South Pole Weekly Report, December 21, 2008

It was a busy week of arrivals and departures for the IceCube team at South Pole. Eight individuals left and six new people arrived this week as planned. The current population stands at 50. We had a very successful week for IceCube construction with three more holes drilled for a total of seven this season. IceTop tanks have all been filled for a total of 38 this year. All cables have now been pulled into the ICL.

The simco drill.

Photo by P. Sandstrom

The week started off with the completion of the partial drilling of the 5th hole for logging and ended with completion of the 7th hole of the season. The drill crew took their day off after drilling of the 5th hole down to 1450m and handed it over for logging at around 5:00am on Dec 14. Once logging was completed, the hole was redrilled according to the drilling charts for a 30 hour hole and was completed at around 10:00am on Dec. 16. Deployment was completed without any problems. During the day off a skeleton drill crew fixed the bad wraps on the drill cable by unwinding it out and rewinding it back under tension while paying close attention to the wrapping. It appears the effort was a success. Drilling of the 6th hole of the season began on Wednesday, Dec. 17 at 8:30am and was completed at 3:00pm on Dec. 18. We discovered that the Yale grip securing the drill head to the cable had slipped, resulting in the signal cable connecting to the drill head being very taut. We added a second Yale grip and at the end of the hole an examination revealed that it was doing the job. The same fix and some additional modifications were used to drill hole 7. The hole was completed on the second shift on Saturday, Dec. 20.

The drill overall continues to behave pretty well. Heaters continue to be generally reliable. The generators continue to require ongoing maintenance to keep them working reliably and some hose and cable reel problems continue to require ongoing maintenance. However the system as a whole continues to operate pretty well. The Rod Well is now very mature and requires minimal heat to keep it developing. The well was measured on Wednesday and found to contain over 100,000 gallons of water. Firn drilling continues ahead of the main drilling operation. The Hole 37 firn hole continues to be a problem. However a few access holes drilled with the Simco drill are promising and we hope to get through one of these holes using some hot water to clear the debris before continuing to drill with the firn drill. The crew all appear to be healthy and are looking forward to a 2 day break over the Christmas period, after completion of the 8th hole.

Drill hose setion being replaced.

Photo by P. Sandstrom

This week featured no new incident reports and zero reportable injuries, marking over 49 days on the ice without a reportable injury. This week's safety audit looked at the cable drag process. Several improvements were made to this process in the off-season including new rollers on the fairlead and more non-slip grating to the top of the TOS.

Strings 19, 20 and 13 were installed in the Antarctic ice last week at the South Pole. We have not identified any anomalous DOM spacings during the three installation activities and only one DOM connector has been broken. According to Kurt Woschnagg, "All in all another smooth and painless deployment."

This week in DOM testing we finished SPATs 11, 12, and 13. SPAT 11 had two stf failures, so there were 60 DOMs ready to be deployed on String 13 and 2 spares. SPAT 12 had no failures, so we have 60 DOMs ready for deployment on String 12 and 4 spares. SPAT 13 has one questionable DOM which will be discussed after the morning meeting on Monday, which means there are 60 DOMs ready for String 11, and at least 3 spares. We currently have around 130 DOMs in our buffer (not including the two that were dedicated to J. Marty and UW Platteville at J. Marty's retirement party). Also this week we saw the same issue as last week with breakout box 2. There seems to be an intermittent problem which shows up only during the LC tests, probably due to a wire that needs resoldered. We discussed whether or not to fix it but, since we don't have any spare breakout boxes and the problem is minor, we decided that it's no problem to just switch around the two affected connectors (10A and 10B) at the end of the cycle and rerun our LC test, which only takes a few minutes. We'll fix this breakout box at the end of the season and hopefully we'll have some spares for next season.

Cables running across the East Tower bridge into the ICL.

Photo by M. Kleist

A major cable milestone was reached on Tuesday with the final cable pull into the ICL. A total of 20 cables were pulled into the ICL this season. This pull enabled IceTop to fill their final 10 tanks (5 stations) and complete their installation season on schedule. Three strings were also deployed this week, #19, #20 and #13. One wire pair (two DOMs) failed the Wet Connector Test (WCT) and all quads passed the Quad Connectivity Test (QCT).

One of the traverse vehicles that arrived at South Pole this week.

Photo by R. Paulos

All 38 IceTop tanks have been deployed and filled; 32 are freezing and 6 are in the cooling pre-freeze phase. Opening the last six tanks, installing their sunshades, and backfilling as appropriate will complete the IceTop phase one. Phase two consists of monitoring the freeze-in of all 38 tanks and keeping the ice surfaces clear of snow and frost.

All In-Ice Hubs were brought online just in time for the commencement of string commissioning. The Event Viewer software was upgraded and is running both in the ICL and in B2 (Science).

The SPATS acoustic pinger was successfully deployed in hole 19 on Dec. 16 between 9:30 pm and 11:15 pm, 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 pinger data for hole 19 has shown that the sensors of string-D, located at over 800m horizontal distance, clearly see a pinger signal above noise after averaging.

J. Marty being saluted as he leaves to board a plane home.

Photo by M. Krasberg

Newly designed quad cables called "Switchers" and "Combiners" were tested in conjunction with SPOTS/SPITS (the South Pole "Outdoor" and "Indoor" test systems) and were found to work as intended. This will simplify commissioning. These cables enable us to route any wire pair to the wire pair of choice on a DOMHub. The first two strings of the season were briefly turned on (strings 18 and 27), both just two weeks after deployment (the timeline estimates frozen commissioning at deployment more than 3 weeks. String 18 had fully frozen-in, and all DOMs worked (including local coincidence). The second string (#27) was turned on by P. Hulth. It had a small section of DOMs that were still in water at around position 45. Everything looked good.

The San Francisco Exploratorium Ice Stories staff arrived on Dec. 18. A webcast with IceCube occurred on Dec. 19. They were given tours of the station and of IceCube. They enjoyed the IceCube event display and would like to place one at the Exploratorium alongside the DOM that is on loan to them.

The South Pole traverse team made it to Pole this week delivering important cargo and fuel.