Transcript Qweak Overview and Target Status Silviu Covrig Hall C for the Qweak Collaboration Hall C Users Meeting January 23, 2010

Qweak Overview and Target Status
Silviu Covrig
Hall C
for the Qweak Collaboration
Hall C Users Meeting
January 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 sin2qw it’s relative uncertainty has to be
<1%
Q  1  4 sin q
p
W
gU(1)
2
W
qW
gSU(2)
Hall C Users Meeting, January 23, 2010
sin2θW in the MS Renormalization Scheme
Experiment
d(sin2qw)
sin2qw
133Cs
0.0046
E158
0.0054
Qweak
0.0030
MOLLER
0.0010
MZ
0.0006
Theory
Q2 ~ 0
0.00086
Hall C Users Meeting, January 23, 2010
Parity Violation Asymmetry
e-

k

k
h+
θ
e-
target
d   d 
M
APV 
 2 NC
d   d 
M
Q2,θ
0
where Q ( M )  (1  4 sin q )  0.072
p
W
2
Z
W
For Qweak optimum Q2 ~ 0.03 (GeV/c)2
APV  AQ p  Ahadronic  Aaxial
W
  (190  90  10 ) ppb
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
k

k
h-
θ
target
GF Q 2
QWp  Q 2 B(Q 2 )

4 2
Hadronic form factor
correction: from G0, SAMPLE,
Happexx, PV-A4
Basic Qweak Parameters
Parameter
Value
Beam Energy
Polarization
Current
1.165 GeV
85%
150-180 A
LH2 Target
Production Running Time
Acceptance: q, j, DW
35 cm, 2500 W
2544 hours
8⁰ ± 3⁰, , 37 msr
Acceptance Averaged Q2
Acceptance Averaged Physics Asymmetry
Acceptance Averaged Expt'l Asymmetry
< Q2 > = 0.026 (GeV/c)2
< A > = -0.234 ppm
< A > = -0.200 ppm
Integrated Cross Section
Integrated Rate (all sectors)
Hall C Users Meeting, January 23, 2010
4.0 b
6.5 GHz (.81 GHz / sector)
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The Qweak Experiment
APV ≈ -200 ppb, DAPV ≈ 5 ppb
Contribution to
Contribution to
DA / A
DQ / Q
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%
Helicitycorrelated
beam
properties
0.5%
0.7%
TOTAL:
2.5%
4.1%
Source of
error
phys
phys
Hall C Users Meeting, January 23, 2010
p
p
W
W
Beam Properties
•
•
•
•
•
DI/I
< 0.1 ppm
Position
< 2 nm
Angle
< 30 nrad
Diameter
< 0.7 m
Energy DE/E
< 10-9
Gzero
HAPPEX 2
TRIUMF E497
SLAC E158
Qweak
500 ppb
130 ppb
35 ppb
17 ppb
5 ppb
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The Qweak Apparatus
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Qweak Magnet: QTOR
• Toroidal magnet with 8 resistive coils
• 4.3 m long / 1.5 m wide / ~3300 kg/coil
 
•  B  d   0.89 Tm
9500 Amps
1.2 MW water cooled
Power Supply
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Qweak Detectors
•
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 System
Region I = GEMs
Region II = HDC
Region III = VDC
Both built
4+1 built
4 built
Hall C Users Meeting, January 23, 2010
New Hall-C Compton Polarimeter
Electron detector
q
D=0 .5 2 m
D1
D4
Q1
1 m2
m
D2
Q2
1 .5 m
D3
9 .5 m
• 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
Photon
Detector
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
fh
A ex p 
APV measured in helicity pairs + - + - + - …
2Th
N  N
N  N
1
1
f

 h
N 0  N 0 2 N 0 2 R
Counting statistics
 02 
Target density fluctuations
r = 5%
10% longer running
 A2   02   b2  (1  r )2  02
Target density reduction
10% @Irun
10% longer running
exp
N 10  N 180
(% / A)
I  N 10
Qweak
fh
σ0 (ppm)
σb (ppm)
r = 0.05
30 Hz
48
15
250 Hz
139
45
Hall C Users Meeting, January 23, 2010
The Qweak Target
CAD model
Cryogenic loop during
assembly
Centrifugal pump
30 Hz, 15 l/s, 1.5 psi
Hybrid Heat
Exchanger
2500 W
Cell Block
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Flow Pattern
e- beam
8⁰±3⁰ Acceptance
Δpcell = 0.262 psid
@ 1 kg/s mass rate
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Density Reduction
Δρ/ρ (%)
e- beam
Boiling
LH2 flow
Heating 180 μA:
LH2 245 W/cm3
Al 3950 W/cm3
7.5 liters
68 cm
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Qweak Target Safety
4 kg of LH2 in 2 metal boundaries
Safety incidents:
• Relief (Sudden Loss of Vacuum): 105g/s
• Vent (cryo-loop breaks), with fluent: 210 g/s
Δp = 1 atm (ø pipe>2”)
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
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4 < cV <74 % : deflagration
Sub-sonic waves
18< cV < 54 % : detonation
Shock Waves
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Case Study: Rastered Beam Heating
Heating densities: same
as Qweak cell
Beam
Direction
Raster
fx = 24960 Hz
fy = 25080 Hz
Transient simulation in
fluent with
ts = 2.25 μs
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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
The Qweak Collaboration
(Funded by DOE, NSF, NSERC and the State of Va)
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
1Spokespersons
2Project
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
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Low Energy Weak Neutral Current Standard
Model Tests
E158 : δ(sin2 qW ) ~ 0.54%
sin2 q W  0.2397  0.0010  0.0008
MOLLER: δ(sin2 qW ) ~ 0.1%
QWe   (1  4 sin2 q W )
QWA   N  Z (1  4 sin2 qW )   N
QWp  1  4 sin 2 q W
QWCs  72.06  0.28  0.34
Qweak : δ(sin2 qW ) ~ 0.3%
APV 133Cs : δ(sin2 qW ) ~ 0.83%
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