I went out to watch the cleaning earlier in the day and returned after work had finished to reproduce some of the cleaning activities. I was on the phone with the operator who monitored DARM for glitches. I found that tapping the beam tube with metal like the water/vacuum nozzles produced large glitches, but brushing with the brushes did not. I found that the softer the instrument, the harder it was to make glitches. I was never able to make glitches with my fist, but there was nearly a one-to-one coincidence with metal taps. All glitches, according to Jim, the operator, were broad band and a couple of orders of magnitude above background. I had to wait quite a time for the spectrum to settle down before tapping again. The glitches were like delta functions, not like scattering shelves. There did not seem to be a difference between locations at a baffle and half way between baffles.

I suggested to Bubba and John that we might make fewer glitches if there was a polymer guard on the nozzles.

I guess that the important quantities for freeing metal oxide particles are either acceleration or change in curvature of the beam tube. The difference between soft and hard "hammers" is consistent with both of these hypotheses. I think that it is important to estimate the inter-site coincidence rate and propose that I mount an accelerometer and a shaker on the tube to study glitching as a function of frequency and amplitude. I suspect that there is a soft threshold in curvature change or acceleration, and that this will be fairly constant with time since the oxide layers should no longer be growing.