10 December 2009 IceTop update and IceCube string deployment

Journal

We are continuing to keep up a great pace on the IceTop DOMs (light sensors) and tanks. At this point, all the DOMs are in place for this year's schedule of IceTop, and most of the electronic interfaces are in place as well. We are filling the tanks rapidly and should easily be finished by the time I leave next Friday.

Looking down into an IceTop tank — An IceTop tank, filled up and ready to start freezing! Those are my feet…

And all this despite some more difficulties!

At some point, a whole series of DOMs was exposed to high voltage at a time when they were also exposed to direct sunlight. The photomultiplier tubes on these DOMs are so sensitive to light that they can detect a single photon, so trillions of uninvited photons could overload the circuitry and cause the DOM to malfunction. So after some panicking and hypostulating, the DOM testers ran some tests and it seems that the DOMs are OK.

IceTop deployment team — Standing in front of an IceTop tank, are James Roth, Dr. Hermann Kolanoski, and Chris Elliott. The cloth cover around the tank is to help prevent direct sunlight from hitting the fragile DOMs and overloading the light sensors.

We have also seen two previously unseen failures in the mechanisms that help freeze the ice to crystal clarity - in one case, an overflow pump refused to work, and in another, the mechanism that removes the dissolved gas from the water flooded and couldn't function any more.

Snow angel — John Salvato is the man when it comes to hauling around the 1600 gallon IceTop fill tank. When he's not hauling stuff around in his bulldozer, he likes to enjoy the light fluffy ice crystals that drifted into our work area.

A third failure was more foreseen, and attributable to me... :( When installing some electronics, it seems that a wire assembly for some temperature sensors got damaged and had to be fixed. Mistakes of this type usually result in the person at fault having to purchase a case of beverages for the rest of the crew... I don't think they'll let me off the hook for this one!

IceTop tank, starting to freeze — Here is a view of an IceTop tank, in the process of freezing. It doesn't look particularly clear, but that's because of a layer of ice crystals on top which don't affect the sensor. It will take approximately 53 days for this amount of water to freeze solid!

It's remarkable about how well-organized these projects are. Of course we expepct to face setbacks, but even the most major setbacks are resolved in relatively short amounts of time due to good planning, communication, and experience of the people working on IceTop and IceCube.

On a related note, I had the opportunity to participate in the deployment of one of the IceCube strings of DOMs. These are the strings that drop into 2.5 km deep holes in the ice, and try to capture the elusive neutrino interactions from deep space. By "participate" I mean: stay out of the way of the people doing the real work. Here are some photos to help show the process: