Max-Planck-Institut für Astronomie Heidelberg PACS SVR 22./23. June 2006 MPE Garching J. Stegmaier, U. Grözinger, D. Lemke, O. Krause, H. Dannerbauer,

Max-Planck-Institut für AstronomieHeidelberg

PACS SVR 22./23. June 2006

MPE Garching

J. Stegmaier, U. Grözinger, D. Lemke, O. Krause, H. Dannerbauer, T. Henning,

R. Hofferbert, U. Klaas, J. Schreiber

Ge:Ga Detector Arrays

PACS SVR phase 1, MPE Garching 22.-23. June 2006

PACS SVR, MPE22.-23.06.2006 Ge:Ga Detector Arrays

Warm Functional Tests- Separate warm functional test on each

module- Warm functional test after integration in

MPIA test cryostat

Cold Performance Tests- Cold functional test- Cold performance test

- Variation of Detector-Bias, Cint, tint

- Using different - Filter combinations- BB-temperatures- Detector temperatures

- Dark measurments

FM-LS Tests

MPIA Test Facility

f-ratio as in PACSIR-flux attenuation: ~ 2.5 · 10-6


FM LS-Sevenpacks

FM-LS during integration into

MPIA test cryostat

FMmodul

e

Warm functional test

Cold performanc

e testcomments

LS 1 2 hot pixels

LS 2 - 2 non-confirming modules (dummy channel)

LS 2_2 1 open pixel

LS 3 - 1 non confirming module(output frame not stable, low VSS current)

LS 4 - 2 modules with weak pixels

LS 5 1 module under higher stress

LS 6 1 open (dummy) channel 2 modules under higher stress


FM LS-Sevenpacks

FMmodul

e

Warm functional test

Cold performanc

e testcomments

LS 1 2 hot pixels

LS 2 - 2 non confirming modules (dummy channel)

LS 2_2 1 open pixel

LS 3 - 1 non confirming module(output frame not stable, low VSS current)

LS 4 - 2 modules with weak pixels

LS 5 1 module under higher stress

LS 6 1 open (dummy) channel 2 modules under higher stress

0 2 4 6 8 10 12 14 16 18 202,5

3,0

3,5

4,0

4,5

5,0

5,5

UBias

= 200mV, Cint

= 0

UBias

= 200mV, Cint

= 1FM 115

Ou

tpu

t Vo

ltag

e [V

]

CRE-Channel

channel #14

0 2 4 6 8 10 12 14 16 18 202,5

3,0

3,5

4,0

4,5

5,0

5,5

UBias

= 200mV, Cint

= 0

UBias

= 200mV, Cint

= 1

FM 122

Out

put V

olta

ge [V

]

CRE-Channel

channel #7

FM 122 (LS 2_2)

FM 115 (LS 1)


ResponsivityNEP

Responsivity / NEP

Responsivity: 7.4 A/W ± 1.7 A/WNEP: 1.18 · 10-16 A/W ± 4.6 · 10-17 A/W

UBias = 200mV, TDet = 2.5K

FM 126, FM 135, FM 136:higher stress (mounting screw of

the test housing pressed the module) modules OK

LS 1 LS 2_2 LS 5 LS 6


Responsivity - Homogenity

LS 1 (FM 120, 118, 115, 114, 110, 108, 107) LS 2_2 (FM 122, 115, 121, 116, 113, 112, 111)

LS 5 (FM 132, 131, 123, 128, 126, 125, 119) LS 6 (FM 130, 137, 136, 135, 134, 133)

0 2 4 6 8 10 12 14 16 180

5

10

15

20 200mV, Cint

= 1

Re

spo

nsi

vity

[A/W

]

channel

FM120 FM118 FM115 FM114 FM110 FM108 FM107

0 2 4 6 8 10 12 14 16 180

5

10

15

20 200mV, Cint

= 1

Re

spo

nsi

vity

[A/W

]

channel

FM122 FM115 FM121 FM116 FM113 FM112 FM111

Spiking pixel FM 115 ch. #14

FM 122 ch. #7 open

0 2 4 6 8 10 12 14 16 180

5

10

15

20

25

30

UBias

= 200mV, Cint

= 1

Re

sp

on

siv

ity [

A/W

]

Channel

FM132 FM131 FM123 FM128 FM126 FM125 FM119

0 2 4 6 8 10 12 14 16 180

5

10

15

20U

Bias = 200mV, C

int = 1

Re

sp

on

siv

ity [A

/W]

Channel

FM130 FM137 FM136 FM135 FM134 FM133

Spiking pixel FM 114 ch. #4

UBias = 200mV, TDet = 2.5K, Cint = 240 pF

higher stress on FM 126

higher stress on FM 135 and FM 136


Responsivity - Bias Scan

0 50 100 150 200 250 3000

5

10

15

20

25 Bias Scan, Cint

= 1

Re

spo

nsi

vity

[A/W

]

bias voltage [mV]

FM120 FM118 FM115 FM114 FM110 FM108 FM107

0 50 100 150 200 250 3000

5

10

15

20

25C

int = 1

Res

pons

ivity

[A/W

]

UBias

[mV]

FM122 FM115 FM121 FM116 FM113 FM112 FM111

0 50 100 150 200 250 3000

5

10

15

20

25C

int = 1

Re

spo

nsi

vity

[A

/W]

UBias

[mV]

FM132 FM131 FM123 FM128 FM126 FM125 FM119

0 50 100 150 200 250 3000

5

10

15

20

25C

int = 1

Re

sp

on

siv

ity [A

/W]

UBias

[mV]

FM130 FM137 FM136 FM135 FM134 FM133

LS 1 (FM 120, 118, 115, 114, 110, 108, 107) LS 2_2 (FM 122, 115, 121, 116, 113, 112, 111)

LS 5 (FM 132, 131, 123, 128, 126, 125, 119) LS 6 (FM 130, 137, 136, 135, 134, 133)

w/o spiking andopen pixels

TDet = 2.5K

FM 126 (LS 5),FM 135 (LS 6),FM 136 (LS 6):higher stress

caused by mounting in the

test housing


NEP - Bias Scan

LS 1 (FM 120, 118, 115, 114, 110, 108, 107) LS 2_2 (FM 122, 115, 121, 116, 113, 112, 111)

LS 5 (FM 132, 131, 123, 128, 126, 125, 119) LS 6 (FM 130, 137, 136, 135, 134, 133)

TDet = 2.5K

0 50 100 150 200 250 300

0

1x10-16

2x10-16

3x10-16

4x10-16

5x10-16

6x10-16 Bias Scan, Cint

= 1

NE

P [W

/Hz1/

2 ]

bias voltage [mV]

FM120 FM118 FM115 FM114 FM110 FM108 FM107

0 50 100 150 200 250 300

0

1x10-16

2x10-16

3x10-16

4x10-16

5x10-16

6x10-16

Cint

= 1

NE

P

UBias

[mV]

FM122 FM115 FM121 FM116 FM113 FM112 FM111

0 50 100 150 200 250 300

0

1x10-16

2x10-16

3x10-16

4x10-16

5x10-16

6x10-16

Cint

= 1

NE

P

UBias

[mV]

FM132 FM131 FM123 FM128 FM126 FM125 FM119

0 50 100 150 200 250 300

0

1x10-16

2x10-16

3x10-16

4x10-16

5x10-16

6x10-16

Cint

= 1

NE

P

UBias

[mV]

FM130 FM137 FM136 FM135 FM134 FM133

w/o spiking andopen pixels

FM 126 (LS 5),FM 135 (LS 6),FM 136 (LS 6):higher stress

caused by mounting in the

test housing


Dark Current [e-/s]UBias = 200mV, TDet = 2.5K

LS1

LS 1

LS 5

Mean: 3550 e-/s ± 600 e-/s

Requirements: CD ≤ 5*104 e-/s


Higher stress on 3 FMs smaller band gap

LS 5 LS 6

1615141312111098765432

Band gap [meV]

Band Gap

0,25 0,30 0,35 0,40 0,45 0,50e-36

e-35

e-34

e-33

e-32

e-31

e-30

e-29

e-28

e-27

e-26

e-25

e-24

e-23

e-22

dark

cur

rent

[A]

1/TDet

[1/K]

ch2

0,25 0,30 0,35e-36

e-35

e-34

e-33

e-32

e-31

e-30

e-29

e-28

e-27

e-26

e-25

e-24

e-23

e-22

Parameter Wert Fehler------------------------------------------------------------A 2,46252 0,49093B -103,80926 1,6843------------------------------------------------------------

R SD N P-------------------------------------------------------------0,99934 0,14967 7 <0.0001------------------------------------------------------------

da

rk c

urr

en

t [A

]

1/T [1/K]

ch2 lin. fit

FM 120, Ch 2(LS 1)

photon flux on detector

Thermal excitation: Idark ~ exp (-E/kTDet)


Goal: High absolute photometric accuracy in the FIR during „quiet“ periods (~ 1%)

Essential: - Stable operation of Ge:Ga-detectors in PACS at L2- Optimize operating conditions: UBias, TDet

- Minimize curing and calibration frequency

Radiation Environment at L2:- Galactic CR particles (low level fluxes: 3-5 ions/cm²/s; typical energy: 500 MeV – few GeV)- Solar particles events (avg. sol max: 2.5 · 105 ions/cm²/s; Ep ≈ 100 MeV, Eions ≈ GeV range)

Radiation damage in extrinsic photoconductors- Generation of electron hole pairs in bulk of detector- Capture of minority carriers by compensating impurities

Effects on Detector Performance:- Spikes / glitches- Higher detector noise, dark current, detector output change of calibration

- Lower S/N

Ionizing Radiation and Curing

No stable operation of Ge:Ga detectors


Ionizing Radiation Tests

Conditions– Simulated PACS operation conditions – Realistic FIR background: 10-14 W/pix – Low stressed Ge:Ga detector array– ~48 hours each– Every 1 to 10 min a measurement

Without irradiation (preparatory test)– Performance of detector and the test setup – Analysis of systematic effects Measurments highly reproducible with stability < 1%

137Cs detector irradiation– L2 radiation environment: 137Cs source (Eγ = 0.662

MeV)– Hit rate (> 3σ): ~16/s/pix

Long term measurments with 137Cs

Generic charge ramp

Radioactive 137Cs source


Deglitching Method

Glitch detection & deglitching:- sigma clipping applied to pairwise differences (values >3σ)

Skewed distributions:- Robust estimator, e.g., Hodge-Lehmann estimator:

μ = median (Xi+Xj)/2 with 1 ≤ i ≤ j ≤ n

Glitches skewed distribution


NEP and Responsivity

Glitch rate: Start irradiation: 9 ± 1 hits/s/pixplateau: 16 ± 2 hits/s/pix

Plateau: Accuracy: 4.5 %# > 3σ : 6%

5h

UBias = 160mV, TDet = 2.5K


Bias ScanTDet = 2.5K

Under Irradiation: Operating Ge:Ga detectors

at Ubias < 160mV


Ionizing Radiation Tests

Preliminary Results:

Measurements w/o irradiation are highly reproducible

137Cs allows simulations of radiation environment at L2

Effective technique for CR rejection: Sigma clipping with robust estimator (e.g., HL)

So far:

- Operating Ge:Ga detectors at a lower bias voltage < 160mV- Long term knowledge of better 5%- Good curing by IR flash (~ 10-12 W/pixel)

Documents

Max-Planck-Institut für Astronomie Heidelberg PACS SVR 22./23. June 2006 MPE Garching J. Stegmaier, U. Grözinger, D. Lemke, O. Krause, H. Dannerbauer,