MADII Design and Physics Program Jian-ping Chen, Jefferson Lab Hall A Collaboration Meeting June 22-23, 2006 MADII Spectrometer Design Optics and background.

MADII Design and Physics ProgramJian-ping Chen, Jefferson Lab

Hall A Collaboration Meeting

June 22-23, 2006

MADII Spectrometer Design

Optics and background

Physics Program Valence quark spin structure: A1 at high x

x > 1

Sea Asymmetry

Transversity

p form factor• Acknowledgement: C. de Jager, P. Brindza, E. Chudakov, J. LeRose, …

X. Zheng, Z. Meziani, X. Qian/H. Gao, L. Zhu/J. Peng, R. Feuerbach, …

Spectrometer Mini-Review

• Spectrometer Mini-Review MAD (+ HRS) vs. SHMS (+ HMS)

4 example experiments form factor, N/ form factors, Few-Body form factors, SIDIS

• Conclusions from the committee: Best option: construction of both MAD and SHMS Consider rate, systematic, risk: HMS+SHMS Best FOM: MAD+HMS MAD+HRS and HMS+SHMS, similar FOM MAD: bold new promising design

concern: reliability after movement and background Further evaluation, include x>1 Strongly recommend: new spectrometer fully optimized before final design

New Design Considerations

• Reliability after movement (attache- to pivot)• Background (E. Chudakov)

Full simulation

Reduce: no direct line of sight, shielding

Improvement in trigger and pattern recognition• Small angle capabilities (~5o)

Septum• Realistic magnet design (P. Brindza, J. LeRose)

Combine-function separate magnets

Reasonable optics• Minimize cost, keep flexibility

MADII Configurations

• Configurations-1

5o-25o, Dipole+Septum

4-7 msr, high lumi ~ 2x1038 cm-2s-1, • Configurations-2

> 25o, Dipole

> 25 msr, low lumi ~ 2x1037 cm-2s-1

• Configurations-3

large angle, QDQ

~ 22 msr, high lumi ~ 2x1038 cm-2s-1

All: +-15% acceptance, 10-3 and 0.5 mr resolution

MADII, configuration-1

MADII Magnets Specifications

Top and Side View of GEANT simulation

Acceptance

Background Rates

MADII and L-HRS Parameters

Physics Examples

A1n, x>1, Sea Asymmetry,

Transversity, Form Factor

• 850 hours• MADII + L-HRS

X>1, Kinematics and Rates• x>1: strongly overlap nucleons, dense nuclear matter

short-range correlations, minimum contaminations

X>1 Projection

Light-Quark Sea Asymmetry

• NMC(DIS), E866(Drell-Yan) and HERMES(SIDIS)

All observed sea asymmetry

Sea Asymmetry Projection

Transversity: 6 GeV Projections (n) and World Data (p, d)

π- π+The errors with approved beam time will be 33% higher.

COMPASS (d)

HERMES (p)

JLab 6 GeV (n)

Collins CollinsSivers Sivers

Collins and Sivers Asymmetries • Projections with MADII (1200 hours)

- +

Collins

Sivers

Pion Form Factor

Physics issue: electromagnetic structure,can be predicted in pQCD

Experimental technique:isolate *vertex

e’

p

e

n

Hall A 12 GeV:- use L-HRS to detect e’

- use MADII to detect

Pion Form Factor, Kinematics• Longitudinal cross section, extrapolate to pion pole

Pion Form Factor Simulation and Rates

Kinematics Coverage and Matching

t t

Systematic Uncertainties

• Statistics ~ 1%, systematic dominating• Realistic estimation: ~2.9%

Summary

• Improved MAD design (MADII), an ideal tool for 12 GeV program• Reliability, flexibility, cost-effective• 3 configurations (Septum+D, D, QDQ)• Kept large acceptance• Background under control

• Five physics examples• A1

n, x>1, sea asymmetry, transversity, form factor

• All can be done effectively and reliably with MADII+L-HRS• Many other physics program will benefit

• MADII will greatly enhance the JLab 12 GeV physics output