His Toe-Gram

A thought for today: Plot a histogram of the distribution of coincidence delays.  This is a good sanity check to see if it's consistent with the known angular distribution of showers.  We should expect to see more from the zenith (near the E-W-zenith plane) than from near the N-S axis.  Ray says he might show the graph in his astronomy class.

Also: Run a hodoscope configuration with perpendicular paddles to reduce slewing.  Picture of that setup (jury-rigged, as usual):

This will (we think) give us a picture of coincidences due to (mostly) single-particle events passing (more or less) vertically through the far ends of both paddles, giving us (perhaps) a clearer picture of the difference in gain of the two paddles.  At this depth inside the building (away from window, under the 5th floor and the roof), the vertical cosmics should be mostly muons.

Whoops, for some reason, threshold 2 seems to be messed up today.  It's reading 70 mV when it is supposed to be 2.000V.  Perhaps a water drip caused a voltage surge that zapped the DAC #2 chip?  Not sure what to do here.  I've tried re-loading a couple different versions of the gelware; it makes no difference.  Could try cleaning the pads on that IC, in case there is some residue causing a short.  If all else fails, we can route around it, just use the other 5 DACs.  It would be nice to first know why it's failing though.

Also need to set up Neutralino accounts for the students.  Need to remember to take pictures of them for the site next time they're here.

Spent a little while inspecting the board.  There is a fair amount of residue on the board, perhaps a result of drips from the cooling system.  We should probably look into washing off the board, in some appropriate way.  Ray says Radio Shack might have an electronics wash spray which we should try.

Anyway, here is a plot of the histogram of absolute time deltas from the run a couple of weeks ago.  The number of events for deltas other than 0 is halved to compensate for the fact that only half of the data comes from positive vs. negative deltas.  (We haven't yet explicitly separated out the data to check for any North/South asymmetry.)

From run of Sep. 6th-7th:  This shows how the number of coincidence events falls off with an increase in the (binned) absolute time difference between arrivals at the two detectors.  (Counts other than at delta=0 have been halved to compensate for the fact that data from positive and negative values of delta are thrown together.)

That's all for tonight.