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Daily Reports

Contents

  1. Daily Reports
    1. March 4th, Tuesday
    2. March 5th, Wednesday
    3. March 6th, Thursday

March 4th, Tuesday

Samuel, Alessandro, Martino and Gregory arrived at the telescope with many others from the IRAM Granada staff.

- First we take the decision that it is useless to check the laser alignment since it was done by Dave a few months ago and nothing was touched since then. We'll use Dave's measurement as reference.
- Today we dismounted the cryostat, with the help of Dave, removing the nose, moving the cryostat to install the rails allowing to slide all the screens to the wall, where was the nose, and access the 100mK structure where the clod optics stands (100mK lenses, dichroic, polariser, arrays). Pictures of all the steps steps are posted below.
At the end of the morning we reached the 4K screen.
On the afternoon we slid away the remaining screens, dismounted the dichroic (#2), the polariser, the smooth array side lenses of the 1mm channels, and the arrays.
- A bit of machining in the mechanical workshop was necessary to enlarge rings allowing to install the AR structured lenses. We installed these lenses and the new 1mm arrays. In parallel we changed the IR filters on the 300K screen, the 100K screen, and the 50K screen, that's the only ones we change given the type of filters provided by Cardiff (C7.5, C15, but no C30). The 3 new double faced filters we installed are all C15 types. We prepared the installation of the dichroic #1 new mount, with some machining also necessary to install the adaptation pieces on the 100 mK structure. We finished these step just before diner. We are a bit ahead of scheduled (originally we thought doing only the dismounting parts today).
- Tomorrow we install the dichroic with the new mount, then close everything back, which will take some time because of the super insulation to change at least on one screen. If everything goes well we might start pumping by the end of the day.

250304_1_starting_dismounting_NIKA2 250304_02_NIKA2_back_before_displacement 250304_03_NIKA2_pedestal_before_displacement 250304_04_NIKA2_lifted_air_pressure 250304_05_NIKA2_pedestal_lifted 250304_06_NIKA2_displaced 250304_07_sliding_rails_insertion 250304_08_NIKA2_back_on_wall 250304_09_sliding_rails_in_place 250304_10_venting_nose 250304_11_removing_nose_head 250304_12_nose_100K_stage 250304_13_nose_100K_2nd-screen 250304_14_nose_50K_stage 250304_15_nose_measuring_50K_stage_height_right 250304_16_nose_measuring_50K_stage_height_left 250304_17_tie-rod_for_50K_stage_height_adjutment 250304_18_tie-rod_dismounted_1of2 250304_19_dismounting_50K_nose_stage_M7-M8 250304_20_50K_nose_stage_M7-M8_dismounted 250304_21_dismounting_nose_4K_stage 250304_22_cryostat_body_1K_stage_entrance 250304_23_sliding_300K_body_screen 250304_24_yellow_wheels_rails_inserted_in_300K_screen 250304_25_positioning_the_rolling_support_for_lower_T_screens 250304_26_rolling_support_bellow_100K_screen 250304_27_sliding_100K_screen 250304_28_inserting_yellow_wheels_rails_in_100K_screen 250304_29_sliding_50K_screen 250304_30_black_wheels_rails_to_insert_in_50K_screen 250304_31_4K_body_screen_not_yet_removed 250304_32_baffle_in_4K_nose_screen 250304_33_4K_and_1K_screens_removed 250304_34_removing_ice_from_the_100mK_stage

More pictures to come...

March 5th, Wednesday

- The dichroic 1 must be mounted with a 0.5 N.m torque on the screws that allow holding in sandwich the dichroic membrane and its rings between the copper parts of its mount. Yesterday we found out we were missing the dynamometric wrench allowing to get this relatively low torque. Carlos called Granada to find the one he had on the lab down there, and this morning Antonio brought it up to the telescope. In the meantime we prepared the mount. A bit of additional machining was necessary in order to install the dichroic already mounted on NIKA2 as it is impossible to install the mount first and fix the dichroic afterward because of lack of space for the wrench. Once the dichroic installed we started closing the cryostat just before lunch.
- After lunch we continued the closing process, screen after screen, checking on the way that the cold mirrors block was exactly at the same height as the one measured during the dismounting process. Around 16h30 we closed the last parts of the 300K assembly, and started pumping. While pumping, look with Carlos and Victor how to add removable wheels to the PIMP mount to ease its displacement ; Victor built the wheels system. Leak check on NIKA2 around 18h30. No leaks found. We then put back the cryostat on its original working place.
- Pumping for a few hours. We might start the cooling already tonight, otherwise tomorrow morning.

March 6th, Thursday

- NIKA2 cryostat under vacuum. Cooling down started.
- Laser alignment checked, removing M3 and using the elevation bearing laser.