Nuruzzaman(http://www.jlab.org/~nur/)

Hampton University Group Meeting1st November 2011

Beamline Optics Using Beam Beamline Optics Using Beam Modulation for the Q-weak Modulation for the Q-weak

ExperimentExperiment

OverviewOverview

• Basics

• Hardware for beam modulation

• Controls and software

• Data analysis

• Optics stability during RUN-I

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The objective of the Qpweak experiment is to measure the parity violating asymmetry

(~250ppb) in elastic electron-proton(e-p) scattering to determine the proton's weak charge with an uncertainty of 4%.[1]

[1] http://www.jlab.org/qweak/

APV = σ+ - σ-_______σ+ + σ-

The e-p scattering asymmetry depends on the five beam parameters: horizontal position (X), horizontal angle (X΄), vertical position (Y), vertical angle (Y΄) and energy (E).

Ameasured = A0 + ∂A ∂Ti

∆Ti ∑i

Ti = X, X´, Y, Y´ & E∂Ti ∂A

= detector sensitivity

The goal of the Injector group is to keep these helicity-correlated parameters as small as possible.

The goal of our beam modulation group is to measure the detector sensitivities to correct remaining false asymmetry.

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2.5% on APV 4% on Qweak 0.3% on sin2 θW

Uncertainty δAPV/APV δQw/Qw

Statistical (~2.5K hours at 150 μA) 2.1% 3.2%

Systematic: 2.6% Hadronic structure uncertainties --- 1.5% Beam polarimetry 1.0% 1.5% Effective Q2 determination 0.5% 1.0% Backgrounds 0.5% 0.7% Helicity-correlated beam properties 0.5% 0.7%

Total: 2.5% 4.1%

1st Coil 2nd Coil

Dipole 3C05 Dipole 3C06 Dipole 3C07

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Hall C Beamline

Zoomed In

Target

z

x / y

θ1

θ2θ1

III

Z=0 Z=d1 Z=d2

2 1 1

1 1

(d d ) 1θ = T T

d d

2

2 1 1

d 1θ = T T

d d m m

m m

T = X Y

T = X Y

Where

Ref: http://www-bdnew.fnal.gov/pbar/organizationalchart/lebedev/OptiM/optim.htm

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Beam Parameter

Modulation Amplitude

Current through 1st Coil

I1 (A)

Field Integrals

for 1st CoilBdL1 (G-cm)

Current through 2nd

Coil I2 (A)

Field Integrals

for 2nd CoilBdL2 (G-cm)

Tune Parameters

(BdL2 / BdL1)

X 159 μm 0.088 29.0 -0.300 -99.0 -3.414

X΄ 3.1 μrad 0.052 17.0 -0.300 -99.0 -5.824

Y 84 μm -0.300 -99.0 0.136 45.0 -2.200

Y΄ 2.1 μrad -0.300 -99.0 0.150 49.5 -2.000

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Beam Position Monitor

Modulation Coil Pair

Hall-C

Injector

Accelerator

1st Pair of

Coils

2nd Pair of Coils

ABC

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35 cm Liquid Hydrogen Target

Polarized Electron Beam

Collimator With Eight Openings = 9 ± 2°

Toroidal Magnet

Eight Fused Silica (quartz)Cerenkov Detectors

5 inch PMT in Low GainIntegrating Mode on Each

End of Quartz Bar

Elastically Scattered Electrons

325 cm

580 cm

LuninosityMonitor

Region 3Drift Chambers

Region 2Drift Chambers

Region 1GEM Detectors

35 cm Liquid Hydrogen Target

Primary Collimator with 8 openings

Drift Chambers

Toroidal Magnet

Drift Chambers

Elastically Scattered Electron

Eight Fused Silica (quartz) Čerenkov Detectors - Integrating Mode

Luminosity Monitors

~3.2 m

Beamline

CoilsX1

Y1

Y2

X2

SRFE

BSY Service Building

BMOD1

X1Y1X2Y2

LEMCurrent

Transducer

X1Y1

Y2

X2

TRIM-IPower Amp.

BPMs

BMOD2

Hall-C

GUI

CONSOLE

Qpweak

PV Daq.

Qpweak Cage

IOChCnmr

TRIUMF

ADC

JLAB

ADC

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Bench Test and ResultsBench Test and Results

VME Signal

Generator

IOC

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We choose frequency 125 Hz to be in linear region

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X X´Y Y´E

Phase

Phase

Phase

Phase

FG

X1

[V]

FG

X2

[V]

BP

MX

[m

m]

BP

MY

[m

m]

Target BPM Response to X ModulationTarget BPM Response to X Modulation

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Run 11116: Hall-C BPM X Response to X Modulation

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Run 11116: Hall-C BPM X Response to X Modulation

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Run 11116: Hall-C BPM Y Response to Y Modulation

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Run 11116: Hall-C BPM X Response to E Modulation

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Run 11116: BPM Response to X Modulation

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General InformationGeneral Information

Run conditions:•Production running•Beam current: 150 -180 µA•Modulation with pair of coils•Modulation frequency: 125 Hz•Three modulation tunes (I2/I1) : I, IIA, IIB

This presentation includes:•Time span: 14th February – 13th May 2011•Run range covered: 10,046 – 12,120 •Mps_Tree

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Non-zero X-Y coupling at target become

obvious here

BPM Response to X Modulation During RUN-I

Small drifts in X !

BM

od P

ositi

on A

mpl

itude

[m

m]

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BPM Response to X Modulation During RUN-I

Wien 1 Wien 2 Wien 3 Wien 4 Wien 5

Are these fluctuations due to FG drive signals ?

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X-Y Correlation for X Modulation During RUN-I

Hypothesis:•Sick quadrupole downstream of 3C12•Problem in Xtgt, Ytgt amplitude

Ytgt is relatively unstable for Y modulation:•Designed that way

BPM Response to Y Modulation During RUN-I

BM

od P

ositi

on A

mpl

itude

[m

m]

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BPM Response for Y Modulation During RUN-I

Wien 1 Wien 2 Wien 3 Wien 4 Wien 5

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X-Y Correlation to Y Modulation During RUN-I

Ytgt (≥Xtgt) has ~ 1/7th dispersion of 3C12X

BPM Response to E Modulation During RUN-I

BM

od P

ositi

on A

mpl

itude

[m

m]

Residual dispersion

coming from upstreamB

Mod

Pos

ition

Am

plitu

de [

mm

]

Run 11116: Hall-C BPM Y Response to E Modulation

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BPM Response to E Modulation During RUN-I

Wien 1 Wien 2 Wien 3 Wien 4 Wien 5

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X-Y Correlation for E Modulation During RUN-I

SummarySummary

Coil positioning has been defined by using OPTIM, and hardware has been installed.

We did bench test with modulation hardware before installation.

Hardware and software worked fine during RUN-I period.

Analyzing data from RUN-I …….

X modulation:Xtgt and Ytgt are relatively unstable, has slow drifts and glitches.•Sick quad, problems with Xtgt and Ytgt amplitude ?•Co-related X-Y coupling.BPM 3C12 X and Y responses are relatively stable.

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SummarySummaryY modulation:Ytgt response is significantly unstable.•Designed that way (tune parameters for Y and Y´ are close).Xtgt, BPM 3C12 X and Y responses are relatively stable.•No obvious X-Y coupling.

E modulation:Non zero Xtgt & Ytgt motion.•Residual dispersion coming from upstream of BPM 3C07A !

To DoTo Do•Track down reasons for outliers.

•Discuss with MCC to reliably reduce the residual dispersion at target (It may help Compton background).

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ReferencesReferences

Other Optics Related Changes

02/17/11 Injector transmission problem, beam steering: ELOG 156884904/13/11 Raised Hall-C laser GSET: ELOG 157917404/14/11 Hall-C laser phase adjustment: ELOG 157921804/22/11 Moller quad adjustment: ELOG 158316804/23/11 Optics change: ELOG 158714005/02/11 2L06-1 common fault dropped to idle: ELOG 162507205/02/11 30hz synchronization errors: ELOG 1625050  05/04/11 Hall-C Moller quads cycled: ELOG 162703305/05/11 Hall-C Moller quads are on: ELOG 1627277

Injector Spot Moved

02/14/11: ELOG 1568337 04/20/11: ELOG 158036802/25/11: ELOG 1570886 04/25/11: ELOG 159640803/01/11: ELOG 1572026 04/29/11: ELOG 161331503/24/11: ELOG 1576310 05/03/11: ELOG 162674004/03/11: ELOG 1577478 05/10/11: ELOG 162831704/07/11: ELOG 1578273

QTOR Corrector Magnet

Q-weak QTOR ELOG

Back up

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BPM3C12

Target BPM

Run 11116: Hall-C BPM X Response to X Modulation

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Hint of correlation

X-Y Correlation to X Modulation During RUN-I

BM

od Y

Ta

rget

Pos

ition

Am

plitu

de

[mm

]

BMod X Target Position Amplitude [mm]39

X-Y Correlation to Y Modulation During RUN-I

BM

od Y

Ta

rget

Pos

ition

Am

plitu

de

[mm

]

BMod X Target Position Amplitude [mm]40

X-Y Correlation to E Modulation During RUN-I

BM

od Y

Ta

rget

Pos

ition

Am

plitu

de

[mm

]

BMod X Target Position Amplitude [mm]41

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Run 11116: Hall-C BPM Y Response to Y Modulation

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Run 11116: Hall-C BPM X Response to E Modulation

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Run 11116: Hall-C BPM X Response to X Angle Modulation

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Run 11116: Hall-C BPM Y Response to Y Angle Modulation

Linked Slide

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Unstable beam vacuum problem

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Large charge asymmetry & BPM

differences

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Unstable beam vacuum problem

Feedback test

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Orbit lock moved

Beam profile scan

Compton lock might be incorrect

Unstable beam

QTOR failure & MCC valve

problem

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X-Y Correlation to Modulation During RUN-I

BM

od Y

Ta

rget

Pos

ition

Am

plitu

de

[mm

]

BMod X Target Position Amplitude [mm]82

Qweakp 1 4 sin2 W ~ 0.072

Qweakp 1 4 sin2 W ~ 0.072 (at tree level)

QpWeak : extract from Parity-Violating Electron Scattering

measures Qp – proton’s electric charge measures QpWeak

– proton’s weak charge

MEM MNC

(as Q2 0 )

Correction involves hadron form factors. Determine using global analysis of recently completed PVES experiments.

The lower the momentum transfer, Q, the more the proton looks point-like; form factor corrections get less important.

“accidental” suppression of Qwp enhances sensitivity to new physics

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APV

N N

N N

2MNC

MEM

G

F

4 2

Q2 Q

weakp Fp Q2 ,

Q2 0 0

GF

4 2

Q2 Q

weakp Q4B Q2

84SM curve by: J. Erler, M. Ramsey-Musolf and P. Langacker

Qweakdecreasing

Qweakincreasing

Running of sin2 θW

Q [GeV]