A Possible Future Long Baseline Neutrino and Nucleon Decay Experiment with a 100 kton Liquid Argon TPC at Okinoshima using the J-PARC Neutrino Facility

Source: arXiv

ABSTRACT In this paper, we consider the physics performance of a single far detector composed of a 100 kton next generation Liquid Argon Time Projection Chamber (LAr TPC) possibly located at shallow depth, coupled to the J-PARC neutrino beam facility with a realistic 1.66 MW operation of the Main Ring. The new far detector could be located in the region of Okinoshima islands (baseline $L\sim 658$ km). Our emphasis is based on the measurement of the $\theta_{13}$ and $\delta_{CP}$ parameters, possibly following indications for a non-vanishing $\theta_{13}$ in T2K, and relies on the opportunity offered by the LAr TPC to reconstruct the incoming neutrino energy with high precision compared to other large detector technologies. We mention other possible baselines like for example J-PARC-Kamioka (baseline $L\sim 295$ km), or J-PARC-Eastern Korean coast (baseline $L\sim 1025$ km). Such a detector would also further explore the existence of proton decays.

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Available from: K. Nishikawa, Nov 18, 2013
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    • "We plan to build a 250L LAr TPC operated in double phase, where the ionization charge, extracted from the liquid, is amplified in the gas phase by means of a Large Electron Multiplier and readout by a two-dimensional projective anode, as described in [8] and references therein. Due to time limitations between January and October 2010, we first built a 250L prototype detector, operated in liquid phase and with coarse readout sampling. "
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    ABSTRACT: At the beginning of 2010, we presented at the J-PARC PAC an R$&$D program towards large (100 kton scale) liquid argon TPCs, suitable to investigate, in conjunction with the J-PARC neutrino beam, the possibility of CP violation in the neutrino sector and to search for nucleon decay. As a first step we proposed a test experiment to identify and measure charged kaons, including their decays, in liquid argon. The detector, a 250L LAr TPC, is exposed to charged kaons, in a momentum range of 540-800 MeV/c, in the K1.1BR beamline of the J-PARC slow extraction facility. This is especially important to estimate efficiency and background for nucleon decay searches in the charged kaon mode ($p \rightarrow \bar{\nu} K^+$, etc.), where the kaon momentum is expected to be in the few hundred MeV/c range. A prototype setup has been exposed in the K1.1BR beamline in the fall of 2010. This paper describes the capabilities of the beamline, the construction and setting up of the detector prototype, along with some preliminary results.
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    • "To illustrate the case, we consider the T2K sensitivity sin 2 2θ 13 > 0.01 (90%C.L.) obtained with 22.5 kton fiducial mass of Superkamiokande and 5 years of neutrino running at a proton beam power of 750 kW. If an excess is found in T2K, we can envisage a precise measurement of the ν µ → ν e oscillation probability with an increase of beam intensity up to 1.66 MW ( ×2), a partial re-optimization of the flux within the constraints of an existing beamline infrastructure – longer baseline but smaller offaxis angle to Okinoshima island to increase beam energy ( ×1) – and a 100 kton liquid Argon TPC ( ×4.5) but higher detection efficiency ( ×2) and lesser background ( ÷2) [23], for an overall gain of ( "
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    ABSTRACT: The feasibility of a European next-generation very massive neutrino observatory in seven potential candidate sites located at distances from CERN ranging from 130 km to 2300 km, is being considered within the LAGUNA design study. The study is providing a coordinated technical design and assessment of the underground research infrastructure in the various sites, and its coherent cost estimation. It aims at a prioritization of the sites within summer 2010 and a start of operation around 2020. In addition to a rich non-accelerator based physics programme including the GUT-scale with proton decay searches, the detection of a next-generation neutrino superbeam tuned to measure the flavor-conversion oscillatory pattern (i.e. 1st and 2nd oscillation maxima) would allow to complete our understanding of the leptonic mixing matrix, in particular by determining the neutrino mass hierarchy and by studying CP-violation in the leptonic sector, thereby addressing the outstanding puzzle of the origin of the excess of matter over antimatter created in the very early stages of evolution of the Universe. We focus on a multi-MW-power neutrino superbeam (="hyperbeam") produced by high-intensity primary protons of energy 30$\div$50 GeV. We argue that this option is an effective way to establish long baseline neutrino physics in Europe with the high-stake prospects of measuring $\theta_{13}$ and addressing CP-violation in the leptonic sector. Comment: 16 pages, 5 figures, based on a document submitted to the CERN SPC Panel on Future Neutrino Facilities (November 2009).
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    • "Large liquid argon time projection chambers (LAr TPC), up to ∼100 kton size, have been proposed as far dectors in these experiments (Refs. [1]– [6]). LAr TPCs, when compared to water Cerenkov detectors, allow lower momentum thresholds for the identification of heavier particles, notably protons, and are predicted to have higher electron identification efficiency with better rejection of the π 0 background. "
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    ABSTRACT: Large liquid argon (LAr) detectors, up to 100 kton scale, are presently being considered for proton decay searches and neutrino astrophysics as well as far detectors for the next generation of long baseline neutrino oscillation experiments, aiming at neutrino mass hierarchy determination and CP violation searches in the leptonic sector. These detectors rely on the possibility of maintaining large LAr masses stably at cryogenic conditions with low thermal losses and of achieving long drifts of the ionization charge, so to minimize the number of readout channels per unit volume. Many R&D initiatives are being undertaken throughout the world, following somewhat different concepts for the final detector design, but with many common basic R&D issues. Comment: Contribution to the Workshop 'European Strategy for Future Neutrino Physics', CERN, Oct. 2009, to appear in the Proceedings
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