FCAL R&D in Minsk Group:Sensors and Electronics

NC PHEP BSU, Minsk K.Afanaciev V.Gilewsky I.Emeliantchik A.Litomin V.Shevtsov A.Solin

FCAL Collaboration Meeting@ MPI Munich

October 17, 2006, Munich, Germany

Presented by Igor Emeliantchik

Current Spectrometric Setup

• NIM + CAMAC

• LeCroy 2249W ADC

• “Tetrode” preamp

Noise:

with Minsk diamond – 580e-

with Freiburg diamond – 750e-

PMT

90Sr

Paraffincollimator

Diamond

Scintillator

Monocrystalline Diamond Detector

Contact device is made for measurement of non-packaged diamond detectors

CCD Measurement Difficulties

Background is much bigger than signal

Two possible reasons:1. Low efficiency of trigger system due to small area of the diamond.2. Non-uniformity of the diamond – “dead” areas give no signal.

Signal

Background

Response dependence on the dose absorbed,measured with oscilloscope

Amplitude versus Dose

0,00100,00200,00300,00400,00500,00600,00700,00800,00

0 0,5 1 1,5 2

Dose, Gy

Am

ol,

mV

Averaged amplitude of response to the whole -spectrum of 90Srwas measured with digital oscilloscope at each dose point.

Detector behavior seems to demonstrate classical pumpingeffect, no polarisation.

Test of trigger efficiency: measurement of natural diamond of the same area

SignalBackground

Trigger efficiency seems to be not the cause of large background in the case of syntethic monocrystalline diamond

CCD versus dosemeasured in standard way

#1 CCD versus Dose

020406080

0 0,1 0,2 0,3 0,4 0,5 0,6

Dose, Gy

CC

D,

mcm

The trendline confirms the previous measurement made with oscilloscope.

No polarization, just pumping

Next Steps

New samples, not yet measured

1. Experimenting with parameters of thermobaric procedure.

2. Comparison of Fe-Ni and Fe-Co grown diamonds and choosing the best.

3. Detailed measurement of stability and dose dependent behavior.

Dependence of N-N and Me-N centers formation on thetemperature and duration of annealing, measurement with optical methods

Nikel and cobalt have different solubilities in diamond andform different types of defects.

Freiburg CVD DiamondsMeasurement of Charge Collection Distance

Desy7, before irradiation Desy7, irradiated with 1 Gy

Fitting with 2 gausses, left one represents the background,right one – the signal

CDD Dependence on the Time and Dose, sample Desy7

CCD versus Dose

-10,00

0,00

10,00

20,00

30,00

40,00

50,00

0,00 0,30 0,60 0,90 1,20 1,50

Dose, Gy

CC

D,

mcm

Desy7

Strong polarisation effects can explain this behavior

CCD versus time

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

0:00 2:00 4:00 6:00

time

CC

D,

mcm

CDD Dependence on the Time and Dose, sample FAP7.3

CCD versus Dose

-10,00

0,00

10,00

20,00

30,00

40,00

0,00 0,10 0,20 0,30 0,40

Dose, Gy

CC

D,

mcm

Polarization effects are expressed even stronger

CCD versus time

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

0:00 2:00 4:00 6:00 8:00 10:00

time

CC

D,

mcm

DESY7 with Replaced MetallizationTi-Ag with proper annealing for titanium carbidization

CCD versus Voltage

0

10

20

30

40

50

60

70

0 60 120 180 240 300

U, V

CC

D, m

cm

Dose related behavior hadn’t changed,but the value of CCD before irradiation increased twofold(CCD = 32m with old metallization, CCD = 65m with new metallization).

CCD versus Dose

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30

Dose, GyC

CD

, mcm

Electronics for a segment of BeamCal detector prototype based on GaAs sensors

GaAs detectors provide:• Strong signal• High radiation hardness: GaAs/Si 10• Small leakage currents (no refrigeration)

Thickness 500mcm

MIP charge 30000e

Bias voltage 100V

Pad number 87

Sensor segment layout Sensor specifications

The sensor, output connectors and a power supply connector are mounted on a common PCB

AS01PDA ASIC meet the detector requirements

AS01PDA main parameters

Channelstructure

Preamplifier -Shaper -50 Ohm Driver

Shaper peaking time

90ns

Maximumdifferential gain

9mV/fC

ENC, e 1000+14.1e/pF

Shaper output +/-1.5V

Powerconsumption

18mW

Package SOP16

ENC vs Cd and Vcc

ENC = 14,123e/pF + 1000e

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 50 100 150 200 250 300

Cd, pF

EN

C,

e

5V

6V

7V

8V

9V

Trend line

AS01PDA block diagram

Positive output (Op)

Negativeoutput(On)

Preamplifier- Shaper- 50 Ohm Driver

1st 3rd

Gain control

Signal input(In)

Ct 0.2pF

Test input(In_t)

2nd

Reference preamplifier

P N

Reference level

AS01PDA on the small PCB and eight channels flat bar PCB

Main unit of the FEE prototype

One flat bar of theFEE prototype

The GaAs prototype electronics will consist of eleven PCB flat bars(87 channels)

FEE prototype measurement results Gain and waveform versus detector capacitancein response to 10fC input charge

Linearity measurements done by Krzysztof Oliwa and Wojciech Wierba

Linearity at different power supply voltages

The IC was earlier tested with Tomsk GaAs detectors (1cm x 1cm) andshown good results

Schedule of assembling of GaAs calorimeter segment prototype

• End of October - 87 channels of the FEE will be done• November – GaAs sensors will be done

Conclusions

1. First measurements of Minsk monocrystalline diamond detector are performed.

2. New metallization for CVD diamonds is tested; the first sample with new metallization works better than with old one.

3. First channel of redout electronics for GaAs calorimeter segment prototype is assembled and tested; the work is going on within the schedule.