Qweak Overview and Target Status
Silviu CovrigHall C
for the Qweak Collaboration
Hall C Users MeetingJanuary 23, 2010
Why Measure Qweak(p)
• Qw(p) is a fundamental property of the proton, never before measured
• Being suppressed in the SM a 4% measurement may provide a window into parity violating physics at the TeV energy scale, complementing colliders
• It is a standalone precision determination of the Weinberg angle at low Q2
• For a useful check of the running of sin2w it’s relative uncertainty has to be <1%
Hall C Users Meeting, January 23, 2010
W
p
WQ 2sin41
W
gU(1)
gSU(2)
sin2θW in the Renormalization SchemeSM
Hall C Users Meeting, January 23, 2010
Experimentsin2w)
sin2w
133Cs 0.0046
E158 0.0054
Qweak 0.0030
MOLLER 0.0010
MZ 0.0006
TheoryQ2 ~ 0 0.00086
Parity Violation Asymmetry
k
h+ targete-
k
θ k
targete-
k
θ
M
M
dd
ddA NC
PV2
Q2,θ 0 )(
2422
2
QBQQQG p
W
F
Hadronic form factor correction: from G0, SAMPLE, Happexx, PV-A4
where
For Qweak optimum Q2 ~ 0.03 (GeV/c)2
072.0)sin41()( 2 WZ
p
WMQ
ppb
AAAA axialhadronicQPV pW
)1090190(
Hall C Users Meeting, January 23, 2010
5
Parameter Value
Beam Energy 1.165 GeV Polarization 85% Current 150-180 A
LH2 Target 35 cm, 2500 W Production Running Time 2544 hours Acceptance: 8⁰ ± 3⁰, msr Acceptance Averaged Q2 < Q2 > = 0.026 (GeV/c)2 Acceptance Averaged Physics Asymmetry < A > = -0.234 ppm Acceptance Averaged Expt'l Asymmetry < A > = -0.200 ppm
Integrated Cross Section 4.0 b Integrated Rate (all sectors) 6.5 GHz (.81 GHz / sector)
Basic Qweak Parameters
Hall C Users Meeting, January 23, 2010
The Qweak Experiment
APV ≈ -200 ppb, APV ≈ 5 ppb
Source of error
Contribution to Contribution to
Counting statistics 2.1% 3.2%
Hadronic structure - 1.5%
Beam polarimetry 1.0% 1.5%
Absolute Q2 0.5% 1.0%
Backgrounds 0.5% 0.7%
Helicity-correlated
beam properties
0.5% 0.7%
TOTAL: 2.5% 4.1%
physphysAA / p
W
p
WQQ /
6Hall C Users Meeting, January 23, 2010
• Gzero 500 ppb• HAPPEX 2 130 ppb• TRIUMF E497 35 ppb• SLAC E158 17 ppb• Qweak 5 ppb
Beam Properties
I/I < 0.1 ppm
Position < 2 nm
Angle < 30 nrad
Diameter < 0.7 m
Energy E/E < 10-9
7
The Qweak Apparatus
Hall C Users Meeting, January 23, 2010
Qweak Magnet: QTOR
9500 Amps1.2 MW water cooled
Power Supply
• Toroidal magnet with 8 resistive coils• 4.3 m long / 1.5 m wide / ~3300 kg/coil• Tm89.0
dB
8Hall C Users Meeting, January 23, 2010
• Main Detectors– All 8 bars assembled in their light tight boxes– Remaining parts (exoskeleton & support frames) are built– 1st bars ready to install late Feb
• Tracking SystemRegion I = GEMs Region II = HDC Region III = VDC
Both built
4+1 built4 built
Qweak Detectors
Hall C Users Meeting, January 23, 2010
Q2
D2
Q1
D3
D1D=0.52 m
1 m2 m 1.5 m
9.5 m
Electron detector
D4
PhotonDetector
New Hall-C Compton Polarimeter
• Compton Polarimeter can run all the time
• Photon and electron coincidences greatly reduce systematic uncertainties due to backgrounds.
• < 1% precision is possible by cross-calibrating with existing Møller polarimeter.
• Hall C Møller <1% precision, but needs dedicated low current runs
Hall C Users Meeting, January 23, 2010
Qweak Target Design
First LH2 target at JLab designed with Computational Fluid Dynamics (CFD) – FLUENT
Cryogenic Loop Highlights
• 54 liters, 2500 W • LH2 centrifugal pump: 15 l/s (1 kg/s) flow @ <1.5 psid
• Hybrid heat exchanger: 27 l, both 4 K and 15 K He coolant• High power heater: 2500 W• Cell
• 35 cm long in beam, 7.8 liters conical cell • LH2 flows transversely to the beam axis @ <v> ~ 2.9 m/s
• Steady-state uniform heating (Δρ/ρ)BV ~ 0.7%, transient rastered heating ~ 1.1%
Hall C Users Meeting, January 23, 2010
LH2 Target Systematics for Parity Violation
APV measured in helicity pairs + - + - + - …
Counting statistics
Target density fluctuationsr = 5% 10% longer running
Target density reduction 10% @Irun 10% longer running
NNNN
Aexp
2Th
R
f
NNNh
22
11
000
2
0
fh
2
0
222
0
2 )1(exp
rbA
)/(%10
18010 ANI
NN
Qweak
fh
σ0 (ppm) σb (ppm)r = 0.05
30 Hz 48 15
250 Hz 139 45Hall C Users Meeting, January 23, 2010
The Qweak Target
CAD model
Cryogenic loop during assembly
Centrifugal pump30 Hz, 15 l/s, 1.5 psi
Hybrid Heat Exchanger
2500 W
Cell Block
13Hall C Users Meeting, January 23, 2010
Flow Pattern
8⁰±3⁰ Acceptance
Δpcell = 0.262 psid@ 1 kg/s mass rate
e- beam
14Hall C Users Meeting, January 23, 2010
Density Reduction
Heating 180 μA:
LH2 245 W/cm3
Al 3950 W/cm3
7.5 liters
LH2 flow
e- beam
68 cm
Δρ/ρ (%)Boiling
15Hall C Users Meeting, January 23, 2010
Qweak Target Safety
4 kg of LH2 in 2 metal boundaries
Safety incidents:• Relief (Sudden Loss of Vacuum): 105g/s Δp = 1 atm (ø pipe>2”)• Vent (cryo-loop breaks), with fluent: 210 g/s Δp < 1 atm (ø pipe>4”)
• Release: hydrogen escapes into Hall C – ODH: none – Flammability: possible (556 MJ from burning 4 kg of hydrogen)
Hydrogen concentration in normal air
4 < cV <74 % : deflagration
18< cV < 54 % : detonation
Sub-sonic waves
Shock Waves 16
Hall C Users Meeting, January 23, 2010
17
Case Study: Rastered Beam Heating
Heating densities: same as Qweak cell
Raster fx = 24960 Hzfy = 25080 Hz
Transient simulation in fluent with ts = 2.25 μs
18
Beam Direction
Hall C Users Meeting, January 23, 2010
19
Schedule Highlights
• Installation period Nov 2009 – May 2010
• Readiness Review July 20, 2009• Target Safety and Design Review Sep 4, 2009 (Passed)
• Commissioning May 25, 2010 – July 22, 2010• First Run Sep 06, 2010 – May 02, 2011• Second Run Nov 07, 2011 – May 14, 2012
Hall C Users Meeting, January 23, 2010
D. Androic, D. Armstrong, A. Asaturyan, T. Averett, R. Beminiwattha, J. Benesch, J. Birchall, P. Bosted, C. Capuano, R. D. Carlini1 (Principal Investigator), G. Cates, S. Covrig, M Dalton, C. A. Davis,
W. Deconinck, K. Dow, J. Dunne, D. Dutta, R. Ent, J. Erler, W. Falk, H. Fenker, J.M. Finn, T. A. Forest, W. Franklin, M. Furic, D. Gaskell, M. Gericke, J. Grames, K. Grimm, D. Higinbotham, M. Holtrop,
J.R. Hoskins, K. Johnston, E. Ihloff, M. Jones, R. Jones, K. Joo, J. Kelsey, C. Keppel, M. Khol, P. King, E. Korkmaz, S. Kowalski1, J. Leacock, J.P. Leckey, J. H. Lee, L. Lee, A. Lung, S. MacEwan, D. Mack, R. Mahurin, J.
Mammei, J. Martin, D. Meekins, A. Micherdzinska, A. Mkrtchyan, H. Mkrtchyan, N. Morgan, K. E. Myers, A. Narayan, Nuruzzaman, A. K. Opper, S. A. Page1, J. Pan, K. Paschke, S. Phillips, M. Pitt, B. (Matt) Poelker, Y. Prok,
W. D. Ramsay, M. Ramsey-Musolf, J. Roche, B. Sawatzky, N. Simicevic, G. Smith2, T. Smith, P. Solvignon, P. Souder, D. Spayde, R. Suleiman, E. Tsentalovich, W.T.H. van Oers, B. Waidyawansa, W. Vulcan, D. Wang, P. Wang,
S. Wells, S. A. Wood, S. Yang, R. Young, X. Zheng, C. Zorn
1Spokespersons2Project Manager
College of William and Mary, University of Connecticut, Instituto de Fisica, Universidad Nacional Autonoma de Mexico, University of Wisconsin, Hendrix College, Louisiana Tech University, University of Manitoba, Massachusetts Institute of Technology, Thomas Jefferson National Accelerator Facility, Virginia Polytechnic Institute & State University, TRIUMF, University of New Hampshire,
Yerevan Physics Institute, Mississippi State University, University of Northern British Columbia, Ohio University, Hampton University,
University of Winnipeg, University of Virginia, George Washington University, Syracuse University,
Idaho State University, University of Connecticut, Christopher Newport University, University of Zagreb
The Qweak Collaboration(Funded by DOE, NSF, NSERC and the State of Va)
Hall C Users Meeting, January 23, 201021
Low Energy Weak Neutral Current Standard Model Tests
NZNQW
A
W )sin41( 2
Qweak : δ(sin2 W ) ~ 0.3%
)sin41( 2
W
e
WQ
W
p
WQ 2sin41
MOLLER: δ(sin2 W ) ~ 0.1%
0008.00010.02397.0sin 2 W
34.028.006.72 Cs
WQ
22
APV 133Cs : δ(sin2 W ) ~ 0.83%
E158 : δ(sin2 W ) ~ 0.54%
Hall C Users Meeting, January 23, 2010
23