Krishna S. Kumar



Chandan Ghosh 

Hanjie Liu

Cameron Clarke

Tao Ye

Ryan Richards


Useful Links


PREX  at Jefferson Laboratory


PhD Thesis of Tao Ye

PhD Thesis of Ryan Richards

PhD Thesis of Cameron Clarke 

Measuring Neutron RMS Radia of Nuclei with Parity-Violating Electron Scattering 

The Lead (Pb) Radius EXperiment (PREX)

The PREX experiment at Jefferson Lab measured the neutron RMS radius of 208Pb for the very first time by measuring the weak neutral current amplitude of elastic electron scattering off Pb nuclei

The first results were published in 2012 from the pilot run in 2010.  The final results of the follow-up PREX2 physics run in summer of 2019 were published in 2021 in the arXiv here and in PRL here.             

The extracted neutron skin of 0.28 +/- 0.07 fm is thicker than expected and in slight tension with other techniques to extract this quantity. The cleanliness of the PREX extraction has resulted in a lot press attention.

2021 PREX Result in the News:

  1.  * Physics Today article

     * Synopsis from Physics to go with PRL

     * College of Natural Sciences Article with additional news article links


The Calcium Radius EXperiment (CREX)

The CREX experiment at Jefferson Lab measured the neutron RMS radius of 48Ca using the same technique and experimental apparatus as PREX. The final results have been submitted tp Physics Review Letters for publication. The arXiv submission can be found here.              

The extracted neutron skin of 0.121+/- 0.035 is thinner than expected but still consistent with many nuclear structure calculations.