The Primakoff Experimental Program on Nuclear Targets in Hall D at Jefferson Lab*

The energy upgrade of the Jefferson Lab’s facility to 22 GeV will allow for the extension of the Primakoff 

experimental program in Hall D. With an upgraded forward calorimeter and the future beam energy upgrade, 

we will significantly improve recent measurements of the PrimEx-eta experiment of the $eta$ differential 

cross sections at forward angles. This cross section will be used for the extraction of the $eta$  decay width. 

This result is essential for determinations of the fundamental QCD parameters, such as the ratio of light 

quark masses and the $eta$ -- $eta^prime$  mixing angle, and will provide an important test of chiral symmetry breaking in QCD. 

The energy upgrade will allow to perform the first measurement of the $eta^prime$ radiative decay width via the 

Primakoff effect, which will complement the existing results from the collider experiments. We will give an 

overview of the experimental setup and discuss the feasibility of the Primakoff physics program on nuclear 

targets at 22 GeV.