June 27, 2014 Nuruzzaman University of Oxford The Q-weak Beam Modulation System and Transverse Asymmetry in the N-to-Δ Transition

 Q-weak Experiment: Built online analysis display software for real time data monitoring Designed QTor corrector magnet and implemented field measurement system o Helped to extract Q-weak preliminary result EPJ Web Conf. 71, (2014) 00100; Phys. Rev. Lett. 111, (2013) o Beam modulation system AIP Conf. Proc (2013) o Beam normal single spin asymmetry in the N-to-Δ transition  Nuclear Transparency of Kaons: Thesis: Effective Kaon-Nucleon Cross Section from Nuclear Transparency Measured in the A(e; e′K+) Reaction Phys. Rev. C 84, (2011)  Evaluation of Nuclear Data Structure: Thesis: Evaluation of Nuclear Structure Data for Mass Chain A = 225 Outline of Recent Contributions 2June 27, 2014

Q-weak Experiment at Jefferson Lab 3June 27, 2014 C A B D Jefferson Lab Newport News, VA, USA Q-weak running periods: Run 0: Jan – Feb 2011 Run 1: Feb – May 2011 Run 2: Nov 2011 – May 2012 Q-weak BMod BNSSA The objective of the Q-weak experiment is to measure the parity violating asymmetry (~250 ± 5 ppb) in elastic e-p scattering to determine the proton's weak charge with an uncertainty of 4% e-e- proton θ p > s( ) + − The PV asymmetry: The tree level asymmetry: A ep = σ + - σ - ______ σ + + σ - [Q p W + Q 2 B(Q 2,θ)] -G F Q 2 4√2πα Q 2,θ 0 ≈ A ep

Beam Modulation System 4June 27, 2014 The e-p scattering rate depends on five beam parameters (T i ): horizontal position (X) horizontal angle (X΄) vertical position (Y) vertical angle (Y΄) energy (E) The goal  keep these helicity- correlated parameters as small as possible  measure detector sensitivity to correct false asymmetry ∂T i ∂A = detector sensitivity z x / y θ1θ1 θ2θ2 θ1θ1 II I I Z=0 Z=d 1 Z=d 2 Incoming beam Dipole 3C05 Dipole 3C06 Diploe 3C07 Quad. 3C11 Quad. 3C11 Q-weak BMod BNSSA A measured = A raw + ∂A ∂T i ∆T i ∑ i corrector magnet filed monitoring system

MD2 YIELD [mV/µA] MD1 YIELD [mV/µA] MD8 YIELD [mV/µA] MD5 YIELD [mV/µA] MD4 YIELD [mV/µA] MD6 YIELD [mV/µA] MD3 YIELD [mV/µA] MD7 YIELD [mV/µA] Target X [mm] MDAll YIELD [mV/µA] 5June 27, 2014 Main Detector Response to Modulation Symmetric detectors give partial cancellation data from 1 h run Q-weak BMod BNSSA horizontal position (X) modulation

each data point is from 1 h run ∂E ∂A ∂X ∂A ∂X ´ ∂A ∂Y ∂A ∂Y ´ ∂A Corrections to the PV Measured Asymmetry 6June 27, 2014 Corrections based on the two methods are in excellent agreement for this data set Beam Modulation (natural jitter) (driven motion) Q-weak BMod BNSSA T i = X, X´, Y, Y´ & E A measured = A raw + ∂A ∂T i ∆T i ∑ i about 77% of the Run 2 data-set only beam parameter correction is used

residual dispersion significantly improved after beamline work Run 2 : second phase of the experiment residual dispersion at the target Run 1 : at the beginning of the experiment 7June 27, 2014 Beamline Optics Using Beam Modulation Hall-C BPM X response to energy modulation Q-weak BMod BNSSA

Beam Normal Single Spin Asymmetry Measured asymmetry: A N is parity conserving and has a small azimuthal dependence 8June 27, 2014 A N = 2T 1γ × Im T 2γ |T 1γ | Needed to calculate 2-γ contribution to cross-sections First measurement of A N in the N-to-Δ transition on LH 2 T 1γ – amplitude for 1- photon exchange T 2γ – amplitude for 2- photon exchange Beam Normal Single Spin Asymmetries (BNSSA) are generated when transversely polarized electrons (polarized perpendicular to their direction of motion) scatter from unpolarized targets A M ( ϕ ) = σ − σ σ + σ = − A N P T.n = A N P T sin( ϕ - ϕ 0 ) ∧ Q-weak BMod BNSSA n = ∧ k × k’ |k × k’| where, P T is transverse polarization and A N is BNSSA Contains information about the Intermediate states of the proton during 2-γ exchange

Raw Transverse Asymmetries on H 2 ~ 9% statistical measurement of regressed transverse asymmetry in the N-to- Δ transition 9June 27, 2014 ~ 90 o phase offset  The uncertainty is dominated by statistics  All other systematics are under control stat reg.scheme reg.time nonlinearity cuts fit scheme Total Uncertainty [ppm] Preliminary Q-weak BMod BNSSA Not corrected for backgrounds and polarization

Extraction of Physics Asymmetry 10June 27, 2014 Extracting A N from the experimental measured asymmetry by  removing false asymmetries  correcting for the beam polarization  removing background asymmetries  correcting for radiative tails and other kinematic correction  A msr = A raw + A reg b1 = Al. window background b2 = Beam line scattering b3 = Other neutral background b4 = Elastics  R total = R RC R Det R Q2 Preliminary A N = Detector Bias Radiative Cor. Q2 Bias Q-weak BMod BNSSA Beam Normal Single Spin Asymmetry: A bi = Background asymmetries f bi = dilution factors  Physics asymmetry is highly diluted by the elastic radiative tail. Careful study is ongoing.

Acknowledgement 11June 27, 2014 I was helped significantly by several members of the Q-weak collaboration. I would like to specifically acknowledge the contributions of the following: Dave Mack Dipangkar Dutta Liguang Tang Roger Carlini Jay Benesch Q-weak Collaboration

How My Experience is Relevant for This Job?  The muon g-2 experiment is a high precision test of SM –Gained extensive understanding on precision measurement in Q-weak experiment  Magnetometer calibration and its commercial applications, construction and testing of an instrument at Oxford, carrying out geomagnetic field modeling and field tests with fluxgate sensors –Experience with magnets in beam modulation system –Designed corrector magnet and Implemented field monitoring system –Experience at accelerator facility and working with support groups  Teaching experience –Teaching assistant, PH-2223 Physics II Lab (2 semesters): demonstration of the experiments, conducting quizzes and grading lab reports for about 40 students 12June 27, 2014

13June 27, 2014 Backup Slides

Light Weighted Signal from Geant 3 Simulation 14June 27, 2014 Elastic peak Inelastic peak From Geant 3 simulation, a ± 5.0% error on dilution due to 10.0% discrepancy between simulation and data after matching at elastic peak. Need to update.

Collimators Quartz Cerenkov bars Trigger scintillator Vertical drift chambers 35 cm LH 2 Target Toroidal magnet spectrometer (QTor) Horizontal drift chambers = low-current tracking mode (production current x ) Red Electro n beam E beam = GeV ~ 7.9° ± 3° ϕ coverage ~ 49% of 2π Current = 180 μA Polarization = 89% 15June 27, 2014 Q-weak Apparatus Blue = production (“integrating”) mode ϕ  (octant # − 1) x 45 o

Extracting PV Asymmetry 16June 27, 2014 Extracting A ep from the experimental measured asymmetry by  removing false asymmetries, parity conserving contamination  correcting for the beam polarization  removing background asymmetries  correcting for radiative tails and other kinematic correction  A msr = A raw + A reg + A T + A L b1 = Al. window bkg. b2 = Beam line scattering. b3 = Other neutral background. b4 = Inelastics. Phys. Rev. Lett. 111, (2013) A reg = Linear regression asym. A T = Residual transverse asym. A L = Non-linearity in PMT A bi = Background asymmetries f bi = dilution factors  R RC = Radiative corr. R Det = Detector bias corr. R Bin = Effective kinematic corr. R Q2 = Q 2 calibration corr.  R total = R RC R Det R Bin R Q2 Extracting physics asymmetry, A ep, from the experimental measured asymmetry by removing false asymmetries, parity conserving contamination correcting for the beam polarization removing background asymmetries correcting for radiative tails and other kinematic correction. A raw P A reg ATAT ALAL A msr Δb1 Δb2Δb3Δb4 R total A ep Extracting physics asymmetry

Extracting PV Asymmetry 17June 27, 2014 Error bar is hard to visualize! Our A & ΔA are ~3 times smaller than nearest competitor. Smallest asymmetry and absolute error bar measured in e-p scattering to date This is ~ 4% of total data set

Q-weak 18June 27, 2014 Global fit (solid line) presented in the forward angle limit as reduced asymmetries derived from this measurement as well as other Parity Violating Electron Scattering (PVES). Q p W (PVES) = ± This is ~ 4% of total data set uncertainty in the fit Our result increased consistency with SM calculation Q p W (SM) = ± Our result increased consistency with SM calculation Q p W (SM) = ± SM Phys. Rev. Lett. 111, (2013)

Impact on C 1u and C 1d 19June 27, 2014 Q p W = -2(2C 1u + C 1d ) Q n W = -2(C 1u + 2C 1d ) Q n W (PVES+APV) = −0.975 ± Neutron weak charge is extracted for the first time. Our result for neutron is in agreement with SM value Q n W (SM) = ± Neutron weak charge is extracted for the first time. Our result for neutron is in agreement with SM value Q n W (SM) = ± Q p W along with Atomic Parity Violation (APV) constrain on the neutral-weak quark coupling constants C 1u − C 1d (isovector) and C 1u + C 1d (isoscalar). SM APV + PVES Combined Result C 1u = ± C 1d = ± This is ~ 4% of total data set World PVES with Q-weak Phys. Rev. Lett. 111, (2013)

Running of sin 2 θ W 20June 27, 2014 Preliminary The running of the weak mixing angle with momentum transfer, Q, as depend in the MS renormalization scheme The SM predicts the running of sin 2 θ W (Q) based on the measurement done at the Z-pole. Running of sin 2 θ W is due to higher order RC varies with Q 2. Q-weak will measure the sin 2 θ W (Q) to 0.3% with full statistics.

Summary of Q-weak Results 21June 27, 2014 Expect to report results with 5 times smaller uncertainties in about a year. Demonstrated the technological base for future high precision SM tests using PVES at an upgraded 12 GeV Jefferson Lab. Measured asymmetry A ep = −279 ± 35 (stat.) ± 31 (sys.) ppb Extracted weak charge of proton Q p W (PVES) = ± Q p W (SM) = ± Extraction of weak vector charges C 1u = ± C 1d = ± Weak charge of neutron Q n W (PVES+APV) = −0.975 ± Q n W (SM) = ± Acceptance averaged incident beam energy E s = ±0.003 (GeV) Acceptance averaged = ± (GeV/c) 2 Effective scattering angle, θ eff = 7.90 ±0.30°

Ancillary Measurements 22June 27, 2014 Plenty of projects, plenty of results, 20+ theses…. In addition to the ~ 4% measurement of the proton’s weak charge, numerous other interesting ancillary measurements: Elastic transverse asymmetry (proton) Elastic transverse asymmetry (aluminum, carbon) PV asymmetry in →Δ region. Transverse asymmetry in the →Δ region (proton) Transverse asymmetry in the →Δ region (aluminum, carbon) PV deep inelastic scattering box diagram constraining Transverse asymmetry in the PVDIS region (3.3 GeV) PV asymmetries in pion photoproduction Transverse asymmetries in pion photoproduction Measurements of elastic PV asymmetry on aluminum(alloys)/ carbon

X X´ Y Y´ E 320 s 4 s 23June 27, 2014 Typical Modulation Cycle 75 s X BMod drive signal for horizontal pair of magnets Phase FGX1 [V] FGX2 [V] BPMX [mm] BPMY [mm] Phase/

Beamline MAT Coils X1X1 Y1Y1 Y2Y2 X2X2 SRF E BSY Service Building BMOD1BMOD1 X1X1 X1X1 Y1Y1 Y1Y1 X2X2 X2X2 Y2Y2 Y2Y2 LEM Current Transducer X1X1 Y1Y1 Y2Y2 X2X2 TRIM Power Amp. BPMs BMOD2BMOD2 Hall-C GUI CONSOLE Q-weak PV Daq. Q-weak Cage I O C hCnmrhCnmr TRIUMF ADC JLAB ADC e - Beam RelayRelay RelayRelay BMod Hardware Sketch 24June 27, 2014 VME crate