HE Seminar
Speaker: Jenny Thomas, University College London
Title: CHIPS : CHerenkov detectors In mine PitS
Host: Svoboda
Room: 432
Abstract:An R&D project has started to develop an innovative approach for building very large water Cherenkov detectors in a neutrino beam. The longer-term goal is to construct a ~100 kT CHIPS detector to be deployed first in the NuMI and later in the LBNE beam, which will significantly extend the discovery potential for CP violation.
The latest measurement of the smallest of the mixing angles, theta_13, has presented the community with an embarrassment of riches. Physicists were preparing to measure a vanishingly small mixing angle, and therefore the design of new facilities and experiments was focused on providing exquisite background rejection. We now know that this mixing angle, and therefore the number of electron neutrino events which can be observed in a long baseline experiment, is large, meaning background rejection may not be the central challenge to the consequent study of CP violation. Instead, we need to collect larger data sets. We find ourselves with a clear set of fundamental quantities to measure, but lacking enough money to do it well. We are faced with a simple question: how do we make neutrino detectors cheaper?
The NuMI beam at FNAL is presently the most powerful neutrino beam in the world and will be ramping up to deliver 600 kW (6 x 10^20 p/year) over the coming 2 years. The NuMI beam is expected to run for the rest of the decade at least: the NOVA experiment will still be statistically limited by then and large improvements will continue to be made by running for longer. However, NOVA is off-axis and while this is perfect for studying the oscillation maximum, it does bring with it the downside of very low neutrino flux. Measurements of dcp require large statistics while the baseline is more forgiving compared to the measurement of mass hierarchy that calls for the longest baseline possible to maximize the matter effects. If more of the NuMI neutrinos could be measured in the coming decade, the knowledge base on which LBNE will build will be significantly improved.
An operational early-prototype was deployed this summer in the Wentworth 2W mine pit in Northern Minnesota, and I will discuss progress, lessons learned, plans and physics reach of the CHIPS series and describe the prognosis for physics on a short but realistic timescale.
