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Jenny Thomas: Mass Hierarchy and Delta_CP Measurements Using Existing Facilities

March 13, 2013

There are a number of existing facilities that have been discussed here already or will be today or tomorrow. There is also an exploitation of the NuMi beam, which is the focus of this talk.

Three options can be considered, and prototypes. NuMI is the worlds’ most intense long baseline neutrino beam. This summer will see an upgrade aiming at 6E20 POT per year. The plan is to run for at least 6 years. So, given the time scale for construction projects in the US and Europe, we need intermediate physics opportunities, and the development of megaton detectors for LBNE and beyond.

Since beams cannot increase by orders of magnitude in the foreseeable future, we need to increase the detector mass.

NoVa is a low-Z, 65% active detector, 14 ktons. At Ash River there is room for 5ktons of liquid argon in addition. One must always think at the recyclability of these detectors for LBNE. Doubling the NoVA volume would cost about 160 million dollars. An European involvement might allow this.

There are three pathways to higher exposure: either run for 6 years at 700 kW with 14 ktons (baseline exposure), or run longer (10 years) with 18 or 29 kilotons., improving by 2.1 or 3.5 times the yields. The extension of mass is low-risk, and would cost 9M$ per kiloton.

A combination of NOVA results with T2K and GLADE would allow sensitivity to the angle delta_CP, and resolve the mass hierarchy at 3-sigma for 35% of the possible delta_CP values.

CHIPS is a water cherenkov detector, aiming at measuring delta_CP. Water is the only way to go to Megaton-scale detectors. One can deploy underwater in a flooded mine. The CHIPS concept is to deploy a floating platform using industrial products from the fisheries industry, using a light-tight material filled with pure water as a neutrino target.

CHIPS uses technology based on ICECUBE developments. One can have 10% HQE PMT coverage, with tubes encased in pressure spheres and deployed along wires.

One needs to run in both a medium-energy and a low-energy beam for the best physics reach of the detector. By the end of the decade, this should push the error on delta_CP to 15-28 degrees, and this is not systematics limited.

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