CMS open data for Ultra-peripheral PbPb collisions (photon-nucleus)

I wish you can help me.
I am a master’s student studying physics in Jordan. The object of my thesis requires the data from 2011 of invariant mass M, the transverse momentum pt and the rapidity y of dimuon from J/psi decay in Ultra-Peripheral photonuclear PbPb collisions. I am the first one who works in this field in my country.

I used root inside a docker container. The path is home/anas/www/example-app/HiForest/HiForestProducer/. All the commands from this site in the screenshot below were completed successfully except the last one “root -l forest2dimuon.C++”. After running it:

$ root -l forest2dimuon.C++
root [0]
Processing forest2dimuon.C++…
Info in TUnixSystem::ACLiC: creating shared library /TOP/www/example-app/HiForest/HiForestProducer/./
Error in TFile::TFile: file /TOP/www/example-app/HiForest/HiForestProducer/HiForestAOD_DATAtest2011.root does not exist

*** Break *** segmentation violation
Generating stack trace…
0x00007f47097f98a3 in from /opt/root/lib/
0x00007f47097f9fe3 in from /opt/root/lib/
0x00007f47097fa3b1 in from /opt/root/lib/
0x00007f47098c22e7 in from /opt/root/lib/
0x00007f470970fcbc in from /opt/root/lib/
0x00007f470972b358 in TCling::ProcessLine(char const*, TInterpreter::EErrorCode*) + 0xff8 from /opt/root/lib/
0x00007f470972b81b in TCling::ProcessLineSynch(char const*, TInterpreter::EErrorCode*) + 0xeb from /opt/root/lib/
0x00007f470ddcfab5 in TApplication::ExecuteFile(char const*, int*, bool) at TApplication.cxx:? from /opt/root/bin/…/lib/
0x00007f470e1f32e0 in TRint::ProcessLineNr(char const*, char const*, int*) + 0x60 from /opt/root/bin/…/lib/
0x00007f470e1f51ec in TRint::Run(bool) + 0x31c from /opt/root/bin/…/lib/
0x000056129f0222f3 in main + 0x53 from /opt/root/bin/root.exe
0x00007f470d7c3d90 in from /lib/x86_64-linux-gnu/
0x00007f470d7c3e40 in __libc_start_main + 0x80 from /lib/x86_64-linux-gnu/
0x000056129f022345 in _start + 0x25 from /opt/root/bin/root.exe
Root >

Q: What should I do?


The error message says that the code cannot find the file in


The example code assumes that you execute the command root -l forest2dimuon.C++ in the same directory in which the file HiForestAOD_DATAtest2011.root is located.
If that’s not the case, make sure that you specify the full path in the code.
The path you’ve specified (home/anas/www/example-app/HiForest/HiForestProducer/) is not the default area in the container so you’ve probably done some changes with respect to the instructions.

If you have not set the display, you can run with the -b flag.
In the container, I would expect the following output (for my test root file containing 100 events)

[14:23:46] cmsusr@dd69f7770616 ~/CMSSW_4_4_7/src/HiForest/HiForestProducer $ root -l -b forest2dimuon.C++
root [0]
Processing forest2dimuon.C++...
Info in <TUnixSystem::ACLiC>: creating shared library /home/cmsusr/CMSSW_4_4_7/src/HiForest/HiForestProducer/./
Events to Analyze: 100
>>>>> EVENT 0

This will produce a plot in file diMuon_Minv.png

Hope this helps.

Best, Kati
for the CMS open data team

Thank you so much for the clarification, dear Kati

I’m sure that I have mistakes with the executing. I still don’t know the right way. Below there are five screenshots, I tried inside docker and in ubuntu distribution, but most commands are not found. In screenshot_5, when I click run, it directly exit.

Please respond me as soon as possible.

The screenshots do not show here. Check the following:

  1. make sure that the output file exists in the directory you want to run the analysis command. If you have followed the instructions you should be in ~/CMSSW_4_4_7/src/HiForest/HiForestProducer in the container and doing ls to list the should give this (without yet the png file)
[20:09:37] cmsusr@dd69f7770616 ~/CMSSW_4_4_7/src/HiForest/HiForestProducer $ ls
BuildFile.xml                                                     src
CMS_HIRun2011_HIDiMuon_RECO_04Mar2013-v1_root_file_index.txt         HiForest_cff.pyc  diMuon_Minv.png
Cert_181530-183126_HI7TeV_PromptReco_Collisions11_JSON_MuonPhys.txt  LICENSE           forest2dimuon.C
HiForestAOD_DATAtest2011.root                                       forest2dimuon_C.d  python
  1. run the analysis code in that directory (in the container, not on your own linux distribution). If you have trouble with setting the display, run it with the -b option i.e. root -l -b forest2dimuon.C++

All the best, Kati

1 Like


I have reached to the same directory that inside your screenshot and all the commands were executed successfully as well as the HiForestAOD_DATAtest2011.root file exist. There is a simple problem with root, the screenshot below shows all things:

Please respond me as soon as you can.

Hi, it looks like something went wrong with the root file production step.
Does the run output in file full.log contain some errors?
You can print out the the contents of that file with

cat full.log

Best, Kati

I did it, is the following screenshot the correct output from the path?

If yes, how can I find the transverse momentum and rapidity?

Thanks in advance