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RUN HISTORY

RUN HISTORY. Preparation: 17/10 Cryostat, pumps and electronics mounted in the cabin (total time 2h) 18/10 Cooling down to 80mK. Resonances OK (SRON array) 19/10 Laser alignment and test on the sky. Seen Venus. Thick clouds. (tot. Time 2h) First slot (SRON array): 20/10 Snow

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RUN HISTORY

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  1. RUN HISTORY Preparation: 17/10 Cryostat, pumps and electronics mounted in the cabin (total time 2h) 18/10 Cooling down to 80mK. Resonances OK (SRON array) 19/10 Laser alignment and test on the sky. Seen Venus. Thick clouds. (tot. Time 2h) First slot (SRON array): 20/10 Snow 21/10 Morning: seen again Venus and then 3C273. Afternoon: wind and rain. 22/10 Morning: rain. Afternoon: good weather. Seen 3C345, MWC349 (6Jy) Preparation second slot: 22/10 20h-24h. Heating up the cryostat 23/10 0h-5h. Open/close, fix a leak on the compressor. 7-8h. Back in place. Second slot (LEKIDs): 24/10 Bonn electronics. Total power scans. Planets, quasars, sub-Jy sources, GRB. 25/10 FPGA electronics. Total power scans. A number of sources. 26/10 FPGA electronics. Try wobbler mode. Various problems. 27/10 FPGA electronics. OK with wobbler and total power. Extended sources.

  2. Tool for finding the resonances - BEFORE

  3. Tool for finding the resonances - AFTER

  4. SRON array • 42 pixels + 2 blinds • total bandwidth 200MHz • Bonn electronics (5Hz)

  5. Clouds Venus Mirror No beam (300K) Telescope crazy (horizon) Frequency scan Working in the cabin SRON array – First Light Time Domain Trace Sky Detectors dynamics 19/10. Technical time for alignment.

  6. SRON array – Noise spectrum Taken with the mirror on the cryostat input  Detectors noise average 12 mdeg/Hz0.5 @ 1Hz 45 mdeg/Hz0.5 @ 0.1Hz

  7. SRON array – Venus response and S/N The response to Venus is, on average, S = 6 deg in phase (TBC !!!) Venus was 10.7 arc-sec in diameter, for a temperature of 232K (http://nssdc.gsfc.nasa.gov/planetary/factsheet) The beams FWHM is 24 arc-sec. So, the effective temperature of Venus is (order of magnitude): T = 232K  (10.7/24)2 = 46K (Dilution of 232K on the beam) So since the noise at 1Hz (previous slide) is N = 12 mdeg/Hz0.5 We have S/N = 500 Hz0.5 @ 1Hz The NET of the single pixel is thus: NETpix = T / (S/N) = 46 / 500 = 92 mK / Hz0.5 Since the beam signal is split over X  4 pixels on average (0.5F) NETbeam = NETpix / X0.5 = 46 mK / Hz0.5

  8. SRON array – 3C273

  9. SRON array – Improvements using radius Should be a factor of 3 in S/N using the radius read-out (Andrey). …….. Applicable to the LEKIDs too.

  10. SRON array – Skydip (1.1 to 1.8 airmasses) Sky was really bad. Barely seeing the EL effect in the clouds.

  11. LEKIDs • 30 pixels • total bandwidth 45MHz • Bonn electronics (5Hz) or FPGA (48Hz)

  12. LEKIDs – Noise spectra (Grenoble) Detectors noise:4 mdeg/Hz0.5 @ 1Hz 10 mdeg/Hz0.5 @ 0.1Hz

  13. SKY noise Detectors noise LEKIDs – Noise spectra (on sky, during total power scan) Sky noise (correlated) dominates below 0.4 Hz Detectors noise: 5 mdeg/Hz0.5 @ 1Hz 12 mdeg/Hz0.5 @ 0.1Hz Well comparable with that measured in Grenoble.

  14. LEKIDs – Noise spectra (on sky, during wobbler scan) The continuous is still comparable. Lines are the wobbler and the harmonics of course (signal).

  15. LEKIDs – Mars signal The PSF “halo” is clearly seen already in the time-domain raw data. We have 5 deg PHASE signal for Mars on the average pixel.

  16. LEKIDs array – Mars response and S/N The response to Mars is, on average, S = 5 deg in phase Mars was 8 arc-sec in diameter, for a temperature of 210K (http://nssdc.gsfc.nasa.gov/planetary/factsheet) The beams FWHM is 24 arc-sec. So, the effective temperature of Mars is (order of magnitude): T = 210K  (8/24)2 = 23 K (Dilution of 210K on the beam) So since the noise at 1Hz (previous slide) is N = 5 mdeg/Hz0.5 We have S/N = 5000/5 = 1000 Hz0.5 @ 1Hz The NET of the single pixel is thus: NETpix = T / (S/N) = 23 / 1000 = 23 mK / Hz0.5 Since the beam signal is split over X  2 pixels on average ( 0.7F) NETbeam = NETpix / X0.5 = 17 mK / Hz0.5

  17. LEKIDs array - BL1418+546 (estimated 500mJy) Visible in the first scan. Faintest source detected 200mJy (WR147) .. Good S/N Quick look not adapted for longer integrations.

  18. LEKIDs array - G34.3

  19. LEKIDs array – M87 with wobbler

  20. LEKIDs array – GRB091024

  21. LEKIDs array – Skydip (1.1 to 1.8 airmasses)

  22. LEKIDs array – Skydip 2 Detectors dynamics The dynamics is OK to include the whole EL range. Sky was not exceptionally good ( 0.3 but TBC)  large signal In case of strong clouds it might be needed to re-center the resonances.

  23. LEKIDs array – B fields during slew Strange behaviour during large telescope slews .. Jumps. Superconducting box ? LEKIDs more sensitive to B fields. Not seeing it during observations.

  24. CONCLUSIONS • Great experience; same performances measured in lab, or a bit better. • OK with cryogenics, alignment, interfacing and so on… • TO BE DONE for the FUTURE (factor of 10 missing on sensitivity, dual band, pixels) • INSTRUMENT/OPTICS: • Design/fabricate the alternate optics for dual band 1.25 and 2mm • Pulse tube cryostat (easier for IRAM) • AR on the lenses/windows • DETECTORS: • Reducing the phase noise by changing the C geometry • Improving the sensitivity by reducing the volume of the resonators and using optimal Q • Optical coupling (e.g. thickness, backshort) • Films quality (for LEKIDs) • Start 1.25mm designs • Improve the homogeneity of the pixels (EM cross-talk, other effects ??) for larger arrays • SOFTWARE/ELECTRONICS: • - Optimise the electronics in general (starting from the cold amplifier) • Radius/amplitude implementation (a factor of 3 better S/N according to Andrey’s results) • Pixels de-correlation • Off-line pipeline • Open Source and LPSC electronics in case Bonn no longer available

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