From CMSExperiment https://twitter.com/CMSExperiment on Twitter: Electrons, photons, it is all explained in this article for the general public, about how we recognise electrons and photons in the CMS experiment: https://cms.cern/news/finding-electrons-and-photons-cms-detector https://twitter.com/CMSExperiment/status/1357351959922098177 https://twitter.com/CMSExperiment/status/1359137882137645059/photo/1 https://chirp.cooleysekula.net/attachment/70727