N. Vassilopoulos

A very intense neutrino super beam experiment for leptonic CP violation discovery based on the European spallation source linac

Very intense neutrino beams and large neutrino detectors will be needed in order to enable the discovery of CP violation in the leptonic sector. We propose to use the proton linac of the European Spoliation Source currently under construction in Lund, Sweden, to deliver, in parallel with the spoliation neutron production, a very intense, cost effective and high performance neutrino beam. The baseline program for the European Spoliation Source linac is that it will be fully operational at 5 MW average power by 2022, producing 2 GeV 2.86 ms long proton pulses at a rate of 14 Hz. Our proposal is to upgrade the linac to 10 MW average power and 28 Hz, producing 14 pulses/s for neutron production and 14 pulses/s for neutrino production. Furthermore, because of the high current required in the pulsed neutrino horn, the length of the pulses used for neutrino production needs to be compressed to a few mu s with the aid of an accumulator ring. A long baseline experiment using this Super Beam and a megaton underground Water Cherenkov detector located in existing mines 300-600 km from Lund will make it possible to discover leptonic CP violation at 5 sigma significance level in up to 50% of the leptonic Dirac CP-violating phase range. This experiment could also determine the neutrino mass hierarchy at a significance level of more than 3 sigma if this issue will not already have been settled by other experiments by then. The mass hierarchy performance could be increased by combining the neutrino beam results with those obtained from atmospheric neutrinos detected by the same large volume detector. This detector will also be used to measure the proton lifetime, detect cosmological neutrinos and neutrinos from supernova explosions. Results on the sensitivity to leptonic CP violation and the neutrino mass hierarchy are presented

Study of the pulse power supply unit for the four-horn system of the CERN to Fréjus neutrino super beam

The power supply studies for the four-horn system for the CERN to Frejus neutrino Super Beam oscillation experiment are discussed here. The power supply is being studied to meet the physics potential and the mega-watt (MW) power requirements of the proton driver of the Super Beam. A one-half sinusoid current waveform with a 350 kA maximum current and pulse length of 100 μs at 50 Hz frequency is generated and distributed to four-horns. In order to provide the necessary current needed to focus the charged mesons producing the neutrino beam, a bench of capacitors is charged at 50 Hz frequency to a +12 kV reference voltage and then discharged through a large switch to each horn via a set of strip-lines at the same rate. A current recovery stage allows to invert rapidly the negative voltage of the capacitor after the discharging stage in order to recuperate large part of the injected energy and thus to limit the power consuption. The energy recovery efficiency of that system is very high at 97%. For feasibility reasons, a modular architecture has been adopted with 8 modules connected in parallel to deliver 44 kA peak currents into the four-horn system.

Future large-scale water-Cherenkov detector

MEMPHYS (MEgaton Mass PHYSics) is a proposed large-scale water-Cherenkov experiment to be performed deep underground. It is dedicated to nucleon decay searches and the detection of neutrinos from supernovae, solar, and atmospheric neutrinos, as well as neutrinos from a future beam to measure the CP violating phase in the leptonic sector and the mass hierarchy. This paper provides an overview of the latest studies on the expected performance of MEMPHYS in view of detailed estimates of its physics reach, mainly concerning neutrino beams.

Target, magnetic horn and safety studies for the CERN to Fréjus Super Beam

In the framework of the EUROnu design study, a new design for the CERN to Frejus neutrino beam based on the SPL is under development by the WP2 group. The main challenge of this project lies with the design of a multi-MW neutrino beam facility. The horn and the decay tunnel parameters have been optimized to maximize any potential discovery. The target design, thermo-mechanical analysis, and power supply design of the horn system as well as any safety issues are being studied to meet the MW power requirements for the proton-beam.