Information on C₄F₁₀ Systems
Relevant to the E907 MIPP RICH Gas System

Terry Tope

Forward RICH of DELPHI

• Evolution of the transparency of C4F10 in the Forward RICH of DELPHI (5.22.00)
• Original gas was cleaned by molecular sieves to get rid of water
  • Transmittance spectra fell for wavelengths lower than 1950 A
  • Used 13X molecular sieve
• Massive use of activated carbon in addition to molecular sieves raised transmittance to good levels
  • Took 1.5 kg of carbon to clean 8 liquid liters of C4F10
• Fabry-Perot interferometer used to measure refractive index
• Operated at ambient temperature
• Sound velocity measurement allowed determination of C4F10 amount in mixture
  • Claimed to be cheap and reliable
• Used massive amounts of molecular sieves and activated carbon

COMPASS RICH

The COMPASS RICH project (10.23.99)

• Gas RICH with 3 m long C4F10 radiator, atm. Pressure, 25 oC
• Goal was water vapor and oxygen traces below 5 ppm
• H2O and O2 removed using molecular sieves and C4F10 and N2 separation is obtained with a liquifier
• Gas flow was 1 volume every 8 hrs.
• Temperature stability at +/- 1oC.

COMPASS RICH-1 (3.13.01)

• Filling and emptying show gas replacement at 97% level.

LHCb RICH

LHCb RICH Gas System Proposal (8.6.00)

• RICH 1 filled with 4 m3 of C4F10.
• Gas systems will run as closed loop circulation with a gas recovery system.
  • Inline liquefaction of return gas to separate volatile impurities
  • C4F10 enters the separation system with N2/O2 and will be pre-cooled while passing the return gas thru 2 heat exchangers.
  • C4F10 cooled down to -50 oC
  • Pure C4F10 is then collected and transferred to a reservoir which serves as a supply for the RICH
  • N2/O2 leave thru exhaust
  • Pump in return line compresses gas before entering the separation plant
  • C4F10 will be liquid behind the compressor
• Oxygen and water not too exceed 100-200 ppm
  • Molecular sieve used to reduce water impurities along with activated carbon
  • 3X and 4X sieves also used
  • Gas analysis before and after purification
• Residual nitrogen has an effect on refractive index and should be kept constant and below 1%
• The gases are circulated in a closed loop with an expected flow rate of 10% of the total gas volume.
• Two gas inlets/two gas outlets
  • C4F10 from bottom and N2 from top

Monitoring, Alignment and Control of the RICH Detectors (9.6.00)

• Refractive index depends upon temperature and pressure
• Gases are clean from trace impurities after 1 week of recirculation
• Ultrasonic sonar measures variations in the refractive index due to increased concentrations of nitrogen in the system
• Monochromator measures transparency

http://dustbunny.physics.indiana.edu/~dzierba/pidtemp/

• Endcup CRID group at SLD
• Can come with oil contamination
• Must recirculate and have a reasonably tight vessel
• Use simple distillation

HERA-B RICH

• Filled with C4F10 and operates at room temperature

HERMES @ DESY

• C4F10 RICH for one radiator and silica aerogel tiles for the other
• Gas control system recirculates the radiator gas through the main volume at a slight over pressure.