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Another day at the ranch
TIGER finished up a 48-hour run today. The instrument
collected 41 "whoppers" yesterday during the first half of its run,
when I set the thresholds rather low, so that more minor particle
showers triggered the instrument. After switching the thresholds
higher to levels similar to what we will be using during flight after
about 24 hours, the instrument was able to collect 16 whoppers.
Although this seems like a rather small amount of data, the higher the
instrument climbs in the atmosphere, the more particles we'll be able
to collect. Of course, by "collect," I mean that we can collect
information about particles passing through the instrument. Since
TIGER is designed only to trigger on particles that escape through the
bottom of the detector, we don't actually "collect" the particles per
se. Since the heavy atoms that we are looking for interact and
blow apart very easily in the atmosphere, the showers they create are
so spread out and so low in energy that it is more rare to see them
this far down. When TIGER is balloon-borne, however, there are
much fewer air molecules between the detection area of the instrument
and outer space, and so TIGER will be seeing a few particles per minute.
Garry spent the majority of his day modifying some circuitry that was only
designed for the integration and testing phase of TIGER. All
electronics that go onto the instrument have to be rigorously tested so
that we can be sure that nothing will go wrong at 135,000 feet, where
TIGER will be nearly in a vacuum. It is easy for high-voltage
electronics to spark and "corona" where there is almost no air to
insulate the circuitry. Because of this, we need to be very
careful to pot all of our high-voltage electronics in a urethane
compound to keep this corona from occurring. Furthermore,
although you would think that being high up over Antarctica would be a
very cold place to be, for our electronics, this is not at all the
situation. Since there is almost no air to dissipate the heat
generated by the instrument, it gets quite hot inside the gondola -
about as hot as a summer day in the Sahara desert.
So after Garry finished soldering, he carted his
work back into town to the Crary Lab to do a "burn-in test," something
that all of our sensitive electronic equipment has been through.
Since the instrumentation that he was working on will most likely be
subjected to extreme heat during flight, he wants to make sure that it
can operate at high temperatures. The circuit board is currently
running in an oven at about 60°C (140°F) for the next 48 to
hours to be sure that it will hold up.
And then it was back to town for the rest of
us. There was a little bit of excitement
on the way back in. I bet someone's embarrassed about that
one! They sure do have their work cut out for them. And if
they don't hurry, it will sink deep into the crevasse region right
there where the land meets the ice.
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