Novel Limits on Dark Photon Mixing from Radiation Safety

Abstract

I propose a novel laboratory search for dark photons based on radiation-safety monitoring at synchrotron radiation facilities, including NanoTerasu, SPring-8, KEK-PF, and ESRF. Dark photons can be produced parasitically in undulators or via photon-mirror interactions, and subsequently traverse optical systems and shielding. Taking into account quantum effects and the internal structure of undulators, mirrors, and detectors, I show that even a simple Geiger-Müller counter, routinely used for radiation-safety monitoring, can detect such dark photons outside the shielding and set competitive limits on the kinetic mixing parameter down to $\chi \lesssim 5\times 10^{-6}$ in the eV mass range, providing some of the strongest bounds among laboratory searches. Because radiation safety is strictly regulated, the resulting limits can be regarded as robust and realistic constraints.

Comments: 13pages, 4figures, 1table, comments welcome