UW-River Falls

O.M. Submersion Test

IceCube 2007 Home

We submerged an O.M. under the water level of our tank in an effort to check how much this would effect the signal size coming from that O.M. The signal area from the O.M. to be submerged was measured at an average of 78% the size of its companion O.M.s signal when both were looking at muon events qualified by a muon telescope. When the O.M. was submerged so that its top was level with the water level it had an average signal area of 88% of its companion. Then when it was submerged another 18 cm it still had an average signal size of 88% of its companion. This doesn't make any sense as I'd expect the the signal size to decrease as the OM saw less and less of the tank in front of it.

Crack Simulation Test

To see what would happen if a crack formed in the ice of an IceTop tank we ran a series of tests in our tank. To simulate the crack we used a large sheet of black material, 40 cm by 2 meters. It was suspended between the O.M.s so that its top was level with the top of the water and it separated top portion of the water. Later, it was suspended at the bottom of the tank so that it separated the bottom half of the water. In both cases the area of the signals from the O.M.s were collected and the average difference between the signal areas was collected. This data was compared to each other and the data from when no sheet was in the tank.

	Signal area as a % of "uncracked" signal area	Difference in OMs as a % of average signal size
No Crack	100	20
Top 40 cm	66	24
Bottom 40 cm	55	25

From this we can see that putting a large "crack" in the tank drastically reduces the average size of the signals the OMs put out. That comes from the first column of data.

Secondly we see that there is a slight increase in the average difference between the OM signals relative to the average signal size of the OMs when they are partially separated by a crack. I think that this effect might have been underestimated by the way my oscilloscope compared the OM signals, but I haven't figured out a better way of doing it yet.

Furthermore, a crack at the bottom of a tank seems to have more effect than a crack at the top of the tank, which makes sense if you consider the OMs field of view. More testing will be done using a larger sheet of material to seperate the OMs more completely. Also, note that we are assuming that a crack in ice would behave rather like a completely black sheet in these experiments, when it might not actually be that opaque.

IceCube 2007 Home

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O.M. Submersion Test

Crack Simulation Test