Néel people involved in NIKA
Researchers:
Engineers/Technicians:
Alain Benoit
Aurelien Bideaud
Philippe Camus
Xavier Desert (LAOG)
Christian Hoffmann
Alessandro Monfardini
Markus Roesch (IRAM PhD)
Loren Swenson
Gregory Garde (mechanics)
Julien Minet (FPGA)
Henri Rodenas (cryogenics)
Coming soon (PhD): A. Cruciani (now at Roma)
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Credit: S. Leclercq
NIKA is for 2mm !
94±18 GHz, 146±20 GHz, 240±45 GHz, 345±12 GHz
3mm
2mm
1.25mm
0.85mm
2
Credit: C. Tucker
Cardiff Filters
Band: 125-170GHz
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2.5 arc-min DCMB+NIKA for IRAM
Dilution Cryostat built at Institut Nèel
as a test bench for different focal
planes.
Telecentric in image space
feff = 51.6m
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Horizontal dilution cryostat views
- LHe and PT versions
- Tbase < 100mK
- LN2-free
- Horizontal
- Large cooling-power
- Fast cool-down (12h)
Baffle + detectors box
All at < 100mK
Mixing
Chamber
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NIKA optics
300K
0.1K
150K
1K
80K
4K
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NIKA datasheet
M7
On the cryostat (horizontal):
- M7 (flat)
- M8 (x-y 2nd degree polyn.)
at the IRAM focal plane (f/10)
In the cryostat:
- 4 K HDPE lens
- 100 mK HDPE lens
M8
Cryostat window
1.6 mm ( = 2.05mm, f/1.7 optics  Nyquist)
3232 mm2
up to 2020 (2.42.4arc-min, pixels spacing 7.2 arc-sec)
FFTS (Bonn): 64 channels (for now)
REALLY low-cost FPGA (up to 24-32 channels)
LPSC - US
Number of cables from the cryostat: 2 coax (f < 8 GHz), 3 for preamplifier bias.
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Pixel pitch:
Array dimensions:
Number of pixels:
Read-outs:
Cryostat Status
- Base Temperature
- Cooling Power at 100 mK
- Number of “useful”cooldowns so far
- To close and start pumping
- Pumping time (small pump)
- From 300K to 4K
- From 4K to 100mK
- Helium to cool down and refill once
- Helium consumption at base T
- Total Cool-down time
60 mK
10-100 W
 10
1 hour
3-6 hours
6-7 hours
4-6 hours
 100 liters
1 liter/h
14-18h
- Cabled for KIDs (LNA at 4K) and Semiconductors (JFETs at 120K)
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KIDs cabling
IN OUT
Home-made feedthroughs (no UHV)
Stainless Steel 2.2mm semirigid cables
External conductor thermalisation (soldered)
300K
150K
Stainless Steel 2.2mm semirigid cables
External conductor thermalisation (soldered)
Stainless Steel 2.2mm semirigid cables
External conductor thermalisation (soldered)
+ 2 DC blocks for inner conductor + LNA
80K
4K
NbTi 1.6mm semirigid cables
1K
External conductor thermalisation (glued)
NbTi 1.6mm semirigid cables
50mK
2 (inner) DC blocks
Copper 2.2mm semirigid cables (10-20cm)
External conductor thermalised one last time (soldered)
KIDs
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High-Q resonators
Example of high-Q measured in this environment
Measured in SRON (not same chip, but same bunch) Qi  3·106
Here we have Qi  2·106
Still not the same, but not even completely off.
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Something to discuss ?
Waiting for the real filters …. Everything to be measured again. With
the old DIABOLO filters + a single layer 2-mm passband mesh
we estimate the following.
From a well-known (dark R-T, I-V etc.) NbSi antenna-coupled array:
When Tbase= 75mK we see that:
- if 77K at cryostat input Tbolos= 95mK 
- if 300K at cryostat input Tbolos= 110mK 
P1=2.4 pW
P2=5 pW
In the ideal World P1P2/4=1.25pW. So we have a kind of plateau of
1-1.2pW (absorbed !) that remain somewhat unexplained.
But:
1) The 77K ECOSORB was a bit smaller than the window
2) In any case the 300K HDPE window is emitting
Let see with the new filters…
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LEKIDs design for IRAM
Samples fabricated by Markus at IRAM in Nb and Al. Tests on Nb samples performed here
at 2K. Problems: Cross-talk between resonators (design to be improved); sputtered Al films of
poor quality (alternative deposition). But some good news too (see Cardiff, Roma).
A new mask is almost ready to order.
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Making progresses on the antennas
LN2/300K chopper on focal plane
Optics OK: de-magnification factor  6
(from f/10 to f/1.6); side-lobes not bad.
Polarization response is reasonable
BIG
HORIZONTAL
VERTICAL POLARIZATION
HORIZONTAL POLARIZATION
NO
ANTENNA
SMALL
HORIZONTAL
BIG
VERTICAL
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New multi-antennas design
In fabrication in Orsay (IEF and CSNSM)
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Electronics for NIKA
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FPGA prototype
ALTERA evaluation board (STRATIX-II)
2 ADC 12-bit 125 MSPS + 2 DAC 14-bit 160MSPS
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FPGA multiplexing
I-Q mixers for
UP/DOWN CONVERSION
DDC CONVERSION
IN FPGA
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FPGA Multiplexing
8 channels have been recently
demonstrated.
Full chain:
- tones generation
- UP/DOWN conversions
- Real high-Q resonators seeing
light (no antennas !)
FPGA ressources occupation
around 24%. 32 channels are
in principle feasible on the
small board (requiring some
optimisation probably).
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Plans for MUX readout
- Bonn FFTS board + new DAC board of course. 64-128 channels are
ALREADY feasible. But not available yet in Grenoble for testing and
interfacing with the acquisition software. Problem should be fixed in the
next month.
- Our small FPGA board should be OK for up to 24 channels at least.
Using it also for other resonators applications.
- A similar (but 400MHz and bigger FPGA) custom board is under
development at LPSC Grenoble. Will work for 64-128 channels. Fully
designed and realised in-house, so potentially allows to be adapted for any
new application we might imagine in the future (and open to hardware
improvements).
- IRAM is participating to the Mazin Open Source project for
developing a 128 channels module. Expected in Autumn 2009.
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