# Very Less Entries for the hottest Cell/bin

Dear Experts

Below is my Code and I am studying the Energy deposition in the hottest bin and the neighboring bins but my Entries are very less. Am I considering all the Events? As An Example I have uploaded one histogram of hottest bin While In order to visualize I am also uploading projection. Once can see that central bin is very dense and contains lot of entries.

My Code run for 1000 events

``````
#include <iostream>
#include <iomanip>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <map>
#include <stdlib.h>

#include "TROOT.h"
#include "TTree.h"
#include "TChain.h"
#include "TFile.h"
#include "TString.h"
#include "TSystem.h"
#include "TCanvas.h"
#include "TLegend.h"
#include "TH1.h"
#include "TH2.h"
#include "TH3.h"
#include "TColor.h"
#include "Riostream.h"
#include "TDatime.h"
#include "TMath.h"
#include "TStyle.h"
#include "TLorentzVector.h"

stringstream ss;

void cell()
{
// *************************************************************************
// Rootfile and Tree
TFile* f = new TFile("lumidet_PbWO4.edm4hep.root");
f->cd();

//TTree* t = (TTree*)f->Get("events");

// Rootfile and Tree
// *************************************************************************

// *************************************************************************
// Histograms
map<string,TH1*> h1;
map<string,TH2*> h2;
map<string,TH3*> h3;

float xmin = -50 - 0.5;
float xmax = 50 + 0.5;
int nx = 100 + 1;
float ymin = -50 - 0.5;
float ymax = 50 + 0.5;
int ny = 100 + 1;
float zmin = 66000 - 0.5;
float zmax = 66300 + 0.5;
int nz = 300 + 1;

// 3D histogram x, y, z. total energy deposit as T axis
h3["energy"] = new TH3F("energy", "Total Energy Deposit;x;y;z", nx, xmin, xmax, ny, ymin, ymax, nz, 0, zmax - zmin);

// Histograms
// *************************************************************************

// *************************************************************************
// Event Loop
// The first for loop to fill 3D histogram
// int nev_max = 10000;
int nev = 0;
{
// if (nev >= nev_max) break;
nev++;
// if (nev % 100 == 0) cout << "Event: " << nev << endl;

float tot_e = 0;
for (int i = 0; i < energy.GetSize(); i++)
{
tot_e += energy[i];
float z_shifted = abs(z[i]) - zmin;
h3["energy"]->Fill(x[i],y[i],z_shifted,energy[i]);
}
}
// Event Loop
// *************************************************************************

// *************************************************************************
// Identify Max Energy Bin
float e_max = 0;
float x_max = -999;
float y_max = -999;
float z_max = -999;
for (int ix = 1; ix <= h3["energy"]->GetNbinsX(); ix++)
{
for (int iy = 1; iy <= h3["energy"]->GetNbinsY(); iy++)
{
for (int iz = 1; iz <= h3["energy"]->GetNbinsZ(); iz++)
{
if (h3["energy"]->GetBinContent(ix,iy,iz) > e_max)
{
e_max = h3["energy"]->GetBinContent(ix,iy,iz);
x_max = h3["energy"]->GetXaxis()->GetBinCenter(ix);
y_max = h3["energy"]->GetYaxis()->GetBinCenter(iy);
z_max = h3["energy"]->GetZaxis()->GetBinCenter(iz);
}
}
}
}
cout << "max-E : " << e_max << endl;
cout << "max-X : " << x_max << endl;
cout << "max-Y : " << y_max << endl;
cout << "max-Z : " << z_max << endl;

// Identify Max Energy Bin
// *************************************************************************

// *************************************************************************
// Plot Energy spectrum of the max bin
// 27 X 1D histograms around and of the bin with the max energy deposit
map<vector<int>,TH1*> h1max;
for (int ix = -1; ix <= 1; ix++)
{
for (int iy = -1; iy <= 1; iy++)
{
for (int iz = -1; iz <= 1; iz++)
{
ss.str(""); ss << "hist_" << ix << "_" << iy << "_" << iz;
vector<int> v = {ix,iy,iz};
h1max[v] = new TH1F(TString(ss.str()), "", 100, 0, 0.1);
}
}
}

// *************************************************************************
// Loop again
nev = 0;
{
// if (nev >= nev_max) break;
nev++;
//if (nev % 100 == 0) cout << "Event: " << nev << endl;

for (int i = 0; i < energy.GetSize(); i++)
{
int ix = x[i] - x_max;
int iy = y[i] - y_max;
float z_shifted = abs(z[i]) - zmin;
int iz = z_shifted - z_max;
// cout << nev << " " << i << " " << ix << " " << iy << " " << iz << endl;
if (abs(ix) > 1 || abs(iy) > 1 || abs(iz) > 1) continue;

cout << ix << endl;
vector<int> v = {ix, iy, iz};
h1max[v]->Fill(energy[i]);
}
}
// Loop again
// *************************************************************************

for (map<vector<int>, TH1*>::const_iterator itr = h1max.begin(); itr != h1max.end(); itr++)
{
int ix = itr->first[0];
int iy = itr->first[1];
int iz = itr->first[2];
TCanvas* c = new TCanvas("c", "", 1000, 1000);
c->cd();
itr->second->Draw("");

ss.str(""); ss << "test_" << ix << "_" << iy << "_" << iz << ".png";
c->SaveAs(TString(ss.str()));
c->Close();
}

``````

Hi,

according to the projection you have content of 71 in the very first bin (though not sure I understand the relation between the bins on the projection and on the 2D histogram - what are the X-axis units for the projection?). And you think 71 is too few?

Units are mm on x -axis of Projection Plot. Actually if you see 1D histogram It shows only 116 Entries in the central hottest cell which I think is too low

Ah, so the projection is only for one bin?

Why?

No smallest unit is 1 bin which is 1mm. Idea is to see deposition in that cell.Projection is not bin. hottest bin is Yellow in the center what is needed is to see all the entries in that bin Thus the plot is between energy and counts. Want to make sure if my code is fine and distribution for hottest cell is OK

A simple check … the printed “`e_max`” (“`max-E`”) value should be equal to: `hist_0_0_0->GetMean() * hist_0_0_0->Integral()`

This is true for the 2D histogram, but for the projection one bin is one-micron wide (because you said the X axis of the projection is in mm). Is my understanding correct?

???

???

You seem to be scaling down the Z-axis values. If you have had it in terms of counts, it would have been much easier to understand the number of entries in that hottest yellow cell just by looking at the max Z-axis value and to compare it to 116.

Ok you mean to plot Z vs Counts

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