Minutes from December 17 meeting

First there was a discussion about a new meeting time--Northwestern University requested that we change the meeting time to Tuesdays so they could attend. Boris Kayser said Tuesday afternoons are busy for theorists but mornings might work. Maury Goodman requested that the meetings be early or late but not in the middle of the day. Stay tuned for the new meeting schedule!

Fritz DeJongh gave an overview of what happened at the Louisiana meeting last week--you can see the agenda (which comprised the slides Fritz showed ) here

Status of the NUSL: negotiations on indemnification are going on -- 10M$ in operating funds to keep the mine open for the next year have been awarded. 1 year from how they hope to have small physics experiments going on there. There were excavation studies presented, it's harder and more expensive to go deeper, and besides one can't go to 8000 feet in 1 elevator ride, so they expect the nusl to just be at 4000 feet. The UNO folks say that 100m might even be okay, no one needs to go to 8000 feet (no one at the meeting, that is). Solar physics not expected to be pursued at UNO.

Initial approval will depend on small scale experiments.

Question: what about the "decision timeline" to make a decision between Homestake and San Jacinto? Fritz says that Homestake will go ahead, but if they don't get the funding in 1 year, then they will let the water into the mine, and that's an irreversible process, so that's the end of considerations for Homestake as the NUSL. If this happens then presumably the case for San Jacinto will be much stronger. The strong reason to go for Homestake (well, one reason) was that there was already something there so there could be physics on a much shorter time scale.

Update from Borexino: they are starting to fill the main volume with scintillator, and they will take data in a year. How long it will be until they have a result depends on the background levels they see once they turn on, so they can't predict that precisely right now. The expect about 100 events/day.

XENON idea: Isotopically separate different Xenon to do double beta decay, solar neutrino experiments, supernovae search...but it's a 100M$ scale experiment. Kamioka site might not be deep enough for the XENON idea. (they are looking fore the pp neutrinos from the sun). Xenon is a good scintillator--so one could get a very high density of phototubes.

Proton decay update: if UNO didn't see anything, they would only rule out a few specific models, but not any overall general concepts. So they are starting to talk about (study) their sensitivity to neutron antineutron oscillation detection. In extra dimensions, this could happen. (???) Shrock says there are currently people at SuperK doing nnbar oscillation analyses. Also, Maury Goodman said there was a thesis on this at Soudan.

In order to be more sensitive to the kaon modes in proton decay, people have started thinking about 100kton liquid scintillator detectors.

Fritz mentioned the talk by Michal Szleper which he gave for Michal, about a new detector idea with 1/4 radiation length steel, followed by scintillator: he was able to reject all the neutral currents by cuts which were 20% efficient at keeping the signal.

Monolith update (actually from Victoria conference)--only half the cost will be supported by INFN, so they are looking for support elsewhere, but otherwise that level of support would kill the project.

There was a discussion at the meeting (both ours and in Louisiana) about the status of SuperK, and what happened with the phototubes. The PMT's were rated to pressures of 8 atmospheres, but they estimate that by the time the wave caused by the imploded phototube reached its nearest neighbor, the pressure on that pmt was 100 atmospheres. There were tests done for "what happens when a wave goes past a pmt that implodes" but the pmt's all survived, it's thought because the tests were not done with enough water to simulate what really happened at this accident.

They are investigating a solution where there's a clear plastic honeycomb structure surrounding the phototubes to absorb any waves.

SuperK is going to use the pmt's they have left (plus some spares) to instrument the detector at half the original coverage so they can finish up the K2K experiment. It wasn't clear if they were going to put in the honeycomb structure before this or not.

Finally, Gabriela Barenboim won the award for the best conference talk title (in the history of the field?): Turning Sacred Cows into Big Mac's. (using CPT violation to explain the three oscillation signatures).

Todd Haines gave a talk on a 100kton MiniBooNE detector--mineral oil plus scintillator...to have higher efficiency than a water cerenkov device (to make up for the fact that it's not an UNO mass...).

Finally, Debbie gave a 5 minute status report on the studies begun on looking at neutral current backgrounds as a function of beam parameters--one can parameterize neutrino beam fluxes as a "gaussian peak" plus an exponential tail. (see this plot for how well the NUMI flux agrees with this function:

(A*(exp(-(x-3)^2/(2*(3*sigma)^2))+ B*exp(-.12*x))

Where for the NUMI Low energy beam, (A+B)/B = about 3.75 and sigma=0.3 Suggestions were to plot the pi0 energy for different beams, not to just look at the "neutral current visible" energy for different beams. also, another suggestion was to look at how the off-axis beam would be parameterized (for a different mean energy and a different tail height).


Deborah Harris
Last modified: Wed Dec 19 16:58:04 CST 2001