madii design and physics program jian-ping chen, jefferson lab hall a collaboration meeting june...
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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