The Heavy Photon Search Experiment

Abstract

In recent years much interest has been given to new physics models which have hidden sectors with massive extra U(1) gauge bosons, so-called heavy photons (or dark photons). Such theories could account for Dark Matter annihilation and explain excess electrons and positrons in cosmic rays. The Heavy Photon Search Experiment (HPS) at Jefferson Lab is a new experiment designed to look for these heavy photons in the mass range 20-1000 MeV that couple to electrons through kinetic mixing with couplings α ′/α in the range 10−5 to 10−10. The HPS will search for the e+e− or μ+μ− decay of the heavy photon, possibly with a displaced vertex, using a compact forward spectrometer, which employs silicon microstrip detectors for vertexing and tracking, and a PbWO4 electromagnetic calorimeter for fast triggering and electron identification, and a muon detector for muon identification. The design, performance, and results from the test run apparatus will be discussed, along with the collaboration’s plans for future construction and data taking.