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

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


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(


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


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


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


• 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


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


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%


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


Flow Pattern

8⁰±3⁰ Acceptance

Δpcell = 0.262 psid@ 1 kg/s mass rate

e- beam


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


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


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


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


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)


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%


23

Documents

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