Preparation visit before Run6
In May 2013, 3 people come to the 30m to install the new 2mm array and replace the 1mm cold amplifier. Then, a cooling down will occur and the NIKA prototype stays cold until the Run6 proper starts.
Tuesday 14-May-2013: 10h (during maintenance) Open cryostat, replace array at 2mm and the 1mm cold amplifier. Install the new DC cables for the amplifier. Install a new 4K magnetic screen. Install electronics rack in the cabin and connect. Mount the anti-vibration legs on the pumping stage. In the evening, start cooling down.
15-17 May 2013: cooling down
18 May 2013: check resonances in a dark configuration and end the preparation as soon as it is ready. The cryostat stays cold until the observational run 6 in June.
Alessandro Monfardini, Martino Calvo and Nello D'Addabbo come by car from Grenoble.
Daily Reports
Tuesday 14-May-2013:
All planned operations completed. Furthermore, mu-metal screening on 4K and 50K stages:
- on 4K screen: (inner) METGLAS 2714A 2.0 inch x 0.6 mil std spec (bat), mu about 10000 @ 4K (see figure below); (outer) VITROVAC (same put on Sionludi @ Institut Néel)
- on 50K screen: only METGLAS
figure: METGLAS mu at 4.2K, real and imaginary parts.
Installed NICA_8f1 18nm IEF (litho at PTA) tested in run HE34 in Grenoble at 2mm. At 1.25mm left the NICA_8e 20nm IRAM we had for runs 4 and 5.
Cooling down started at 17:30. Everything seems correct. Only (known already) problem is a small leak (1.5e-7) while circulating for the preref. The leak is proportional to the flux.
Wednesday 15-May-2013:
Fixed a problem preventing the NIKEL boards to kick on automatically (still to be investigated in Grenoble with Olivier). Fixed an annoying problem preventing to control properly the cryostat. We have installed a brand new blue ethernet cable going directly from the main NIKA switch in the cabin down to the "automate" of the cryostat. Now the connection is OK, no more risks of losing control so far.
In the afternoon, taking advantage of bad weather preventing observations, we have installed the whole NIKA optics (curved M6) and laser-aligned the system in order to be ready for the next run. Replaced, with Santiago and Gregorio, one broken anti-vibration leg of the table holding the cryostat. We also made new semi-rigid cables for better connecting the electronics to the cryostat. Gregorio says we have used the VERY LAST one available at Pico Veleta. Since they break very often (every time more or less) not to be forgotten buying few more before the next run.
21h30. Snowing. T_4K=6K; T_still=8.4K; T_BM=9.5K. Reduced strongly the preref flux. Now ev5=0; J4=1200mbar; J2=270mbar.
figures: Cryostat status at 21h30 today. J1 zero-point is at -15mbar actually, means the 3He pump in is at 15mbar.