Silvia%20Dalla%20Torre

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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
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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 LUMAMETALL OSRAM)
• 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
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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
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RICH-1 RADIATOR GAS, 2001 MATERIAL

• C4F10 pre-cleaning (in liquid phase)
• and on-line monitoring 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 7
pre-cleaning material loss up to 50
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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
2000 immediately after coating
mirror n. 2
2000
reflectivity
2001

• reflectance of 2 test mirrors
• measured after 2 year in RICH-1
• vessel
• no degradation above 165 nm

2002
wave length
mirror n. 5
2000
reflectivity
2001
2002
wave length
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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
RICH-1 2001 DATA
b 1
Qphoton
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
RICH-1 2001 DATA
b 1
Qphoton
all PDs, image of superimposed events
Qring
angular spectra for reconstructed Rings (signal
and uncorrelated)
all b
Qring
typical ring image