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![Page 1: X. Zheng, PAVI06, Milos, Greece Massachusetts Institute of Technology Parity Violation in Deep Inelastic Region at JLab 6 GeV — Experiment 05-007 – Motivation,](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649eb25503460f94bb9acf/html5/thumbnails/1.jpg)
X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Parity Violation in Deep Inelastic Region at JLab 6 GeV
— Experiment 05-007
– Motivation, PVDIS, Implication on EW standard model and hadronic physics;
– Requirement on Instrumentation and Status
– Summary and Outlook
Xiaochao ZhengMassachusetts Institute of
TechnologyMay 19, 2006
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Observables — parity violating asymmetries (APV)
(polarized beam + unpolarized target)
study nuclear matter (neutron skin) PREx
study hadron structure
elastic scattering: strange form factors A4, G0, HAPPEX, SAMPLE
DIS: non-perturbative higher twist effects, etc... PVDIS
test EW standard model E158, Atomic PV, Qweak
Parity Violation in Electron Scattering
ALR≡
r− l
r l≈
Q2
MZ
2≈120 ppm at Q2=1GeV /c2
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
SM works well at present energy range, however:
Data exist: cannot be explained by the SM ( m? NuTeV
anomaly?..);
Conceptual reasons: What happens in the “high-energy desert” (250GeV ~ 5 x 1014 GeV ~ 2.4 x 1018 GeV)?
Search for Physics beyond the Standard Model
Direct: LEP, LHC
Indirect: E158, Atomic PV, NuTeV, Qweak, PVDIS
Electro-Weak Standard Model
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
From Ad can extract C1,2q and sin2W.
PV DIS Asymmetries
For a deuterium target
In the SM, tree level
Ad= 540 ppmQ2
2 C1u[1R
C x ]−C
1d[1R
S x ]Y 2 C
2u−C
2dR
V x
5RS x 4 R
C x
C1d=g
A
e gV
d =1
2−
2
3sin2
W
C1u=g
A
e gV
u =−1
2
4
3sin2
W
C2d=g
V
e gA
d =1
2−2 sin2
W
C2u=g
V
e gA
u =−1
22 sin2
W
Rc,Rs,Rv: nucleon PDF; Y: kinematic factor
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
DIS Parity Experiment – History and Future
1970's, result from SLAC E122 consistent with sin2W=1/4, confirmed
the Standard Model prediction;C.Y. Prescott, et al., Phys. Lett. B77, 347 (1978)
Development in experimental technique allows to search for new physics
If all hadronic effects are small or can be understood, then any deviation of sin2W or Ciq from their SM predictions would be a hint of
new physics.
P. Bosted, et al., SLAC E149 (1993), LOI2003-1;
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Current Knowledge on Weak Coupling Coeffecients
Facility Process Result SM Value
SLAC 1.39 -0.7185
SLAC 1.39 -0.0983
CERN 34 1.4351
CERN 66 1.4204
MAINZ 0.20 -0.8544
Bates 0.0225 0.1528
Bates 0.1 -0.0624
Bates 0.04 -0.0624
JLab 0.03 approved 0.0357
0 -73.16
0 -116.8
Q2 Ciq Combination
e--D DIS 2C1u-C1d -0.90± 0.17
e--D DIS 2C2u-C2d 0.62± 0.81
m±-D DIS 0.66(2C2u-C2d)+2C3u-C3d 1.80± 0.83
m±-D DIS 0.81(2C2u-C2d)+2C3u-C3d 1.53± 0.45
e--Be QE 2.68C1u-0.64C1d+2.16C2u-2C2d -0.94± 0.21
e--C elastic 2C1u+C1d 0.138±0.034
e--D QE C2u-C2d -0.042± 0.057
e--D QE C2u-C2d -0.12± 0.074
e--p elastic 2C1u+C1d
133Cs APV -376C1u-422C1d -72.69±0.48205Tl APV -572C1u-658C1d -116.6±3.7
J. Erler, M.J. Ramsey-Musolf, hep-ph/0404291 or Prog. Part. Nucl. Phys. 54, 351 (2005)
C2q=g
V
e gA
q C3q=g
A
e gA
qC1q=g
A
e gV
q
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
JLab Experiment 05-007
Use 85mA, 6 GeV, 80% polarized beam on a 25-cm LD2 target;
Two Hall A High Resolution Spectrometers (HRS) detect scattered electrons;
Measure Ad at Q2=1.10 and 1.90 GeV2 to about 2% (stat.);
Co-spokesperson & contact: X. Zheng (MIT)Co-spokesperson: P.E. Reimer (ANL), R. Michaels (JLab)
(Hall-A Collaboration Experiment, approved by PAC27, rated A-)
ANL, Calstate, FIU, Jlab, Kentucky, U. of Ljubljana (Slovenia), MIT, UMD, UMass, UNH, Universidad Nacional Autonoma de Mexico, Rutgers, Smith C., Syracuse, UVa,
W&M
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
From Ad at Q2=1.90 (GeV/c)2, can
extract (2C2u-C2d) to ±0.03 — order
of magnitude improvement compared to world data (PDG);
provide constraints on new physics up to 1 TeV mass limit (complementary to Qweak, E158);
Z' Searches; Compositeness; Leptoquarks.
help to extract C3q
= gA
egA
q from CERN
m±-DIS data
E05-007 Physics Goals
Ad=
3GF
Q2
2 2
2 C1u[1R
C x ]−C
1d[1R
S x ]Y 2 C
2u−C
2dR
V x
5RS x 4 R
C x
(for review of new physics from PVES:J. Ramsey-Musolf, et al., hep-ph/0001250; hep-ph/0307270; nucl-th/0501023;
SM
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
To cleanly separate higher-twist (HT) from New Physics will require precision measurement at various kinematics, and we are making the first step now;
Existing models show negligible HT effects;
Ad at Q2=1.10 (GeV/c)2 will help to investigate if there are significant
HT effects:
Will help to investigate the HT contribution to the NuTeV anomaly:
May provide “clean” extraction of HT, and help with DIS analysis:
extract S at low Q2 from DIS data — test pQCD and understand
confinement.
Will provide important guidance for the future PVDIS program;
E05-007 Physics Goals
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
If 80% of this deviation is from HT, it would imply a 6% HT contribution to our Ad at Q2 = 1.9 and 10% at Q2 = 1.1 (GeV/c)2, way larger than our
expected error bar;
The NuTeV Anomaly
and Higher Twist
sin2W reported by NuTeV is 3s
away from SM;
Possible hadronic causes: CSV, strange sea asymmetry, HT, etc.
M. Gluck and E. Reya, Phys. Rev. Lett. 47, 1104 (1981);also: G.A. Miller & A.W. thomas, hep-ex/0204007
G.P. Zeller et al, PRL88,091802(2002)
T. Londergan, PAVI06 E158: P.L. Anthoney et al., PRL95, 081601 (2005)Cs-APV: S.C. Bennett, C.E. Wieman, PRL82,2484(1999)
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Extraction of S at Low Q2 and Higher Twist
S extracted from Bjorken sum rule
at low Q includes HT;
HT from DIS (F2, g1...) — difficult to separate from higher order effects;
HT from PVDIS:
Leading Twist unambiguously determined by the SM;
More precise than polDIS;
If can use PVDIS HT for low Q DIS analysis, then may correct HT and compareS with pQCD predictions
® Test standard model of strong interaction.
A. Deur, V. Burkert, J.P. Chen, W. Korsch, hep-ph/0509113
Perhaps PVDIS can serve as a (powerful?) tool to study some long-lasting problem in hadronic physics — HT, d/u, anything else???
Ad=AdSM1
C4HT
Q 2
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
EXPERIMENTALHALLS
INJECTOR
RECIRCULATIONARCs (Magnets)
NORTHLINAC SOUTH
LINAC
CBA
“parity-quality”beam since 1998K. Paschke, PAVI06
The Accelerator at Jefferson Lab, Virginia, USA
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Experimental Hall A
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
PV-DIS (E05-007) Requirements and Status
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
PV-DIS (E05-007) Requirements and Status
upgrade from IR to green laser to provide 1% precision
upgrade to flash-ADC based DAQ to count 1MHz rate
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Compton Polarimetry
Compton polarimeter: measure asymmetry of Compton scattering of electron beam and high power laser (Fabry-Pérot cavity);
Non-invasive, high current capacity;
Currently using: 200mW 1064nm laser;
Difficult for < 2GeV beam;
Providing 2-3% precision for 4 GeV beam, larger for <4 GeV;
see also: J. Diefenbach, PAVI06
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Present UpgradeWavelength(nm) 1064 532Cavity Power (W) 1500 3000
Upgrade required by: PVDIS, PRex, 12 GeV
Upgrade includes:
from IR to Green (532nm) laser, completely new optics including the Fabry-Pérot cavity, factor of 4 increase in FOM — JLab;
Green Compton Upgrade
new electron detectors (narrower micro-strip) to improve resolution — Univ. of Clement-Ferrand;Photon integration method — improve systematics (JLab);
Will provide 1% precision down to 1 GeV beam energy;
(PRex) R. Michaels, PAVI06
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Green Compton Lab
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Green Compton Optics Setup
CurrentlyIn Progress
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Green Compton Cavity Alignment
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Green Compton Optics Setup
Green laserwith safty cover FOI
L1QWP
PA510
L2
Aiming in cavity locking July/August 2006.
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
DAQ Upgrade
Current Hall A HRS DAQ:
Max event rate 4KHz (VDC limited);
Previous Hall A PV Experiments (HAPPEX) used Integrating DAQ
Will not work for DIS (large pion background);
Flash ADC (FADC) based DAQ is required:
FADC: 250MHz main sampling rate with on-board processor (FPGA);
Provide on-board fast PID on a counting basis up to 1MHz;
Full event information sampled at lower rate for cross-check;
Can be used for other high rate experiments.
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
FADC DAQ on HRS
Inputs:
Scintillators (S1, S2, 12 channels each);
Gas cherenkov (GC,10CH);
Lead glass counter (“Pre-shower” 48CH, “Shower” 80CH);
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
FADC DAQ on HRS
On-board Processing:
S1+S2 for track quality evaluation;sum GC, Lead glass for PID;segments GC and Lead glass blocks for pile-up rejection;pile-up separation (signal shape analysis);
Shower sum
pions
electrons
Outputs:
helicity-gated electron and pion counts (per ~second);full event sampling at low rate for quality control, including pile-up events for further off-line evaluation;cross check with regular DAQ at low event rate (<4KHz);
Pre
-Sho
wer
sum
Regular DAQ Spectrum
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Status:
Preliminary test using a 100 MHz module (no processor built-in) completed — design algorithm, signal shape analysis (Oct.2005):
Specification/algorithm provided to JLab DAQ group — Dec 2005;
First prototype will be available in summer 2006, more tests will follow;
Expect to completely test the full system in late 2007.
Schedule of E05-007:
Phase I (13 days) approved, will run in late 2008 – early 2009;
Will re-propose phase II (33 days) soon, hopefully will complete both at the same time;
FADC DAQ on HRS
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
The approval of E05-007 started the PV-DIS program @ JLab:
SM test, precision C2q and sin2W
(complimentary to other HEP and Nuclear experiments)
Study of hadronic effects:
Higher-twist study (low Q2 S , test pQCD);
Using a proton target: measure PDF ratio d/u at high x;
Measure Charge Symmetry Violation (CSV).
Leading program @ 12 GeV upgrade (2012?~)
Future of PV-DIS at JLab
JLab Hall A pCDR
P.E. Reimer, PAVI06
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Summary
PV-DIS is a powerful tool to test the Standard Model and to study many interesting hadronic effects:
C2q's, sin W;
low Q2 S , d/u at high x, higher twist... Anything else?
This program will start soon at JLab (E05-007):
Two major instrumentation need to be upgraded, in progress;
Will run in late 2008-2009;
extract (2C2u-C2d) to ±0.03, factor of 8 improvement w.r.t PDG;
first HT extraction from PVDIS.
Will be one of the leading experiments of JLab 12 GeV.
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Experimental Hall A
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
The CollaborationA. Afanasev, D.S. Armstrong, J. Arrington, T.D. Averett, E.J. Beise,
W. Bertozzi, P.E. Bosted, J.R. Calarco, G.D. Cates, J.-P. Chen, E. Chudakov, P. Decowski, A. Deur, J. Erler, R. Feuerbach, J.M. Finn,
O. Gayou, S. Gilad, R. Gilman, C. Glashausser, K.A. Griffioen, K. Hafidi,J.-O. Hansen, R. Holmes, R.J. Holt, T. Holmstrom, H.E. Jackson, X.
Jiang,W. Korsch, K. Kumar, N. Liyanage, D.J. Mack, D.J. Margoziotis, P. Markowitz, R. Michaels (co-spokesperson), P. Monaghan,
V. Nelyubin, K. Paschke, D.H. Potterveld, A.J. Puckett, Y. Qiang, R. Ransome, P.E. Reimer (co-spokesperson), B. Reitz, E.C. Schulte, J. Singh, S. Sirca, R. Snyder, P. Souder, V. Sulkosky, W.A. Tobias,
B. Zeidman, X. Zhan, X. Zheng (spokesperon)The Hall A Collaboration
ANL, Calstate, FIU, Jlab, Kentucky, U. of Ljubljana (Slovenia), MIT, UMD, Umass, UNH, Universidad Nacional Autonoma de Mexico, Rutgers, Smith C.,
Syracuse, Uva, W&M
We have strong support from theorists and experts of parity experiments.
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Beam Time Allocation for Running In Two Phases
Phase I: 13 days
4 days of commissioning and systematic checks including:
Commissioning fast counting DAQ and Compton
9 days with the HRS-L at Q2=1.10 (GeV/c)2 and the HRS-R at Q2=1.90 (GeV/c)2
Phase II: 33 days
complete both Q2 measurements.
Approved (Jan.2005), rated A-
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Data Analysis
Electron asymmetries
3He asymmetries
From 3He to Neutron
Araw=N p /Q p−Nm /Q m
N p /Q pNm /Q m
Aparallel ,perp=A raw
f PbPt
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Exploring Nucleon Structure Using EM Probe (cont.)
elastic
quasi-elastic
resonances
DIS
The nucleon changes its appearance with the way we study it, and we have developed different models/languages for each facet;However, all of them shall form a coherent picture, and perhaps one day all these aspects can be unified within QCD.
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Scaling Violation in QCDBjorken limit: , xBj fixed, (strict) one photon exchange
no scale (Q2 )dependence, scaling
High , soft gluon emission, logQ2 dependence
Low , hard gluon emission 1/(Q2)(t-2) dependence “higher-twist effects”
Q2∞
Q2 0
Q2
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Structure Functions in the Quark-Parton Model
After 35 years of DIS experiments, the unpolarized structure of the nucleon is reasonably well understood (for moderate xBj
region).
F1 x =
1
2 e
i
2 [qi x ] in the infinite momentum frame
(IMF)
(P ® ∞)
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Jlab 6 GeV
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Upgrade magnets Upgrade magnets and power and power suppliessupplies
CHL-2CHL-2
Jlab 6 GeV12
Add new hallAdd new hall
Enhance equipment Enhance equipment in existing hallsin existing halls
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Design on-board algorithm;Event pile-up at 3% level at 1MHz (e-e pileup <1%), on-board identification possible;
Preliminary test using 100MHz module and 1-2 CH/detector (Oct.2005):
Gas cherenkov (10 ch sum)
Pre-shower (2ch sum) Shower (1ch)
First FADC Test and Design for Algorithm
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
Extraction of S at Low Q2 and Higher Twist
A. Deur, V. Burkert, J.P. Chen, W. Korsch, hep-ph/0509113
S extracted from Bjorken sum rule
at low Q includes HT;
HT from DIS (F2, g1...) — difficult to separate from higher order effects;
HT from PVDIS:
Leading Twist unambiguously determined by the SM;
More precise than polDIS;
If can use PVDIS HT for low Q DIS analysis, then may correct HT and compareS with pQCD predictions
® Test standard model of strong interaction.
Perhaps PVDIS can serve as a (powerful?) tool to study some long-lasting problem in hadronic physics — HT, d/u, anything else???
Prelim
inary
!
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X. Zheng, PAVI06, Milos, GreeceMassachusetts Institute of Technology
The Accelerator at Jefferson Lab, Virginia, USA