The BDX experiment at Jefferson Laboratoty
The Beam Dump Experiment (BDX) at Jefferson Laboratory (JLab) is an electron-beam thick-target experiment to search for Light Dark Matter (LDM) particles in the MeV-GeV mass range. BDX will exploit the high-intensity 10.6 GeV 𝑒− beam from CEBAF accelerator impinging on the beam dump of experimental Hall-A, collecting up to 1022 electrons-on-target (EOT) in a few years time. Any LDM particle produced by the interaction of the primary 𝑒− beam with the beamdump will be detected by measuring their scattering inside the BDX detector, an electromagnetic calorimeter surrounded by an hermetic veto system, which is to be installed in a dedicated underground facility, located 20 m downstream. Thanks to the large detection efficiency and background rejection capabilities, BDX will be able to explore a so-far unknown region in the LDM parameter space, improving current exclusion limits by one order of magnitude in case of a null observation.
A. Celentano et al. "The BDX experiment at Jefferson Laboratory", PoS ICHEP2022 (2022) 327, DOI: 10.22323/1.414.0327.
The BDX Proposals to Jefferson Lab:
- M. Battaglieri et al. (BDX Collaboration), "Dark Matter Search in a Beam-Dump eXperiment (BDX) at Jefferson Lab", e-Print: 1607.01390 [hep-ex].
- M. Battaglieri et al. (BDX Collaboration), "Dark Matter Search in a Beam-Dump EXperiment (BDX) at Jefferson Lab – 2018 Update to PR12-16-001", e-Print: 1910.03532 [physics.ins-det].
BDX MINI
BDX-MINI is a beam dump experiment optimized to search for light dark matter produced in the interaction of the intense CEBAF 2.176 GeV electron beam with the Hall A beam dump at Jefferson Lab. The BDX-MINI detector consists of a PbWO4 electromagnetic calorimeter surrounded by a hermetic veto system for background rejection. The experiment accumulated 2.56 ×1021 EOT in six months of running. Simulations of fermionic and scalar dark matter interactions with electrons of the active volume of the BDX-MINI detector were used to estimate the expected signal. Data collected during the beam-off time allowed us to characterize the background dominated by cosmic rays. A blind data analysis based on a maximum-likelihood approach was used to optimize the experiment sensitivity. An upper limit on the production of light dark matter was set using the combined event samples collected during beam-on and beam-off configurations. In some kinematic regions of interest, this pilot experiment is sensitive to the parameter space covered by some of the most sensitive experiments to date, which demonstrates the discovery potential of the next generation beam dump experiment planned at intense electron beam facilities.
M. Battaglieri et al. "Dark matter search with the BDX-MINI experiment", Phys. Rev. D 106 (2022) 072011, DOI: 10.1103/PhysRevD.106.072011, e-Print: 2208.01387 [hep-ex].
