High efficiency veto hadron calorimeter in the NA64 experiment at CERN
Abstract
NA64 is a fixed-target experiment at the CERN SPS designed to search for Light particle Dark Matter (LDM) candidates with masses in the sub-GeV range. During the 2016-2022 runs, the experiment obtained the world-leading constraints, leaving however part of the well-motivated region of parameter space suggested by benchmark LDM models still unexplored. To further improve sensitivity, as part of the upgrades to the setup of NA64 at the CERN SPS H4 beamline, a prototype veto hadron calorimeter (VHCAL) was installed in the downstream region of the experiment during the 2023 run. The VHCAL, made of Cu-Sc layers, was expected to be an efficient veto against upstream electroproduction of large-angle hadrons or photon-nuclear interactions, reducing the background from secondary particles escaping the detector acceptance. With the collected statistics of electrons on target (EOT), we demonstrate the effectiveness of this approach by rejecting this background by more than an order of magnitude. This result provides an essential input for designing a full-scale optimized VHCAL to continue running background-free during LHC Run 4, when we expect to collect EOT. Furthermore, this technique combined with improvements in the analysis enables us to decrease our missing energy threshold from 50 GeV to 40 GeV thereby enhancing the signal sensitivity of NA64.
Keywords
Cite
@article{arxiv.2503.11275,
title = {High efficiency veto hadron calorimeter in the NA64 experiment at CERN},
author = {Yu. M. Andreev and A. Antonov and M. A. Ayala Torres and D. Banerjee and B. Banto Oberhauser and V. Bautin and J. Bernhard and P. Bisio and M. Bondì and A. Celentano and N. Charitonidis and P. Crivelli and A. V. Dermenev and S. V. Donskov and R. R. Dusaev and T. Enik and V. N. Frolov and S. V. Gertsenberger and S. Girod and S. N. Gninenko and M. Hösgen and Y. Kambar and A. E. Karneyeu and G. Kekelidze and B. Ketzer and D. V. Kirpichnikov and M. M. Kirsanov and V. A. Kramarenko and L. V. Kravchuk and N. V. Krasnikov and S. V. Kuleshov and V. E. Lyubovitskij and V. Lysan and A. Marini and L. Marsicano and V. A. Matveev and R. Mena Fredes and R. Mena Yanssen and L. Molina Bueno and M. Mongillo and D. V. Peshekhonov and V. A. Polyakov and B. Radics and K. Salamatin and V. D. Samoylenko and H. Sieber and D. Shchukin and O. Soto and V. O. Tikhomirov and I. Tlisova and A. N. Toropin and M. Tuzi and P. V. Volkov and I. V. Voronchikhin and J. Zamora-Saá and A. S. Zhevlakov},
journal= {arXiv preprint arXiv:2503.11275},
year = {2025}
}
Comments
13 pages, 12 figures