Extracting matter effects, masses and mixings at a neutrino factory

Abstract

We discuss and quantify different possibilities to determine matter effects, the value and the sign of ∆m 2 31 , as well as the magnitude of sin 2 2θ 13 in very long baseline neutrino oscillation experiments. We study neutrino oscillation at a neutrino factory in the ν µ → ν µ disappearance and ν e → ν µ appearance channels with and without muon charge identification. One possibility is to analyze the ν e → ν µ appearance channels leading to wrong sign muon events, which requires however very good muon charge identification. Without charge identification it is still possible to operate the neutrino factory both with µ − and µ + beams and to analyze the differences in the total neutrino event rate spectra. We show that this leads already to a quite good sensitivity, which may be important if right sign charge rejection capabilities are insufficient. With muon charge identification one can study the ν µ → ν µ disappearance and the ν e → ν µ appearance channels independently. The best method is finally achieved by combining all available information of the ν µ → ν µ disappearance and ν e → ν µ appearance channels with charge identification and we show the sensitivity which can be achieved.

Systematic exploration of the neutrino factory parameter space including errors and correlations

“…A numerical scan of the full six dimensional input parameter with a subsequent extraction of the input parameters is an enormous numerical task. Therefore, up to now most studies performed only two parameter fits to evaluate the physics reach of a neutrino factory [12,3,24,21,25,26,27,28,1]. Often two parameters of the full parameter set, which were thought to be most relevant, were selected and a fit to this two parameters was performed using a χ 2 -method.…”

“…Matter effects have so far not been measured and an experimental test of MSW-effects [7,8,9,10] will be possible if θ 13 is large enough. The measurement of θ 13 and the search for matter effects [2,3,1,12] are thus important topics for the physics program of a neutrino factory, which do not depend on ∆m 2 21 and θ 12 being in the LMA-MSW range. Measurements of rates in the appearance channel depend, however, crucially on the capability to identify the charges of the secondary muons very reliably [3], which requires improved detector technology.…”

“…The measurement of θ 13 and the search for matter effects [2,3,1,12] are thus important topics for the physics program of a neutrino factory, which do not depend on ∆m 2 21 and θ 12 being in the LMA-MSW range. Measurements of rates in the appearance channel depend, however, crucially on the capability to identify the charges of the secondary muons very reliably [3], which requires improved detector technology. Sensitivity limits to θ 13 and statistical errors are studied in section 4.2, where also baseline and beam energy optimization are discussed.…”

“…This requires for the appearance channels excellent charge identification capabilities of the detector. Insufficient charge identification would reduce the physics reach of such an experiment as pointed out in [3]. The type of detector assumed for this study is a magnetized iron detector with a mass of 10 kt.…”

“…[1,2,3]). Among the main points discussed are the achievable precision for the oscillation parameters, the optimal baseline and the best muon energy, the search for matter effects, the search for CP violation and specifically, whether measurements of the CP phase are possible.…”