DarkSHINE: Search for Light Dark Matter at the SHINE Facility in Shanghai

TL;DR

DarkSHINE targets light dark matter in the MeV–GeV range via invisible decays of a dark photon using an electron-on-target approach at the SHINE facility. It combines a dedicated single-electron beam, AC-LGAD tracking, a LYSO ECAL, and a scintillator HCAL with a Geant4-ROOT-based simulation framework (DSimu-DAna) to predict signals and backgrounds and to project sensitivity to $ε^{2}$ and the thermal target $y$ across $m_{A'}$ and $m_{χ}$. The work delivers a detailed detector concept validated by beam tests, a full simulation-and-analysis chain, and sensitivity projections that promise substantial improvements over current constraints in the MeV region. As China’s first electron-fixed-target DM program, DarkSHINE offers a rapid, complementary path to explore the light-dark sector and informs future prototype deployment and trigger-level innovations.

Abstract

DarkSHINE is an electron fixed target experiment under proposal that aims to probe light dark matter in the MeV-GeV mass range via the invisible decay of dark photons, leveraging the High repetition rate 8 GeV electron beam from the Shanghai High repetition-rate XFEL and Extreme Light Facility. This proceeding presents the core detector design of the experiment, the simulation framework, and the prospects of the physics. The detector system integrates an AC-coupled Low Gain Avalanche Diode silicon tracker, a LYSO crystal electromagnetic calorimeter, and a scintillator-based hadronic calorimeter, all optimized for SHINE high-radiation, high-rate environment. The prototype tests at DESY and CERN have validated key performance metrics, including a spatial resolution of 6.5-8.2 microns for silicon strip sensor, an electromagnetic calorimeter energy resolution of 1.8%. Based on MC simulations and 9E14 EOT, the DarkSHINE experiment is expected to rule out most of the sensitive regions predicted by popular dark photon models.

Figures (8)

• Figure 1: The conceptual design of the FEL kicker, DarkSHINE kicker and beamline.
• Figure 2: The conceptual design of the DarkSHINE detector is structured as follows: along the electron incident direction (from left to right), a tagging tracker, tungsten target, and recoil tracker are mounted inside a dipole magnet with a 1.5 T magnetic field. These are followed by a crystal electromagnetic calorimeter (ECAL) encircled by a side hadronic calorimeter (sideHCAL), and a large hadronic calorimeter (HCAL) positioned downstream.
• Figure 3: Image of the AC-LGAD silicon strip sensor.
• Figure 4: Configuration of the ECAL.
• Figure 5: Energy resolution and containment of the ECAL.