6 GeV Program Overview

Rolf EntPAC38 Meeting

August 22nd 2011Hall Physics

BeganExperimentsCompleted(full/partial)

ExperimentsCompleted(equivalent

C 10/95 37  /  6 40.1 A 5/97 62  / 0 62.0B 11/97 75  /  5 78.6

Totals Today 174 / 110 180.7Totals PAC37 168 / 120 174.6

Good FY11 Operations

• Did run as promised until May 13, 2011 & started 6 Month Shut Down work• Cumulative delivered beam used: Hall A 101% (routine running)

Hall B 70% (HDIce delay)Hall C 82% (Qweak catching up)

Ongoing 6 GeV Program

Issues remaining:• Completion of g2p/GEp apparatus in Hall A• Proof of polarized HDIce operations in Hall B• Sufficient beam in Hall C

Year(Expt. #)

Experiment Major Installation Tasks Special Accel. Requirements

ScientificRating

PAC Days

FY2010  

E05-109 HAPPEx-III Completion Small helicity correlations(~ 1/20*HAPPEX I)

A- Complete 

E08-011 DIS-parity High-speed DAQ A- 32 

E06-002 PREx: Lead Parity Room-temperature septaMøller and Compton upgrade

Small helicity correlations(~ 1/20*HAPPEX I)

A 30 

E07-007E08-025

DVCS on the proton and neutron

PbF2 calorimeter A, B+ 40 

 FY2011  

E07-007E08-025

DVCS on the proton and neutron

Completion A, B+ 40 

E08-008 Deuteron electrodisintegration near threshold

BigBite B+ (C3) 18

E08-010 N-D Coulomb quadrupole amplitude at low Q2

B+ 3

E07-006 Short Range Correlations via (e,e’pN)

BigBite A- 23

E08-009 4He Nuclei Response Functions

C3 0.5

E08-014 Three-nucleon correlations (x>2)

A- 12

Accelerator Down for 12 GeV Work

Now UnderwayNot shown on the FY2010 Schedule is the APEX test run; it took place just after PREx

Hall A: Ongoing 6 GeV Program

Page 5

Lead (208Pb) Radius Experiment : PREXElastic Scattering Parity-Violating Asymmetry

Z0 : Clean Probe Couples Mainly to Neutrons

Applications : Nuclear Physics, Neutron Stars, Atomic Parity, Heavy Ion Collisions

• The Lead (208Pb) Radius Experiment (PREX) finds neutron radius larger than proton radius by +0.35 fm (+0.15, -0.17).

• This result provides model-independent confirmation of the existence of a neutron skin relevant for neutron star calculations.

• Follow-up experiment to reduce uncertainties by factor of 3 and pin down symmetry energy in EOS.

A neutron skin of 0.2 fm or more has implications for our understanding of neutron stars and their ultimate fate

Relativistic mean field

Nonrelativistic skyrme

PREXPREX

Page 6

HAPPEx-III results final, publication in preparation - accurate measurement at Q2 = 0.6 GeV2, completing the parity-violating program constraining

the contributions of strange quarks to the proton’s charge & magnetization.- contributions to these distributions are found to be minimal.- strange quarks do not play a substantial role in the long-range electromagnetic structure of

nucleons

Strangeness Contribution to Nucleon Form Factors

Completes Performance Measure HP4

Pink line represents 2% of the proton form factors (in the same combination of electric and magnetic as the strange form factors) strange quarks represent less than 2% of the proton form factors.

Page 7

Searches for a gauge boson A’ – APEX Test Run Result

Future searches for a new force carrier:- APEX – electron-nucleus fixed-target, an e+e- pair in two focusing spectrometers- HPS – same, the e+e-, m+m- pairs in a custom Si-tracker magnetic spectrometer- DarkLight – an internal target with an electron beam in Jefferson Lab ERL, detect an e+e- pair and e’p - VEPP3 – a positron beam incident on an internal H2 target, missing mass in (e+e-, g X) - MAMI – APEX type scheme with lower beam energy

Electroproduction of A’

decay

Published results :- Beam dump searches: SLAC:E137, 141; FNAL: E774- electron and muon (g-2), limits- BaBar, U(3s)-> g and m+m- (inferred limit)- KLOE, mass of an e+e- pair (bump search)- APEX test run, mass of e+e- pair – arXiv:1108.2750- MAMI – APEX type scheme

Year(Expt. #)

Experiment Major Installation Tasks Special Accel. Requirements

ScientificRating

PAC Days

FY2012Accelerator Down for 12 GeV work

E08-027 g2p and the LT Spin

polarizabilitySepta + beamline chicanePolarized target

A- 24

E08-007 GEp at low Q2 A- 14

E08-027 g2p and the LT Spin

polarizabilityCompletion A- 24

E07-012 Hypernuclear 16O and production

Septa B+ 12

Last piece of incremental equipment funding provided by DOE/NP

Hall A: Upcoming Program up to May 2012 Shutdown for 12-GeV

installation

Removed from schedule due to extended time needed for g2p /Gep transitions

• Hall A submitted draft plan for initial operations in FY14-FY16 to Director, expected to continue iterations in 2011• MIE for Super Bigbite System submitted to DOE, DOE science & technical review scheduled for October 13 + 14• Draft MIE proposal for Moller experiment in hand

Year(Expt. #)

Experiment Major Installation Tasks Special Accel. Requirements

ScientificRating

PAC Days

FY2010

E07-009E08-024

Eg6: DVCS and meson spectroscopy on 4He

Modified e1-DVCS setup Standard (E>5.9GeV)

A, A- 45

E02-112E03-105E04-102E05-012E06-013

G9 – FrostMissing N* Resonances(completion – started in 2008)

Frozen spin target Standard3 A-, 2B+ 91 (remaining 60

days here)

Install PRIMEx-II

FY2011

E08-023 PRIMEx-II Re-Install PRIMEx Beam Stability A- 20

E07-005 EG5-Two Photon exchange in elastic e+p/e-p scattering

Installation of conversion/target apparatus

Standard A 35

Install HDIce & Commission

E06-101 G14 – N* Searches (HDIce) (& electron test)

HD polarized target Standard A 7

Accelerator Down for 12 GeV work

FY2012

Accelerator Down for 12 GeV workE06-101E08-015E08-021

G14 Completion, then DVCS and SIDIS w/ HDIce Target

Conversion of HD polarized target for electron beam operation

Standard A, A and A- 65

Technical feasibility to be established

Almost …

Hall B: Ongoing 6 GeV Program

HDice commissioningApril-May/11 • In-beam Cryostat (IBC) passed ASME pressure-code tests • IBC installed in CLAS and aligned • LHe circuit cooled; auto-fill from ESR established • magnets (3 superconducting, 1 normal) commissioned at full current • in-beam NMR successfully tested • test transfer of solid HD from HDice Lab -to- Hall B –to- IBC

• low target temperatures prevented by blocked capillary

First photo sent to us from HDIce in Hall B April 2011

HDice commissioningMay-August/11 • Blocked capillary was found to be piece of low-tech solder • Achieved 48 mK July 31, 2011 (and I believe they reached 43 mK in the end) •Produced additional three spare polarized target batches in July/August

• IBC moved to Hall B again last week

• Start cooling when ESR availability permits

• Need to do HD spin transfer tests in Hall

Beam-spin asymmetry for π0 SIDIS A 5.75 GeV polarized electron beam was used with CLAS to measure the azimuthal dependence of the beam spin asymmetry for in a large xB, and PT range.

Significant asymmetries are observed for 0.3<PT<0.7 GeV and in the range xB ≤ 0.4. Structure function FLU receives contributions from contributions from the convolution of twist-2 and twist-3 distribution and fragmentation functions, e.g. twist-2 Boers-Mulders DF, Collins FF and twist-3 DFs e and g T

The observed asymmetry for π0

suggests that the major contribution to pion beam SSA originates from spin-orbit correlations.

ep e’π0X

M. Aghasyan et al. (CLAS), arXiv:1106.2293, PLB accepted

Year(Expt. #)

Experiment Major Installation Tasks Special Accel. Requirements

ScientificRating

PAC Days

FY2010E05-115 HKS/HES (completion) Run to completion Energy stability of

10-4, Position stability < 100 mm

A- 20

E08-016 QWeak (Install and begin commissioning)

Major installation6 months

Complete overhaul of Hall C beamlineNew PolarimeterMajor Cryo Load See Published Beam Specs.

A 198

FY2011E08-016 QWeak (complete

commissioning and run Phase I)

See Published Beam Specs.

A 198

Accelerator Down for 12 GeV work

FY2012Accelerator Down for 12 GeV work

E08-016 QWeak (run Phase II) See Published Beam Specs.

A 198

Now Underway

Hall C: Ongoing 6 GeV Program

Hall C: Qweak status

σ = 236 ppm

Asymmetry Width• Beam: routine data-taking at 165 μA @ ~88% polarization (and tests up to 180 mA)• Helicity-correlated properties acceptable!

Status at 05/13/11

• Precision measurement of the proton’s weak charge in the simplest system• Search for parity-violating new physics up to the ~ 2 TeV scale• No show-stoppers found, on track for proposed 4% precision on Qp

Weak

Above: 6.5 minutes of data @ 165 μATotal detected rate = ~5.83 GHzPure counting statistics: ~215 ppm+ detector energy resolution -> 232 ppm+ beam current normalization -> 235

ppm agrees with data

Evolution of PVES Helicity Correlated Beam Properties

Qweak Run Average

8 ± 15 x: 3.9 ± 0.5y: -5.7 ± 0.5

x’: -0.11 ± 0.02

y’: -0.00 ± 0.02

The QWEAK Experiment: Measurement of the Proton’s Weak Charge

Elastic ep Scattering Parity-Violating Asymmetry

Anticipated constraints if QP

W is consistent with the Standard Model.

MS Theory Curve : J. Erler, M. J. Ramsey-Musolf et al.,See Particle Data Group 2010

Anticipated QPW

uncertainty:

Run I (completed)

Run I + Run II

Q (GeV)

• First direct measurement of the proton’s weak charge.• Precision determination of the neutral current weak couplings

to the quarks (C1u & C1d).• Mass scale reach for parity-violating new physics at expected

final uncertainty (95% CL) is ~2.3 TeV.

Isovector weak charge

sin2 q

W

QPW = - 2 (2C1u + C1d )

Young, Carlini, Thomas & Roche, PRL

Isos

cala

r wea

k ch

arge

The TAC Process

Please note that for this PAC, we have asked a team of experienced and critical scientists, representing all Hall groups to look at some of the more technically challenging proposals. You will find the comments of this technical review attached to the individual reports. Our hope is, that this will be useful to both the PAC and the experiment proponents, and adds a layer of coherence to the technical review process.

If a proposal was selected, this simply reflects our feeling that the proposal could benefit from this independent technical review.  On the other hand, if a proposal was not selected, it does not mean it will not have technically challenging components. We welcome any feedback you might have on the use of this independent technical review process.

Added for PAC38 an independent technical review process, and tried this on five proposals

The 12 GeV PAC Process (cont.)Planning the Initial Operation in Each Hall

Following the model used for the initial CEBAF program, ~2-3 years before start of 12 GeV operation hall-by-hall:

• Each hall will provide for PAC review and comment (and potential improvement) a “commissioning and early running” plan folding in guidance of DOE/NP on early operations in FY14-FY16.

• The collaboration’s tradeoff between the best possible science and the realities of commissioning equipment.

• 3 years after the start of physics in each hall, jeopardy will begin.

• Status: Hall A early draft submitted to Director and iterations ongoing, Hall B plan started, Hall C plan just discussed at Summer workshop. Submit all for PAC review and comments Summer 2012?