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A RICH Detector for strangeness physics in Hall A at Jefferson Lab

IMAGING 2003 – Stockholm – 24 th – 27 th June 2003. A RICH Detector for strangeness physics in Hall A at Jefferson Lab. F. Cusanno – Hall A RICH collaboration. . Why . How . Main Characteristics/Expected performances. . Tests . CERN . Cosmics . Beam

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A RICH Detector for strangeness physics in Hall A at Jefferson Lab

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  1. IMAGING 2003 – Stockholm – 24th – 27th June 2003 A RICH Detector for strangeness physics in Hall A at Jefferson Lab F. Cusanno – Hall A RICH collaboration .Why . How . Main Characteristics/Expected performances. . Tests . CERN . Cosmics . Beam . Conclusions and outlook

  2. E-94-107 - F. Garibaldi, S. Frullani, J. LeRose, P. Markowitz, T. Saito L-N Interaction VLN = V( r ) + Vs( r ) SL.SN + VL(r ) SN.lNL + VT( r) S12 Very important for astrophysics (neutron star formation)

  3. RICH Project started Summer 98 • Test CERN November 00

  4. DW = 5 msr Dp/p = 5% dp/p =1 x 10-4

  5. Cosq =1/nbDb/b = tg Dq With N p.e. per ring DqD q /N • n fixed by the momentum(2GeV/c) • C6F14, transparent down to 160 nm • compact (~ 50 cm) • 310 x 1820 mm2 • relatively thin (18% X0) • quarz window 5 mm 15 mm 300 nm

  6. MCarlo

  7. radiator • NEOCERAM • Quartz cylinders, 5mm quartz window

  8. 6.4 6.4KHz

  9. Freon System

  10. The fluid is degassed by bubbling high purity nitrogen through a bed of 2 micron pore, sintered stainless steel cylinders and then through the liquid to scavenge air in solution in the fluid. The sintered stainless cylinders maximize the contact area between the nitrogen and the radiator liquid. This significantly speeds the degassing of the radiator liquid. The nitrogen then passes through a cold condenser that removes the perfluorohexane from the air/nitrogen/perfluorhexane stream and returns the perfluorhexane to the tank. The fluid also passes over an alternating pair of molecular sieve filters before being pumped to the radiator. Several methods are used to verify the quality of the radiator fluid. The effluent from the degassing tank passes through an oxygen and moisture sensor. An on-line transmission monitor measures the transmission of the liquid in the return flow from the radiator. Periodically the return flow is temporally diverted through an optical sample cell. The light from a mercury vapor light, filtered to select the appropriate wavelength (184 nanometers) is passed through a beam splitter. One light beam goes through the sample cell and its intensity measured with photodiode. The other light beam goes directly to another photodiode and is used as a reference. The ratio of outputs from the two photodiodes is an approximate measure of radiator liquid transmission at the selected wavelength.

  11. Bandpass filter

  12. gas system

  13. CERN tests Nov ‘00

  14. CERN tests 11/00 7 GeV/C p beam Argon CH4 (25/75) 2 photocathodes (Rome and CERN) Equal performances N = ~ 12

  15. Jlab Cosmic tests Aug 01 2100 V

  16. On beam tests March 02

  17. 2150 V 2250 V G~ 5 x 104 G~ 1 x 105

  18. MPWC Gain Comparison STAR PRESENT STATUS OLD STATUS ‘Good working’ range MIP signal size (# of pads)

  19. 2150 V Jlab Cosmic tests June 03 G~ 2.5 x 105 A0=26 Scan in positioning: presently we are on the left side, 160 mm distance from boundary (and q>0). Extrapolating to q=0 in with the whole ring in the active area: ~ 10-11 p.e. (as at CERN)

  20. Conclusions • The present Hall A PID setup is not sufficient for unambiguous K identification needed for hypernuclear spectroscopy • A Proximity focusing C6F14/CsI RICH detector has been built and tested • Performances in the expectations - gain problem understood and fixed • CsI evaporation technique unders control • Detector ready to be installed for the Hypernuclear experiment

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