Cooling channel instrumentation

1. Cooling channel instrumentation • Cooling channel environment • Particle fluence and dose (very rough estimates) • X-ray flux from cavities • How much material is too much? • Detector technologies under consideration • Scintillating fibre • Semiconductor: silicon, rad. Tolerant e.g. CdTd • Cherenkov radiation from foils Distinguish between cooling ‘engineering demo’ and ‘production cooling channel’

2. Cooling channel environment Particle fluence and dose (very rough estimates) • Goal: 1014 muons/second in storage ring. • Assume: 1014 muons/second at end of cooling channel • Beam is circular with 20 cm radius • mu/pi ratio at end of cooling channel 0.05 • (Lombardi 19Sep01) • Charged particle fluence at end of cooling channel ~21019 cm-2 (per year) • Dose in 100 m silicon ~10 Mrads/yr • sci. fi. ~ 5 Mrads/yr

3. Cooling channel environment X-ray flux from cavities • Fluxes will depend on geometry/cavity … but • Fluxes ~106 100 keV photons/cm2/pulse expected • Intense low energy electron fluxes on axis J. Norem (July 1999) • CERN preparing cavity/instrumentation test facility. Current plan is to look at at least silicon and sci. fi.

4. Cooling channel environment How much material is too much? • Driven by material in liquid hydrogen absorber and windows of liquid hydrogen vessels • Designs differ in length of liquid hydrogen and type of material … but • Take ‘typical’ 20 cm liquid hydrogen and 300 m aluminium foils  2.3% X0 in L-H2 and 0.9% X0 in foils • Cooling demo needs to see each particle so detector material is important • Instrumentation of channel may be moved out of beam when not in use - so may not be so critical

5. Detector technologies under consideration - Development of MUSCAT detectors: Use: Cooling demo and cooling channel Scintillating fibre • Planar: • 250 m square fibres bonded with epoxy  u, v, w planes • Readout - Use hybrid r/o? HPDs for channel by channel position and multi-anode PM for timing • Cooling demo: R/o each fibre to allow reconstruction of beam profile (high flux) and particle trajectory (low flux) • Cooling channel: Possibly gang fibres and reconstruct profile of beam. Rotate detectors into beam when required R&D? Mechanical stability, r/o / multiplexing. Cost: Something like £100k/plane (?) (based on MUSCAT det.)

6. Cooling channel environment - Scintillating fibre E. McKigney • Pad: • Not really a fully worked out idea - but - need to measure 2D beam profile. Consider sci. tiles: • Can afford thin tiles since many muons • Read-out with HPDs? • Can it work? Need to understand light yield etc. • Better (?) than semiconductor tiles?

7. Cooling channel environment Semiconductor: silicon, rad. Tolerant e.g. CdTd - M. Placidi (CERN) et al. Nov 2000 • 1010 cm2 si or CdTe detectors on Al2O3 covering 2020 cm2 • Charge collection on each CdTe element - get charge proportional to muon flux • Use: Cooling channel and cooling demo

8. Cooling channel environment Cherenkov radiation from foils • Collect Cherenkov light from foil inserted into beam • Image point - point - gives spatial distribution of muons • Image line to point gives trajectory • Use: Emittance measurement in cooling demo

9. Cooling • Potentially good place for UK contribution • Very rough - but - for 250 m long cooling channel need several (~10?) stations - would lead to instrumentation cost of order £2 M. • UK could make a strong contribution here - existing expertise in semiconductor devices and already developing scintillating fibres • Deserves furthe study