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RUN 2001 – RICH-1 FULLY INSTRUMENTED

RUN 2001 – RICH-1 FULLY INSTRUMENTED. Photon detectors (PD) : 5.3 m 2 of CsI MWPCs, 84,000 analogic read-out channels. VUV mirror wall, 20 m 2 , 116 mirror pieces. RICH-1 – PHOTON DETECTORS. PDs electrical instability at high beam rate (6 over 8 PDs operated at

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RUN 2001 – RICH-1 FULLY INSTRUMENTED

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  1. RUN 2001 – RICH-1 FULLY INSTRUMENTED Photon detectors (PD) : 5.3 m2 of CsI MWPCs, 84,000 analogic read-out channels VUV mirror wall, 20 m2, 116 mirror pieces

  2. RICH-1 – PHOTON DETECTORS PDs electrical instability at high beam rate (6 over 8 PDs operated at 100-150 V lower than nominal HV) Actions taken: • hunting the technical problem: local wire defects • 4 refurbished wire planes • 2 new wire planes (wire LUMAMETALLOSRAM) Status: PDs mounted again on RICH-1 vessel wire defect, diameter 20 mm CsI photocathodes mounted with glove box Setup for anode wire alignment and soldering Photon detectors mounted On RICH-1 vessel

  3. RICH-1 – READ-OUT Front End BORA boards mounted on photon detector • analogic read-out system, 84,000 channels with local intelligence (DSP, FPGA in FE BORA board) working • dead time: limited to 500 ns / event up to trigger rates of 75 KHz • average noise level: ~ 2000 e- , non homogeneous (2001) • reinforced ground lines (2002), expected noise level: ~ 1100 e- PC resident control board DOLINA

  4. RICH-1 – RADIATOR GAS, 2001 MATERIAL pre-cleaning material loss: ~7% C4F10 pre-cleaning (in liquid phase) and on-linemonitoring of VUV light transmission measured through 5 cm of liquid (~ 7 m of gas, 1 bar) scaled to 5 m of gas (mean photon path in vessel) In 2001 radiator gas was a mixture C4F10 : N2 = 50 : 50 pre-cleaning material loss: up to 50%

  5. RICH-1 – RADIATOR GAS, 2002 MATERIAL • new C4F10 delivery, 570 Kg • better quality, polluting contamination: mainly water • new pre-cleaning installation: cleaning in gas phase raw material

  6. RICH-1 – MIRROR WALL • reflectance of 2 test mirrors measured after2 year in RICH-1 vessel: no degradation above 165 nm 2000 = immediately after coating mirror n. 2 2000 reflectivity 2001 2002 wave length mirror n. 5 2000 reflectivity 2001 2002 wave length

  7. RICH-1 – MIRROR WALL • mirror alignment checked: misalignments up to 1.5 mrad, correlated in position (overall mechanics deformation; temperature ?) repeated measurements, on-line alignment monitor needed top mirror set horizontal angular misalignment bottom mirror set vertical angular misalignment horizontal angular misalignment vertical angular misalignment

  8. b = 1 Qphoton RICH-1 – 2001 DATA all PDs, image of superimposed events Qring number of photons per ring: expected for nominal HV & noise level: ~19.5 angular spectra for reconstructed Rings (signal and uncorrelated) all b all b Qring typical ring image

  9. RICH-1 – 2001 DATA all PDs, image of superimposed events angular spectra for reconstructed Rings (signal and uncorrelated) b = 1 all b Qphoton Qring Qring number of photons per ring: expected for nominal HV & noise level: ~19.5 Qring typical ring image

  10. b = 1 Qphoton RICH-1 – 2001 DATA all PDs, image of superimposed events Qring angular spectra for reconstructed Rings (signal and uncorrelated) all b Qring typical ring image

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