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Another whopper run
Today was a
very intense day out at old Willy Field.
With Paul Dowkontt and Garry Simburger in full force helping out with
both TIGER and ANITA, things were pretty busy all day long. TIGER
saw its final tweaking before getting buttoned up. One of the
last things to do before buttoning up was to check to make sure that
the electronics systems are properly matched for flight. Imagine
this: the particles that TIGER is detecting are move about 1 foot
every nanosecond. At that rate, a particle will only spend a few
nanoseconds in TIGER before exiting out the bottom. Because of
this, our electronics have to act quickly.
As a particle passes through the plastic
scintillator and interacts with molecules in the blue dye, excitation
and ionization of the atoms in these molecules cause light to be
emitted. The photomultiplier tubes accept these photons, which
cause a shower of electrons to flow through the tube and out the signal
wire coming out of the back of the tube. This signal is shaped in
electronic circuits so it can be converted to a digital value, because
in the end, it is a lot easier to analyze numbers. And so, our
electronics have to be able to "read" a plot of voltage versus time
really quickly as the signal comes in from a photomultiplier
tube. In order to do this, it is necessary to set the electronics
so that it can "grab" the signal when its voltage is the highest.
This peak height is then converted to a number in a chip called an
analog-to-digital converter. A particle that passes through is
known as an event is represented in our data by a row of 219
numbers! These numbers give the digital value from each of the
192 photomultiplier tubes and other information about the time and type
of event. By plotting and adding up and plotting some of these
numbers, we can get information on the charge and energy of the
incoming particle, which as you might imagine, can be somewhat of a
tedious process.
So as the day ended, we decided to turn on the
instrument and let it run over the weekend to collect some more whopper
data. Since we have only been "talking" to TIGER directly out of
our computer system, we agreed with NSBF to begin running through the
air all the time to test the equipment and make sure it will be solid
during our flight. But as luck would have it, we all had problems
just as we were about to leave to head back to McMurdo for
dinner. With such a dry atmosphere down here, problems with
static electricity can have a detrimental effect on some of the
sensitive electronics with which we work. At least, that's the
best theory for the problems that we had today. So, at any rate,
we were able to hook things up to send commands directly to the
instrument and yet receive data through the air.
All right, enough of the technical talk. I am
beginning to see the light at the end of the crud tunnel. But,
even so, I've decided to take the day off tomorrow to rest. I
have to admit, I'm looking forward to sleeping late tomorrow.
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