208Pb   Radius   Experiment   PREX

This file: hallaweb.jlab.org/parity/prex 

quick links:    Hall A    HALOG / (legacy HALOG)    HAPPEX   HAPLOG   private docDB    public docDB   wiki 

PREX Wiki:   prex.jlab.org

The Lead Radius Experiment ("PREX"), experiment number E12-11-101, uses the parity violating weak neutral interaction to probe the neutron distribution in a heavy nucleus, namely 208Pb, thus measuring the RMS neutron radius to 1% accuracy, which has an important impact on nuclear theory.   Its sister experiment "CREX" (E12-12-004) will use a 48Ca target. The experiments are being performed by the   Hall A Parity Collaboration which has has performed   HAPPEX   and   PVDIS .   Many of our collaborators were also in   Qweak.
^ Concept of PREX/CREX target area. Experiments completed in September 2020 ^


  • CREX run plan
  • PREX   Wiki
  • Document Database   (use JLab CUE login)
  • Experimental Readiness Review
  • Proposals and Updates
  • Physics Information
  • Status and Plans
  • Talks and Meetings
  • Photographs from 2010 Run

    Experimental  Readiness  Review   (ERR)

  • The 2017 Experimental Readiness Review.   We passed !
  • The PREX-CREX Design document (v3).   This is our engineering blueprint for what we need.


  • PREX-II   (June 2011)
  • C-REX   on 48Ca (PAC40)
  • 2005 Proposal Update (Postscript), and   Same, PDF
  • 2002 Proposal Update
  • Original Proposal (Dec 1999)


  • CREX letter in Phys. Rev. Lett. 129, 042501   July 20, 2022.
  • CREX press release (Oct 12, 2021)
  • FOR   THE   PUBLIC   PREX, Simplifed   and   Physics Today article
  • Talks and Meetings
  • Letter about PREX-II data   Phys. Rev. Lett. 126, 172502 (2021). Published April 27, 2021.
  • Letter about PREX-I data   Phys. Rev. Lett. 108, 112502 (2012). Published Mar 15, 2012.
  • PREX II proposal   for PAC38.   Exp E12-11-101. (Status: approved with A rating in August 2011.)
  • C-REX Propoal   to do a PREX-style measurement on 48Ca. Approved by PAC40.
  • Article about PREX/CREX   EPJA 50 (2014) 48.
  • C-REX workshop (Mar 17-19, 2013)     Group Photo
  • Letter about Weak FF of Lead   PRC 85, 032501(R) (2012). Published Mar 26, 2012.
  • Letter on A_T   transverse asymmetry measurements on 1H, 4He, 12C, and 208Pb. Published Nov 9, 2012.
  • HAMC Monte Carlo simulates parity-violating single-arm HRS experiments PREX, HAPPEX-III, and PVDIS.
  • Acceptance function needed for theoretical interpretation of our results.
  • GRC 2012 Poster about PREX (powerpoint).
  • Paper on Parity Violating Neutron Densities (PDF)   and same (PS)   Phys. Rev. C63, 025501 (2001).   244 citations (inSPIRE, May 2017).

  • PhD and MSc Theses

    STATUS   and   PLANS

  • The PREX-CREX Design document (v3).   This is our engineering blueprint for what we need.
  • The PREX Beam Requirements
  • A TO DO List for PREX-II and for for CREX
  • The Attic of older information  : if you're missing something from around 2010, it's probably here.

    TALKS   and   MEETINGS

  • Meetings
  • Workshops
  • Talks about PREX   including seminars and PAC Defenses

    maintained by   Robert Michaels      rom@jlab.org   last updated 21-Jul-2022