Speaker
Description
J/ψ near-threshold photoproduction plays a key role in the physics program at the Thomas Jefferson National Accelerator Facility (JLab) 12 GeV upgrade due to the wealth of information it has to offer. Near threshold, J/ψ photoproduction proceeds through the exchange of gluons in the t-channel and is expected to provide unique insight about the nucleon gluonic form factors and the nucleon mass radius.
The JLab based CLAS Collaboration, which uses the CEBAF Large Acceptance Spectrometer at 12 GeV (CLAS12), aims to measure the J/ψ near-threshold photoproduction cross section using both a proton and a deuteron target. The latter further offers the possibility of comparing the proton and neutron gluonic mass radii in a first measurement of the cross sections off a proton or neutron within the deuteron target. The analysis towards these measurements is well advanced and being finalized for publication.
This talk will describe the aims and experimental design for the measurement of J/ψ near-threshold photoproduction off the proton and neutron in deuteron with the CLAS12 detector along with preliminary first measurements of the J/ψ total and differential cross sections. The differential cross section in particular can be used to estimate the mass radius of the neutron which will be compared to previous estimates of the mass radius of the proton.
