MADII Design and Physics Program Jian-ping Chen, Jefferson Lab Hall A Collaboration Meeting June 22-23, 2006 MADII Spectrometer Design Optics and background Physics Program Valence quark spin structure: A 1 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 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 (~5 o ) Septum Realistic magnet design (P. Brindza, J. LeRose) Combine-function separate magnets Reasonable optics Minimize cost, keep flexibility

MADII Configurations Configurations-1 5 o -25 o, Dipole+Septum 4-7 msr, high lumi ~ 2x10 38 cm -2 s -1, Configurations-2 > 25 o, Dipole > 25 msr, low lumi ~ 2x10 37 cm -2 s -1 Configurations-3 large angle, QDQ ~ 22 msr, high lumi ~ 2x10 38 cm -2 s -1 All: +-15% acceptance, 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 A 1 n, 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 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 A 1 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