# The ENUBET narrow band neutrino beam

## TL;DR

The ENUBET narrow band neutrino beam is a pioneering monitored neutrino beam designed to precisely measure neutrino flux and provide a controlled electron neutrino source for short baseline experiments, demonstrated through prototype tests.

## Contribution

This paper presents the first implementation of the monitored neutrino beam technique and reports on the performance of positron tagger prototypes tested at CERN.

## Key findings

- Positron tagger prototypes achieved effective monitoring of lepton production.
- The beam provides a fully controlled $
u_{e}$ source at GeV energies.
- Performance tests at CERN validated the design concept.

## Abstract

The narrow band beam of ENUBET is the first implementation of the "monitored neutrino beam" technique proposed in 2015. ENUBET has been designed to monitor lepton production in the decay tunnel of neutrino beams and to provide a 1% measurement of the neutrino flux at source. In particular, the three body semi-leptonic decay of kaons monitored by large angle positron production offers a fully controlled $\nu_{e}$ source at the GeV scale for a new generation of short baseline experiments. In this contribution the performances of the positron tagger prototypes tested at CERN beamlines in 2016-2018 are presented.