²⁰⁸Pb Radius Experiment PREX

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

quick links:    Hall A    HALOG   HAPPEX   HAPLOG

For Run Info, see the Wiki: prex.jlab.org

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 Hall A Parity Collaboration which has recently completed HAPPEX and PVDIS .

C-REX Proposal to do a PREX-style measurement on ⁴⁸Ca. Submitted to PAC40 on May 6, 2013.

The C-REX workshop (Mar 17-19, 2013) Group Photo

Letter on A_T transverse asymmetry measurements on ¹H, ⁴He, ¹²C, and ²⁰⁸Pb. Published Nov 9, 2012.

Letter about PREX data Phys. Rev. Lett. 108, 112502 (2012). Published Mar 15, 2012.

Letter about Weak FF of Lead PRC 85, 032501(R) (2012). Published Mar 26, 2012.

The acceptance function needed for theoretical interpretation of our results.

PREX II proposal for PAC38. Exp E12-11-101. (Status: approved with A rating in August 2011.)

INDEX

SHIFT SIGNUP (pw: "leadradius")

Operations manual ("HOWTO") Please read before taking shifts.

Proposals and Updates

Physics Information

Status and Plans

Talks and Meetings

PROPOSAL and UPDATES

(talks are further down)

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

PREX PHYSICS INFO

FOR THE PUBLIC PREX, Simplifed and Science NOW article

The C-REX workshop leading to C-REX Proposal (PAC40)

Letter about PREX data Phys. Rev. Lett. 108, 112502 (2012).

Letter about Weak FF of Lead PRC 85, 032501(R) (2012).

GRC 2012 Poster about PREX (powerpoint).

The acceptance function needed for theoretical interpretation of our results.

PREX II proposal for PAC38. Exp E12-11-101. (Status: approved with A rating in August 2011.)

Paper on Parity Violating Neutron Densities (PDF) and same (PS) published in Phys. Rev. C63, 025501 (2001). Cited 183 times according to SPIRES (as of Feb 2013).

Bob's PAVI11 writeup for the PAVI11 Conference (Sept 2011).

EINN 2005 Poster about PREX (powerpoint).

The 2009 PREX workshop at Trento, Italy.

2008 PREX Workshop at JLab.

Trento 2000 Workshop on Parity Violation.

STATUS and PLANS

A TO DO List for PREX-II
A TO DO List for C-REX (⁴⁸Ca proposal)

-- Much of the following is now OLD NEWS but I leave it here for now ---

The Global Run Plan and Daily Run Plan for the Spring 2010 run
The COO and Safety documents. (COO, RSAD, ESAD, OSPs)
A shutdown work list for the Jan 2010 shutdown.
Older worklists: old worklist (from May, 2009, now old) and Paul Souder's even older work list .
A document describing the Beam Requirements
Local meetings to prepare for experiment.
A somewhat older index of Meeting Minutes and Talks
Working on a new Monte Carlo. And here are rate estimates.
Here is Paul's note on slits for transverse asymmetry systematic (March, 2009).
Photographs
18-bit ADCs
- Specification of the 18-bit ADCs.
- Performance Report.
- File list of circuit diagrams and other files.
- schematic from Fernando Barbosa.
Sieve
- Here is the design of sieve slit (PDF)
Septum
- Here is a report on field measurements from J. Gomez.
- 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
Cavity Monitors
- Low-current cavities: written report and meeting talk.
- Update from 2007 : meeting talk
- Lisa Kaufmann's 2005 report. Note, the problems were fixed with the new receiver electronics.
Collimator
- A procedure to align 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
- March 2010 Run Target Info
  - Conceptual drawing for the optics and calibration phase
  - Conceptual drawing for the production mode
  - Target list inclu. operational restrictions.
  - detailed target measurements and Target Config from Dave Meekins (Mar 19)
  - Note to Shift workers: target 1 is at the top as Dave defines it.
  - Docushare links from Dave Meekins :
    - Collection-10193 (PREX)
    - All Hall A target configs
  - C12 background correction, syst. error estimate.
- (Old) 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
Q² Measurements
- Report from 2005 run of HAPPEX.
- Report from 2004 run .
- Report from 1998-1999 run .
Polarimetry
- Here is an Status Update on the new DAQ (Dec 29, 2009) for Moller based on a FADC.
- 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 and MEETINGS

Meetings
- The C-REX workshop .
- Jan 29, 2011 Collaboration Meeting
- 2010 Run Run-related meetings
- Collaboration Meetings
- older stuff.
Talks about PREX including seminars and PAC Defenses
The PREX Beam Requirements
Here was the recent PREX workshop 2008 held at JLAB.
Here are some old transparencies .

maintained by Robert Michaels rom@jlab.org last updated 5-May-2013