CMS Guide on how to calculate luminosity

Documentation Guide

What is this?

This document provides instruction for how to calculate the luminosity information for CMS in the open data environment. This is done using brilcalc, which is a command line tool from the CMS Beam Radiation Instrumentation and Luminosity (BRIL) group.

Before you continue, consider that some of the information that you wish to calculate is already available for 2010, 2011, 2012, and 2015 data. The information available includes:

  • the integrated luminosity for validated runs and luminosity sections
  • the trigger prescales by run and luminosity section
  • the luminosity by luminosity section for the list of validated runs and luminosity sections

Prerequisites

There are three options for using brilcalc: using a docker container with the brilcalc software installed, or installing brilcalc either in the CMS open data Virtual Machine (VM) or in the CMS open data docker container.

Brilcalc container

If you have docker installed, donwload and run the container with

docker run -it --name brilws gitlab-registry.cern.ch/cms-cloud/brilws-docker

The software is preinstalled in the container and you can directly test brilcalc.

Virtual machine

Follow the instructions here to install the CMS VM and then the instructions for getting started.

Click on the CMS Shell icon on the desktop to open the terminal. At the terminal prompt, run the command

cmsrel CMSSW_5_3_32

and then change directory

cd CMSSW_5_3_32/src

and then finally intialize the CMS environment

cmsenv

Now we are ready to install the brilcalc package.

Docker container

Following the instructions here we download and install an image and run a Docker container using the following command:

docker run --name my_od -P -p 5901:5901 -it cmsopendata/cmssw_5_3_32-slc6_amd64_gcc472 /bin/bash

When completed successfully we should be at the command prompt:

cmsusr@a17b2a79d067 ~/CMSSW_5_3_32/src $

Now we are ready to install the brilcalc package.

Install brilcalc

cvmfs

If you are using the VM, or if are using the docker container and have the cvmfs file system installed locally, you have access to cvmfs. In these cases, follow these instructions:

  1. Set your PATH:

    export PATH=$HOME/.local/bin:/cvmfs/cms-bril.cern.ch/brilconda/bin:$PATH

  2. Install using pip with the command:

    pip install --user brilws

    At the end of a successful installation you should see the messages:

    Successfully built brilws
Installing collected packages: brilws
Successfully installed brilws

  3. Check the installation by running the command:

    brilcalc --version

    which should output 3.6.2

Now you are ready to test brilcalc.

conda

Alternatively you can install a conda environment:

  1. In the command prompt go to the home directory in your container with the command cd

  2. Fetch the installer for the brilcalc conda environment:

    wget https://cern.ch/cmslumisw/installers/linux-64/Brilconda-1.1.7-Linux-x86_64.sh

    (you may need to use the --no-check-certificate option with wget)

  3. Run the installer:

    bash Brilconda-1.1.7-Linux-x86_64.sh -b -p <localbrilcondabase>

    where we substitute <localbrilcondabase> with brilconda. This is the directory in which the brilcalc tools will be installed.

  4. Once installed successfully add the tools to your PATH with the following command:

    export PATH=$HOME/.local/bin:$HOME/brilconda/bin:$PATH

  5. Then install brilcalc with this command:

    pip install brilws

  6. Finally check by running the following:

    brilcalc --version

    which should output 3.53

Now you are ready to test brilcalc.

Test brilcalc

As a test, let's see what the integrated luminosity was for run 160431 by running the command

brilcalc lumi -c web -r 160431

which should output

#Data tag : 19v3 , Norm tag: onlineresult
+-------------+-------------------+-----+------+----------------+----------------+
| run:fill    | time              | nls | ncms | delivered(/ub) | recorded(/ub)  |
+-------------+-------------------+-----+------+----------------+----------------+
| 160431:1615 | 03/14/11 03:08:07 | 243 | 218  | 8781.334977241 | 7879.289611261 |
+-------------+-------------------+-----+------+----------------+----------------+
#Summary:
+-------+------+-----+------+-------------------+------------------+
| nfill | nrun | nls | ncms | totdelivered(/ub) | totrecorded(/ub) |
+-------+------+-----+------+-------------------+------------------+
| 1     | 1    | 243 | 218  | 8781.334977241    | 7879.289611261   |
+-------+------+-----+------+-------------------+------------------+

Note: It is important that you use the -c web option when running brilcalc. This specifies that you use indirect access to BRIL servers via web cache. For users of CMS open data outside CERN and CMS this is the only option that will work.

Note: There is a useful help option for brilcalc and its commands:

brilcalc --help

usage:
   brilcalc (-h|--help|--version)
   brilcalc [--debug|--warn] <command> [<args>...]

 commands:
   lumi Luminosity
   beam Beam
   trg Trigger configurations
 See 'brilcalc <command> --help' for more information on a specific command.

Common queries

Integrated luminosity for a run

See test above

Integrated luminosity for validated runs and luminosity sections

First obtain the file with the list of validated runs and luminosity sections. Here we use the list for 2011 data.

wget http://opendata.cern.ch/record/1001/files/Cert_160404-180252_7TeV_ReRecoNov08_Collisions11_JSON.txt

It is recommended to steer the output to a file (e.g. called 2011lumi.txt) using this command:

brilcalc lumi -c web -i Cert_160404-180252_7TeV_ReRecoNov08_Collisions11_JSON.txt > 2011lumi.txt

The output will appear as follows:

#Data tag : v1 , Norm tag: onlineresult
+-------------+-------------------+------+------+----------------+---------------+
| run:fill    | time              | nls  | ncms | delivered(/ub) | recorded(/ub) |
+-------------+-------------------+------+------+----------------+---------------+
| 160431:1615 | 03/14/11 03:14:43 | 200  | 200  | 7366.884       | 7366.875      |
| 160577:1622 | 03/16/11 01:44:38 | 53   | 53   | 1719.888       | 1631.386      |
| 160578:1622 | 03/16/11 02:20:03 | 175  | 175  | 5201.105       | 4952.155      |
| 160871:1636 | 03/19/11 02:43:57 | 141  | 141  | 109739.586     | 106354.581    |
| 160872:1636 | 03/19/11 03:50:05 | 38   | 38   | 28346.738      | 23977.109     |
| 160873:1636 | 03/19/11 04:20:20 | 147  | 147  | 104914.534     | 103031.004    |

The units are inverse microbarns as default and can be changed to inverse femtobarns with the option -u /fb. Note that the lists of validated runs are usually given for the full data-taking period, whereas the open data are a part of it. See the intructions below on how to get the values over a range of runs.

Select luminometer

CMS measures the luminosity with different luminometers (luminosity detectors) and algorithms. You can choose which to use with the --type option as below. Here we use the list of validated runs from 2012.

brilcalc lumi --type pxl -c web -i Cert_190456-208686_8TeV_22Jan2013ReReco_Collisions12_JSON.txt -u /fb > 2012lumi.txt

In this example the pixel detectors are used. This is the preferred option. For 2010 data a calculation using the hadronic forward calorimeters is used and is given by the option --type hfoc.

For Run-2 data, the luminometer giving the best value for each luminosity section is recorded in a 'normtag' file, provided in the 2015 luminosity information record ('normtag_PHYSICS_2015.json'). Use it with the corresponding list of validated runs from 2015 as in

brilcalc lumi -c web -i Cert_13TeV_16Dec2015ReReco_Collisions15_25ns_JSON_v2.txt -u /fb --normtag normtag_PHYSICS_2015.json > 2015lumi.txt

Note You may notice at the end of the output luminosity sections that are listed in the json quality file but do not have any luminosity values corresponding to them. These correspond to sections that are left-overs at the end of a run, which where still tagged as STABLE RUN, but actually did not provide any luminosity. These are safe to ignore as they do not contain any events.

Integrated luminosity for validated runs and luminosity sections over a range of runs

First obtain the file with the list of validated runs and luminosity sections. Here we use the list for 2011 data.

wget http://opendata.cern.ch/record/1001/files/Cert_160404-180252_7TeV_ReRecoNov08_Collisions11_JSON.txt

RunA of 2011 proton-proton data comprises runs 160431 to 173692 (inclusive) so to calculate the integrated luminosity for this era run the command:

brilcalc lumi -c web --begin 160431 --end 173692 -i Cert_160404-180252_7TeV_ReRecoNov08_Collisions11_JSON.txt > RunA2011lumi.txt

For 2015 data, obtain the corresponding list of validated runs:

wget https://opendata.cern.ch/record/14210/files/Cert_13TeV_16Dec2015ReReco_Collisions15_25ns_JSON_v2.txt

and the normtage file

wget https://opendata.cern.ch/record/1055/files/normtag_PHYSICS_2015.json

RunD of 2015 proton-proton data comprises runs 256630 to 260627 (inclusive) so to calculate the integrated luminosity for this era using the best luminometer estimates defined in normtag_PHYSICS_2015.json run the command:

brilcalc lumi -c web --begin 256630 --end 260627 -i Cert_13TeV_16Dec2015ReReco_Collisions15_25ns_JSON_v2.txt --normtag normtag_PHYSICS_2015.json > RunD2015lumi.txt

Integrated luminosity for validated runs and luminosity sections, separated by luminosity sections

If you want to fetch the integrated luminosity by luminosity section and output the results to a csv file (which is recommended), first obtain the file with the list of validated runs and luminosity sections. Here we use the list for 2011 data.

wget http://opendata.cern.ch/record/1001/files/Cert_160404-180252_7TeV_ReRecoNov08_Collisions11_JSON.txt

Then run the command:

brilcalc lumi --byls --output-style csv -c web -i Cert_160404-180252_7TeV_ReRecoNov08_Collisions11_JSON.txt > my2011lumibyls.csv

The contents of the csv file will appear as below:

#Data tag : v1 , Norm tag: None
#run:fill,ls,time,beamstatus,E(GeV),delivered(/ub),recorded(/ub),avgpu,source
160431:1615,19:19,03/14/11 03:14:43,STABLE BEAMS,3500,39.312,39.312,3.4,hfoc
160431:1615,20:20,03/14/11 03:15:07,STABLE BEAMS,3500,39.368,39.368,3.4,hfoc
160431:1615,21:21,03/14/11 03:15:30,STABLE BEAMS,3500,39.305,39.305,3.4,hfoc
160431:1615,22:22,03/14/11 03:15:53,STABLE BEAMS,3500,35.843,35.843,3.1,hfoc
160431:1615,23:23,03/14/11 03:16:17,STABLE BEAMS,3500,37.093,37.093,3.2,hfoc
160431:1615,24:24,03/14/11 03:16:40,STABLE BEAMS,3500,39.620,39.620,3.4,hfoc
160431:1615,25:25,03/14/11 03:17:03,STABLE BEAMS,3500,34.396,34.396,3.0,hfoc
160431:1615,26:26,03/14/11 03:17:27,STABLE BEAMS,3500,39.874,39.874,3.4,hfoc

Integrated luminosity for a HLT trigger path

Here as an example we calculate the total integrated luminosity for a particular for high-level triggers whose name matches the pattern HLT_DoubleMu and output the results to a csv file:

brilcalc lumi -c web -r 173692 --hltpath="HLT_DoubleMu*" --output-style csv > run173692_DoubleMu.csv

Note: It is strongly recommended to make your HLT query as specific as possible and to output to csv.

Calculate trigger prescales for a run and trigger path

brilcalc trg --prescale -c web -r 148002 --hltpath "HLT_Jet*"

+--------+-------+----------+-------------+---------------------------------+-------+--------------------+
| run    | cmsls | prescidx | totprescval | hltpath/prescval                | logic | l1bit/prescval     |
+--------+-------+----------+-------------+---------------------------------+-------+--------------------+
| 148002 | 1     | 1        | 12000       | HLT_Jet15U/20                   | ONE   | L1_SingleJet6U/600 |
| 148002 | 1     | 1        | 12000       | HLT_Jet15U_HcalNoiseFiltered/20 | ONE   | L1_SingleJet6U/600 |
| 148002 | 1     | 1        | 1200        | HLT_Jet30U/1200                 | ONE   | L1_SingleJet20U/1  |
| 148002 | 1     | 1        | 170         | HLT_Jet50U/170                  | ONE   | L1_SingleJet30U/1  |
| 148002 | 1     | 1        | 30          | HLT_Jet70U_v2/30                | ONE   | L1_SingleJet40U/1  |
| 148002 | 1     | 1        | 1           | HLT_Jet100U_v2/1                | ONE   | L1_SingleJet60U/1  |
| 148002 | 1     | 1        | 1           | HLT_Jet140U_v1/1                | ONE   | L1_SingleJet60U/1  |
+--------+-------+----------+-------------+---------------------------------+-------+--------------------+

Change of prescales over a run

brilcalc trg --prescale -c web -r 173243

+--------+-------+----------+
| run    | cmsls | prescidx |
+--------+-------+----------+
| 173243 | 1     | 5        |
| 173243 | 14    | 4        |
+--------+-------+----------+
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