]-%d",id,i,off[id-1]));
        tree->SetAlias(Form("y%da%d",id,i),Form("y%de[%d]-%d",id,i,off[id-1]));    
    }
}

Total energy difference cuts¶

In [3]:
gROOT->LoadMacro("cutd1esc.cut");
gROOT->LoadMacro("cutd2esc.cut");
gROOT->LoadMacro("cutd3esc.cut");
In [4]:
c1->Clear();
c1->SetWindowSize(1200,300);
gStyle->SetOptStat(0);
c1->Divide(3,1);
c1->cd(1);
TCut cdet1 ="x1hit>0 && y1hit>0 ";
tree->SetAlias("x1esc","x1es+x1hit*(-25)");
tree->SetAlias("y1esc","y1es+y1hit*(-25)");
tree->Draw("x1esc:x1esc-y1esc>>hds1(200,-100,100,200,0,8000)",cdet1,"colz");
cutd1esc->Draw("same");
gPad->SetLogz();
c1->cd(2);
TCut cdet2 ="x2hit>0 && y2hit>0";
tree->SetAlias("x2esc","x2es+x2hit*(-25)");
tree->SetAlias("y2esc","y2es+y2hit*(-25)");
tree->Draw("x2esc:x2esc-y2esc>>hds2(200,-100,100,200,0,8000)",cdet2,"colz");
cutd2esc->Draw("same");
gPad->SetLogz();
c1->cd(3);
TCut cdet3 ="x3hit>0 && y3hit>0 ";
tree->SetAlias("x3esc","x3es+x3hit*(-30)");
tree->SetAlias("y3esc","y3es+y3hit*(-30)");
tree->Draw("x3esc:x3esc-y3esc>>hds3(200,-100,100,200,0,8000)",cdet3,"colz");
cutd3esc->Draw("same");
gPad->SetLogz();
c1->Draw();

classify events¶

  • Select the cross-shaped region around the central bright spot in the following correlation plots as the condition for classifing different events.

The conditions of two incident particles.¶

xhit=2 and yhit=2¶

In [5]:
TCut cut ;
c1->SetWindowSize(1200,800);
c1->Clear();
c1->Divide(3,2);
/* 
   x: 0 1 |   01  |  0  1  |  01 |
   y: 0 1 |  0  1 |   01   |  01 |
       ——                         
*/
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==2 && y%dhit==2 && x%dm==2 && y%dm==2 && cutd%desc",i,i,i,i,i);
    c1->cd(i);
    TString sdraw = Form("x%da0-y%da0:x%da1-y%da1>>h%da(200,-50,50,200,-50,50)",i,i,i,i,i);
    tree->Draw(sdraw,cut,"colz");
    gPad->SetLogz();
}
/* 
   x: 0 1 |   01  |  0  1  |  01 |
   y: 0 1 |  0  1 |   01   |  01 |
               ——                         
*/
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==2 && y%dhit==2 && x%dm==1 && y%dm==2 && cutd%desc",i,i,i,i,i);
    c1->cd(i+3);
    TString sdraw = Form("x%da0-y%da0:x%da1-y%da1>>h%db(200,-50,50,200,-50,50)",i,i,i,i,i);
    tree->Draw(sdraw,cut,"colz");
    gPad->SetLogz();
}

c1->Draw();
In [6]:
TCut cut ;
c1->SetWindowSize(1200,800);
c1->Clear();
c1->Divide(3,2);
/* 
   x: 0 1 |   01  |  0  1  |  01 |
   y: 0 1 |  0  1 |   01   |  01 |
                      ——                         
*/
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==2 && y%dhit==2 && x%dm==2 && y%dm==1 && cutd%desc",i,i,i,i,i);
    c1->cd(i);
    TString sdraw = Form("x%da0-y%da0:x%da1-y%da1>>h%dc(200,-50,50,200,-50,50)",i,i,i,i,i);
    tree->Draw(sdraw,cut,"colz");
    gPad->SetLogz();
}
/* 
   x: 0 1 |   01  |  0  1  |  01 |
   y: 0 1 |  0  1 |   01   |  01 |
                              ——                         
*/
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==2 && y%dhit==2 && x%dm==1 && y%dm==1 && cutd%desc",i,i,i,i,i);
    c1->cd(i+3);
    TString sdraw = Form("x%da0-y%da0:x%da1-y%da1>>h%dd(200,-50,50,200,-50,50)",i,i,i,i,i);
    tree->Draw(sdraw,cut,"colz");
    gPad->SetLogz();
}
c1->Draw();

xhit=2 and yhit=3¶

In [7]:
TCut cut ;
c1->SetWindowSize(1200,1000);
c1->Clear();
c1->Divide(3,3);
/*
x:   0  1 |   0  1  |  0  1 | 01  2 |  0 12  | 02  1  |
y:  01  2 |   0  12 | 02  1 |  0  1 |  0  1  |  0  1  |
      ——
*/

for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==2 && y%dhit==3 && x%dm==2 && y%dm==2 && abs(y%d[0]-y%d[1])==1 && cutd%desc",i,i,i,i,i,i,i);
    c1->cd(i);
    gPad->SetLogz();
    tree->Draw(Form("x%da0-(y%da0+y%da1):x%da1-y%da2>>h%da(200,-50,50,200,-50,50)",i,i,i,i,i,i),cut,"colz");;
}
/*
x:   0  1 |   0  1  |  0  1 | 01  2 |  0 12  | 02  1  |
y:  01  2 |   0  12 | 02  1 |  0  1 |  0  1  |  0  1  |
               ——
*/
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==2 && y%dhit==3 && x%dm==2 && y%dm==2 && abs(y%d[1]-y%d[2])==1 && cutd%desc",i,i,i,i,i,i,i);
    c1->cd(i+3);
    gPad->SetLogz();
    tree->Draw(Form("x%da0-y%da0:x%da1-(y%da1+y%da2)>>h%db(200,-50,50,200,-50,50)",i,i,i,i,i,i),cut,"colz");;
}
/*
x:   0  1 |   0  1  |  0  1 | 01  2 |  0 12  | 02  1  |
y:  01  2 |   0  12 | 02  1 |  0  1 |  0  1  |  0  1  |
                        ——
*/
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==2 && y%dhit==3 && x%dm==2 && y%dm==2 && abs(y%d[0]-y%d[2])==1 && cutd%desc",i,i,i,i,i,i,i);
    c1->cd(i+6);
    gPad->SetLogz();
    tree->Draw(Form("x%da0-(y%da0+y%da2):x%da1-y%da1>>h%dc(200,-50,50,200,-50,50)",i,i,i,i,i,i),cut,"colz");;
}

c1->Draw();

xhit=3 and yhit=2¶

In [8]:
TCut cut ;
c1->SetWindowSize(1200,1000);
c1->Clear();
c1->Divide(3,3);
/*
x:   0  1 |   0  1  |  0  1 | 01  2 |  0 12  | 02  1  |
y:  01  2 |   0  12 | 02  1 |  0  1 |  0  1  |  0  1  |
                                ——
*/
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==3 && y%dhit==2 && x%dm==2 && y%dm==2 && abs(x%d[0]-x%d[1])==1 && cutd%desc",i,i,i,i,i,i,i);
    c1->cd(i);
    gPad->SetLogz();
    tree->Draw(Form("(x%da0+x%da1)-y%da0:x%da2-y%da1>>h%de(200,-50,50,200,-50,50)",i,i,i,i,i,i),cut,"colz");;
}
/*
x:   0  1 |   0  1  |  0  1 | 01  2 |  0 12  | 02  1  |
y:  01  2 |   0  12 | 02  1 |  0  1 |  0  1  |  0  1  |
                                        ——
*/
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==3 && y%dhit==2 && x%dm==2 && y%dm==2 && abs(x%d[1]-x%d[2])==1 && cutd%desc",i,i,i,i,i,i,i);
    c1->cd(i+3);
    gPad->SetLogz();
    tree->Draw(Form("x%da0-y%da0:(x%da1+x%da2)-y%da1>>h%df(200,-50,50,200,-50,50)",i,i,i,i,i,i),cut,"colz");;
}
/*
x:   0  1 |   0  1  |  0  1 | 01  2 |  0 12  | 02  1  |
y:  01  2 |   0  12 | 02  1 |  0  1 |  0  1  |  0  1  |
                                                 ——
*/
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==3 && y%dhit==2 && x%dm==2 && y%dm==2 && abs(x%d[0]-x%d[2])==1 && cutd%desc",i,i,i,i,i,i,i);
    c1->cd(i+6);
    gPad->SetLogz();
    tree->Draw(Form("(x%da0+x%da2-y%da0):x%da1-y%da1>>h%dg(200,-50,50,200,-50,50)",i,i,i,i,i,i),cut,"colz");;
}
c1->Draw();

three particles¶

xhit=3 && yhit =3¶

In [9]:
TCut cut ;
c1->SetWindowSize(1200,1200);
c1->Clear();
c1->Divide(3,3);
for(int i=1; i<=3; i++) {
    cut = Form("x%dhit==3 && y%dhit==3 && x%dm==3 && y%dm==3 && cutd%desc",i,i,i,i,i);
    c1->cd(3*i-2);
    gPad->SetLogz();
    tree->Draw(Form("x%da0-y%da0:x%da1-y%da1>>h%da(200,-50,50,200,-50,50)",i,i,i,i,i),cut ,"colz");
    c1->cd(3*i-1);
    gPad->SetLogz();
    tree->Draw(Form("x%da0-y%da0:x%da2-y%da2>>h%db(200,-50,50,200,-50,50)",i,i,i,i,i),cut ,"colz");
    c1->cd(3*i);
    gPad->SetLogz();
    tree->Draw(Form("x%da1-y%da1:x%da2-y%da2>>h%dc(200,-50,50,200,-50,50)",i,i,i,i,i),cut ,"colz");
}
c1->Draw();

Assignment¶

Note: Multiple particles may be incident on the same strip, for example, two particles at coordinates (16,14) and (16,15). In such cases, the amplitude relationship is given by $A'_{x16} = A'_{y14} + A'_{y15}$ .

  1. Find the conditions for additional three-particle incidents and all possible two-particle incidents when xhit=3 and yhit=3, and provide corresponding figures.

  2. For cases where xhit=2 and yhit=3 or xhit=3 and yhit=2, determine the conditions for three-particle incidents and provide figures.

  3. Based on the above discussion, reclassify events according to the number of incident particles and save them to new ROOT files:

    • hit represents the number of incident particles for each detector, with the incident particle energy e equal to the x-side energy.

Event structure:

//det1
Int_t hit1;
double e1[hit1];
Int_t x1[hit1],y1[hit1];
//det2
Int_t hit2;
double e2[hit2];
Int_t x2[hit2],y1[hit2];
//det3
Int_t hit3;
double e3[hit3];
Int_t x3[hit3],y3[hit3];
In [ ]: