Recently I moved my codes to the UF HiPerGator machines (also referred to as the HPC machines) which are running RHEL 7. Info about HiPerGator can be found on:

• https://help.rc.ufl.edu/doc/Getting_Started
• https://help.rc.ufl.edu/doc/Training

One issue that I ran into was that the grid tools used by CMS, e.g. voms-proxy-*, uberftp, gfal-copy, globus-url-copy, etc, are not automatically set up. To get them working, I got the following instructions from Bockjoo Kim:

source /cvmfs/oasis.opensciencegrid.org/osg-software/osg-wn-client/current/el7-x86_64/setup.sh
export X509_CERT_DIR=/cvmfs/cms.cern.ch/grid/etc/grid-security/certificates
export X509_VOMS_DIR=/cvmfs/cms.cern.ch/grid/etc/grid-security/vomsdir
export VOMS_USERCONF=/cvmfs/cms.cern.ch/grid/etc/vomses

The Jupyter notebook code indentation is 4 spaces by default. It can be configured as documented here. Basically, to change it to 2 spaces, look for the file ~/.jupyter/nbconfig/notebook.json. If the directory or the file doesn’t exist, create them. Then edit the file to add the following:

{
  "CodeCell": {
    "cm_config": {
      "indentUnit": 2
    }
  }
}

(Tested on Jupyter 4.4.0.)

Trying to install CMSSW in an OS that is not officially supported (e.g. Mac OS, Arch Linux, etc) can be very difficult. It’s possible to run a virtual machine with Scientific Linux or CentOS as the guest OS instead. But there is also a more lightweight solution, which is to use a Docker container.

The official Docker images provided by ‘cmssw’ are huge (5-10 GB). Apparently there is a different Docker image that you can use, which is provided by ‘hepsw’, and is smaller (~200 MB). You can find the Dockerfiles used to build the images at https://github.com/cms-sw/cms-docker (for ‘cmssw’) and at https://github.com/hepsw/docks (for ‘hepsw’).

The following instructions should provide a functional CMSSW environment using the hepsw/cvmfs-cms image (tested on Linux Mint 18 as the host OS). Note that the image is based on slc-6.

# Install Docker from the repository
sudo apt install docker.io

# Load the Docker image
# '--privileged' option is required because of FUSE
sudo systemctl start docker
sudo docker run -h dev --privileged -i -t hepsw/cvmfs-cms

Once the image is loaded, you should be in the interactive session in the guest OS. To setup CMSSW:

yum install -y glibc glibc-headers glibc-devel.x86_64

export SCRAM_ARCH=slc6_amd64_gcc700
scramv1 project CMSSW CMSSW_10_4_0
cd CMSSW_10_4_0/src
eval `scramv1 runtime -sh`
scram b

To disable the annoying fastestmirror plugin for yum, open the file /etc/yum/pluginconf.d/fastestmirror.conf, and change enabled=1 to enabled=0.

Bash

• Parameter expansion: https://wiki.bash-hackers.org/syntax/pe

Sed

Vim

Git

• Pro Git book: https://git-scm.com/book/en/v2

Regex

• Regular expressions cheat sheet: https://cheatography.com/davechild/cheat-sheets/regular-expressions/pdf/

The muon $p_{\mathrm{T}}$ is measured from the curvature of its trajectory in the magnetic field. The curvature is proportional to $1/p_{\mathrm{T}}$. So, the error in the curvature measurement is related to the $p_{\mathrm{T}}$ resolution:

If the error in the curvature measurement is independent of $p_{\mathrm{T}}$, i.e. $k(p) = k$, then we find that the fractional $p_{\mathrm{T}}$ resolution is proportional to $p_{\mathrm{T}}$: