nuSTORM at CERN: Feasibility Study

The Neutrinos from Stored Muons, nuSTORM, facility has been designed to deliver a definitive neutrino-nucleus scattering programme using beams of $\bar{\nu}_e$ and $\bar{\nu}_\mu$ from the decay of muons confined within a storage ring. The facility is unique, it will be capable of storing $\mu^\pm$ beams with a central momentum of between 1 GeV/c and 6 GeV/c and a momentum spread of 16%. This specification will allow neutrino-scattering measurements to be made over the kinematic range of interest to the DUNE and Hyper-K collaborations. At nuSTORM, the flavour composition of the beam and the neutrino-energy spectrum are both precisely known. The storage-ring instrumentation will allow the neutrino flux to be determined to a precision of 1% or better. By exploiting sophisticated neutrino-detector techniques such as those being developed for the near detectors of DUNE and Hyper-K, the nuSTORM facility will: Serve the future long- and short-baseline neutrino-oscillation programmes by providing definitive measurements of $\bar{\nu}_e A$ and $\bar{\nu}_{\mu} A$ scattering cross-sections with percent-level precision; Provide a probe that is 100% polarised and sensitive to isospin to allow incisive studies of nuclear dynamics and collective effects in nuclei; Deliver the capability to extend the search for light sterile neutrinos beyond the sensitivities that will be provided by the FNAL Short Baseline Neutrino (SBN) programme; and Create an essential test facility for the development of muon accelerators to serve as the basis of a multi-TeV lepton-antilepton collider. To maximise its impact, nuSTORM should be implemented such that data-taking begins by $\approx 2027/28$ when the DUNE and Hyper-K collaborations will each be accumulating data sets capable of determining oscillation probabilities with percent-level precision. With its existing proton-beam infrastructure, CERN is uniquely well-placed to implement nuSTORM. The feasibility of implementing nuSTORM at CERN has been studied by a CERN Physics Beyond Colliders study group. The muon storage ring has been optimised for the neutrino-scattering programme to store muon beams with momenta in the range 1 GeV to 6 GeV. The implementation of nuSTORM exploits an existing fast-extraction from the SPS that delivers beam to the LHC and to HiRadMat. A summary of the proposed implementation of nuSTORM at CERN is presented along with an indicative cost estimate and a preliminary discussion of a possible time-line for the implementation

SPS Beam Dump Facility - Comprehensive Design Study

The proposed Beam Dump Facility (BDF) is foreseen to be located in the North Area of the Super Proton Synchrotron (SPS). It is designed to be able to serve both beam-dump-like and fixed-target experiments. The SPS and the new facility would offer unique possibilities to enter a new era of exploration at the intensity frontier. Possible options include searches for very weakly interacting particles predicted by Hidden Sector models, and flavour physics measurements. Following the first evaluation of the BDF in 2014–2016, CERN management launched a Comprehensive Design Study over three years for the BDF. The BDF study team has executed an in-depth feasibility study of proton delivery to target, the target complex, and the underground experimental area, including prototyping of key subsystems and evaluations of radiological aspects and safety. A first iteration of detailed integration and civil engineering studies has been performed to produce a realistic schedule and cost. This document gives a detailed overview of the proposed facility together with the results of the in-depth studies, and draws up a road map and project plan for a three years Technical Design Report phase and a five–six years construction phase.The proposed Beam Dump Facility (BDF) is foreseen to be located in the North Area of the Super Proton Synchrotron (SPS). It is designed to be able to serve both beam-dump-like and fixed-target experiments. The SPS and the new facility would offer unique possibilities to enter a new era of exploration at the intensity frontier. Possible options include searches for very weakly interacting particles predicted by Hidden Sector models, and flavour physics measurements. Following the first evaluation of the BDF in 2014–2016, CERN management launched a Comprehensive Design Study over three years for the BDF. The BDF study team has executed an in-depth feasibility study of proton delivery to target, the target complex, and the underground experimental area, including prototyping of key subsystems and evaluations of radiological aspects and safety. A first iteration of detailed integration and civil engineering studies has been performed to produce a realistic schedule and cost. This document gives a detailed overview of the proposed facility together with the results of the in-depth studies, and draws up a road map and project plan for a three years Technical Design Report phase and a five–six years construction phase

Filamentation of a relativistic proton bunch in plasma

International audienceWe show in experiments that a long, underdense, relativistic proton bunch propagating in plasma undergoes the oblique instability, which we observe as filamentation. We determine a threshold value for the ratio between the bunch transverse size and plasma skin depth for the instability to occur. At the threshold, the outcome of the experiment alternates between filamentation and self-modulation instability (evidenced by longitudinal modulation into microbunches). Time-resolved images of the bunch density distribution reveal that filamentation grows to an observable level late along the bunch, confirming the spatiotemporal nature of the instability. We provide a rough estimate of the amplitude of the magnetic field generated in the plasma by the instability and show that the associated magnetic energy increases with plasma density