A New, Robust Beam Modulation Strategy for the Q p weak Experiment Nuruzzaman ( Advisors: Dr. Dipangkar Dutta ( Dr. Dave Mack ( for the beam modulation team 19 th June 2009

Conserves ParityViolates Parity M NC M EM σ + - σ - 2 M NC A PV = _______ σ + + σ - _______ M EM ~~0.2 ppm A PV = _______ - G F 4πα√ 2 [Q 2 Q p w + Q 4 B(Q 2 )] As Q 2 → 0, θ → 0 Weak Charge Q p w = 1- 4sin 2 θ w Hadronic contribution contains G γ E,M and G z E,M ↑↑ σ = |M EM | |M EM | |M NC | *+ … [1], [6]

The search for fundamental description beyond SM can be done in two ways: 1. Build increasingly energetic colliders. Or 2. High precision measurements. [1] The objective of the Q p weak 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] The e-p scattering The e-p scattering rate depends on the five beam parameters: horizontal position (X), horizontal angle (X΄), vertical position (Y), vertical angle (Y΄) and energy (E). The goal of the Q p weak 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. In order to measure the detector sensitivities, Small changes in these parameters will create a change in rate. If these parameters are beam helicity dependent, this will create a false asymmetry. Measurement of Sin 2 θ w at Q 2 =0.03 to 0.3 %

To make multiple measurements with few percent statistical errors, on each of 5 beam parameters( x, x΄, y, y΄, E), and still spend most of our time taking uncontaminated production data, the minimum amplitude should be 10 ppm. A modulation Clock Time Required 10% DF (Hours) Clock Time Required 1% DF (Hours) Clock Time Required 0.1% DF (Hours) 1 ppm ppm At nominal luminosity, the Qweak experiment requires 156 seconds to reach 1 ppm sensitivity. Should one want to measure sensitivities to 10% statistical accuracy, the required measurement times for a single beam parameter are: These times are easily scaled to preferred statistical error.

Beam Parameter Single Detector Sensitivity Assumed Cancellation Whole Detector Sensitivity Modulation Amplitude for 10 ppm Position10 ppb/nm500.2 ppb/nm50 µm Angle10 ppb/nrad500.2 ppb/nrad50 µrad Energy1 ppb/ppb1 10 ppm (~10 keV) To estimate dX i for Abeam = 10 ppm, we need the detector sensitivities. We assumed a factor of 50, where appropriate for cancellation between opposite octants. We believe these magnitudes are sufficiently larger than natural beam jitter that the latter does not appreciably affect the measurement times.

[2], [5]

Target: m m Coil 1 & Coil 2=100G-cm z x Inverse Beamline

Coil 1=100G-cm m Target: m z x Inverse Beamline

10G-cm Target: m m Coil z x Forward Beamline

Advantages of Using Pair of Coils: Greater Flexibility in Coil Positioning Coil Positions does not depend upon Design Optics The Coil pair is compact in 100 cm rather than being scattered over 100 m of beamline  In a meeting with Accelerator Ops[4], it was strongly suggested we consider a pair of coils for beam modulation!  This is more complicated than our previous strategy of placing single coils at orbit zero crossings.

Target: m Match Point m z x Pair of Coils Forward Beamline

θ1θ1 θ2θ2 θ1θ1 Z=0 Z=d 1 Z=d 2 Where z x / y Forward Beamline

Hall C Beamline Zoomed In Target 1 st Coil2 nd Coil Dipole 3C05 Dipole 3C06 Dipole 3C07

No Reliable Design Optics ! Target Target: m Match Point m Match Point Pair of Coils z x Forward BeamlineInverse Beamline

No Reliable Design Optics ! Target Target: m Match Point m Match Point Pair of Coils z x Inverse BeamlineForward Beamline

3C12 Quad Compton Energy Modulation

Beam Parameter Modulation Amplitude for 10 ppm Current through 1 st Coil I 1 (A) Field Integrals for 1 st Coil BdL 1 (G-cm) Tune Parameters (BdL 2 / BdL 1 ) X50 µm X΄X΄50 µrad Y50 µm Y΄Y΄50 µrad N.B: The Length of the Coils are Taken 10 cm

Trim Card II (Power Amp) Trim Card II (Power Amp) OscilloscopeOscilloscope Signal Generator Tesla Meter Modulation Coil 1 AmmeterAmmeter LEMLEM PowerSupplyPowerSupply 91Ω 15V-15V Hz ~ I max = 3 A ~ B max = 60 G ~ 10 cm Modulation Coil 2 Trim Card II (Power Amp) Trim Card II (Power Amp) AmmeterAmmeter ~ 10 cm ~ I max = 3 A

To make sure that the planned hardware could provide the required field integral at frequencies of up to 500 Hz, we did the following bench tests: Powered a JLab MAT(HF) coil with a Trim-II power supply at 10Hz-500Hz Determined that only sinusoidal waveforms are feasible Determined I max = 5A based on the observed coil temperature rise Determined that Trim-II can be used reliably up to 250 Hz with 3A output Measured the field integral with a GMW Hall Probe Monitored the output waveform quality using a LEM current transducer Drove two coils simultaneously from our FANUC VME function generator

The power amp. voltage vs. coil currentCoil current vs. field integral

Field integrals for different currentsNormalized field integrals w.r.t. 2 amps.

Clockwise from left corner: 1.Two inputs from VME signal generator & LEM current transducer 2.Two inputs from VME and two output from TRIM II 3.One input from VME, LEM output & TRIM II output 4.One input from VME, LEM output & TRIM II output

 Calculation of beam parameters for 10 % statistical accuracy  Coil positioning using OPTIM [2]  Bench tests with a pair of coils with VME-4145 signal generator and TRIM-II were successful  Accelerator Ops. Will install hardware this summer [5]  Working on control system  This new strategy for beam modulation with a pair of coils[4] will benefit any parity violating experiment.

[1] [2] [3] Nuruzzaman, PPT, Q p weak Collaboration Meeting, 1st Order Beam Modulation in the 3C Line [4] Private communication with Mike Tiefenback [5] Private communication with Jay Benesch [6] Katherine Myers, PPT, Hall C Users Meeting January 2009, Status of the Q p weak Experiment

Questions ?

Extra Slides

Conserves ParityViolates Parity M NC M EM σ + - σ - 2 M NC A PV = _______ σ + + σ - _______ M EM =~0.2 ppm A PV = _______ - G F 4πα√ 2 [Q 2 Q p w + Q 4 B(Q 2 )]= As Q 2 → 0, θ → 0 Weak Charge Q p w = 1- 4sin 2 θ w Hadronic contribution contains G γ E,M and G z E,M ↑↑ [6]

Pair of Coils Single TRIM-II

dA = = (i.e., 1 ppm) N = counts = Rt = seconds = t =

Q3C07 Q3C08, kvirt3, D3C05, D3CO6 D3C08, Q3C12 TARGET Q3C21 Pivot G0

[6]