The Short Baseline Program at Fermilab
Joel Mousseau (above) discussed the program of short-baseline experiments at Fermilab. He started by pointing out the well-known fact that the LSND experiment observed a 3.8 sigma excess consistent with oscillations at a delta_m^2 of 1 eV^2; this was also observed in reactor experiments. The global knowledge of electron neutrino oscillations can be summarized by the well-known graph shown on the right side in the slide shown above.
The L/E for that oscillation signal is of 1m/MeV, so neutrinos of energy of 100 MeV require baselines of 100 meters. This is a motivation for the plan ongoing at Fermilab.
MiniBooNE is a 600 ton tank of mineral oil, primarily a Cherenkov detector. It also found an excess of events in the range of 200 to 475 MeV., both in the neutrino and antineutrino modes. Resolving this and the previous effect requires a new technology, and new expertise. This is where the short baseline program comes in: it consists in three detectors at one neutrino beam, with a common technology of LAr TPC. These are SBND, MicroBooNE, and ICARUS. Their distance from the BNB target is of 110, 470 and 600 meters respectively.
The speaker then described in detail the MicroBooNe experiment. You can find more details in the slides in the conference web site.
Combined, the three experiments will exclude at 5-sigma the region allowed by LSND. But it will be possible to also study nuclear effects of neutrino-nucleus scattering, and also study multinucleon events already observed in MiniBooNE and other experiments (T2K, MINERvA). The neutrino selection will be fully automated, and a common software and simulation framework is expected to be deployed for the three experiments.
Carlo Rubbia after the talk asked on a rumor that MicroBooNE has some problems. The speaker replied that it is true that it had some difficulties, and they have been worked on it – the feed-through of the high-voltage in the cathodes. They have been documenting what was wrong. They have now been running smoothly.