Posts

Fishing for dark matter using displaced muons
(Originally published as a CMS Physics Briefing) Dark matter is mysterious. In some ways, we know a lot about it, including its average density in the universe and upper limits for how strongly the dark matter particles might interact with each other or with “normal” Standard Model particles.
Mar 20, 2023 4 min read paper review
What the eta meson does when no one's looking
(Originally published as a CMS Physics Briefing) The amount of data that CMS has collected so far is truly astounding, thanks to the very large number of proton-proton collisions that the LHC has provided, over more than a decade, and to the large rate of events that CMS can record.
Mar 14, 2023 5 min read paper review
Kerberos and SSH Keys with macOS Keychain
Previously I have discussed how to get SSH, Kerberos, and keytabs working together on macOS. But there is an easier way on macOS to work with both SSH keys and Kerberos keytabs in a password-less (but still safe) world.
Jan 25, 2021 2 min read technical notes
Lazy photons at the LHC
Title: “Search for long-lived particles using delayed photons in proton-proton collisions at $\sqrt{s}$ = 13 TeV” Author: CMS Collaboration Reference: https://arxiv.org/abs/1909.06166 (submitted to Phys. Rev. D) (Originally published on Particle Bites)
Nov 24, 2019 6 min read paper review
When light and light collide
Title: “Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC” Author: ATLAS Collaboration Reference: doi:10.1038/nphys4208 (Originally published on Particle Bites) According to classical wave theory, two electromagnetic waves that happen to cross each other in space will not interfere.
Aug 27, 2019 7 min read paper review
Pyxrootd bindings on macOS
The homebrew version of xrootd doesn’t come with python bindings for some reason. The python bindings are needed for reading remote ROOT files with python/uproot (not needed for C++ ROOT).
Last updated on Jun 18, 2019 1 min read technical notes
Tmux on lxplus - part II
(this is a continuation of “Tmux on lxplus - part I”, please check it out first!) Lxplus comes with native tmux installed. However, the native version is 1.8 which is very old.
Nov 29, 2018 2 min read technical notes
Tmux on lxplus - part I
(This is actually a prequel to “Tmux on lxplus - part II”, despite being uploaded after it) The tmux version on CERN’s lxplus is very old, 1.8. Since version 2.0 tmux has a host of neat new features, which makes it worth the pain of installing it locally.
Last updated on Jul 16, 2017 2 min read technical notes
AFS + Kerberos on MacOS
CERN provides AFS access to its remote machines. When you log in via SSH you are directed to your own personal folder in the AFS filesystem. It turns out you can mount the remote AFS filesystem on your local machine and “skip” the SSH step, treating the folder as if it were local (SSHFS-style).
Last updated on Jul 11, 2017 2 min read technical notes
SSH + Kerberos + Keytabs on MacOS
Kerberos is a convenient way to authenticate and obtain access to remote machines via SSH. Instead of typing your password every time you want to access a remote computer, you can type your password only once and obtain a Kerberos ticket, which serves as a ‘passport’ and saves typing effort during subsequent connections.
Last updated on Jan 25, 2021 4 min read technical notes