The CODEX\u2011b collaboration at CERN has achieved, in an important milestone, the recording of the first data with the prototype of its CODEX\u2011beta detector, installed at the Large Hadron Collider (LHC). This represents a key step toward demonstrating the search capabilities of this new class of detectors, focused on the search for the so\u2011called \u201cdark sectors\u201d, particles and fields beyond the Standard Model as we know it, which remain elusive for the current LHC detection systems. <\/p>\n
These hidden sectors could provide answers to some of the major unresolved mysteries in physics, such as the composition of dark matter, the origin of the matter\u2013antimatter asymmetry in the universe, or the naturalness of the electroweak vacuum.<\/p>\n
CODEX\u2011b (acronym for COmpact Detector for EXotics at LHCb) was proposed in 2017 by a collaboration of four scientists from Lawrence Berkeley National Laboratory, the University of Cincinnati and the LPNHE in Paris. Since then, the collaboration has grown to more than 60 members in 20 institutions around the world. And Galicia, through the IGFAE<\/a> and the University of A Coru\u00f1a, has a relevant role in this collaboration. <\/p>\n On the IGFAE side, the team is led by Xabier Cid, physics coordinator of the project, and also includes Miguel Fern\u00e1ndez G\u00f3mez, Alberto Mart\u00ednez Armas, Pablo Men\u00e9ndez-Vald\u00e9s, Alejandro Novo Cal, Mar\u00eda Pereira Mart\u00ednez, Emilio Xos\u00e9 Rodr\u00edguez Fern\u00e1ndez and Alejandro Rodr\u00edguez Gonz\u00e1lez. Contributions from the UDC also had a critical impact, with a team led by Carlos V\u00e1zquez Sierra, software development coordinator and deputy physics coordinator of the project; and Titus Momb\u00e4cher, technical coordinator of CODEX-b. <\/p>\n In this sense, the collaboration between both groups at IGFAE and UDC was key to meeting the necessary deadlines for data collection before the end of Run 3, the last data collection period of the LHC, at the end of June 2026.<\/p>\n Shifting the focus toward \u201clong\u2011lived particles\u201d<\/strong><\/p>\n The purpose of CODEX\u2011b is to shift the focus toward long\u2011lived particles, which tend to appear far from the collision points where the LHC detectors are looking. The key to the experiment is a special \u201cactively shielded, zero\u2011background\u201d environment, where only these hidden long\u2011lived particles can appear before decaying. <\/p>\n The collaboration is currently working with the CODEX\u2011beta prototype, a 1:5 scale version of CODEX\u2011b, with an approximate volume of 2 m\u00b3. Its main purpose is to take critical measurements needed to design the active shielding of the full\u2011size detector and to optimize the detector concept, which is also used in other proposed devices for long\u2011lived particles. Despite its small size, CODEX\u2011beta can also explore some new scenarios of new physics. <\/p>\n