Search by the SENSEI Experiment for Millicharged Particles Produced in the NuMI Beam
L. Barak, Itay M. Bloch, Ana Martina Botti, Mariano Cababié, Gustavo Cancelo, Brenda A. Cervantes-Vergara, Luke Chaplinsky, M. B. Crisler, A. Drlica-Wagner, Rouven Essig, J. Estrada, Erez Etzion, Guillermo Fernández Moroni, S. Holland, Yaron Korn, Ian T. Lawson, Steffon Luoma, Sravan Munagavalasa, Aviv Orly, Santiago E. Perez, Darío Rodrigues, N. Saffold, S. Scorza, Aman Singal, Miguel Sofo Haro, Leandro Stefanazzi, Kelly Stifter, Javier Tiffenberg, Sho Uemura, Tomer Volansky, T. Yu, Roni Harnik, Zhen Liu, Ryan Plestid
Abstract
Millicharged particles appear in several extensions of the standard model, but have not yet been detected. These hypothetical particles could be produced by an intense proton beam striking a fixed target. We use data collected in 2020 by the SENSEI experiment in the MINOS cavern at the Fermi National Accelerator Laboratory to search for ultrarelativistic millicharged particles produced in collisions of protons in the NuMI beam with a fixed graphite target. The absence of any ionization events with 3 to 6 electrons in the SENSEI data allow us to place world-leading constraints on millicharged particles for masses between 30 to 380 MeV. This work also demonstrates the potential of utilizing low-threshold detectors to investigate new particles in beam-dump experiments, and motivates a future experiment designed specifically for this purpose.