Rotation Projects in Heavy Photon Search

The Heavy Photon Search Group at SLAC is collaborating with physicists at Jefferson Lab, Fermilab, UCSC, Italy, and France in an experiment aimed at discovering a hidden-sector, heavy photon. Such a particle would have mass in the range 0.02 to 1.0 GeV, couple weakly to electrons, and decay to

. It would be produced by electron bremstrahlung on a heavy target, and be identified as a narrow

resonance. The very weak couplings of the heavy photon to electrons account for its 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 because they may explain the abundance of high energy electrons and positrons in cosmic rays and be intimately linked to dark matter and the existence of hidden sectors. Our primary effort at SLAC is the Heavy Photon Search experiment (HPS). During 2011 and 2012, we built, installed, commissioned, and ran the HPS Test Run Experiment at JLab during Spring 2012. The experiment used LHC style readout of silicon microstrip detectors for tracking and vertex reconstruction of

pairs and a PbWO₄ crystal calorimeter to deal with the extremely high trigger rates expected. The run successfully demonstrated that backgrounds are manageable and that the apparatus worked as designed. Following the run and the submission of a new proposal, DOE has approved and funded the Heavy Photon Search and JLAB has scheduled running time in 2014 and 2015 

HPS offers many opportunities for rotation students. Simulation studies are needed, tracking pattern recognition and vertexing code is being improved, the data acquisition system for the experiment is being refined and upgraded, a new silicon tracker/vertexer is being designed and built, detector monitoring software is being coded, and the physics analysis is being 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. Rotation Projects are available for the 2013-2014 academic year, outlined below. 

Our SLAC group is also involved in the APEX experiment, which has already completed a test run in 2010 and published results of its initial search, excluding a new region of heavy photon parameter space. The experiment makes use of two existing spectrometers in Jlab's experimental Hall A. The experiment hopes to take more data during the 2013-2014 JLab cycle and we hope to contribute. John Jaros.

Possible Projects for 2013-2014