8/6/2019 Calculation of the CTI

1/10

Calculation of the CTI

Meeting 27.02.2009Meeting 27.02.2009

Khaled Bekhouche

Biskra/Lancaster University

8/6/2019 Calculation of the CTI

2/10

Calculation method1- Construction of the distribution of ADC codes of each 10 pixels

(Slide 3). The number of frames is 10000.

2- Fit the noise and the X-ray by a Gaussian functions (Slide 3).

3- For each pixel we calculate the noise centroid and the X-ray centroid

by averaging the ADC codes within the two intervals:

(X0noise-mnoise)< ADC code

8/6/2019 Calculation of the CTI

3/10

0 100 200 300 400 500 10

0

101

102

103

ADC code

Counts

Distr ibution

Fit noise

Fit X-ray

T=-40 oC

f=1 M Hz

OPV =-1.2 V

CLK vol tage=3 V

Pixel 31 to pixel 40

X-ray peak

8/6/2019 Calculation of the CTI

4/10

50 100 150 200 250 300 350 400 450 500 425

430

435

440

445

450

455

Pixel number

X-raypeak

X-ray peakLinear fit

T=-40 oC

f=1 M Hz

OPV =-1.2 V

CLK vol tage=3 V

8/6/2019 Calculation of the CTI

5/10

Results

The figure in slide 6 shows the effect of the OPV

for two values of the CLK voltage.

The temperature effect on the CTI is presented

in Slide 7 with 1000 and 10000 frames. The

integration time used is 100 ms.

The effect of the integration time on the CTI is

presented in slide 8. Slide 9 represents the variation of the noise with

the temperature in some pixels of the CCD.

8/6/2019 Calculation of the CTI

6/10

-2.5 -2 -1.5 -1 -0.5 0 0

1

2

3

4

5

6

7

8

9

10

OP V ( V )

CTI/10-5

CLK vol tage=3 V

CLK vol tage=4 V

f=1 M Hz

T=-40oC

8/6/2019 Calculation of the CTI

7/10

-60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -2

-1

0

1

2

3

4

5

6

7

8

Temperature ( oC)

CTI/10-5

1000 fram es

10000 fram es

f=1 M Hz

Integration t ime=100 ms

OPV =-0.81 V

CLK voltage

8/6/2019 Calculation of the CTI

8/10

0 1 2 3 4 5 6 7 8 91

2

3

4

5

6

7

8

9

10

11

Integration t ime (ms )

CTI/10-5

f=1 M HzOPV =-0.8 V

CLK vol tage=4 V

T=+10oC

8/6/2019 Calculation of the CTI

9/10

-55 -50 -45 -40 -35 -30 -25 -20 -15 50

60

70

80

90

100

110

120

Temperature ( oC)

Noise(e-)

Pixel 131Pixel 231

Pixel 331

Pixel 431

f=1 M HzOPV =-0.8 V

CLK vol tage=4 V

8/6/2019 Calculation of the CTI

10/10

The higher is the CLK voltage, the larger is the OPVoperating interval.

The noise is quite constant, at least in this range oftemperature.

The CTI should be studied by taking in account both thereadout frequency and the integration time.

To study the effect of the traps, we plan to do theexperiments with different readout frequencies andintegration times after irradiating the CCD.

Discussion