|Title||Measurement of the proton form factor ratio at low momentum transfer|
|Supported by U.S. Naval Research:||No|
|Supported by Jefferson Lab LDRD Funding:||No|
|Funding Source:||Nuclear Physics (NP)|
A PHD thesis
Douglas Higinbotham (JLab)
Guy Ron (University of Tel Aviv)
|Publication Abstract:|| Experiment E08-007-II measured the proton elastic form factor ratio muGE=GM in the momentum transfer range of Q2 ~ 0.02 - 0.08 GeV2, the lowest ever measured by polarization transfer techniques. The experiment was performed at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia, USA during 2012. A polarized electron beam with energies of 1.1, 1.7, and 2.2 GeV was elastically scattered off a polarized solid NH3 target. The asymmetries between the cross section of positive and negative helicity states of the beam were determined. These asymmetries can be used to determine the form factor ratio.
In this thesis, we present the asymmetry analysis of the experiment, discuss the main challenges and show preliminary results for part of the data. Preliminary asymmetries indicate an increase in the form factor ratio above unity. However, a complete analysis is required before any conclusion can be made. Further analysis is ongoing, and final asymmetry results and form factor extraction is expected during 2017.
We also present first results for 14N asymmetries for elastic and quasi-elastic scattering. The measured asymmetries are in agreement with the shell model approximation, within the low accuracy of the measurement. A change in the asymmetry sign between the elastic and the quasi-elastic processes is seen, and should motivate further theoretical studies. These experimental asymmetries will also be useful for systematic studies of other experiments using polarized NH3 targets.