Future Neutrino Beam Studies Under the Framework of Physics Beyond Colliders

International audienceA Physics Beyond Colliders (PBC) initiative was recently established at CERN to exploit the full scientific potential of its accelerator complex and scientific infrastructure to tackle fundamental open questions in particle physics through experiments complementary to those in current and future colliders. This initiative brings together similar studies to optimize resources globally in order to reach a common goal and promote scientific development efficiently. In this work, we present the work performed by the Conventional Beam Working Group (CBWG) and specifically from the Neutrino Beams (NB) subgroup. The subgroup currently deals with two novel neutrino-tagged beams projects, ENUBET and NUTAG, as well as with a more classic, low energy, beamline dedicated to hadron cross-sections for neutrino beams with the NA61 experiment already installed in the H₂ beamline of the CERN North Area. This contribution will detail the advances made with these three projects as well as their status and future plans

A high precision narrow-band neutrino beam: The ENUBET project

The knowledge of the initial flux, energy and flavor of current neutrino beams is the main limitation for a precise measurement of neutrino cross-sections. The ENUBET ERC project is studying a facility based on a narrow-band neutrino beam capable of constraining the neutrino fluxes normalization through the monitoring of the associated charged leptons in an instrumented decay tunnel. In ENUBET, the identification of large-angle positrons from Ke3 decays at single particle level can potentially reduce the νe flux uncertainty at the level of 1%. This setup would allow for an unprecedented measurement of the νe cross-section at the GeV scale. This input would be highly beneficial to reduce the budget of systematic uncertainties in the next long baseline oscillation projects. Furthermore, in narrow-band beams, the transverse position of the neutrino interaction at the detector can be exploited to determine a priori with significant precision the neutrino energy spectrum without relying on the final state reconstruction. This contribution will present the advances in the design and simulation of the hadronic beam line. Special emphasis will be given to a static focusing system of secondary mesons that can be coupled to a slow extraction proton scheme. The consequent reduction of particle rates and pile-up effects makes the determination of the νμ flux through a direct monitoring of muons after the hadron dump viable, and paves the way to a time-tagged neutrino beam. Time-coincidences among the lepton at the source and the neutrino at the detector would enable an unprecedented purity and the possibility to reconstruct the neutrino kinematics at source on an event-by-event basis. We will also present the performance of positron tagger prototypes tested at CERN beamlines, a full simulation of the positron reconstruction chain and the expected physics reach of ENUBET

ENUBET: a monitored neutrino beam for the precision era of neutrino physics

The ENUBET ERC project, also included in the CERN Neutrino Platform as NP06/ENUBET, is developing a new neutrino beam based on conventional techniques in which the flux and the flavor composition are known with unprecedented precision (O (1%)). Such a goal is accomplished monitoring the associated charged leptons produced in the decay region of the ENUBET facility. Positrons and muons from kaon decays are measured by a segmented calorimeter instrumenting the walls of the decay tunnel, while muon stations after the hadron dump can be used to monitor the neutrino component from pion decays. Furthermore, the narrow momentum width (<10%) of the beam provides a precise measurement (O (10%)) of the neutrino energy on an event by event basis, thanks to its correlation with the radial position of the interaction at the neutrino detector. ENUBET is therefore an ideal facility for a high precision neutrino cross-section measurement at the GeV scale, that could enhance the discovery potential of the next-generation of long baseline experiments. It is also a powerful tool for testing the sterile neutrino hypothesis and to investigate possible non-standard interactions

The ENUBET monitored neutrino beam: a progress report

The ENUBET experiment, included in the CERN Neutrino Platform effort as NP06/ENUBET, is developing a monitored neutrino beam based on conventional techniques. The aim is to constrain the flux and the flavor composition with a precision of O(1%) by monitoring the associated charged leptons produced in the decay tunnel. The narrow momentum width (<10%) of the beam also allows to obtain a precise measurement of the neutrino energy. This paper summarizes the latestdevelopment and the status of the project

A Monitored Neutrino Beam at the European Spallation Source

International audienceMonitored neutrino beams are facilities where beam diagnostics enable the counting and identification of charged leptons in the decay tunnel of a narrow band beam. These facilities can monitor neutrino production at the single particle level (flux precision %) and provide information about the neutrino energy at the 10% level. The ENUBET Collaboration has demonstrated that lepton monitoring might be achieved not only by employing kaon decays but also by identifying muons from the decays and positrons from the decay-in-flight of muons before the hadron dump. As a consequence, beam monitoring can be performed using the ENUBET technique even when the kaon production yield is kinematically suppressed. This finding opens up a wealth of opportunities for measuring neutrino cross-sections below 1 GeV. In this paper, we investigate this opportunity at the European Spallation Source (ESS), which is an ideal facility to measure and cross-sections in the 0.2–1 GeV range. We also describe the planned activities for the design of this beam at the ESS within the framework of the ESSSB+ design study, which was approved by the EU in July 2022

The NP06/ENUBET Project: Towards a Monitored Neutrino Beam

International audienceThe ENUBET experiment is developing a new narrow-band neutrino beam in which the flux and the flavor composition are known at 1$\%$ level, and the energy with O(10$\%$) precision. Such a goal is accomplished monitoring the associated charged leptons produced in the decay region of the ENUBET facility: $e^{+}$ and $\mu^{+}$ from kaons are measured by a segmented calorimeter instrumenting the walls of the decay tunnel, while muon stations after the hadron dump can monitor muons from pions. We report an update on the status of the project

Silicon Photomultipliers for the decay tunnel instrumentation of the ENUBET neutrino beam

The goal of the ENUBET project is to demonstrate that a precision of ∼1% on measurement of the absolute neutrino cross section at GeV scale can be achieved by monitoring the positron production in the decay tunnel coming from the three-body semileptonic decays of kaons. The baseline option for the tunnel instrumentation employs a fine-grained shashlik calorimeter with a 4.3 X 0 longitudinal segmentation to separate positrons and pions coming from other decay modes of kaons. The system is complemented by rings of plastic scintillator doublets below the calorimeter acting as a photon veto to suppress the π 0 background and to provide timing informations. SiPMs instrumenting the detector will be exposed to sizeble amounts of neutrons arising in hadronic showers. In order to reproduce such a working environment, SiPMs with different cell size (from 12 to 20 μm ) were irradiated at the INFN-LNL CN Van Der Graaf with neutron fluences up to 2×10 11 n/cm 2 (1 MeV-eq.). The exposed light sensors were characterized in terms of I–V curves at different irradiation levels, and their response tested by exposing a prototype on beam at CERN. In this contribution we will report the results of the described tests on SiPMs, together with the advances in their integration with the ENUBET detectors

Monitored neutrino beams and the next generation of high precision cross section experiments

International audienceThe main source of systematic uncertainty on neutrino cross section measurements at the GeV scale originates from the poor knowledge of the initial flux. The reduction of this uncertainty to 1% can be achieved through the monitoring of charged leptons produced in association with neutrinos. The goal of the ENUBET ERC project is to prove the feasibility of such a monitored neutrino beam. In this contribution, the final results of the ERC project, together with the complete assessment of the feasibility of its concept, are presented. An overview of the detector technology for a next generation of high precision neutrino-nucleus cross section measurements, to be performed with the ENUBET neutrino beam, is also given

Development and optimization of the ENUBET beamline

International audienceThe ENUBET experiment (NP06/ENUBET at CERN) has the goal of proving the concept of a "monitored neutrino beam", for a superior knowledge of the produced neutrino flux and high-precision cross-section measurement. To achieve this, an instrumented decay tunnel will be used in order to directly monitor the products of the neutrino production vertices. The ENUBET collaboration is studying and designing this facility in all its different aspects: from the data acquisition and detector hardware, to the assessment of systematics and analysis. The present contribution will focus on the topic of the beamline design, highlighting the main results and the most recent developments

Design and performance of the ENUBET monitored neutrino beam

International audienceThe ENUBET project is aimed at designing and experimentally demonstrating the concept of monitored neutrino beams. These novel beams are enhanced by an instrumented decay tunnel, whose detectors reconstruct large-angle charged leptons produced in the tunnel and give a direct estimate of the neutrino flux at the source. These facilities are thus the ideal tool for high-precision neutrino cross-section measurements at the GeV scale because they offer superior control of beam systematics with respect to existing facilities. In this paper, we present the first end-to-end design of a monitored neutrino beam capable of monitoring lepton production at the single particle level. This goal is achieved by a new focusing system without magnetic horns, a 20 m normal-conducting transfer line for charge and momentum selection, and a 40 m tunnel instrumented with cost-effective particle detectors. Employing such a design, we show that percent precision in cross-section measurements can be achieved at the CERN SPS complex with existing neutrino detectors