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Plan for the NIKA2 upgrade operations (March 1st to 11th)

The elements on the following sections focus on the upgrade operation plan and people coming to do it.
- For more information on the historical background of the upgrade (since the discovery of the dichroic #2 "shadow effect" in 2018 we knew we wanted to upgrade NIKA2, changing several elements once the dichroic problem could be solved), browse the NIKA2 collaboration private wiki commissioning notebook, hardware development, and documentation sub pages.
- For more information on the upgrade as we have planned it, from the motivations to the various elements that will be changed and the expected gains in performances, see the June 2023 and November 2024 special meetings pages. In complement see also the w24 Pool #2 Daily report, and NIKA2 weekly meetings with a section about the upgrade (24/05/15, 24/05/29, 24/06/12, 24/06/26, 24/07/12, 24/08/24, 25/01/08, 25/01/22, 25/01/29).
- For more information about what is planed once the new elements are installed, see the upgrade re-commissioning pages.

Participants

On site: Samuel, Alessandro, Martino, Gregory Garde (from NEEL workshop), Granada staff (Dave, Carlos, Victor...)

Remotely (people who may be contacted for particular questions in their domain of expertise) : Andrea, Juan , Nico , Xavier...

Hardware & tools situation

Hardware currently in Grenoble, to transport to the telescope (early January Samuel brought to NEEL everything that was at IRAM Grenoble except the Cu spacers):

• 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 new IR filters
  

• Special M2.5 screws and washers
  

• Spacers in Cu for arrays in fab at IRAM (important, Samuel don't forget these are NOT in NEEL yet)
  

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
  • measure the position of the NIKA2 window

  • 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 cryo lenses array-side
  • Change dichroic (#2 out, #1 back in with new mount)
  • 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 screens one by one, change IR-blocking filters mounted on them
• March 11th - 17th: NIKA2 cooling down (maybe start already on the 7th 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.