Search

Abstract This study provides an analysis of atmospheric neutrino oscillations at the ESSnuSB far detector facility. The prospects of the two cylindrical Water Cherenkov detectors with a total fiducial mass of 540 kt are investigated over 10 years of data taking in the standard three-flavor oscillation scenario. We present the confidence intervals for the determination of mass ordering, θ 23 octant as well as for the precisions on sin2 θ 23 and Δ m 31 2 $$ \left|\Delta {m}_{31}^2\right| $$ . It is shown that mass ordering can be resolved by 3σ CL (5σ CL) after 4 years (10 years) regardless of the true neutrino mass ordering. Correspondingly, the wrong θ 23 octant could be excluded by 3σ CL after 4 years (8 years) in the case where the true neutrino mass ordering is normal ordering (inverted ordering). The results presented in this work are complementary to the accelerator neutrino program in the ESSnuSB project.

Abstract Neutrino oscillation experiments provide a unique window in exploring several new physics scenarios beyond the standard three flavour. One such scenario is quantum decoherence in neutrino oscillation which tends to destroy the interference pattern of neutrinos reaching the far detector from the source. In this work, we study the decoherence in neutrino oscillation in the context of the ESSnuSB experiment. We consider the energy-independent decoherence parameter and derive the analytical expressions for P μe and P μμ probabilities in vacuum. We have computed the capability of ESSnuSB to put bounds on the decoherence parameters namely, Γ21 and Γ32 and found that the constraints on Γ21 are competitive compared to the DUNE bounds and better than the most stringent LBL ones from MINOS/MINOS+. We have also investigated the impact of decoherence on the ESSnuSB measurement of the Dirac CP phase δ CP and concluded that it remains robust in the presence of new physics.

Abstract In this paper, we present the physics performance of the ESSnuSB experiment in the standard three flavor scenario using the updated neutrino flux calculated specifically for the ESSnuSB configuration and updated migration matrices for the far detector. Taking conservative systematic uncertainties corresponding to a normalization error of $$5\%$$ 5 % for signal and $$10\%$$ 10 % for background, we find that there is $$10\sigma $$ 10 σ $$(13\sigma )$$ ( 13 σ ) CP violation discovery sensitivity for the baseline option of 540 km (360 km) at $$\delta _\mathrm{CP} = \pm 90^\circ $$ δ CP = ± 90 ∘ . The corresponding fraction of $$\delta _\mathrm{CP}$$ δ CP for which CP violation can be discovered at more than $$5 \sigma $$ 5 σ is $$70\%$$ 70 % . Regarding CP precision measurements, the $$1\sigma $$ 1 σ error associated with $$\delta _\mathrm{CP} = 0^\circ $$ δ CP = 0 ∘ is around $$5^\circ $$ 5 ∘ and with $$\delta _\mathrm{CP} = -90^\circ $$ δ CP = - 90 ∘ is around $$14^\circ $$ 14 ∘ $$(7^\circ )$$ ( 7 ∘ ) for the baseline option of 540 km (360 km). For hierarchy sensitivity, one can have $$3\sigma $$ 3 σ sensitivity for 540 km baseline except $$\delta _\mathrm{CP} = \pm 90^\circ $$ δ CP = ± 90 ∘ and $$5\sigma $$ 5 σ sensitivity for 360 km baseline for all values of $$\delta _\mathrm{CP}$$ δ CP . The octant of $$\theta _{23}$$ θ 23 can be determined at $$3 \sigma $$ 3 σ for the values of: $$\theta _{23} > 51^\circ $$ θ 23 > 51 ∘ ( $$\theta _{23} < 42^\circ $$ θ 23 < 42 ∘ and $$\theta _{23} > 49^\circ $$ θ 23 > 49 ∘ ) for baseline of 540 km (360 km). Regarding measurement precision of the atmospheric mixing parameters, the allowed values at $$3 \sigma $$ 3 σ are: $$40^\circ< \theta _{23} < 52^\circ $$ 40 ∘ < θ 23 < 52 ∘ ( $$42^\circ< \theta _{23} < 51.5^\circ $$ 42 ∘ < θ 23 < 51 . 5 ∘ ) and $$2.485 \times 10^{-3}$$ 2.485 × 10 - 3 eV $$^2< \varDelta m^2_{31} < 2.545 \times 10^{-3}$$ 2 < Δ m 31 2 < 2.545 × 10 - 3 eV $$^2$$ 2 ( $$2.49 \times 10^{-3}$$ 2.49 × 10 - 3 eV $$^2< \varDelta m^2_{31} < 2.54 \times 10^{-3}$$ 2 < Δ m 31 2 < 2.54 × 10 - 3 eV $$^2$$ 2 ) for the baseline of 540 km (360 km).

ESSnuSB is a design study for an experiment to measure the CP violation in the leptonic sector at the second neutrino oscillation maximum using a neutrino beam driven by the uniquely powerful ESS linear accelerator. The reduced impact of systematic errors on sensitivity at the second maximum allows for a very precise measurement of the CP violating parameter. This review describes the fundamental advantages of measurement at the second maximum, the necessary upgrades to the ESS linac in order to produce a neutrino beam, the near and far detector complexes, and the expected physics reach of the proposed ESSnuSB experiment, concluding with the near future developments aimed at the project realization.

The European Spallation Source (ESS), currently under construction in Lund, Sweden, is a research center that will provide, by 2023, the world’s most powerful neutron source. The average power of the proton linac will be 5 MW. Pulsing this linac at higher frequency will make it possible to raise the average total beam power to 10 MW to produce, in parallel with the spallation neutron production, a very intense neutrino Super Beam of about 0.4 GeV mean neutrino energy. This will allow searching for leptonic CP violation at the second oscillation maximum where the sensitivity is about 3 times higher than at the first. The ESS neutrino Super Beam, ESSnuSB operated with a 2.0 GeV linac proton beam, together with a large underground Water Cherenkov detector located at 540 km from Lund, will make it possible to discover leptonic CP violation at 5σ significance level in 56% (65% for an upgrade to 2.5 GeV beam energy) of the leptonic CP-violating phase range after 10 years of data taking, assuming a 5% systematic error in the neutrino flux and 10% in the neutrino cross section. The paper presents the outstanding physics reach possible for CP violation with ESSnuSB obtainable under these assumptions for the systematic errors. It also describes the upgrade of the ESS accelerator complex required for ESSnuSB.

We discuss beam deceleration through a series of 12 power extraction and transfer structures, at the CLIC test facility 3 at CERN, as a proof-of-principle of the CLIC deceleration scheme. Up to 36% of the kinetic energy of an electron drive beam is extracted and converted to 12 GHz rf power. We look at the average and maximum energy loss of the particles, and compare them with simulations performed with the placet tracking code. The measured final energy is also compared to predictions based on the measured beam current and rf power in the structures. In the analysis we make use of the charge distribution form factor, taking into account the bunch length and the bunch phase. Finally, we look at the evolution of the transverse emittance with deceleration and compare the measured emittance with simulations.

The Compact Linear Collider (CLIC) is a study for a future linear electron-positron collider based on a two-beam acceleration scheme in which a high-intensity drive beam is decelerated in order to provide the power to accelerate the main beam for collision in the TeV range. The power extracted from the drive beam deteriorates the beam quality and increases the energy spread significantly. Monitoring of the beam properties is therefore challenging but essential. These challenges are being addressed experimentally at the CLIC test facility where up to 55% of the power is extracted from the beam in the test beam line, a small-scale version of the CLIC drive-beam decelerator, leaving the beam with a very wide energy profile. For monitoring of the transverse beam profile and Twiss parameters we use optical transition radiation screens and quadrupole scans. The intra-pulse-train energy spectrum before and after deceleration is measured with segmented beam dumps. In this paper we discuss the performance of these diagnostic devices with a particular emphasis on the large energy spread and its effect on the beam imaging techniques, and with a final outlook to the CLIC drive-beam diagnostics.