Tile uniformity, current measurements Cosmic s monitor Comparisons Conclusions

Tile and fibre measurements (Tile HCAL)

J. Cvach, S. Němeček Institute of Physics AS CR, Prague (Calice Coll.)

1. Tile uniformity, current measurements

2. Cosmics monitor

3. Comparisons

4. Conclusions

ECFA-DESY, St. Malo 13/04/02

J. Cvach: Tiles & fibres ... 2



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 sourcehas a fixed grid for uniformity measurements:

- multiples of 4 mm in x direction- 10 mm in y direction

• Uniformity = / <I> calculated over area smaller by ~10 mm than tile size (due to the source profile),

– 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



Setup for uniformity measurements



Example: tile with middle groove0

0,8

1,6

2,4

3,2 4

4,8

5,6

6,4

0

1,5

3

4,5

6

0

4

8

12

16

20

24

28

32

36

res

po

ns

e t

o S

r90

x axis (cm)

y ax

is (

cm)

32-36

28-32

24-28

20-24

16-20

12-16

8-12

4-8

0-4

0

0,8

1,6

2,4

3,2 4

4,8

5,6

6,4

0

1,5

3

4,5

6

048

12162024

28

32

36

res

po

ns

e t

o S

r90

x axis (cm)

y ax

is (

cm)

fiber on side

fiber in groove

Groove effect not masked by source profile

PM



Summary for tile Kuraray SCSN81 5x5 cm2

2

4

6

8

10

12

20 30 40 50 60 70 80 90 100

PM current (nA)

un

ifo

rmit

y (

%)

mid groove

edge groove

diagonal groove

plain tile

1 loop 2 loops

Worse Corner

Best Corner



Example: tiles bc408 - uniformity0

1,6

3,2

4,8

6,4

8

9,6

11,2

0

2

4

6

8 10

12

05

1015202530354045

50

55

60

65

res

po

ns

e t

o S

r90

x axis (cm) y axis (cm)

60-65

55-60

50-55

45-50

40-45

35-40

30-35

25-30

20-25

15-20

10-15

5-10

0-5

PM

10 x 10 cm2

Tile (cm2) 5 x 5 10 x 10 15 x 15

Uniformity (%) 4.0 – 6.0 5.0 – 6.5 4.0 – 5.5no dependence on size!

PM

15 x 15 cm2

01,63,

24,86,

4

89,611

,2

0

3

6

9

12

15

05

1015

20

25

30

35

40

45

50

res

po

ns

e t

o S

r90

x axis (cm)

y axis (cm)

fibre on side



Tile+fiber response to 90Sr – source in the tile centre

0

10

20

30

40

50

60

70

80

90

0,6 0,8 1

fibre thickness (mm)

PM

cu

rre

nt

(nA

) Y11(200)M

bc91A mc

bc91A

bc92 mc

Y11(200)M

bc91A mc

bc91A

bc92 mc

tile bc408

tile vladimir

fibre



Tile+fibre response to 90Sr – cont.

0

10

20

30

40

50

60

70

80

90

0,6 0,8 1

fibre thickness (mm)

PM

cu

rre

nt

(nA

)

Y11(200)M

bc91A mc

tile kuraray



2. Cosmics monitor

Two plastic scintillator bars, 50 cm long, 5*2 cm² ( detector : Up, Down)

– separated vertically by 2.5 cm thick Pb bar (larger Eμ for Coinc.) => ~Eloss of MIP

– read by PMTs EMI 9813 (d=46mm, 14 dynodes)

– connected by PMMA (Plexiglas) lightquide: 5*2 cm² => π*(2.3 cm) ²

Sliding Up detector the Test area L*5 cm ² is prepared:

– Three optically separated Scintillator tiles Bicron BC-408, 5*5 cm²

– Two optically separated Scintillator tiles Bicron BC-408, 15*15 cm²

– Read by PMTs HAMA H3165 (d=10mm, 10 dynodes)

μ



Cosmics monitor, DAQ

PULSER from Dual Timer CAEN, N93A

1

2

3

4

5

LRS 2249W

CAMAC to

PC by

KK 00950 Ohm

Gate

Left

Right Delay

Delay

Down

Up Delay

Delay

Linear FAN-OUT 428A

Pulser

LRS 645LRS 645

100 Hz

300 ns

LRS 623A



Scintillator Tiles BICRON bc408 spectra

RightPMT

Left

PMT

μ

30%

29%



Npe from left and right PM

Npe.: C * < Q(L+R)> ²

σ(L-R) ² - σ02

C = up to 1.25 to correct for statistical

fluctuations in the first few dynodes( C=1 used)

σ0 = Noise ( neglected)

E.H.Bellamy, ..,S.Tokar,..NIM A339(1994)468

CUT (L+R) > 6



Corespondance of LY and cosmics - bc408

• 3 tiles 5x5, 3 tiles 10x10, 2 tiles 15x15 cm2 used in cosmic 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



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

y = -20 mm

0

0,2

0,4

0,6

0,8

1

1,2

-30 -20 -10 0 10 20 30

x (mm)

y = 0 mm

0

0,2

0,4

0,6

0,8

1

1,2

-30 -20 -10 0 10 20 30

x (mm)

y = 20 mm

0

0,2

0,4

0,6

0,8

1

1,2

-30 -20 -10 0 10 20 30

x (mm)

PRG – fibre on side

PRG fibre end



LY comparison - comments

• DESY subtracts correction ~ 6-10 % which is x dependent, not y dependent

• PRG no corrections, background dark current < 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?

• --> DESY measurement: better uniformity

• PRG: try to collimate source or unfold the source profile



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

relative LY, bc408, 15x15 cm2

0,84

0,88

0,92

0,96

1

1,04

0 2 4 6 8 10 12 14 16

y (cm)

x=2,4 cm

x=7,2 cm

x=11,2 cm



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 < 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?)

Documents

Tile uniformity, current measurements Cosmic s monitor Comparisons Conclusions