SIDIS/PVDIS Cherenkov

Tuesday 6/24/13

A look at the trigger efficiencies for one PMT sum vs multi-pmt.

Fig. 1: SIDIS trigger efficiency comparison.

Tuesday 4/30/13

To expand to lower angles of SIDIS coverage, an additional 3rd mirror was added to the simulation.

• Details and concerns:
  • The middle set of mirrors share the overlap coverage of PVDIS 22-33 deg and SIDIS 8-15 deg, The PVDIS angles > 33 deg are handled by the outermost of mirrors, and the SIDIS angles from 7-8 deg are handled by the innermost set of mirrors.
    • This is needed if we want to incline the middle mirror for use in both SIDIS and PVDIS.
  • The middle mirror quickly looses efficiency due to a reflection offset for SIDIS low angles. This is due to the size of the mirror and an inefficiency of a simple spherical mirror to uniformly reflect the incident rays onto the PMT face, due to the transport of the radiating particle in the magnetic field.
  • The new set of mirrors sits unrealistically close to the border of the tank. Would probably need to extend tank or reduce angle coverage of mirrors.
  • If we wanted SIDIS < 7 deg, we would need to not only change the diameter of the snout, but also adjust the winston cones between SIDIS and PVDIS configurations; the cones aren't wide enough to accept SIDS < 7 deg and PVDIS > 34 deg simultaneously.

Fig. 1: Cross section of 3 mirror design

Fig. 2: Reflections vs Angle

Fig. 3: P.E's vs Angle

• Some possibilities:
  • Redesign for a larger inner most and smaller middle mirror, have both mirrors incline when switching to PVDIS.
    • Expected result: larger SIDIS p.e.'s at small angles, less PVDIS p.e.'s at small angles.
  • Redisign for separate mirrors and cone positions for PVDIS and SIDIS:
    • Expected result: Better overall acceptance at edges (small angle / large angle). Large increase in mirror cost and difficulties in tank design.