Neel IRAM KIDs ArrayNeel IRAM KIDs Array

- Cryostat - Filters- Cold electronics- Measurement methods and assumptions for Sensitivity calculation- Antenna-coupled 42 pixels KIDs (first option)- 32 pixels LEKIDs (second option)- 196 pixels LEKIDs (TBT)- Best LEKIDs pixel tested in Cardiff (for 2010 …)

The Cryostat OpticsThe Cryostat Optics

300K:300K: ZITEX G110ZITEX G110HDPE (t=10mm) windowHDPE (t=10mm) windowThermal Filter (metal-mesh)Thermal Filter (metal-mesh)

150K:150K: ----

80K:80K: 2 thermal filters (metal-2 thermal filters (metal-mesh)mesh)

1 low-pass filter 270GHz1 low-pass filter 270GHz

5K:5K: 1 low-pass filter 240GHz1 low-pass filter 240GHzL1 – HDPE lens (t=11mm)L1 – HDPE lens (t=11mm)

1K:1K: 1 low-pass filter 210GHz1 low-pass filter 210GHz

100mK:100mK: Reflecting BaffleReflecting BaffleL2 – HDPE lens (t=12mm)L2 – HDPE lens (t=12mm)Low-pass filter 170GHzLow-pass filter 170GHzHigh-pass filter 130GHzHigh-pass filter 130GHz(optional) bandpass 130-160GHz(optional) bandpass 130-160GHz

Designed for f/1.6 on the detectors (from f/10 at M8). De-magnifying factor: 6

300K

160K

80K 4K

0.1K1K

4th Sepember 2009: added new 4K baffle (ECOSORB inside) + ZITEX G110 at 80K4th Sepember 2009: added new 4K baffle (ECOSORB inside) + ZITEX G110 at 80K

The FiltersThe Filters

- 4 thermal (including ZITEX)- 4 low-pass- 1 high-pass

HDPE window and lenses are not AR-coated.We have 4.5% loss at each surface, plus 10+11+12mm Bulk absorption. We estimateTHDPE=0.7

Band: 130-170GHzFilters transmission: 0.5HDPE transmission: 0.7

So our best estimation of the in-band transmission is

Total Transmission 0.35

Cold ElectronicsCold Electronics

We can now easily (cabled for both down to 4K, just has to un-screw the amplifier) change between:

- IRAM cryogenic amplifier 1IRAM cryogenic amplifier 1÷÷2 GHz. T2 GHz. Tnoise noise = 5K. Power dissipated: 50 mW= 5K. Power dissipated: 50 mW- LNF cryogenic amplifier 3LNF cryogenic amplifier 3÷÷9 GHz. T9 GHz. Tnoise noise = 5K. Power dissipated: 4 mW= 5K. Power dissipated: 4 mW

Still waiting for the Caltech 1÷12GHz amplifier.

Both are mounted at 4K. The IN of the amplifier is connected to the array with:

- 15cm superconducting NbTi 1.6mm semi-rigid COAX (thermalised at 1K)- 16cm Copper 2.2mm semi-rigid COAX (at 100mK)

Measurements « protocol »Measurements « protocol »

300K

160K

80K 4K

0.1K1K

CH

OP

PE

R 7

7K /

300

KC

HO

PP

ER

77K

/ 3

00K

30x

30cm

EC

OS

OR

B 7

7K30

x30

cm E

CO

SO

RB

77K

EC

OS

OR

B 7

7KE

CO

SO

RB

77K

12 mm dia. hole in the 2nd ECOSORB2nd ECOSORB is to fake M8 in some way (not perfect)

Everything on XY stage

580 mm

750 mm

Estimation of the power Estimation of the power 1/21/2

Assuming h<<kT (OK):

So, between 300K and 77K (perfect emissivity): Pe = 0.2 mW/m2 (max=170GHz, min=130GHz)

Power emitted over the 2π, both polarisations, with a cos() distribution.

For a chopped Φ=12mm surface (S = 1.1·10-4 m2) Pchopped = 22nW

The Lambertian « beam » is propagating forward toward the 4K lenses, d=80mm and distance D=750mm from the chopper. The 4K lens collects the part going mostly on the focal plane. So the useful fraction of solid angle is:

frac = (πd2/4) / (2πD2) = (1/8)·(d/D)2 = 1.4·10-3

Total transmission (from the chopped source to the array):

- Filter + lenses TFL = 0.35 (0.45 possible)- Cold pupil cutoff (cutting the external ring) TCP = 0.8- Measurement system (from chopper to cryostat): TCH = 0.5 (n.a. on the sky)

- TOTAL TRANSMISSION- TOTAL TRANSMISSION T = 0.14 T = 0.14 (0.36 possible)(0.36 possible)

3min

3max2

2

3

2)/(

c

TkmWPe

Estimation of the powerEstimation of the power 2/22/2So we have: P frac · TTOT · Pchopped 4 pW

Total power, in the two polarisations, hitting the focal plane and spreading (PSF - gaussian 2-D distribution) on a number of pixels to be determined experimentally (aberrations + diffraction).

ZEMAX full 3-D simulation (better calculating the pupil cut and taking properly into account the Lambertian and extended nature of the emitter).

PZEMAX = 5.9pW (Basically estimating frac in 3-D ray-tracing)

Now, the mean beam FWHM is fitted to be 31mm. It means, roughly, a factor (12/31)2 = 0.15Working out the integral of the gaussian in 2-D we find a factor of 0.098 instead.

So, the power hitting the pixel in this model is 5.9 5.9 · · 0.1 = 0.59 pW0.1 = 0.59 pW (2 polarisations)

In case of the measurement of the SRON array, since we have used an additional filter 2mm, we estimate 0.4 pW0.4 pW instead of 0.6 pW.

1.0112222222

2

222

0

2

RRR r

eRIedrer

The antennas 42 (6x7) pixels array – XY scanThe antennas 42 (6x7) pixels array – XY scan

PIXELS identifications: 37/42 working pixels.Mean inter-pixel distance: 10mm (means f/1.6 on focal plane, dpixels=1.6mm)Mean beam FWHM: 30mm

The antennas 42 (6x7) pixels array: XY scanThe antennas 42 (6x7) pixels array: XY scan

PIXELS identifications: 37/42 working pixels.Mean inter-pixel distance: 10mm (means f/1.6 on detectors plane, dpixels=1.6mm)Mean beam FWHM: 29 mm

The antennas array: FPGA sensitivityThe antennas array: FPGA sensitivity

Sensitivity measured with FPGA electronics, LNA at 4K mounted, GrenobleUp/Down converter.

It seems it’s still limited by the background.. May be some excess phase noise ?

NEP are for the 2 polarisations !! Should divide by 2 to be fair ..

NEPNEP1Hz1Hz 2 2··1010-15 -15 W/HzW/Hz0.50.5

NEPNEP10Hz10Hz 7 7··1010-16 -16 W/HzW/Hz0.50.5

The antennas array: Bonn sensitivityThe antennas array: Bonn sensitivity

From Andrey.

Antennas MKIDs next steps

• Improve f-distribution (possible before Oct)– Change to optimum f-distribution on chip– Use e-beam mask (current is optical)

• Improve coupling– Current lens array E=2.7 instead of 5 (loss 3dB)– Change extension length (possible before Oct)– Change lens material (Spring)– Possible to Niquist reduce oversampling (max gain 6dB)

• Improve F-noise– Integrate capacitor at coupler (demonstrated at JPL) improves

phase noise by 10dB• Multi frequency pixels (+ kid parametric optimization)• Optimise for operation under sky loadingOptimise for operation under sky loading

LEKIDs: 32 pixels focal plane scanLEKIDs: 32 pixels focal plane scan

24 working pixels within the 48 MHz band of the FPGAelectronics.

FWHM = 31FWHM = 31+/-4+/-4 mm mm

It’s OK !It’s OK !

LEKIDs: 32 pixels unchoppedLEKIDs: 32 pixels unchopped

Image of two hot spots on the focal plane; no chopperno chopper

LEKIDs: 32 (4x8) pixels array (NEP)LEKIDs: 32 (4x8) pixels array (NEP)

LEKIDs: 32 pixels focal plane scanLEKIDs: 32 pixels focal plane scan

PIXELS identifications: 28 working pixels, but only 24 within the FPGA bandwidth Mean inter-pixel distance: 12mm (means f/1.6 on detectors plane, dpixels = 2 mm)Mean beam FWHM: 31 mm

LEKIDs: 196 (14x14) pixels arrayLEKIDs: 196 (14x14) pixels array

CHOPPER

NO CHOPPER

S/N ~ 1000 (down to 0.5Hz)S/N ~ 200 (at 0.1Hz) but …(dia. pupil 2cm)Assuming 0.5pW power NEP ~ 5·10-16W/Hz0.5

Ongoing to improve:Ongoing to improve:- 16-32 pixels arrays (FPGA electronics)- Fabrication on Sapphire - Change of resonator impedance (phase noiseand power handling)- Cryogenic amplifier (amplitude readout)- Better control of backshort distance- Superconducting box + filter (Cardiff)- Post-processing: KIDs circle calibration- Test with Bonn electronics to read-out thewhole array.

CAREFUL:CAREFUL: still to be tested with the Bonn electronics still to be tested with the Bonn electronics (need to change to 16k bins) and in the same background (need to change to 16k bins) and in the same background conditions. Scheduled when we repair the cryostat.conditions. Scheduled when we repair the cryostat.

LEKIDs: Best Pixels TestedLEKIDs: Best Pixels Tested

Border conditions:Border conditions:

- 40nm film (UHV at SRON). - Less C fingers (helps reducing the phase noise)- Tested in low background Tested in low background environment (Cardiff).environment (Cardiff).(0.1pW per pixel)(0.1pW per pixel)

To further reduce the NEP:To further reduce the NEP:

- Change the impedance of the resonator - 2 polarisations design- fabricate on sapphire- further optimise the electricalpower on the KIDs- use an additional AR coating- optimise the film thickness…..

Bonn ElectronicsBonn Electronics

Available in Grenoble since end of July.

Bandwidth: 400 MHzMax. readout rate: 10 HzFFT points: 8,192 / 16,384Bins spacing: 48.8 / 24.4 kHz

Interfaced with Acquisition program OK

Néel FPGA ElectronicsNéel FPGA Electronics

Bandwidth: 48 MHzMax. readout rate*: 100 HzMax. number of channels 27

* Can be used also for fast (MHz) read-out.

Interfaced with Acquisition program OK

Electronics developmentsElectronics developments

USA Open Source:USA Open Source: DAC and ADC boards OK up to 500MSPS. Developing the CASPER Core. We’ll have two full copies, with the possibility of using them in parallel. Same concept as FPGA readout.Minimal goal: 128 channels each board (256 hopefully)

Delivery: end 2009 ?

LPSC, Grenoble:LPSC, Grenoble:Making a « copy » of our FPGA, but with 200MHz bandwidth and able to read at least 64 channels. Prototype delivery: November ?

Bonn:Bonn: planning 32k bins and 800MHz bandwidth.

ConclusionsConclusions

Demonstrated NEP is not exceptionally low

BUT:BUT:

- Imaging capabilities OK for both antennas and LEKIDs- Expected better performances on the telescope (background limiting both Qi and qp)- Need to understand real problems at the 30-m- Developments are ongoing to reduce the NEP.For both LEKIDs and antennas.