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Plan for the NIKA2 upgrade operations (March 1st to 11th)
The elements below focus on the upgrade operation plan and people coming to do it.
Since the discovery of the dichroic #2 gradient effect in 2018 we knew we wanted to upgrade NIKA2 one day, changing several elements once the dichroic problem could be solved since it's the main element limiting performances. For more information on this historical background browse the NIKA2 collaboration private wiki commissioning notebook, hardware development, and documentation sub pages.
For more information on the upgrade motivation in the form it will be implemented now, and various elements that will be changed, see the related wiki pages, in particular the June 2023 special meeting where fixed the short list of elements we decided to change for the upgrade, the November 2024 special meeting where fixed the date of the upgrade, describe the various operation to do and the time line, and also the [https://publicwiki.iram.es/DailyReportsNika2Pool140125|[w24 Pool #2 Daily report which contains description of some preparatory work]], as well as the NIKA2 weekly meetings where we discussed the upgrade (May 15th 2024, May 29th 2024, June 12th 2024, June 26th 2024, July 12th 2024, August 24th 2024, January 8th 2025, January 22nd 2025, and January 29th 2025).
For more information about what will happen once the new elements are installed, see the upgrade re-commissioning pages..
Participants
(preliminary)
On site: Samuel, Alessandro, Martino, Gregory Garde (from NEEL workshop) (to be confirmed), others (Dave, Carlos...) ?
Remotely (people who may be contacted for particular questions in their domain of expertise) : Andrea, Juan ?, Nico ?, Xavier ?, others ?
Hardware & tools situation
Hardware currently in Grenoble, to transport to the telescope (early January Samuel brought to NEEL everything that was at IRAM Grenoble):
3x 1 mm Arrays new design + spares
Dichroic #1 with new Cu mount + Al+SS rings
1x AR pyramids machined array-side lens
New "funny shape" extra optics baffle shield
5x nex IR filters
Already at the telescope (checked by Samuel during Jan 14-21 pool):
2x AR pyramids machined array-side lenses
NIKA2 operation tool boxes
Super-insulator spare roll
PIMP with its mount, electronic gray box, and Raspberry control unit
Overall schedule
- Feb 25th - March 3rd: warm up NIKA2
- NIKA2 will be already warm on 2025/03/04
- March 4th - 11th: NIKA2 hardware upgrade
Remove NIKA2 Nose (entrance window, temperature screen behind, M7 & M8 mirrors unit).
- Slide all cryostat main body screens to the position were the nose was to access the 100 mK mount (aka "Robot Dog") on which all cold elements are mounted (dichroic, lenses, arrays...). Be extra careful with super insulator.
- Change 1mm arrays
- Change of cryo lenses
- Change dichroic
- Slide all cryostat main body screens back in place
- Put back the M7-M8 unit, take care of the long tie rods in order to get the best possible alignment of the cryostat optics (important not only to get the optical axis of the whole system aligned with the center of the arrays so that without Nasmyth correction the image of the point source is at the center of the arrays, but more importantly to get the pupils well aligned so that the illumination of M1 from the cryostat optics is well centered, otherwise we would pickup some warm spillover from the background behind the telescope, degrading the signal to noise (sensitivity) and the beam shape quality).
- While putting back the nose screen one by one, change IR-blocking filters mounted on them
- March 11th - 17th: NIKA2 cooling down (maybe start already on the 9th if we are as efficient as we hope for the preceding operations)
Once cool down has been started: check the optical alignment using the elevation axis lasers, and possibly the cryostat laser plate to be placed on the entrance window.
March 18th: Once the cryostat is cold, that KID traces can be displayed on the acquisition software GUI, and that the telescope can point a blank sky in good atmosphere conditions perform a radio alignment (has to be done by the team on site during the Mar 18th-25th week; see the re-commissioning preparation page, which contain a detailed description of the radio alignment procedure)
For more details on the optical and radio alignments with NIKA2 check the following link: History of optical and_radio alignments of NIKA2; this document (which is also available from the NIKA2 wiki main page) contains drawings that help understanding the procedures.
Detailed operations
Not sure it makes sense to describe all the operations the team will perform in details. This would be quite cumbersome and not necessarily super useful.