" EXPERIMENTAL METHOD" STATISTICAL ERROR ( 5 × 108 Pulses; ~½ of E158 running)

δAD/AD = 0.006

δ sin2θW = 0.0006

" EXPERIMENTAL SYSTEMATIC ERRORS

δAD/AD = 0.006

δ sin2θW = 0.0006 (ASSUMING STANDARD MODEL)

" THEORETICAL SYSTEMATIC ERRORS

δ sin2θW = 0.0004 (ASSUMING STANDARD MODEL)

" TOTAL ERRORδAD/AD = 0.008

δ sin2θW = 0.0009 (ASSUMING STANDARD MODEL)

OUTLINE

" DEEP INELASTIC SCATTERING ( e + d → e + X )

" MEASURE ASYMMETRY: A D =(σR

−σL) / (σ

L+σ

R)

AD ≈ 10−4 Q2 ≈ 0.002

" POLARIZED ( 85%) ELECTRON BEAM (E= 36, 39 GeV)" UNPOLARIZED LD 2 TARGET (1.0 m)

" 2 MAGNETIC SPECTROMETERS" LEAD GLASS DETECTORS

COUNT INDIVIDUAL ELECTRONS INSENSITIVE TO SOFT BACKGROUND

" KINEMATICS

16 < Q2 < 26 GeV2 (AVOID HIGHER TWIST)

0.3 < x < 0.7 9 < E′ < 17 GeV

10 < W2 < 36 GeV2 (DIS)

EXPERIMENTAL METHOD

" HIGH STABILITY FROM E158NEW TOROIDSNEW POSITION MONITORSNEW ACCELERATOR FEEDBACK LOOPS

" HIGH INTENSITY FROM E158 " POLARIMETER FROM SLD

BEAM

MOMENTUM FOCUSING

� ~0.8 msr ACCEPTANCE FOR 9 < P < 16 GeV

" LEAD GLASS ARRAYS FROM E142−E155X20 Vertical x 10 Horizontal BLOCKS: 6 cm squareRESOLUTION: σ/E < 5% IN OUR ENERGY RANGE

COLLIMATORS DETERMINE FIDUCIAL REGION" ELECTRONICS:

250 MHz FLASH ADCs on EACH BLOCK10 BIT RESOLUTIONDEVELOPED FOR KAMLAND by BERKELEY

" COUNTING SINGLE ELECTRONS

" RATE DEPENDENCESPACE AND TIME SEPARATION OF PARTICLESPULSE HEIGHT AND SHAPE FOR OVERLAPSMEASURE RESIDUAL RATE DEPENDENCE

DETECTOR

Momentum Range of electronshitting a given row of PbG blocks.Red curve is minimum P cut for 1 e.Blue curve is minimum P cut for 2 e.

Number of events/spill in eachrow of PbG blocks.

14 electrons/spill : Dashed blue curve 4 pions/spillSolid Red Curve is e and π

" BEAM POLARIZATION

" MEAN Q 2

" ELECTROMAGNETIC RADIATIVE CORRECTION" PILE UP AND DEAD TIME" TARGET PURITY AND DENSITY" PION CONTAMINATION" FALSE ASYMMETRIES" PAIR SYMMETRIC BACKGROUND

EXPERIMENTAL SYSTEMATIC ERRORS

" COMPTON POLARIMETERPHOTON−ELECTRON SCATTERINGRADIATIVE CORRECTIONS <0.1%USED AT SLD WITH 0.5% ACCURACYHIGH POWER LASERDETECT SCATTERED ELECTRONDETECT SCATTERED PHOTON (INDEPENDENT MEASUREMENT)MEASURE CONTINUOUSLYMEASUREMENT TAKES ~5 MINUTES

BEAM POLARIZATION

ESA

POLARIMETER ANALIZING POWER AND RATES DETECTOR EDGES AND BACKGROUND

Signal

Background

" BACKGROUNDS" FROM ELECTRON BEAM

e.g. BREMSSTRAHLUNG FROM GAS IN BEAMLINE� MEASURE WITH LASER OFF

� LASER PULSES AT 17 Hz

ELECTRONIC NOISE: PULSING LASER� MEASURE WITH BEAM OFF

" SLD EXPERIENCE (Mike Woods)

SIMILAR SETUP ⇒ δPe = 0.5%

" NLC NEEDS 0.25% ACCURACYIMPORTANT TO TEST TECHNIQUESESA BEAM NOW SIMILAR TO NLC BEAM

" WE CAN DO δ P = 0.3%

BEAM POLARIZATION

" NEED TO KNOW: δ<Q2>/<Q2> ≤ 0.3%

" Q2 = 4 E E′ SIN2θ /2 (θ =12o ~200 mr)

" MEASURE δ E/E ≤ 0.1%

ZERO CROSSING OF BEAM POLARIZATION

" OPTICS MEASUREMENTS FOR E′ (0.2%) & θ (0.2 mr)

" METHODS FROM PAST EXPERIMENTS

FLOATING WIRE USED IN E140 (We have shorter spectrometer)

CENTRAL ANGLE ±0.05 mr

CENTRAL MOMENTUM δE′/E′ ±0.03%

AGREEMENT WITH ELASTIC PEAK 0.13%

AVERAGE Q 2 OF EVENTS

FIELD MAPS OF MAGNETS AND SURVEY

SPECIAL ACCEPTANCE RUNS

SHORT TARGETS IN VARIOUS POSITIONS

BEAM ENERGY SWEEP (E154)

QUADS ON / OFF

APERATURE DEFINING MASKS (E154)

CROSS SECTION WELL KNOWN FROM PREVIOUS FITS

" OVERALL UNCERTAINTY: δ<Q2>/<Q2> ≤ 0.3%

AVERAGE Q 2 OF EVENTS

" WELL KNOWN TECHNIQUE

Mo and Tsai

Bardin

USED IN ALL ELECTRON SCATTERING EXPERIMENTS

INTERNAL CORRECTIONS

AT THE SCATTERING NUCLEON

EXTERNAL CORRECTIONS

ENERGY LOSS IN TARGET

POLARIZATION LOSS IN TARGET

" OUR KINEMATICS HAVE SMALL CORRECTIONS

EM RADIATIVE CORRECTIONS

" INTERNAL COMPARE Mo −Tsai WITH Bardin

AVERAGE DIFFERENCE δAD/AD = < 0.001

" EXTERNAL:

USE DIFFERENT FITS TO F2(X,Q2) AS INPUT:

GET AVERAGE DIFFERENCE IN ASYMMETRY

RESONANCE MODELS δAD/AD < 0.001

DIS MODELS δAD/AD ~ 0.002

" TOTAL ERROR: δAD/AD < 0.003

EM RC ERROR DETERMINATION

.

THEORETICAL SYSTEMATIC ERRORS

" AD IS EXPERIMENTALLY MEASURED

� FOCUS: EXTRACT sin2θW FROM ADASSUME STANDARD MODEL

sin2θW IS BURIED IN THE C ij

C1U ~ −1/2 +4/3 sin2θW

" ERRORS FROM R’s, Y, ETC.

" R = fi(x)/(Σf) : Fraction of sea or valence quarks

" Rc, Rs SMALL; R V ~ 1.0 at our values of x

Determined from Parton Distribution Functions

CTEQ, MRS Groups Provide Errors (2002)

Over 25 Distributions Considered

Uncertainties from CTEQ Errors, and Most Different Distribution

" δ sin2θW ~ 0.0002

"Ad Depends on Couplings and Quark Distributions

PARTON DISTIBUTIONS

" Higher Order pQCD easy to do." Higher Twist

DECREASES ~ Q−2 Compared to leading twist 2

Q2 =20: δsin2θW < 2×10−5 (Castorina & Mulders)

NACHTMANN MOMENTS OF F 2 : HT < .4% OF LT

(Osipenko et al.)

WE USE CONSERVATIVE δsin2θW ~ 0.0001

LOI at JLAB for Experiment at low Q 2

QCD and HIGHER TWIST

" NO VIOLATION : un = dp ; up = dn; sp = sn ; cp = cn

Assumes that n and p are perfect isospin doublet Broken by E & M Mp ≠ Mn But only by about 0.1%

md/mu ≈1.8 ; md−mu ≈3 MeV : ~ 1% of ΛQCD

So Expect δ(un −dp) ≈ 0" CAN BE CALCULATED

MIT bag modelMeson Cloud Model

AVERAGE OF MODELS: δ sin2θW ≈0.0002 ± 0.0002SAME MODEL FOR NuTeV: 0.0015

CHARGE SYMMETRY VIOLATION IN DEUTERON

"Very Well Determined in Standard Model

" Depends on α, MZ, MW, MH ,Q2, sin2θW

C1U

= ρ′(−1/2 +4/3 κ′sin2θW) + λ1u

ρ′,κ′≈1; λ1u≈0" Overall Correction to Asymmetry < 1%" Weak Dependence on Higgs Mass

"Cut off’s depend on Q2 , not on quark masses" Jens Erler & Michael Ramsey−Musolf in collaboration

" δ sin2θW ≈ 0.0002

ELECTROWEAK RADIATIVE CORRECTIONS

" EMC EFFECT IN DEUTERIUM?σD/ (σp + σn) ~ 0.98 to 1.00 IN OUR X RANGE

IF PARTON DISTRIBUTION SHIFTED TO LOWER X� Rs, Rc, Rv RATIOS UNCHANGED.

� NO EFFECT ON ASYMMETRYVALENCE & SEA SHIFTED DIFFERENTLY (Frankfurt & Strikman)

� δ sin2θW ≈ 0.00002" NUCLEAR EFFECTS SHOULD BE SAME FOR γ & Z EXCHANGE

NO CHANGE IN ASYMMETRYONLY NEUTRAL CURRENTS

" CALCULATION BEING DONE BY Alekhin, Kulagin and Liuti

NULEAR EFFECTS

.

" MEASURES UNIQUE INDEPENDENT PARAMETERS Cij" SPECIFIC SENSITIVITY TO NEW PHYSICS" FACTOR OF 20 DECREASE IN ERRORS

" δ sin 2θW = 0.0009 (ΑSSUMING STANDARD MODEL)

NuTeV ~ 0.0016 (εL , εR)

E158 ~ 0.001 ( lepton couplings)"THEORETICAL CORRECTIONS SMALL"THEORETICAL SYSTEMATIC ERRORS SMALL ( 0.0004) "IN A LONG TRADITION OF HIGH ACCURACY

MEASUREMENTS IN ESA"EXPERIENCED COLLABORATION READY TO START "LOW COST: < 0.001 NLC"WANT RESULTS BEFORE LHC ( BUT DIFFERENT THAN LHC)

SUMMARY

OPTICS

Errors on Asymmetry from Uncertainty in Parton Distributions

UNCERTAINTY ON R = σL/σT

� R ~ 0.03± 0.025 (E140)

� AVERAGE: δ sin2θW ≈0.0001

ElectroWeak Corrections

� Running of αs due to γ−Z Mixing

� Axial−vector renormalization: small

� Anapole moment: negligible

� Charge−radii: 0.1% on Ad.

� WW and ZZ box diagrams: < 0.1% on Ad.

� γ−Z box diagram: < 0.1% uncertainty on Ad

� OVERALL UNCERTAINTY:

δ sin2θW ≈ 0.0002

INTERNALDIFFERENT CODESAvg < 0.001

EXTERNAL DIFFERENT MODELSAvg = 0.002

RADIATIVE CORRECTIONS

RATE DEPENDENCE

� SPACE AND TIME SEPARATION OF SHOWERS

OVERLAP of 2 electrons : 4% of electrons merge

� ENERGY SEPARATION

2 Electrons of E > Emin

Additional separation of factor of 15� Energy Straggling� Gaps between blocks

Leaves 0.3% confusion between 1 electron and 2 electrons

� MEASURE RATE DEPENDENCE OF CONFUSION

Another factor of 10

δ ΑD/AD ~ 0.03%

REQUEST FOR BEAM

ENERGY PULSES 35.6 2 × 108

38. 8 2 × 108

35.6 4 × 107 Checkout

35.6 3 × 107 backgrounds

12 to 38 3 × 107 energy scan

TOTAL 5 × 108 2.3 Mo @120 Hz, 70% eff

SPECTROMETERS� 2 IDENTICAL SPECTROMETERS AT ± 120

� QUAD−DIPOLE−QUAD

� FOCUS MOMENTUM

� MAXIMIZE ACCEPTANCE USING EXISING MAGNETS

� ~0.8 msr ACCEPTANCE FOR 9 < P < 16 GeV

� 18 PARTICLES/SPILL/SPECTROMETER

� 14 e− SPREAD UNIFORMLY OVER DETECTOR

� 4 π /spill CONCENTRATED AT BOTTOM

" USE OLDBEAM FROM E158 (VERY STABLE )TARGET FROM E158SPECTROMETER DESIGN FROM E155XMAGNETS FROM E1DETECTOR FROM E142 −E155XCALIBRATION METHOD FROM E140XCOMPTON POLARIMETER FROM SLDPEOPLE FROM ALL THE ABOVE + MANY MORE

" USE NEWFLASH ADC FROM BERKELEY /KAMALAND

EXPERIMENTAL METHOD

" π /e < 1 IN ALL ROWS (AVERAGE: 0.25) ⇒

LEAD GLASS SUFFICIENT FOR REJECTION

PULSE HEIGHT AND SHAPE

REJECT 95% OF π 1% UNDER ELECTRON PEAK

� FIT FOR REMAINDER

" 2nd LAYER OF LEAD GLASS

e SHOWER STOPPED EARLY

EXTRA REJECTION

MEASURE π ΑSYMMETRY

" MEASURE π /e TO BETTER THAN 10%

" DONE IN MANY PREVIOUS EXPERIMENTS

π CONTAMINATION

pi/e=3E154