South Pole Weekly Report, January 19, 2008

The 14th, 15th, and 16th strings of the season were successfully deployed this week. Drilling has been going steadily and a logging run was performed on the last hole of this week. Eight strings have been commissioned with a few quads not connected because the sensors were not frozen yet.

The safe production of deep ice holes and the subsequent string installation continue to be the focus of on-ice construction operations. The IceCube population at the end of the week is at 44. We now have all 18 Surface to DOM cables at the Pole as well as enough DOMs to support 18 strings. A small amount of additional DOMs arrived this week which will be stored in the ICL for next year's start-up. We have 17 Surface to DOM cables on the ice as well as enough DOMs to support 18 strings. The 18th cable is scheduled for delivery this coming week. A small number of additional DOMs coming in will go to next year's startup. We are planning only one string of DOMs plus IceTop DOMs as an early season startup buffer (one less than originally envisioned).

A Basler aircraft is taking off to support the Norwegian-United States traverse team. The ICL and the SES are visible in the background.

Photo by Ethan Dicks

This week saw a lot activity in drilling as it began on Monday morning with 3 holes being completed by Saturday afternoon. Work continues on next season's Seasonal Equipment Site (SES) berm and on compaction of the hole locations and roads. We expect that this activity will be completed by around next Thursday and will become available for us to start relocating equipment and to continue drilling firn holes for next season. We unpacked the hose heating equipment, tested the heating blankets, and are awaiting additional equipment for the hose heating and hope to have it in time to install it on the hose reel during the last hole. We have also begun some preparatory work to be ready to start winterizing the system as soon as the 18th hole is completed.

We are currently slightly ahead of schedule and expect to finish hole 18 sometime on Thursday evening, then blow the water out of the system before taking a 2 day weekend and completing the rest of the shutdown activity the following week.

Strings 52, 44, and 53 have been deployed within the last week. The night shift has been busy handling the DOM installation over while the day shift has been helping with the preparations for the deployments and running the special device activities. An inclinometer was installed in Hole 44, the Dust Logger was run prior to the installation of String 52 and, most recently, the Hole Logger was run prior to the installation of the DOMs in Hole 53. While the data from the Hole Logger is still being analyzed, last night's run went extremely well and data from the exercise should help with future freeze-back models.

The day shift doing the cable drag.

Photo by Albrecht Karle

After the installation of each string, the deployment crew meets to check on the status of the Surface to DOM cable, makes sure that the cable is secure and drags the excess cable from the deployment winch over the tower and into the Ice Top trench. The cable guys connect the cable to the Surface Junction Box and make sure that the signal is received in the IceCube Laboratory (ICL). The procedure requires the dedicated effort of the cable staff, full and part-time deployers and management-volunteers who are available. After the cable is properly positioned in the trench deployers disconnect the power, brake, information cables, and the associated winch from the TOS and roll them up for the drillers to pick up during the next drill site move.

The freeze control on IceTop now runs smoothly, which is probably due to having three heaters in the Freeze Control Units (FCUs) instead of light bulbs, so the heat inside the FCUs is very stable and does not drop.

The freeze process itself has been slightly slowed down by mild ambient temperatures and snow buildup, but cleaning the tanks helps, so four stations are already frozen almost to the bottom. These are the first four stations that were deployed, namely 62, 54, 63, and 45.

Drill and string installation times are shown for the strings deployed to date in this season. The deployment times include the time for removal of the drill from the hole. They also include in some cases special logging runs.

Graph by Albrecht Karle

Three strings were deployed this week: 52 , 44 and 53. Numbers 52 and 44 passed both connectivity tests and had patch cables run to the DOR cards. All strings up to 44 have been tested and are attached to the DOR cards awaiting commissioning. All but 6 Surface Junction Boxes (SJBs) have been buried and the trenches backfilled. A second inclinometer was deployed this week and a successful hole log took place at hole #53, prior to string installation.

Preparations for winter storage in the ICL continue. The snow ramp is scheduled to be removed by Jan 29th and all winter storage DOMs are scheduled to be in the ICL by that time.

The STD (South pole Tester of DOMs) gathered all DOMs that for some reason needed to be retested. There are 32 new and 24 old DOMs, of which 6 have broken connectors. We will try to deploy as many of these as possible or use them in IceTop; also, an inventory of all DOMs not needed for this season is being set up. We expect to ship 8 or possibly 12 DOMs north and store about 80 DOMs in the ICL over the winter.

Beginning on Jan 13 we took many hours of TestDAQ and pDAQ data using string 62 (which was in water) together with five of the newly frozen strings. During this 3-day data-taking period, the real-time DOM Hub Monitor software was used to closely watch the in-water DOMs for signs of dangerous current increases (this happened on two DOMs last year), and TestDAQ data was periodically taken to determine if the DOMs were stable. On the third day, during a period when pDAQ was crashing mysteriously, TestDAQ was used to quickly determine that the cause was an external light source. It turned out that the dust-logger was being used during the deployment of string 52!

DOMs being frozen-in

Stefan Klepser

As of Jan 20, eight strings have been commissioned and we are ahead of schedule. However, by moving ahead of schedule, we now have four commissioned strings with one or two unplugged "orphaned" quads (because they contained DOMs which were not yet frozen-in). These strings will need to be re-commissioned later in the season.

We began commissioning three new strings with 22 strings previously commissioned. As planned, the individual strings were first run stand-alone, yet in parallel with the normal physics run. Four hours of unfiltered data with old+new strings was taken on January 16 without AMANDA (TWR) data and saved for transmission over the satellite. Filtered data was taken January 19 which included AMANDA (TWR). The runs were all successful. Though the number of additional strings is small, the runs were important to test and refine the commissioning procedures, and demonstrate that commissioning can occur without undue perturbation of the physics run. The next milestone will be to run unfiltered 8 new strings with the previous 22.

There was one reportable safety incident this week. A scientist fell off a snowmobile and unluckily got his foot caught and pulled in between the tracks and the body of the vehicle. He was on crutches for two days, but should now be fine (he left pole on schedule). Those new to snowmobiling will be advised on how to drive over uneven terrain safely in the future, to wear ECW gear, and to carry radios in case of emergency.