STATUS on PWO crystals from Bogoroditsk after one year of preproduction for CMS-ECAL

August 99 E.Auffray CMS/ECAL

STATUS on PWO crystals from Bogoroditsk

after one year of preproduction for CMS-ECAL

Etiennette Auffray

SCINT 99, 16 August 1999


Importance of R&D effort

95 98

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300 350 400 450 500 550 600 650 700

Tran

sm

issio

n (

%)

Wavelength (nm)

Theoretical transmission from Fresnel losses

95 crystal98 crystal


Since the 4th September 98, we received :1000 preproduction crystals from BTCP:

100 : 04/09/98100 : 03/11/98200 : 08/12/98 200 : 22/03/99 400 : 22/06/99

All have been visually Inspected•All have been characterised with ACCOS(Automatic machine to measure :

3D, transmission, decay time,LY)•Some have been irradiated

•61 irradiated in High dose rate (500Gy, 240Gy/h)•129 irradiated in Low dose rate (3Gy, 0.15Gy/h)

•400 used for the 1st module of CMS/ECALin CERN/lab27 regional center

First crystals La doped&

progressively changed to Y-Nb doped


Reception of first 100 preproduction crystals


Quality check of first 1000 preproduction crystals


Optical Specifications for Preproduction

Longitudinal transmission

10% at 350nm

55 % at 420nm

65 % at 600nm Transversal transmission

– For T=50% 6nm

S >1.5 %/nm between 340 and 370nm

For “blue” crystals :

LY in labo27 at 8Xo 8 pe/MeV

2 pe/MeV with 1 EG&G APD (BT97)

Decay time

LY(100ns)/LY(1s) > 90%

No visible afterglow » < 0.5% background with 1MBq source in standart

decay time measurement

Good radiation Hardness


Bogoroditsk Preproduction Status

0

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1000

Sep

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Planning Delivered

16 August, 99

1500 crystals delivered Mid of August

1998 1999 2000


Dimensions

02468

101214161820222426283032343638404244464850

Range m

AR-Nominal value

Batch 119/100 rejected

19%

On all dimensions

02468

101214161820222426283032343638404244464850

Range m


14%

0102030405060708090

100110120130140150160170180190200

Range mm


8.5%

-100 0


020406080

100120140160180200220240260280300320340360380400

Range mm

Dimensions AR-Nominal value


4%

On all dimensions


2.25 %

-100 0

048

12162024283236404448525660646872768084889296

100

Range m


420nm Optical Transmission

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300 350 400 450 500 550 600 650 700 Wavelength (nm)

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30 35 40 45 50 55 60 65 70 75 80Transmission at 420nm (%)

Distribution for 1000 crystals

3.2%below 55%




11%


6%


7.5%

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Nu

mber

of

cry

sta

ls

Transmission at 420nm (%)

Mean Value : 61.47%Standard dev. : 4.85%

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Nu

mber

of

crys

tals


Mean value: 61.88%Standard dev. : 7.5%

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mber

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stals






0%

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Nu

mber

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sta

ls



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30 35 40 45 50 55 60 65 70 75 80Transmission at 420nm (%)

Mean Value : 68.49%Standard dev. : 1.66%


0%


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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16LY (pe/MeV)

Light Yield

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0 50 100 150 200 250Distance from front side (mm)


LY at 8Xo

2.2% below 8pe/MeV


Light Yield

0/100 rejected0%

0/100 rejected0%

1/200 rejected0.5%

Batch 3

Batch 2

Batch 1

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Nu

mber

of

cry

sta

ls

Ly at ACCOS at 8Xo (pe/MeV)

Statistic on 100crystalsMean Value : 10.67pe-/MeV

Standard deviation : 1.05pe-/MeV

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mber

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sta

ls


Statistic on 200crystalsMean Value : 9.86 pe-/MeV

Standard deviation : 1.74pe-/MeV

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Nu

mber

of

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tals


Statistic on 100crystalsMean Value : 9.84 pe-/MeV

Standard deviation : 0.67 pe-/MeV


Decay time


% of emitted light in 100ns

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90 91 92 93 94 95 96 97 98 99 100% of light in 100ns


The slope of longitudinal transmission

between 340nm & 370nm

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Definition of the slope (340-370nm)

Tra

nsm

issio

n (

%)

Wavelength (nm)

Slope of the Linear fit of the longitudinal transmission


0

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25

0 0.5 1 1.5 2 2.5

LY loss after 1.5Gy versus the slope

LY

loss a

fter

1.5

Gy (

%)

Slope (T%/nm)

LY loss < 6%

Slope >1.5 (T %/nm)1964

1963

1958


The slope of longitudinal transmission


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Definition of the slope (340-370nm)

Tra

nsm

issio

n (

%)

Wavelength (nm)

Slope of the Linear fit of the longitudinal transmission


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0 0.5 1 1.5 2 2.5 3

Slope (%/nm)

0.1% below 1.5%


Radiation damage certification of Russian crystals

Irradiation of ingot’s top and bottom parts– All crystals– At Bogoroditsk– To control radiation hardness uniformity

High dose & dose rate side irradiation (induced absorption at all )– Sampling (20%)– At Bogoroditsk after March 99– To control absolute radiation hardness and uniformity

Transverse transmission along the crystal– All crystals– At Bogoroditsk and at CERN– To control doping uniformity

Longitudinal transmission band edge slope– All crystals– At Bogoroditsk and at CERN– To predict radiation hardness

High dose & dose rate side irradiation (induced absorption at all )– Sampling (20%)– At Geneva hospital (CERN)– To control absolute radiation hardness & uniformity

Low dose rate front irradiation (LY loss)– Sampling (20%)– At CERN (TIS)– To control radiation hardness in LHC conditions

Low dose rate side irradiation (transmission loss at ≠ )– Sampling (20%)– At CERN (X5)– To control radiation hardness uniformity


Sampling irradiation tests

90

91

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95

96

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98

99

100

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

LY a

fter/L

Yb

efo

re (

%)

Dose (Gy)

also test at PSI

Batch 3 & 4

Front irradiation 0.15Gy/h


Radiation Hardness

Lateral irrad., 500Gy, 240Gy/h

Front irrad., 1.5Gy, 0.15Gy/h

0

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Induced absorption at 420nm (m-1)

86 Crystals

Mean value : 0.9m-1

Standard dev : 0.38m-1

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LY loss (%)

Statistic on 141 crystalsMean Value : 2.96 %

Standard deviation 1.07%


Status of crystal deliveryfrom Bogoroditsk (Russia)

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Delivered crystals

Planning Delivered

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50S

ep

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Rejected Crystals

Dimensions TransmissionLight Yield Decay timeSlope/Rad.hardness

1998 1999 2000

1000 crystals delivered28 May 1999


Conclusion

•Ramping up in production rate according to plans•Continous improvement of the crystal characteristics from batch to batch :• Improvement of dimensions• Improvement of the transparency

(no more core defect)

• Exceptional rejection for bad radiation hardness

The results on first 1000 preproduction crystals

are very encouraging

STATUS on PWO crystals from Bogoroditsk after one year of preproduction for CMS-ECAL

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