1. SBS Magnet, Optics, and Spin Transport John J. LeRose with help from David Hamilton and others Technical Review of the Super BigBite Spectrometer January 22, 2010

2. The main component of SBS is the 48D48 dipole, previously used at BNL. The most significant constraint for the new design is related to shielding both the target and the outgoing beamline from the SBS fields, which has required the addition of new components. What version or versions of SBS are we presenting here? Most simple? Most complicated? Something in between? See “Exotic stuff” at the end

3. 48D48 Basic Geometry

7. Bx By Bz |B|

8. Optics It’s really very simple!

9. This is what it looks like to me!

10. 1 st Order Optics xx’yY’ x tar 1000 x’ tar 3.304100 y tar 000.9950.005 y’ tar 003.2960.988 δ0.0860.08500 e.g. Etc. Subsequently: If you know how well you can measure x, x’, y, and y’, you know how well you can determine the target parameters (provided x tar = 0)

11. Projected Errors 1 st order Resolution 1 st Order P = 8 Δ (%) 0.03p+0.290.53 x’ tar (mrad)0.09 + 0.59/p0.16 y tar (mm)0.53 + 4.49/p1.09 y’ tar (mrad)0.14+1.34/p0.31

12. Higher Order Effects? Strategy:  Use SNAKE to create a database of trajectories and then fit the reconstruction tensor. (higher order terms)  Use the reconstruction tensor in a Monte-Carlo fashion to evaluate the errors.

13. 1 st Order resolution 1 st Order P = 8 GeV/c SNAKE P = 7-9 GeV/c Δ (%) 0.03p+0.290.530.48 x’ tar (mrad)0.09 + 0.59/p0.16 y tar (mm)0.53 + 4.49/p1.090.9 y’ tar (mrad)0.14+1.34/p0.310.30

14. Momentum Dependence of ΔΩ 8 GeV/c 1 GeV/c

15. Spin Transport Non-dispersive precession Dispersive precession to Reaction Plane Reaction Plane Target

16. Spin Transport Because of Pl - Pt mixing, the non-dispersive bend angle contributes a factor ~100 to the FF ratio systematic error. However, it is very small: ±1.1 mrad (FWHM) and can be reconstructed with high precision (~0.1mrad).

17. Calibration scheme? As has been very successfully done with the HRS – Do a series of elastic scattering runs ∂ scans with and without sieve thin target(s) (e.g. C and Ta) segmented extended target

18. Conclusion Magnet exists and is available Magnet will work nicely (with modifications) Optics are very simple.

19. Another game we’ve played Exotic stuff