Tile and fibre measurements (Tile HCAL) J. Cvach, S. Nemecek Institute of Physics AS CR, Prague (Calice Coll.)

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Tile and fibre measurements (Tile HCAL)J.
Cvach, S. Nemecek Institute of Physics AS CR,
Prague (Calice Coll.)

1. Tile uniformity, current measurements
2. Cosmics monitor
3. Comparisons
4. Conclusions

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1. Tile uniformity with source measurement

• Our setup consists of
• light tight box PM Hamamatsu R5505 at 2 kV
  Keithley 6514 electrometer
• 90Sr ( 1.5 MBq) radioactive source
• has a fixed grid for uniformity measurements
• - multiples of 4 mm in x direction
• - 10 mm in y direction
• Uniformity s / ltIgt calculated over area
  smaller by 10 mm than tile size (due to the
  source profile),
• s STD of one meas.
• Different tile sizes Bicron bc908 tiles 5x5,
  10x10, 15x15 cm2
• (read by fiber bc91A mc, 0.8 mm thick)
• Different grooves, tile size 5x5 cm2, Kuraray
  SCSN81
• - middle, edge, diagonal groove
• - 1 and 2 circular grooves (read by fiber bc91A)

Result no dependence of uniformity on tile size
observed
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Setup for uniformity measurements
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Example tile with middle groove
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Summary for tile Kuraray SCSN81 5x5 cm2
Worse Corner
Best Corner
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Example tiles bc408 - uniformity
fibre on side
Tile (cm2) 5 x 5 10 x 10 15 x 15
Uniformity () 4.0 6.0 5.0 6.5 4.0 5.5
no dependence on size!
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Tilefiber response to 90Sr source in the tile
centre
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Tilefibre response to 90Sr cont.
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2. Cosmics monitor
µ

• Two plastic scintillator bars, 50 cm long, 52
  cm² ( detector Up, Down)
• separated vertically by 2.5 cm thick Pb bar
  (larger Eµ for Coinc.) gt Eloss of MIP
• read by PMTs EMI 9813 (d46mm, 14 dynodes)
• connected by PMMA (Plexiglas) lightquide 52
  cm² gt p(2.3 cm) ²
• Sliding Up detector the Test area L5 cm ² is
  prepared
• Three optically separated Scintillator tiles
  Bicron BC-408, 55 cm²
• Two optically separated Scintillator tiles
  Bicron BC-408, 1515 cm²
• Read by PMTs HAMA H3165 (d10mm, 10 dynodes)

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Cosmics monitor, DAQ
Pulser
100 Hz
300 ns
LRS 645
LRS 645
LRS 2249W
Gate
Down
Delay
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CAMAC to PC by KK 009
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Up
Delay
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Right
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50 Ohm
Delay
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Left
Delay
Linear FAN-OUT 428A

• PULSER from Dual Timer CAEN, N93A

LRS 623A
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Scintillator Tiles BICRON bc408 spectra

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µ
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Left PMT
Right PMT
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Npe from left and right PM

• Npe.
• C lt Q(LR)gt ²
• s(L-R) ² - s02
• C up to 1.25
• to correct for statistical fluctuations in the
  first few dynodes
• ( C1 used)
• s0 Noise ( neglected)
• E.H.Bellamy, ..,S.Tokar,..NIM A339(1994)468

CUT (LR) gt 6
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Corespondance of LY and cosmics - bc408

• 3 tiles 5x5, 3 tiles 10x10, 2 tiles 15x15 cm2
  used in cosmic m measurements
• Light yield measured - Sr source in the middle
  of the tile
• 2 fibres Kuraray Y11(200), 1 mm with mirror on
  tile side, Tyvek, Alu reflect.
• Results per tile fibre

Tile a x a (cm2) 5 x 5 10 x 10 15 x 15
LY (nA) 105 - 6 60 - 4 39 - 6
Relative LY 2.4 - 0.4 1.5 - 0.3 1
Photo e- 6.5-0.4 ) 4 - 0.2 2.5 - 0.2
LY / photo e- (nA) 16 - 1.7 15 - 1.4 16 - 2.8

• approximate scaling 1/a observed in ATLAS
  collaboration
• our normalization factor 16 nA/ photo e-
• ) cf. to 6.57 given in S. Reiche, Diploma
  thesis, Hamburg 2001

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Comparison of LY measurements

• DESY effort made to have collimated Sr source,
  hand device ( )
• Prague Sr source with divergence of 45o,
  semiautomatic device, grid 10 mm x 4 mm ( )
• each data sample normalized to its max value

PRG fibre on side
PRG fibre end
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LY comparison - comments

• DESY subtracts correction 6-10 which is x
  dependent, not y dependent
• PRG no corrections, background dark current lt 2
  and not x, y dependent
• PRG tile position in coordinate system known to
  - 2 mm for x, y
• DESY tiles in Tyvek, mirrored fibre end
• PRG tiles in white paper, fibre end cut and not
  mirrored
• PRG LY increases toward fibre end
• DESY measurements smaller decrease towards tile
  edges collimated source
• DESY meas symmetric in x, understanding of x
  dependent correction?
• --gt DESY measurement better uniformity
• PRG try to collimate source or unfold the source
  profile

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Comparison

• measurement of attenuation length for bc408
  scintillator (Kuraray Y11 fibre)
• left S. Reiche, Diploma thesis, bc408 (box),
  Kuraray SCSN (triangle), 5x5cm2
• right this talk, bc408, 15x15 cm2

Measurements consistent drop 6 at 4 cm
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4. Conclusions

• Measurements with radioactive source and cosmic
  muons provide consistent results
• Cosmic muon measurements confirm assumption from
  TDR about Npe
• Uniformity of different tile geometries/sizes lt
  7
• Comparison of measurements from different labs
  important
• Simulation needed to better understand
  measurements/ improve design
• Fiber on tile side is a recommended option but
  fiber in circular groove gives 3x larger LY
  (option for larger tiles?)