Si Strip Detector (SSD) Acceptance

Recoil angle (θ) acceptance of the SSD:

    Δθ = 90° ± 2.7°


If we shift the target postion back:
target shift     recoil angle acceptance
2 mm 92.3° > Δθ > 86.8°
5 mm 91.6° > Δθ > 86.1°
7 mm 91.1° > Δθ > 85.7°


Multiple scattering effect:
The RHIC CNI polarimeter observed a spread or widening in the angular distribution of recoil carbons. This is because the carbons undergo multiple scattering within the target. Based on the RMS values of the angular distributions seen in RHIC, we can estimate the multiple scattering effect for the AGS CNI polarimeter.
RMS of θ dist.     recoil carbon energy (keV)     -t (GeV/c)2
0.9°1,1000.025
1.7°2000.004

If we extend our measurement to a higher -t region, then we expect the multiple scattering effect to decrease.

-t dependence of recoil carbon scattering angle
  • Scattering angle (deg.) vs. -t with detector acceptance

  • -t vs. scattering angle (mrad) with strip width at 25 cm



    • maintained by: Jeff Wood, wood@physics.ucla.edu
    last updated: 10/1/02