6 GeV Program Overview
Rolf Ent
PAC38 Meeting
August 22nd 2011
Hall
Physics
Began
Experiments
Completed
(full/partial)
Experiments
Completed
(equivalent
C
10/95
37 / 6
40.1
A
5/97
62 / 0
62.0
B
11/97
75 / 5
78.6
Totals
Today
174 / 110
180.7
Totals
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
Hall A: Ongoing 6 GeV Program
Year
(Expt. #)
Experiment
Major Installation Tasks
Special Accel.
Requirements
E05-109
HAPPEx-III
Completion
Small helicity correlations
(~ 1/20*HAPPEX I)
E08-011
DIS-parity
High-speed DAQ
E06-002
PREx: Lead Parity
Room-temperature septa
Møller and Compton upgrade
E07-007
E08-025
DVCS on the proton and
neutron
PbF2 calorimeter
Scientific
Rating
PAC Days
A-
Complete
A-
32
A
30
A, B+
40
A, B+
40
B+ (C3)
18
B+
3
A-
23
C3
0.5
A-
12
FY2010
Small helicity correlations
(~ 1/20*HAPPEX I)
FY2011
E07-007
E08-025
E08-008
E08-010
E07-006
E08-009
E08-014
DVCS on the proton and
Completion
neutron
Deuteron
BigBite
electrodisintegration near
threshold
N-D Coulomb quadrupole
amplitude at low Q2
Short Range Correlations via BigBite
(e,e’pN)
4He Nuclei Response
Functions
Three-nucleon correlations
(x>2)
Accelerator Down for 12 GeV Work
Now Underway
Not shown on the FY2010 Schedule is the APEX test run; it took place just after PREx
Lead (208Pb) Radius Experiment : PREX
Elastic Scattering Parity-Violating Asymmetry
Z0 : Clean Probe Couples Mainly to Neutrons
Applications : Nuclear Physics, Neutron Stars,
Atomic Parity, Heavy Ion Collisions
PREX
PREX
Relativistic mean field
Nonrelativistic skyrme
A neutron skin of 0.2 fm or
more has implications for our
understanding of neutron
stars and their ultimate fate
• 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.
Page 5
Strangeness Contribution to Nucleon Form Factors
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.
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
Completes Performance Measure HP4
Page 6
Searches for a gauge boson A’ – APEX Test Run Result
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
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
Page 7
Hall A: Upcoming Program up to May
2012 Shutdown for 12-GeV installation
Year
(Expt. #)
Experiment
Major Installation Tasks
Special Accel.
Requirements
Scientific
Rating
PAC Days
A-
24
A-
14
A-
24
B+
12
FY2012
Accelerator Down for 12 GeV work
E08-027
g2p and the LT Spin
polarizability
E08-007
GEp at low Q2
E08-027
g2p and the LT Spin
polarizability
Completion
E07-012
Hypernuclear 16O and
production
Septa
Septa + beamline chicane
Polarized target
Last piece of incremental
equipment funding
provided by DOE/NP
Removed from schedule due to extended
time needed for g2p /Gep transitions
• Hall A submitted draft plan for initial operations in FY14FY16 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
Hall B: Ongoing 6 GeV Program
Year
(Expt. #)
Experiment
Major Installation Tasks Special Accel.
Requirements
E07-009
E08-024
Eg6: DVCS and meson
spectroscopy on 4He
Modified e1-DVCS setup
Standard
(E>5.9GeV)
E02-112
E03-105
E04-102
E05-012
E06-013
G9 – Frost
Missing N* Resonances
(completion – started in
2008)
Frozen spin target
Standard
Scientific
Rating
PAC Days
A, A-
45
3 A-, 2B+
91 (remaining 60
days here)
FY2010
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
Install HDIce &
Commission
G14 – N* Searches
(HDIce) (& electron test)
Installation of
conversion/target
apparatus
Standard
A
35
HD polarized target
Standard
A
7
Standard
A, A and A-
65
E06-101
Accelerator Down for 12 GeV work
Almost …
FY2012
E06-101
E08-015
E08-021
Accelerator Down for 12 GeV work
G14 Completion, then
Conversion of HD
DVCS and SIDIS w/
polarized target for
HDIce Target
electron beam operation
Technical feasibility
to be established
HDice commissioning
April-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
First photo sent to us from
HDIce in Hall B April 2011
• low target temperatures prevented by
blocked capillary
HDice commissioning
May-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
ep  e’π0X
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.
M. Aghasyan et al. (CLAS), arXiv:1106.2293, PLB accepted
Hall C: Ongoing 6 GeV Program
Year
(Expt. #)
Experiment
Major Installation Tasks Special Accel.
Requirements
Scientific
Rating
PAC Days
E05-115
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 installation
6 months
Complete overhaul
of Hall C beamline
New Polarimeter
Major Cryo Load
See Published Beam
Specs.
A
198
See Published Beam
Specs.
A
198
FY2010
FY2011
E08-016
QWeak (complete
commissioning and run
Phase I)
Accelerator Down for 12 GeV work
Now Underway
FY2012
Accelerator Down for 12 GeV work
E08-016
QWeak (run Phase II)
See Published Beam
Specs.
A
198
Hall C: Qweak status
• 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 QpWeak
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
Above: 6.5 minutes of data @ 165 μA
Total detected rate = ~5.83 GHz
Pure 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 ± 0.5
y: -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
Run I + Run II
MS Theory Curve : J. Erler,
M. J. Ramsey-Musolf et al.,
See Particle Data Group 2010
Isoscalar weak charge
Run I (completed)
sin2qW
Anticipated QPW
uncertainty:
QPW = - 2 (2C1u + C1d )
Young, Carlini,
Thomas & Roche, PRL
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
Anticipated constraints if
QPW is consistent with the
Standard Model.
The TAC Process
Added for PAC38 an independent technical
review process, and tried this on five proposals
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.
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?