The week was dominated by the shut-down of drilling operations as well as String and IceTop Commissioning, and the start of Verification and Calibration. Major activities continue to be ahead of schedule and preparations are underway for the departure of IceCube personnel, station close, and the transition to winter-over activities.
The IceCube population at the end of the week is at 43. All cargo has been received that is scheduled to date. All Retro Cargo for vessel has been delivered into the USAP cargo system. There are a few minor air shipments (as planned) of items that could not meet the vessel shipment date.
Drilling activities this past week concentrated on winterizing the camp for the winter. The beginning of the week saw us complete the process of blowing water out of the system, then running glycol through the plumbing before finally blowing the system dry. After that all the hoses were disconnected and "ran dry", then the Do Not Freeze (DNF) items removed from all the buildings before they were sealed for the winter and had power shut off.
Both Tower Operating Systems (TOSs) were moved into their winter position on Thursday afternoon and the Seasonal Equipment Site (SES) was relocated to the 2008-09 site on Friday morning. The move took around 2.5 hours and went very smoothly. Once the SES was relocated all the crates were positioned between the buildings to minimize drift between them. The camp is now fully winterized.
The hose reel heating blankets were installed and the hose reel was moved into position. The system appears to be working but some temperature set point adjustments still need to be done.
Firn drilling of next year's holes continues, although not without its problems. We encountered debris in 3 of the 4 holes drilled so far. It appears we hit a parachute in holes 27 and 28, but we managed to drill around it and complete the firn hole down to 40m. In hole 37 we hit a box of meat sitting directly under the drill. We were unable to easily proceed past this obstruction, so we temporarily abandoned this hole until we come up with an alternate plan. Ratheon Polar Services Company (RPSC) has been asked if they have any documentation on the area which would give us a clue as to what is down there and we plan to have another look at the ground penetrating radar data to see if there is anything we missed. We are currently drilling next year's Rod Well hole and that is nearing completion as this report is being written.
Most of the drill team will be departing South Pole on February 5. Four drillers will remain until February 11 to complete some maintenance work on the camp, install the fall restraint system, conduct inventory of the drill equipment and winterize the firn drill.
This is the final drill report for the 07-08 summer. Thanks to everyone for their help and support in making this a very productive season.
This week the Deployers inventoried all of the left over equipment from the 2007-2008 season. One nine sensors remained from the 18 hole season as well as twelve of the 15.5 meter and 11 of the 2.5 meters steel cables along with 144 Deployment weights. All of the equipment was boxed, secured and transported to the new SES where is will be stored for the coming season. The DNF equipment was either stored in TOS 1 or shipped north for evaluation.
I would like to take this opportunity to thank everyone who worked with the Deployers over the season. Thank you for your dedication and hard work!
All IceTop tanks were closed by Jan 30. Many thanks to GAs who did an excellent job in 3 days and brought back all the sunshade frames in good shape. Sunshades themselves show usual tear and wear, inspection & repair is continuing. Low level commissioning of the IceTop DOMs was started immediately after the tanks were closed. All passed the current and timing tests. As of now, 14 tanks were declared fully frozen and safe to remove their Freeze Control Units (FCUs). The rest of 14 tanks still show some sump activity; 1 or 2 more is expected to be removed in the next couple days.
As the 2007-08 Austral season is winding down, there is less and less to complete. This week the remainder of the newly deployed strings were tested in the ICL (some re-tested) for Quad Conductance Test and Wet Conductance Test. All strings have been connected to their respective hubs and handed off to commissioning and verification. Most of the strings are frozen in.
The winter storage cargo continues to show up at the ICL and the first floor is filling fast. At last count there were 149 DOMs in storage, 14 IceTop freeze control units and a handful of DOM test cables and harnesses. Final counts will be made on Monday, Feb 4th when there is a final cable inventory of the ICL.
On Sunday, Jan 27th, the first annual South Pole Bocce Outing took place. Michelangelo D'Agostino, Ryan Bay, Olle Engdegard and Mike Kleist competed in a two team race to 15 points. Temperatures were around -30F and windchills were around -50F. The final point was played using the geographical pole as the target. The D'Agostino/Kleist team won a resounding victory by a large margin and will be the team to beat next year.
Congratulations and thanks to all who gave a tremendous effort to this season's drilling and deploying. It's been a great season!
All on-ice DOM testing for the 07/08 season is complete. The Optical Module Laboratory (OML) was repositioned to a new location closer to the station Hypertats to make set-up easier and quicker. Station IT services were removed and the power shut off. The module will go cold for the winter. The total DOM storage at the ICL is: 149
Operations in the ICL data center are running smoothly with nothing major to report. Additional environmental monitoring sensors are being installed so better environmental information from inside the data center is available during the winter.
Commissioning: (Alfio Rizzo) On Jan 28 we finished commissioning the group of four strings, which would represent IC34. To mention that on string 61 we noticed a fluctuating rate on DOM 32 (Norman_Bates) as shown in the picture below. The commissioning of the new IceTop stations is also ongoing and will be finished on Feb 03.
pDAQ commissioning continues to go smoothly with the current maximum number of strings tested at 34. CPU loads and data flow consistency in IC34 look good. The entire set of new IceTop DOMs are expected to be turned over to pDAQ for testing within 48 hours; this set will represent the next integration milestone to tackle. On the pDAQ side, verification operations have been relatively trouble-free despite the newness of the flasher functionality and our emphasis is on supporting verification activities described below.
We started data taking for flasher-based timing verification and phase II geometry calibration on 29 Jan 08 SPT. To check that the software was working, an initial dry run was performed using an IC22 string whose timing and geometry were already well known. N.B.: We wish to highlight the virtually flawless performance of pDAQ in taking this data and express our thanks to the pDAQ team for making the verification and calibration job that much easier.
The dry run was successful, so on 30 Jan timing and geometry data were taken for strings 64, 71, and 77. The timing verification runs with a single string and requires 8 minutes/string. The geometry calibration algorithm uses surrounding strings (up to 6) and requires 20 minutes/string. Errors in geometry are reduced by taking data on one or more nearest neighbor strings. Since many of the new strings are nearest neighbors to IC22 strings, data was taken on some IC22 strings as well. Strings 64 (new) and 65 (IC22) are two such nearest neighbor strings.
The next day timing verification data was taken on strings 63, 55, 70, 76, 75, 69, 68, 61, and 62. Geometry data was taken on 63, 70, 76, 75, and 69. We have not taken geometry data on 4 strings that are otherwise ready, pending the handoff of additional new strings from low-level commissioning and pDAQ. At that point, when we reach IC37+, there will be better nearest-neighbor coverage, and we will take geometry data on additional new strings. The handoffs from pDAQ to Commissioning and Verification have gone very smoothly. Some issues with getting DOM information into the database cropped up but were resolved in about a day. All timing and geometry data are processed at Pole using the Verification cluster.
The phase II geometry measurements agree at the level expected with the phase I geometry measurements from the deployment logs. String 64's final depth was by cable mark (the pressure sensors failed) and not surprisingly has the largest delta relative to its phase I depth. The figure below shows the first rough guess depth for the geometry data processed thus far. The turnaround time for producing this plot was extremely quick - only about 24 hours - due to the extensive work done over the past year to automate this process. Final geometry numbers will be produced in the north after global fits involving larger numbers of strings are completed. We anticipate completing the phase II geometry measurement for all strings several weeks after station close, well ahead of schedule.