Fall 2010 Rotation Projects in Heavy Photon Search

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 experiment provides many opportunities for rotation students, and could provide data for a very topical particle physics thesis. SLAC has responsibilities for constructing and testing the target for the experiment, taking shifts, and helping to develop the data analysis. For more information on APEX rotation projects, please contact John Jaros.

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 PbWO4 crystal calorimeter to deal with the extremely high trigger rates expected. There are many opportunities for rotation students. Experimental design and simulation studies will continue, tracking pattern recognition and vertexing code is being developed, the data acquisition system for the experiment will be designed and tested, a silicon tracker/vertexer will be built, and the physics analysis techniques will be developed. This experiment is very small by modern standards, but exploits cutting edge detection and readout technologies to address a very fascinating piece of physics. It provides a perfect opportunity for a thesis student, offering all aspects of experimental work, from design to hardware implementation to data analysis. Some specific proposals for Fall 2010 HPS rotation projects are listed below.