Back to the NIKA run 4

Daily reports

New strategy for editing the page: With the log of Saturday it appeared that the ANTI-CHRONOLOGICAL ORDER makes it difficult to follow updates and discussions since the latest entry may answer an older entry possibly difficult to find for someone not following the updates in real time. So we go back to CHRONOLOGICAL ORDER and use the table of content with hyper links TO AVOID ENDLESS SCROLL DOWNS :)

Monday 14-05-2012

The cryostat with its new optics

the new optics

Saturday 19-05-2012

Je suis a 490 MHz sur la click FPGA soit un bin de 1.869 MHz je mets 50kHz de deviation modulation sur les 2 bandes matrice A : 1mm : 2.288149 GHz dac 3db HF 0 db sortie 10db - 1 ampli matrice B : 2mm : 1.3013 GHz dac 3db HF 20 db sortie directe - 1 ampli

12h51m11_0001_T scan table xy pas 5mm et 20% (50x50)

13h02m45_0002_B un balayage complet des 2 bandes la 1 mm a beaucoup bouge : je recherche les résonances sur les 2 matrices 13h29m01_B Je relance un balayage 13h31m01_0004_T puis une carte scan table xy pas 5mm et 20% (50x50) 13h48m41_B balayage complet la 1mm est montee en frequence de 110 KHz : je recentre la 1mm et ne touche pas a la 2mm

13h58m01_0005_T Nouvelle carte avec un pas plus faible (3mm)

2mm matrix 1mm matrix

14h22m30 balayage complet pour regarder les derives: la 1mm est montee de 140 kHz (on est a 181 mK en train de refroidir lineairement 5mK par heure 14h30m57_0006_T encore une carte pas de 5mm apres un reglage pour voir la stabilite de la photometrie

14h40m20_0007_T Un petit balayage et je refaits une carte : a priori, plus d'erreur et plus de sauts

2mm matrix 1mm matrix

14h47m50_T 14h50 : corps noir a 12.32 ohm : je chauffe a 20V 1.3A puis 30V 2A

15h10 : je baisse la puissance de 5db sur la matrice A : dac 3db HF 5 db sortie 5db - 1 ampli

15h18m35_B Un balayage complet matrice A 15h20m08_B un petit balayage pour verifier et recentrer 15h22m50 2 passages d'une feuille de polystyrene puis mesure de bruit

Friday 25-05-2012

NIKA was moved into the truck. Early start on Monday for Philippe and Martino.

Monday, 28-05-2012

Alain, Xavier, Samuel and Nico took the plane from Lyon to Granada. Juan picked them up at the aiport and drove all of them up to the observatory. Everybody was happy to be there for dinner and taste Maria-Carmen's special pasta. Poor Philippe and Martino arrived around only around 11pm after a 18 hour road trip. We unloaded the truck and started to plug in computers.

We had the visit of a fox in the evening (photos to come) and from local wild goats. As you can see, the weather is quite nice for now.

picture 1picture 2picture 3

Tuesday, 29-05-2012

We only had access to the telescope this morning at 10.30 and started to install all the hardware. It took us until the end of the technical time (16:30) before being ready to cool down; installation a bit longer than we expected with some minor problems to solve (e.g. pressure in the anti-vibration table, the data acquisition computer which died, etc.), but at the end of the day we are nearly there: cooling has started, and the work on the NIKA network is ongoing.

01_Unloading_NIKA_truck.jpg 02_NIKA_cryostat.jpg 03_lifting_NIKA.jpg 04_installing_NIKA_cryocooler_compressor.jpg 05_antivibration_table_for_NIKA.jpg 06_installing_NIKA.jpg 07_checking_NIKA_circulation_unit.jpg 08_NIKA_installed.jpg 09_aligning_NIKA_with_laser.jpg

Wednesday 30-05-2012

Cooling down is going according to plan. Better overall cooling speed compared to the last 'critical' run we had in Grenoble. But let's see what happens, Alain is planning to start condensation overnight. To get an idea, below the screenshots of the cooling down so far.

width=350 width=350

We took a ~1-2h slot in the evening to do the pre-alignment in order to set the final fixed position of M4 for NIKA, and drill holes in the M4 mount in order to screw the locking component. Working on the software, data transfers, and procedures.

Photos: The 3He gas stock for the dilutions stored in the cabin between the elevation motors box and an electric box, the NIKA electronics on top of the cryostat and the dilution circulation unit, laser alignment to define the definitive fixed position of M4 matching the best position of NIKA in the cabin, marking the place for the locking component on M4, drilling holes for the locking component, and Alain doing acrobatics to help blocking M4 at the right position.

10_NIKA_3He_gas_stock.jpg 11_NIKA_electronics.jpg 12_NIKA_electronics_and_mirrors.jpg 13_laser_alignment_to_set_M4_for_NIKA.jpg 14_marking_locking_component_place_on_M4_for_NIKA.jpg 15_drilling_holes_of_locking_component_on_M4_for_NIKA.jpg 16_Alain_acrobat.jpg

Thursday 31-05-2012

Still cooling down. 1.5K at 15h00; looks a bit slower than expected, maybe due to cooling power necessary for the extra black stuff that was added to mitigate further stray light ?

Now that M4 is locked on its NIKA position, put back in place the new M6 (it was removed yesterday so that Gregorio could access the mount of M4 on EMIR side to drill holes for wheel lock), and perform the final laser alignment => extremely fast.

17_M4_locked_at_the_NIKA_position.jpg 18_final_laser_alignment_M4-M6.jpg 19_final_laser_alignment_M5-NIKAentrance.jpg

For our observation slot the dilution had not started yet; so we gave away 1h, and took the rest of the slot to test the Pako procedures and correct and finalize the merging of the telescope data with NIKA FITS data. We also improved the ELVIN broadcast. Note that the weather was not suitable for observations anyway (opacity > 1.5).

Dilution started in the evening. 1h (Friday): ~300 mK.

Friday 1-06-2012

T detectors = 200mK at 8h00. AM 12h. 200mK and stable or cooling slowly ? Which steepness ?

Though the temperature was still around 200mK and the weather not great (tau ~1), the 1st 6h session was very useful, with many things to do; here's the main facts:

At the end of the session we had enough observations to check IMBFITs format, start and test offline processing, and get first crude information on the array characteristics, e.g. pointing, geometry, focus, response.

At night the temperature was continuing to go down on a gentle slope; we entered the sub-200mK region !

We dismounted the dis-functioning ROACH board, and used a RF-generator and spectrum analyzer from the workshop to investigate the problem: when moving the tones frequencies we saw a very significant attenuation every 50GHz. Visibly the problem was not the mixer.

Saturday 2-06-2012

Good news from the cryostat. Tbm is now 120mK, and it keeps cooling (overnight, the rate was about 2mK/h). So maybe the loooong cooling time is a consequence of all the extra added material (black varnish to prevent straylight) that gives us a huge added thermal capacity, and not to some fundamental issue in the dilution system. We'll see where we get.

Good news also from RoachB. We had been experiencing strange issues (the output of the downconverting IQ mixer changed depending on the LO frequency, sometimes very rapidly, so that the variations due to the resonators were effectively hidden by this effect). Apparently though it was just the consequence of one of the cables of the FPGA I/Q outputs used to generate the tones that was making a false contact (though tightly screwed...). Taking out the cables and putting them back in place solved everything. We are going to take everything up to the cabin again so that we can install it again as soon as possible.

Important note concerning the Roaches! In the end we decided, for the joy of Xavier, to use Roach A for the 2mm array and Roach B for the 1mm array!

Hopefully this afternoon we'll be able to observe using both channels.

AM 12h30. OK, if we are below 150mK not a problem in any case. I am not sure it's the new added material because we have already seen this behaviour with the same old optics and before touching anything. But it is reproducible (last 3-4 runs): 48 hours to start the condensation, 12h to condense and then in another 12 hours below 200mK and cooling very slowly. If don't get worse each time that's already good. Luckly as I said less than 150mK shouldn't make any difference (if we're not planning to use TiN soon, and I think that's not the case). I see the sky is still bad, but there's a number of issues already interesting that are not mentioned in the WIKI. In particular my three more urgent questions are: 1) the plateau is still there or not ? 2) what about the glitches ? 3) is the baseline frequency noise the same we had in lab for these arrays ?

RZ, 13:02 the plateau is there, glitches did not check: see dedicated in run processing page

AM 13h30. OK, we'll have time later for deeper discussions. Now I wish you all good (at least decent) weather !

Observations 16h - 22h

Cryostat cold at 110 mK. Array 1mm repaired! Cloudy, tau = 0.7.

Mainly dedicated to arrays characterization: pointing, focus, FWHM, geometry, response on Mars, and data formating, and processing.

Test of skydips, and automatic frequency sweeps at each airmass steps.

Few sans also on sources fainter than Mars (OJ286, IRC10216). Too soon to give numbers, but from these 1st observation it seems very likely that the sensitivities are better than run 3.

Tomorrow we will investigate the plateau based on a procedure discussed today.

Sunday 3-06-2012

RZ, 23:29 More news concerning the plateau: see dedicated in run processing page

JFMP Noise measurements 2mm : 4 Hz/sqrt(Hz) 1mm: 4.5 Hz/sqrt(Hz) ; see dedicated in run processing page

Monday 4-06-2012

RZ, 13:07 Update on the plateau: the off. resonance pixels @1mm show a positive plateau (below), the working pixels show in all but 4 cases a negative plateau see dedicated in run processing page

To give a hint of an answer to AMs question of 2-6-2012: there are gliches, quite different intensity and number per observation; some clearly correlated between the pixels, some not. Just two examples below. Shown are data of all OK pixels. see dedicated in run processing page

Synchronization: there is a remaining mismatch between the time of NIKA and the telescope of roughly -0.1sec. see dedicated in run processing page

History of the cryostat cooldown summarized in 4 snapshots of the dilution temperature (cold stage = temperature of the detectors): 6 days, last 4 days, last 3 days, last 2 days. Though the cooling down is pretty long, the behavior of the dilution is perfectly normal ==> let the cryostat at the telescope. Current temperature: 90 mK.

NIKA_2012_dilution_cool_down_6_days.png NIKA_2012_dilution_cool_down_last_4_days.png NIKA_2012_dilution_cool_down_last_3_days.png NIKA_2012_dilution_cool_down_last_2_days.png

Afternoon events before observations, and more pictures of the cryostat, showing the entrance HDPE lens and the final setup of the electronics for run4:

20_Guardia_Civil_helicoptere_exercise.jpg 21_Alain_ready_to_bike_down.jpg 22_Alain_leaving_the_telescope_by_bike.jpg 23_cryostat_noze_M5-M6-WarmLens.jpg 24_M6-WarmLens.jpg 25_electronics_final_run4_setup.jpg 26_Martino_controlling_two_arrays.jpg

Observations 16h - 24h

Effect of focus on the error beam: getting negative is not quite as expected (see dedicated in run processing page). An effect of the electronics ?

A similar (or same) effect shows the plateau: @1mm it is negative in a defocused map (see the figure "negative plateau @1mm per pixel" on 3-06-2012) and positive in a focused map (below). Any further systematics and dependance on other factors (e.g. sky load) are currently not known. see dedicated in run processing page

End of the run: switching off NIKA, dismounting the electronics, loading the truck:

27_switching_off_NIKA_and_dismounting_electronics.jpg 28_cryostat_closed_shuter_back_in_place.jpg 29_warming_up_the_nitrogen_trap.jpg 30_good_night.jpg 24_M6-WarmLens.jpg 31_loading_the_truck_by_night.jpg

back up of page

Observations information page (targets, procedures, strategies

Logbook pages

Offline Processing

DailyRepots (last edited 2012-06-15 15:30:25 by NikaBolometer)