South Pole Weekly Report, December 14, 2008

With the arrival of the new On-Ice Lead on December 9, the total IceCube population stands at 52. This has been a big week on all fronts: two more holes drilled (total now 4); 3 more strings deployed (total now 4); surface cables for trunks 2 and 3 (out of 4 for the season) pulled into the East tower and connected; 18 more IceTop tanks filled (total now 28 of 38); and DOMs tested for the next two strings.

Drilling at Hole 19 deploying at Hole 28 on December 13.

Photo by T. Gaisser

The week started with the completion of the second hole of the season and ended with the partial drilling of the 5th hole down to 1400m in preparation for logging the hole. Drilling of the second hole of the season was completed on Monday. This proved to be a little more difficult than the first hole due to problems with level winds, some other sensor reading problems and drill cable wrapping problems causing the cable to knife. However the drillers persisted, producing a hole which was estimated to be slightly smaller than anticipated at its narrowest spot, however, still good enough to deploy. Deployment was completed in this hole without a hitch.

Night-shift deployment team with the last DOM of String 27, December 8.

Photo by T. Ham

Following completion of hole 2 (#27) the drillers took a well earned day off before commencing drilling of hole 3 (#36) at around 3:00pm on Tuesday and completing the hole on Thursday. The 4th hole of the season (#28) was commenced on Thursday, Dec. 11 at around 3:00pm and completed at 3:30am on Saturday, Dec. 13. We had to temporarily bypass hole 37 (the original 5th hole of the season) due to problems with firn drilling of that hole. We've encountered debris at the 3 attempts we have had to firn drill that hole and decided to skip it and to return to it when we do the deep core hole later in the season. In the meantime we had another look at the GPR survey and discussed that hole with S. Arconis, the survey author. This confirmed that hole 37 has a lot of debris around it. The decision was made in the field to try and find a way through the debris using the Simco drill, as this was a much faster way than the firn drill to determine if there was debris at a particular spot. After a few attempts with the Simco drill we found a way through the debris field some 8m away from the original hole location, toward the ice top tanks. It remains to be seen if the firn drill will get through that hole.

In the meantime, drilling of hole 19 (the new fifth hole for the season) began at about 11:00am on Saturday and had reached 1400m by the end of the afternoon shift that day (around 11:30pm). As this report comes out, the hole should be in the process of being logged over a 24 hour period while the drillers take their assigned day off. The equipment is generally behaving itself. We have had some cable wrap problems as discussed above, but that seems to be slowly coming along well. Some sensor problems with level winds, shaft encoders and load cells have been corrected or are being worked on. The fuel system continues to work very well. The new Y-strainer flushing system continues to work well, with only the occasional heater problem which is quickly resolved. Firn drilling continues to go smoothly (when we don't hit debris) and is currently drilling at hole 11. It appears that the firn drill couldn't get through the Simco drilled hole at 37, so more test holes with the Simco drill are being planned. The firn drill is still operating manually while tests are being conducted on the new automatic control software.

Cable artistry: Connecting the surface junction box at Station 18.

Photo by J. Haugen

This week we had no lost time or OSHA reportable injuries. One safety audit was conducted this week with first shift drilling operations in TOS1 the focus. Proper personal protective equipment was worn by both drillers in the TOS (hard hats, gloves). Also, good teamwork was used during the process as one driller taped the drill cable and hose and another monitored the computer and the level wind on the supply hose reel. Safety scissors were used to cut the tape and although the TOS was a bit cluttered, all pathways to exits were clear. No safety deviations were noted.

The week began with deployment of the second string of the season at location 27. The third and fourth strings were deployed at locations 36 and 28 on December 11 and 13th. Hole logging at location 19 is underway during the weekend.

In the last week of DOM-testing we completed the SPAT 9 and 10. SPAT 9 and 10 consists of 64 regular DOMs (in ice) and 60 of each SPAT will be deployed on Strings 19 and 20. In SPAT 9 no DOMs failed during the test cycle, but in SPAT 10 there is 1 light leak and 1 database problem. The failed DOMs will be retested in one of the next SPATs. SPAT 11 is already in the tent and the test-cycle will start at the beginning of this week.

DOMs freezing in at Station 6.

Photo by J. Roth

The past week was very busy and eventful for the cable team. We managed to get 10 surface cables pulled into the ICL in two cable pulls, trunk #2 on Monday and trunk #3 on Thursday. Along with pulling into the ICL, the cables were also patched into the patch panels and connected to IceTop power, comms and DOMs. Parallel to that, two strings were deployed, connected in junction boxes and patched through to DOR cards. All strings this season have passed Wet Connector Testing (WCT) and Quad Connectivity Testing (QCT). Cable drags (post-deployment) and TU-20 winch preparation have become routine and continue on a schedule of every two or three days.

In order to keep the aggressive schedule of filling four IceTop tanks a day it takes a tremendous amount of work. IceTop cables need to be connected in the ICL, SJBs connected in the pits, DOMs installed, FCUs installed in the tanks, contactor assemblies installed in the tanks and water supplied at the tanks. Thanks to the team members who are leaving. They leave us in good shape with all of the DOMs installed and the remaining tanks well prepared for filling. They will be missed!

We worked on the transition of servers and addition of new storage. In the past week the processing and filtering storage was added, and the new SPADE (data processing) servers were commissioned. Maintenance and upgrading all network devices is almost finished. Work on reconfiguring rack 15 to support inner core hubs was started, and hopefully with the transition to new DAQ servers this work can be completed in the coming week.

Attaching DRM to Yale Grip

Photo by P. Sandstrom

The first of three radio detection clusters of NARC was successfully deployed in Hole 36. The deployment involved the attachment of five antennas, five electronics vessels and a Digital Radio Module (DRM) spaced out along 32 meters near the top of the IceCube cable. This cluster was a "shallow deployment" at a depth of 250 meters and uses a separate, small diameter cable for power and communications to the surface. The installation, final drop, and string tie-off took about four hours and went quite smoothly. Extensive pre-deployment testing was performed on all three clusters while they remained packed in their specialized shipping/testing crates; communications during testing was via a temporary connection through the surface junction box of IceTop trench 36.

The SPATS acoustic pinger was successfully deployed in hole 28 on December 13 between 7 am and 9am, it went down to -500m, stopping at 5 of the 9 SPATS instrumented levels. The pinger was set to transmit pulses at a 10Hz rate, the sensors recorded 18s of data every 4 minutes. First analysis of the data is ongoing. Last week the SPATS array was in transient mode, we clearly heard the IceCube drill passing by our instrumented levels.

We have had a series of visits from distinguished visitors (DVs) recently. The event display is a real asset that needs to be maintained and always available in B2 and, if possible, in the ICL. The group below started their visit to the drill camp with a visit to the IceTop weatherport, which is a convenient place to show off a DOM and answer questions inside.