1 Néel people involved in NIKA Researchers:Engineers/Technicians: Alain BenoitGregory Garde (mechanics) Aurelien BideaudJulien Minet (FPGA) Philippe Camus Henri Rodenas (cryogenics) Xavier Desert(LAOG) Christian Hoffmann Alessandro Monfardini Markus Roesch (IRAM PhD) Loren Swenson Coming soon (PhD): A. Cruciani (now at Roma)

2 NIKA is for 2mm ! 94±18 GHz, 146±20 GHz, 240±45 GHz, 345±12 GHz 3mm2mm1.25mm0.85mm 3mm 2mm 1.25mm 0.85mm Credit: S. Leclercq

3 Cardiff Filters Credit: C. Tucker Band: GHz

4 2.5 arc-min DCMB+NIKA for IRAM Dilution Cryostat built at Institut Nèel as a test bench for different focal planes. f eff = 51.6m Telecentric in image space

5 Horizontal dilution cryostat views - LHe and PT versions - Tbase < 100mK - LN2-free - Horizontal - Large cooling-power - Fast cool-down (  12h) MixingChamber Baffle + detectors box All at < 100mK

6 NIKA optics 300K 150K 80K 4K 0.1K 1K

7 NIKA datasheet Pixel pitch: Pixel pitch: 1.6 mm ( = 2.05mm, f/1.7 optics  Nyquist) Array dimensions: Array dimensions: 32  32 mm 2 Number of pixels: Number of pixels:up to 20  20 (2.4  2.4arc-min, pixels spacing 7.2 arc-sec) Read-outs: Read-outs: FFTS (Bonn): 64 channels (for now) REALLY low-cost FPGA (up to channels) LPSC - US Number of cables from the cryostat: 2 coax (f < 8 GHz), 3 for preamplifier bias. On the cryostat (horizontal): - M7 (flat) - M8 (x-y 2 nd degree polyn.) at the IRAM focal plane (f/10) In the cryostat: - 4 K HDPE lens mK HDPE lens M7 M8 Cryostat window

8 Cryostat Status - Base Temperature 60 mK - Cooling Power at 100 mK  W - Number of “useful”cooldowns so far  10 - To close and start pumping1 hour - Pumping time (small pump)3-6 hours - From 300K to 4K6-7 hours - From 4K to 100mK4-6 hours - Helium to cool down and refill once  100 liters - Helium consumption at base T1 liter/h - Total Cool-down time14-18h - Cabled for KIDs (LNA at 4K) and Semiconductors (JFETs at 120K)

9 KIDs cabling Home-made feedthroughs (no UHV) External conductor thermalisation (soldered) Stainless Steel 2.2mm semirigid cables 300K 150K 80K External conductor thermalisation (soldered) Stainless Steel 2.2mm semirigid cables 4K Stainless Steel 2.2mm semirigid cables External conductor thermalisation (soldered) + 2 DC blocks for inner conductor + LNA 1K 50mK External conductor thermalisation (glued) NbTi 1.6mm semirigid cablesIN KIDs NbTi 1.6mm semirigid cables Copper 2.2mm semirigid cables (10-20cm) External conductor thermalised one last time (soldered) 2 (inner) DC blocks OUT

10 High-Q resonators Example of high-Q measured in this environment Measured in SRON (not same chip, but same bunch) Q i  3·10 6 Here we have Q i  2·10 6 Still not the same, but not even completely off.

11 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 T base = 75mK we see that: - if 77K at cryostat input T bolos = 95mK  P 1 =2.4 pW - if 300K at cryostat input T bolos = 110mK  P 2 =5 pW In the ideal World P 1  P 2 /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…

12 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.

13 Making progresses on the antennas LN2/300K chopper on focal plane Optics OK: de-magnification factor  6 side-lobes not bad. (from f/10 to f/1.6); side-lobes not bad. Polarization response is reasonable BIG HORIZONTAL NO ANTENNA SMALL HORIZONTAL BIG VERTICAL VERTICAL POLARIZATION HORIZONTAL POLARIZATION

14 New multi-antennas design In fabrication in Orsay (IEF and CSNSM)

15 Electronics for NIKA

16 FPGA prototype ALTERA evaluation board (STRATIX-II) 2 ADC 12-bit 125 MSPS + 2 DAC 14-bit 160MSPS

17 FPGA multiplexing DDC CONVERSION IN FPGA I-Q mixers for UP/DOWN CONVERSION

18 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).

19 Plans for MUX readout Bonn FFTS board - Bonn FFTS board + new DAC board of course 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 - Our small FPGA board should be OK for up to 24 channels at least. Using it also for other resonators applications. custom board - A similar (but 400MHz and bigger FPGA) custom board is under LPSC Grenoble development at LPSC Grenoble. Will work for 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). Mazin Open Source project - IRAM is participating to the Mazin Open Source project for developing a 128 channels module. Expected in Autumn 2009.