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 0.02 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. Weak couplings of this 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 recently because they may explain high energy electrons and positrons in cosmic rays and be intimately linked to dark matter annihilation.

Our primary effort at SLAC is the Heavy Photon Search experiment (HPS). During the past year, 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 the technical feasibility of the experiment, so the JLAB program committee rewarded us with a 6 week data taking run at the end of 2014. An extended run in 2015 is likely as well. Both these runs will use a new apparatus, just now in the design phase, but based on the technologies and techniques we demonstrated in the Test Run.

HPS offers many opportunities for rotation students. Experimental design and 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 must be designed and built, 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. Some of the previous HPS rotation projects are listed below. New projects will be added.

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.

Fall/Winter 2011 Projects

Spring/Summer 2012 Projects