Drilling and deployment of the 13th hole of the season – hole 56, was finished in the early morning of January 29th. This brings the total count of deployed in-ice strings to 22 containing 1320 Digital Optical Modules, and 26 IceTop stations (52 tanks) with 104 IceTop DOMs. As the installation activity draws to a close the emphasis shifts to packing up the equipment for next year, connecting and closing all of the newly-deployed strings, DOM commissioning, and getting the data acquisition and data handling systems running. The IceCube population at South Pole on February 5, 2007 is 48 - 24 drillers and 24 non-drillers.
Drilling of hole 13 concluded on Sunday, Jan 28, and draining the system of water began immediately after deployment was underway. Once water was drained from all external hoses and the hose reels, the drillers took a day off on Monday Jan 29. On return, the pack up began again in earnest. All the water was blown out of the heaters and pumps in all buildings, then the whole system was flushed with Glycol and drained. This took about 2 days. All do not freeze (DNF) equipment was removed from all buildings and each building was sealed up in preparation for winter. All buildings are now ready to move to next year's seasonal equipment site (SES). The pad has been compacted and we expect to move all the buildings into position on Tuesday, February 6.
String 56 is now in place and has begun the freeze-in process. The deployment team took a break on Monday, then began the week-long task to inventory all of the equipment and pack the equipment for storage on the winter berm. The deployment photographs that have been stored on the local server have also now been archived and prepared for transport back to Madison. Additionally, work has begun to close all of the trenches for the summer season.
Of the 780 new in-ice DOMs, only 1 DOM failed the connectivity test and appears to be totally unrecoverable. Quads feeding the newly-deployed IceTop tanks remain disconnected until IceTop tank closing due to the potential danger of accidentally powering up a DOM that is still exposed to the sunlight.
The ICL was officially released on January 22. The west cable silo of the ICL is quickly being constructed.
There is reason to expect that recent upgrades to one of the satellites (TDRSS) may result in higher-than-anticipated bandwidth available for the South Pole science community. During a recent satellite pass, it was reported that TDRSS transferred over 97 GB of data from Pole. If it is possible to sustain such rates then the two largest clients of this satellite service, IceCube and the South Pole Telescope, will be able to send more data north.
To date, eight of the nine old strings and the first five of this year's strings (58, 67, 66, 74 and 73) have undergone all of the commissioning tests. A large volume of data has been taken. The recent TDRSS satellite upgrade has resulted in IceCube being able to transfer more data than previous years via another satellite–SPADE. Hence, most of the data we take during commissioning can be transferred into the data storage warehouse in Madison quickly. A large amount of IceTop data has been taken for calibration purposes, in coincidence with the muon telescopes. The data-quality has been good. We are currently working to bring the AMANDA system under IceCube experiment control which will allow a common starting and stopping of runs. Additionally, the IceCube trigger is being modified to accept AMANDA software triggers.
After exactly one week of on-ice time, the DAQ group covered a lot of ground. The DAQ developers are quite confident that we have no insurmountable problems at the moment. The system is showing itself to be quite flexible and easy to use and debug. During the next two weeks, as IceTop hubs become fully available, the DAQ will integrate the IceTop system.
The IceTop crew, with the help of many IceCubers, was busy packing the SPASE shack and the IceTop summer camp. The SPASE shack has been completely cleared. Staff began the closing procedure of this year's IceTop tanks. Four out of 10 stations are closed as of today. The figure at the right shows IceTop Tank 65A just before it is dark-adapted and closed up.
On Saturday, IceCube hosted a party organized by the drillers to celebrate the successful season. The Southern Hemisphere was the place to be in late January – Comet McNaught has produced spectacular astronomical photographs. Here is a photo of the comet taken in Christchurch on a partially clear night. Absolutely a fantastic sight!