The IceCube population is 48 as of January 14. There are 30 drillers and 18 others, including staff from IceTop, deployment, cables, counting house and data systems as well as winterovers.
Excellent progress was made in drilling in the past two weeks. Four holes were drilled since January 1 with the drillers operate in three shifts. The total time for one complete cycle of firn drilling, drilling in ice and moving the equipment is around three days.
The most recent string (78), the 8th string of the season was deployed on January 14.
Severe weather constrained the drillers as they battled winds of well above 20 knots when they moved equipment and hoses to the next location. Special compliments go to them for working through that move without any delay. The ground visibility was at times below 20 m making all outside work difficult. It made it also a challenge to keep orientation when driving a vehicle.
Deployment has been going very smoothly on most strings. There will be no more holelogger or dustlogger runs this season. Additional acoustics detectors were deployed at shallow depth on string 72 and string 78. Radio sensors were deployed on string 78. The deployment went well and first inspection of the sensors after deployment look good.
All surface cables are pulled inside the ICL and connected to the patch panels. All new cables have been tested for WCT (wet connector test) QCT (quad connectivity test) 8 strings.
Last week the South Pole System was released for use. This is the software that handles the data as it comes from the Digital Optical Modules. The GPS clock is up and running, but not yet synchronized permanently to the satellite. Synchronization fiber link between MAPO and ICL has been debugged and awaits final testing. A lot of work was done last week with decommissioning of the Temporary IceCube Lab and preparing equipment for retro shipping. RPSC reported that the satellite upgrade has been tested and found good. Total throughput will be ~60GB/day. Our requirements are 15 GB/day.
To date, five IceCube strings have been powered up in the ICL. They are strings 38 and 39 from last season, and 58, 67 and 78 from this season. Strings 58 and 67 are the first two strings deployed from this season (deployment dates were Dec 15 and Dec 19) and string 78 is the most recently deployed string (deployed Jan 14) which started being operated in water a few hours after deployment. All DOMs look good so far on strings 58 and 67. One DOM on string 58 (58-51) is still in water.
IceTop filled the last two stations on January 8. The filling of all tanks went very smooth. Thanks to all who helped make IceTop deployment successful! All tanks have now been opened and are freezing nicely.
The water transport tank has be decommissioned and it is ready to be stored for next season. The storm mentioned above dumped several inches of snow on top of the IceTop tanks. The snow must be scooped off or the ice freeze rate will be reduced dramatically. A barometer was added to the IceTop freeze control system.
DOM testing is proceeding as planned. All DOMs up to string 12 are tested. To date 749 DOMs were tested this season. The system of on-ice testing works very well and is significantly more efficient than in the previous season.
Only about two weeks remain for drilling and deployment. Then it will be time to secure the site and equipment for the season. All hands will depart by February 15 except the winterovers, of course.