APEX: A Prime EXperiment at Jefferson Lab

Abstract

APEX is an experiment at Thomas Jefferson National Accelerator Facility (JLab) in Virginia, USA, that searches for a new gauge boson ($A^{\prime }$) with sub-GeV mass and coupling to ordinary matter of $g^{\prime }\sim (10^{-6}-10^{-2})e$. Electrons impinge upon a fixed target of high-Z material. An $A^{\prime }$ is produced via a process analogous to photon bremsstrahlung, decaying to an $e^{+}{e}^{-}$ pair. A test run was held in July of 2010, covering $m_{A^{\prime }}$ = 175 to 250 MeV and couplings $g^\prime/e \; \textgreater \; 10^{-3}$. A full run is approved and will cover $m_{A^{\prime }}\sim$ 65 to 525 MeV and $g^\prime/e \; \textgreater \; 2.3 \times10^{-4}$.

Contributed to the 8th Patras Workshop on Axions, WIMPs and WISPs, Chicago, July 18-22, 2012. 4 pages, 4 figures