The leptonic CP phase from muon decay at rest with two detectors

Abstract

We propose a novel experimental setup for the determination of the leptonic CP-violating phase δ using the decay at rest (DAR) of µ + from a single source located at distances of 10 and 30 km from two 20 kton organic liquid scintillator detectors. The µ + are created by bombarding a target with a 9 mA beam of 800 MeV protons. With this proposal δ can be determined with a precision of 20 (15) degrees in 6 (12) years. In contrast with the DAEδALUS project, only a single source is required and it runs with a duty factor limited only by maintenance requirements. As a result 9 mA is the maximum instantaneous current, greatly reducing both the technological challenges and the costs.

Neutrino physics with accelerator driven subcritical reactors

“…Such a setup has several advantages for measuring δ [20,21]. Not only is the ν e spectrum well known, but since they are detected via IBD the cross section is also well known and the capture of the resulting neutron provides a double coincidence which can be used for background rejection.…”

“…Unlike beam experiments the µDAR ν energy is also below the muon mass, and so there is no background from charged current ν µ or ν µ interactions. The spectrum is broad enough that such experiments can cleanly distinguish δ from π −δ [20,21]. Finally the main background that appears in water Cherenkov µDAR experiments [2,21], the invisible muons, is not present in a scintillator detector as even low energy muons, via ionization, emit scintillation light.…”

Neutrino CP violating phase from muon decay at rest

“…Moreover, if the second detector will be built, the difference between the baselines would be within the optimal range for µDARTS [3]. Since the energy range will be quite different from the one of reactor neutrinos (30-55 MeV with respect to 2-10 MeV) it will be possible to run the two experiments at the same time, without interfering with the mass hierarchy determination.…”

“…In the experimental setup we considered [3,4]ν µ are produced in an accelerator via µ decay at rest (µDAR). They propagate, oscillating intoν e , which are detected via Inverse Beta Decay (IBD) in two large liquid scintillators.…”

Slow liquid scintillator candidates for MeV-scale neutrino experiments

“…In addition, it is possible to further perform particle identification based on the ratio of Cherenkov light yield to scintillation light yield. Both features are also useful for neutrinoless double beta decay experiments [8,9,10], neutrino CP phase measurements [11,12], proton decay searches [6] and the study of geoneutrinos [13].…”