Heavy Photon Search Experiment

About

The Heavy Photon Search Group at SLAC is collaborating with physicists at Jefferson Lab, Fermilab, and UCSC in two experiments aimed at discovering a hidden-sector, heavy photon. Such a particle would have mass in the range 0.1 to 1.0 GeV, couple weakly to electrons, and decay to e^+^e^. It would be produced by electron bremstrahlung on a heavy target, and be identified as a narrow e+e resonance. Weak couplings of this heavy photon to electrons account for it having not yet been discovered and can give rise to separated vertices in its decay, providing a spectacular signature. Heavy photons have become a hot topic recently because they may explain high energy electrons and positrons in cosmic rays, and be intimately linked to dark matter annihilation.

The first experiment is the APEX experiment, which has been conditionally approved at Jlab, and which has already completed a test run this past Summer. The experiment makes use of two large spectrometers in Jlab's experimental Hall B to search for a heavy photon. If successful, several more data taking runs will be scheduled in 2010-2012.

The second experiment is the Heavy Photon Search experiment (HPS). Our SLAC group, in collaboration with others, has just submitted a proposal to Jefferson Laboratory and hopes for approval this Fall. The experiment will use LHC style readout of silicon microstrip detectors for tracking and vertex reconstruction of e^+^e-^ pairs and a PbWO~4~ crystal calorimeter to deal with the extremely high trigger rates expected.