²⁰⁸Pb Radius Experiment PREX

maintained by Robert Michaels rom@jlab.org last updated 4-Nov-2009

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The Lead Radius Experiment ("PREX"), experiment number E06002, 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. The experiment is being performed by the HAPPEX collaboration which has recently completed experiments E99115 & E00114 -- i.e. HAPPEX II and HAPPEX Helium.

Spokespersons: Krishna Kumar (U. Mass), Paul Souder (Syracuse), Robert Michaels (JLab), Guido Urciuoli (INFN).

PROPOSAL and UPDATES (talks are further down)

2005 Proposal Update (Postscript), and Same, PDF.
2002 Proposal Update
Original Proposal (Dec 1999).

RELATED PHYSICS INFO

Paper on Parity Violating Neutron Densities published in Phys. Rev. C63, 025501 (2001). Cited 100 times according to SPIRES (Oct 2008).
1-Page Experiment Summary for the Public Postscript or PDF
EINN 2005 Poster about PREX (powerpoint).
References from C. Horowitz (needs to be updated).
The 2008 PREX workshop
- List of 2008 PREX Workshop talks .
- Here is C. Horowitz's page on the workshop.
The Trento 2000 Workshop on Parity Violation.

STATUS and PLANS

A work list (updated May, 2009) which supercedes Paul Souder's old work list necessary to perform the experiment. Schedule is March 2010 !
An index of Meeting Minutes and Talks
Working on a new Monte Carlo.
Here are recent (Dec 5, 2007) diagrams of the 18-bit ADC and the somewhat older schematic from Fernando Barbosa.
Here is Paul's note on slits for transverse asymmetry systematic (March, 2009).
Info about the Septum
- Here is a Test plan for Septum magnet to be done in Nov 2009 .
- Some drawings of the 5 degree septum courtesy M. Hodges. See also sept*.pdf in pics
Info about the Collimator
- Overview of collimator to put in the mouth of Q1.
- Some specs for collimator to help engineer it.
- Possible way to stop 2-bounce photons
- The specification to taper the sides to reduce slit scattering.
Target Info
- Oct 2009 Proposed target ladder:
  - During the optics and calibration phase
  - During the production mode
- Target info for the Jan 2008 test run.
- Here are Design Drawings from J. Miller . And here are assembly pics (was for the Jan 2008 test run)
- Early tests Pb target. See diagram of target and writeup about test (postscript) and same, PDF
Polarimetry is crucial.
- Here is a specification for Moller FADC DAQ.
- In 2003 JLab held a Polarimetry Workshop
- There is an idea to use atomic hydrogen polarimetry.
- Here is a draft of plans to upgrade the Compton polarimeter.
In Nov 2005 we had a 2 day run to test all aspects of the experiment at ~850 MeV. Results were explained in the 2005 propsal update (see talks, below).

TALKS including seminars and PAC Defenses

B-team notes for Nov 4, 2009.
Here was the recent PREX workshop 2008 held at JLAB.
Here are some talks about PREX at workshops, etc.
An index of Collaboration Meetings and Weekly Meetings plus some older stuff.

SLIDES

Here are some old transparencies .

208Pb Radius Experiment PREX

²⁰⁸Pb Radius Experiment PREX