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NIKA
This page is maintained by CK and SL
Contents
NIKA-1 Overview
|
Pixels |
Wavelength |
Bandwidth |
Sensitivity |
HPBW |
Field-of-View |
Spacing |
NIKA-1 run 5 |
132 (91 valid) |
2 mm |
122-166 GHz |
30 mJy*s1/2 |
18.5" |
2.3' diameter |
9.8" |
NIKA-1 run 5 |
224 (126 valid) |
1.25 mm |
213-251 GHz |
80 mJy*s1/2 |
12.5" |
2.3' diameter |
6.8" |
The New IRAM KIDs Array (NIKA) is a Kinetic Inductance Detectors camera for bolometric observations at the IRAM 30m telescope. It has been build by the Institut Néel, in Grenoble, France under the lead of Alain Benoit, and with the contributions of other persons forming the NIKA collaboration and comming from the following institutes: IPAG, LPSC, SRON, AIG Cardiff, CEA. NIKA consists of a dual band instrument using few hundreds of Kinetic Inductance Detectors (KID). The KID resonances variations which are dependent on the incoming power are probed by a comb of tones allowing to perform frequency domain multiplexing. Being a prototype in constant evolution the arrays characteristics (number of pixels, field of view, sensitivity, etc.) have evolved over the years from each test run to the other. The main characteristics of the latest configuration are summarized on the above table.
Procedure for cooling down the PT NIKA cryostat
1) "Rapide" (ev5=1; ev2=1; ev1=ev17=ev19=0) with J2 initially at 750mbar (J4 around 3500mbar), going down slowly. Continue this way until T_still = T_4K (usually satisfied at about 20K; takes roughly 16h).
2) J2=500mbar (ev5=1) until further flattening; then J2=300mbar (ev5=1) until further flattening.
3) When (T_still < 10K and T_BM < 10K), close ev5, ev5=0. Steps 2 and 3 together take about 4-6 hours. From now on ev5 stays closed.
4) When flattening again, the only other choice is passing through the pump (ev2=0, ev1=ev17=1, compressor ON, J1=15-20mbar); now it should be 24h roughly from the beginning. Pay attention to the J1 zero-point, could be not zero.
5) Leave this way (ev2=ev5=0; ev1=ev17=ev19=ev3=ev6=1; ev7=ev8=1; preref ON regulating J2 at 300mbar; compressor ON) for the night or in any case for about 8 hours until (T_still < 7K and R_BM > 1240-Ohm). If they're still cooling down reasonably when you arrive there, you might leave further until flattening. Very important to leave the "preref" switched ON. Otherwise, when the 4K reaches the LHe temperature a large part of the gas circulating condenses, leaving with a largely insufficient gas flux to cool down. So you basically lose the night entirely.
6) If (T_still < 7K and R_BM > 1240-Ohm) you could try to condense the mixture. To do that, simply close ev7, thus ev7=0, and switch ON the condensation procedure to regulate J4 at 4000mbar. Open ev18 to help the still and BM cooling. In case, increase slightly the pressure to J4=4500mbar (never more than that) but then decrease the target regulation value to 4000mbar.
7) At some point at the beginning of the condensation (e.g. after a few cycles of ev11 open/close) you might want to close ev18 to open it again when J5<50mbar. Or not, it depends on how it goes. Condensation should take no more than 12 hours (TBC).
8) When (J5 < 10mbar and J4 < 2000mbar) open ev18 if it's closed. ev18=1. Switch ON the turbo and stop the condensation procedure. Now just a matter of waiting it to reach base T.
Publications
Team
Overall coordinator: Samuel Leclercq <leclercq@iram.fr> (IRAM/Grenoble)
- NIKA team: collaboration between groups from the Institut Néel, IPAG, LPSC, AIG Cardiff, SRON, CEA, and IRAM. The Néel Institute is the main constructor of the NIKA prototype, and is coordinating the various groups. Main support team:
Alain Benoit <alain.benoit@grenoble.cnrs.fr> (PI, IN)
Alessandro Monfardini <monfardini@grenoble.cnrs.fr> (co-PI, IN)
François-Xavier Désert <francois-xavier.desert@obs.ujf-grenoble.fr> (IPAG)
Martino Calvo <martino.calvo@grenoble.cnrs.fr> (IN)
Antonio D'Addabbo <antonio.d-addabbo@grenoble.cnrs.fr> (IN)
- Nicolas Ponthieu (IPAG)
Juan Macias-Perez <macias@lpsc.in2p3.fr> (LPSC)
Andrea Catalano <catalano@lpsc.in2p3.fr> (LPSC)
Remi Adam <adam@lpsc.in2p3.fr> (LPSC)
- IRAM support team:
Carsten Kramer (station manager, <kramer@iram.es>)
- Robert Zylka
- Albrecht Sievers
- Nicolas Billot
- Walter Brunswig
Test runs 2009-2013
6th test run, June 2013
5th test run, November 2012
4th test run, June 2012
3rd test run, October 2011
2nd test run, October 2010
1st test run, October 2009
NIKA-2
NIKA-1 is a 2.3' FOV prototype used to test the technologies to be used in the bigger 6.5' FOV NIKA-2 instrument currently in development phase.