Status of the Jefferson Lab Eta Factory (JEF) experiment

The Jefferson Lab Eta Factory (JEF) experiment is an experiment running in Hall

D at Jefferson Lab that focuses on studying the decays of the η meson.

These decays provide a rich laboratory for searching for new charge conjugation violating / parity conserving (CVPC) processes,

looking for hints of Beyond Standard Model physics, and probing higher order

terms in Chiral Perturbation Theory. The flagship channel is the rare decay

η→π⁰γγ, the measurement of which required an upgrade to the

existing equipment in Hall D. The experiment uses the GlueX detector, a

fixed-target large acceptance spectrometer based on a solenoid magnet containing

drift chambers for tracking charged particles and a lead-scintillator barrel

calorimeter in the central region and an array of 4×4×45 cm³

lead glass blocks in the forward region for detecting neutral particles.

During the last two years the inner 80×80 cm² region of the

forward calorimeter has been replaced by an array of 2×2×20 cm³

lead tungstate crystals, which provide factors of two improvement in energy

and position resolution. The first round of data taking with this

configuration took place this year. A first look at the data will be presented.