2 TFile *
f =
new TFile(
"../hadron_track/pion/pion.root");
3 TTree *
t = (TTree*)
f->Get(
"n103");
4 TCanvas *c1 =
new TCanvas(
"c1",
"dE/dx distribution",10,10,800,642);
5 t->Draw(
"dEdx_hit>>h(400, 0,3000)",
"ptrk>0.802 & ptrk<0.803",
"", 100000);
6 TArrow *a1 =
new TArrow(1040.5, 50., 1040.5, 5., 0.02,
"|>");
7 TArrow *a2 =
new TArrow(1454.5, 50., 1454.5, 5., 0.02,
"|>");
8 TArrow *a3 =
new TArrow(1578.7, 50., 1578.7, 5., 0.02,
"|>");
12 c1->SaveAs(
"figs/hist_illustration.eps");