NIRCam Detector Behavior

1

March 11, 2014

NIRCam Detector Behavior

Marcia Rieke

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March 11, 2014

Replacement Detectors Have Been Installed

SFM3

SFM4

LFM3

LFM4

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March 11, 2014

Performance Parameters

Basic Performance CharacteristicsLinearity regimeSaturation levelsSubarray behavior -- timing, performance, size constraintsPersistanceStabilityJitter tracking

5 MHz column buffersfast normal shift register + logic

glow

and

cross

talk shield

g low and crosstalk shield

Additional row of reference pixels for diagnostic purposes

2048 x 2048 pixel array(2040 x 2040 sensitive pixels)

4 rows and columns containing reference pixels

4 rows and columns containing reference pixels

serial interface

clock buffers

fast guide shift register + logic

Slow

gui

de s

hift

regi

ster

+ lo

gic

Slow

nor

mal

shi

ft re

gist

er +

logi

c

decoders for horizontal start and stop address

I/O Pads & output buffers

deco

ders

for v

ertic

al s

tart

and

sto

p ad

dres

s

SW and LW arms view same patch of sky but with different pixel scales.

Two variants on full frame mode:

Subarray uses a single output and can be positioned any where.

Stripe reads out a number of rows through 4 outputs, restricted to 2048xnrows.

NIRCam uses “Sample Up the Ramp” aka Multiaccum but may have co-adds.

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March 11, 2014

QE and Noise QE: (values from Teledyne tests) SW ≥ 0.80 at 2.0 microns LW ≥ 0.80 at 3.5 microns SFM3 SFM4 LFM3 LFM416991: 0.80 16989: 0.92 17161: 0.87 17158: 0.8317005: 0.92 17023: 0.9317011: 0.95 17024: 0.9117047: 0.92 17048: 0.88 Total Noise: (values from Arizona tests) Requirement is ≤ 9.0 e- in 1000 secs, all noise sources included SFM3 SFM4 LFM3 LFM416991: 5.9e- 16989: 6.0e- 17161: 8.4e- 17158: 7.9e-17005: 5.7e- 17023: 6.0e-17011: 6.4e- 17024: 6.4e-17047: 6.0e- 17048: 5.8e-

Correlated Double Sample Noise:(values from Arizona tests)Requirement is ≤ 21 e SFM3 SFM4 LFM3 LFM416991: 15.2 e- 16989: 15.1 e- 17161: 15.6e- 17158: 15.2 e-17005: 14.2 e- 17023: 15.2 e-17011: 17.8 e- 17024: 18.1 e-17047: 11.1 e- 17048: 11.7 e-

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March 11, 2014

Sample QE Data From Teledyne

LFM4 17158LFM3 17161

SFM3 16991 SFM4 17048

The SW parts shown have the lowest QEs of all the SW parts.

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March 11, 2014

Sample Total Noise Measurements

SFM4 17023SFM3 17011

LFM3 17161

Upturn due to light leak

Upturn due to light leak

LFM4 17158

Blue = CDS Red = Total Noise

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March 11, 2014

SW Illuminated Images

SFM3 SFM4GL Dewar illumination pattern has not been removed from these images.

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March 11, 2014

LW Illuminated Images

LFM3 LFM4

Test dewar illumination pattern has not been removed from these images.

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March 11, 2014

Linearity

0 200 400 600 800 1000 1200 14000

5000

10000

15000

20000

25000

30000

35000

40000

Data Linear Fit

Time (seconds)

Sign

al D

N (1

DN

=3.0

e-)

80%

50%

The unit cell for the H2RG arrays with its source follower circuit is inherently non-linear. We have demonstrated that the non-linearity can be adequately corrected to 90% of full well. The final linearity calibration will be derived from ISIM-level testing using the ASICs.

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March 11, 2014

Well Depths

The well depth is required to be greater than 60,000 e- with a detector back bias of 0.25 volts.

90% Fill Well Depths (e-) SFM3 SFM4

16991: 91800 16989: 98800 17005: 99400 17023: 102600 17011: 92900 17024: 93700 17047: 90200 17048: 91000

LFM3 – 17161: 78400LFM4 – 17158: 76500

From Arizona tests and analysis.

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March 11, 2014

Saturation LevelsSaturation levels have been computed for as-built telescope and NIRCam, and assume 80% well fill for LW parts (eg. 60,000 e-).Parameters:Telescope area: 25.37 m2 Telescope reflectivity >1.6l mm: 0.94Grism throughput: 0.45Grism R: 1600Detector QE: 0.85

Filter NIRCam Throughput

Background e-/sec/pixel

Johnson L limit

Johnson V, K for G2V

L limit for imaging

F277W 0.54 0.5 2.6 4.1, 2.65 7.1

F322W2 0.54 0.9 2.6 4.1, 2.65 7.8

F356W 0.59 0.4 2.7 4.2, 2.75 7.2

F410M 0.58 0.2 2.7 4.2, 2.75 6.1

F444W 0.58 1.2 2.7 4.2, 2.75 7.1

Saturation Limits for 32x2048 Grism Subarray, 32x32 Imaging Subarray

Fraction of flux in brightest pixel: 0.15

How many candidate stars are we likely to miss with these limits?

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March 11, 2014

Subarrays/Stripe Mode

Size FOV (arcsec) Frame

Comment (pixels) SW LW (msec)

16x16 0.512 1.04 9.56 Smallest useful LW subarray without target acquisition (TA)32x32 1.02 2.08 19.00 LED imaging; Smallest useful SW subarray w/out TA64x64 2.05 4.16 53.24 Nominal LW TA subarray

96x96 3.07 6.24 107.96Small-defocus transit photometry, SW channel; WFSC fine-phasing and routine monitoring operations

128x128 4.10 8.32 183.16 Nominal SW TA subarray160x160 5.12 10.4 278.84 Large-defocus transit photometry, SW channel320x320 10.24 20.8 1064 Nominal LW coronagraphic subarray640x640 20.48 41.6 4172 Nominal SW coronagraphic subarray

102416 N/A67 1.0

170.84LW grism spectroscopy (TA may be required)

2048x32 N/A134 x2.0

683.36 Includes top,bottom ref pixels, allows for some curvature in spectrum

• Subarrays need to be sized in 64 pixel increments but can be any rectangular location

• Subarrays are read out through a single output amplifier• Stripe mode gives regions of nrowsx2048 pixels through 4 output amplifiers• Timings below are approximate and will include ~0.5% overheads for rolling

reset of the rest of the array• Performance is similar to full array (eg. CDS noise) but “reset anomaly” is

very apparent

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March 11, 2014

Series of Subarray Dark Ramps

0 20 40 60 80 100 120 140 160 180 20026700

26750

26800

26850

26900

26950

27000

27050

27100

27150

27200

Sample

DC

LEVE

L

Output of a single pixel in a 160x160 subarray with 20-samples per ramp. Reset behavior will be different with ASIC readout (and will be checked during Thermal-Vac). Baseline varies due to kTC noise (~35 electrons).

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March 11, 2014

Latent Images

We have taken data to allow a calibration of the form below where the two time constants are ~60 seconds and ~1000 seconds.

Our latent data were taken using flood illumination (have a check that point source illumination produces the same result). Acquisition started from having the array in the dark followed by illumination, followed by 4000 secs of dark. Rapid illumination produces smaller latents than slow illumination.Latents are smaller in 5-micron cut-off arrays than in the 2.5 micron devices.

10 100 1000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

17005

vvh vh hrate mrate srate rate

Time since illumination

Pea

k po

st il

lum

rat

e D

N /

s

10 100 1000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

17005

Medium 0.37 Medium high 0.53 high 0.70vhigh 1.0 vvh 1.4 max 1.7

Time since illumination (sec)

Post

Illu

min

ation

Rat

e (D

N/s

)

Rate Dependence Well Fill Dependence

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March 11, 2014

First Look at Stability

0 5000 10000 15000 20000 2500062

64

66

68

70

72

74

S01 S02 S03 S04Time (secs)

Sign

al (D

N/s

ec)

0 5000 10000 15000 20000 250000.99

11.011.021.031.041.051.061.07

S01/S02 S03/S04Time (secs)

Ratio

• 100 ramps with 20 full frame reads each were acquired (one ramp collected ~40000e- each, 4x106 for entire set)

• Set-up used Leach electronics• Well fill for data shown was ~40%• 1.7 micron LED provided flood

illumination• All four arrays comprising a short

wavelength focal plane were illuminated simultaneously

• Slopes were fit to each ramp• Clear evidence of LED out drift seen• Ratio variablility suggests that the

noise is dominated by photon statistics (more careful analysis needed)

• Special test will be executed during ISIM thermal-vac to look at this using ASICs

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March 11, 2014

Jitter Tracking

Rectangle is 32 pixels wide

+4 Waves Weak Lens ImageIf desirable, the short wavelength arm could be used to observe the target star simultaneously with a grism or filter in the long wavelength arm.

Use of a 1% filter and/or weak lenses to spread out the light would likely be required.

There may also be operational constraints on the shape of the region to be readout (might have to be the same size as the LW subarray). A 32x2048 subarray would give pointing information every 1.31 to 1.98 seconds. Is this mode worth pursuing? And a corollary, should we measure in SW and LW arms simultaneously?

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March 11, 2014

Other Issues• Adjacent pixels are not completely independent of each

other – they are capacitatively coupled at the 0.5-1% level. Called “IPC”, Interpixel Capacitance

1484 1485 1486 1487 1488

1605 0.003 0.003 0.002 0.003 0.002

1604 0.001 0.003 0.003 0.002 0.003

1603 0.003 0.004 0.019 0.004 0.002

1602 0.002 0.02 2.847 0.02 0.002

1601 0.002 0.004 0.018 0.003 0.002

1600 0.003 0.003 0.003 0.003 0.003

1599 0.003 0.002 0.003 0.003 0.003

Illustrated using a hot pixel.

• Arrays have “Random Telegraph Noise” (popcorn noise)• Pixel will spontaneously jump in its DC-Level, may return to

baseline even within same ramp• Quoted noise includes the effect• Is a rare occurrance, need to analyze existing data to check

whether some pixels are “repeaters”, measure rates• NIRCam is close to properly sampled spatially but still will

be vulnerable to small amounts of “missing” charge due to centration

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March 11, 2014

Backup Information

April 10, 2013

16989

Dark Illuminated

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April 10, 2013

16989 Latent ImagesLatent Map

10 100 1000 100000

0.05

0.1

0.15

0.2

0.25

0.3

0.35 16689



Pea

k po

st il

lum

rate

AD

U/s

20

1000 10000 100000-0.01

-1.73472347597681E-18

0.01

0.02

0.03

0.04

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2.

8e-)

10 100 1000 10000 1000000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

16689 - 1st Set 16689 - 2nd set 17023 - pre 1

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2

.8e-

)

April 10, 2013

16991

Dark Illuminated

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April 10, 2013


10 100 1000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7 16691

vvh vh hrate mrate srate rateTime since illumination

Peak

pos

t illu

m ra

te A

DU/s

22

10 100 1000 10000 1000000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

16691 - 1st Set 16691 - 2nd set 17023 - pre 1

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2

.8e-

)

100 1000 10000 100000-0.01

-1.73472347597681E-18

0.01

0.02

0.03

0.04

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2.

8e-)

17005

Dark Illuminated

23


10 100 1000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.917005

vvh vh hrate mrate srate rateTime since illumination

Pea

k po

st il

lum

rate

ADU

/s

10 100 1000 10000 1000000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

17005 - 1st Set 17005 - 2nd set 17005 - pre 117005 - pre 2

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2

.8e-

)

100 1000 10000 100000-0.01

-1.73472347597681E-18

0.01

0.02

0.03

0.04

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2

.8e-

)

24

17011

Dark Illuminated

25


10 100 1000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.817011


Time since illumination P

eak

post

illu

m ra

te A

DU/s

26

100 1000 10000 100000-0.01

-1.73472347597681E-18

0.01

0.02

0.03

0.04

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2.

8e-)

10 100 1000 10000 1000000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

17011- 1st Set 17011 - 2nd set 17007 - pre 1Time (sec)

Rate

(Dn/

sec ,

1 D

N=2

.8e-

)

17023

Dark Illuminated

27


10 100 1000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8 17023



Pea

k po

st il

lum

rate

ADU

/s

28

10 100 1000 10000 1000000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

17023 - 1st Set 17023 - 2nd set 17023 - pre 1Time (sec)

Rate

(Dn/

sec ,

1 D

N=2

.8e-

)

1000 10000 100000-0.01

-1.73472347597681E-18

0.01

0.02

0.03

0.04

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2.

8e-)

17047

Dark Illuminated

29


10 100 1000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8 17025



eak

post

illu

m ra

te A

DU/s

30

100 1000 10000 100000-0.01

-1.73472347597681E-18

0.01

0.02

0.03

0.04

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2.

8e-)

10 100 1000 10000 1000000

0.10.20.30.40.50.60.70.80.9

1

17025- 1st Set 17025- 2nd set 17023 - pre 1

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2

.8e-

)

17024

Dark Illuminated

31


10 100 1000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7 17047



eak

post

illu

m ra

te A

DU/s

32

100 1000 10000 100000-0.01

-1.73472347597681E-18

0.01

0.02

0.03

0.04

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2.

8e-)

10 100 1000 10000 1000000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

17047 - 1st Set 17047 - 2nd set 17023 - pre 1

Time (sec)

Rate

(Dn/

sec ,

1 D

N=2

.8e-

)

17161 = Long Wavelength Replacement #1 (LFM3)

Dark Illuminated

17161

10 100 1000 10000 1000000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Tconstant1 Tconstant2 darkTime since illumination

AD

U/s

ec

10 100 1000 10000 1000000

0.010.020.030.040.050.060.070.080.09

0.1


AD

U/s

ec

10 100 1000 100000.00

0.05

0.10

0.15

0.20

0.25

0.30

vvlow vlow low medium high


Pea

k po

st il

lum

rate

A

DU

/s

17158 = Long Wavelength Replacement #2 (LFM4)

Dark Illuminated

17158

10 100 1000 100000.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

vvlow vlow low medium high vhigh


Pea

k po

st il

lum

rate

A

DU

/s

10 100 1000 10000 1000000

0.1

0.2

0.3

0.4

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0.6

Tconstant1 Tconstant2 dark


AD

U/s

ec

10 100 1000 10000 1000000

0.02

0.04

0.06

0.08

0.1


ADU

/sec

NIRCam Detector Behavior

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