Various useful links for getting started on (co-op) Track Trigger related work

Introductory material

CMS experiment and physics introduction

CMS experiment:

More on CMS detector (and the links on the right sidebar):

More on CMS physics (and the links on the right sidebar):

Overview lectures:

These are some nice lectures from the "CERN summer student" program that are publicly available. In particular these ones is a good introduction:

- One series (3 lectures) on "particle world":




- First lecture on "detectors":

- Another series (3 lectures) on "from raw data to physics results":




Computing accounts & general useful links

CMS computing workbook has a ton of details (in particular go through chapter 1):

ROOT (for data analysis, making figures, etc.), recommend installing it locally on your computer (

Basic tutorial about ROOT:

Full site about ROOT:

Obtaining a grid certificate:

Password-less login:

Linux commands:

cernbox (CERN's version of dropbox):

L1 tracking software stuff

The first time to set up all the software, use this:

Set up CMS software release:

cmsrel CMSSW_11_1_0_pre8
cd CMSSW_11_1_0_pre8/src/

Check out some additional code specific to the L1 tracking:

git cms-checkout-topic -u cms-L1TK:L1TK-dev-11_1_0_pre8
git clone

Compile the code:

scram b -j 8

Go to the "test" directory where we will execute (run) the code:

cd L1Trigger/TrackFindingTracklet/test/

Finally, run the L1 tracking (this requires that you have requested and set up the grid certificate (using voms-proxy-init --voms cms) , see link above):


You can browse the python script in github here.

==> This will process 10 events from a Monte Carlo simulated sample of top quark pair production, with an average of 200 "pileup" interactions. Creates an output file called "TTbar_PU200_D49.root" that you can directly open in ROOT:

root -l TTbar_PU200_D49.root 

Once you have set up the software the first time, use this:

Set up CMS software release and grid certificate:

cd CMSSW_11_1_0_pre8/src/
voms-proxy-init --voms cms 

IF you have made changes to any of the C++ code, then you need to recompile the code, otherwise it is not necessary:

scram b -j 8

Go to the "test" directory and run the L1 tracking:

cd L1Trigger/TrackFindingTracklet/test/

Make histograms

To make histograms from the ROOT ntuple files that are created when you run, you can use the L1TrackNtuplePlot.C script. You can look at the plotting script in github here.

To run it in ROOT, the first time (only) -- create the following output directory (this is where the histograms will be saved):

mkdir TrkPlots

Then open ROOT:

root -l 

... and run as follows (assuming that the root file is called TTbar_PU200_D49.root, otherwise change the name accordingly):

.L L1TrackNtuplePlot.C++

Hardware (TIF) stuff


Looong document describing in all its detail the upgraded L1 trigger system, can use this as a reference. Suggest to read:

  • First part of introduction section, section 1.1 "Physics motivations and CMS Phase-2 trigger upgrade"
  • Section 2.1 about the L1 tracking "Track finder primitives"

Setting up (mac os x) computer for working:

Install XQuartz:

Install XCode:

Set up a text editor, there are many many out there. I (Louise) use Aquamacs (

Install ROOT and cernbox (as linked above).

-- LouiseSkinnari - 2020-02-21

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