The NOMAD experiment at the CERN SPS

Abstract

The NOMAD experiment is a short base-line search for ν µ → ν τ oscillations in the CERN neutrino beam. The ν τ 's are searched for through their charged-current interactions followed by the observation of the resulting τ − through its electronic, muonic or hadronic decays. These decays are recognized using kinematical criteria necessitating the use of a light target which enables the reconstruction of individual particles produced in the neutrino interactions. This paper describes the various components of the NOMAD detector: the target and muon drift chambers, the electromagnetic and hadronic calorimeters, the preshower and transition radiation detectors, and the veto and trigger scintillation counters. The beam and data acquisition system are also described. The quality of the reconstruction of individual particles is demonstrated through the ability of NOMAD to observe K 0 s 's, Λ 0 's and π 0 's. Finally, the observation of τ − through its electronic decay being one of the most promising channels in the search, the identification of electrons in NOMAD is discussed.

Interim Design Report

“…Building upon the NOMAD-experience [416], we propose a low-density tracking detector with a fiducial mass of 7.4 Ton as a neutrino target. The active-target tracker will have a factor of two more sampling points along the z-axis (ν -direction) and a factor of six more sampling points in the plane transverse to the neutrino compared to the NOMAD experiment.…”

“…Such a vertex detector could be similar to the NOMAD-STAR detector that was installed upstream of the first drift chamber of the NOMAD neutrino oscillation experiment [416] (see figure 141). The main aim of this detector was to test the capabilities of silicon detectors for short-baseline neutrino oscillation searches [438,439].…”

Statistical Pattern Recognition: Application to νμ→ντOscillation Searches Based on Kinematic Criteria

“…Given the previous experimental efforts [14,15] and present interest in direct ν τ appearance, we assess in this note the performance of several statistical techniques applied to the search for ν τ using kinematic techniques. Classic statistical methods (like multidimensional likelihood and Fischer's discriminant schemes) and Neural Networks based ones (like multi-layer perceptron and self-organized neural networks) have been applied in order to find the approach that offers the best sensitivity.…”

“…NOMAD [14] was a pioneering experiment in the use of kinematic criteria applied to a ν µ → ν τ oscillation search. The kinematic approach was validated after several years of successful operation at the CERN WANF neutrino beam [17,18].…”

A B4C-silicon target for the detection of neutrino interactions

“…At present, two experiments, CHORUS and NOMAD [1,2], are searching for the exclusive ( e ) $ oscillation modes in the CERN-SPS neutrino beam. Furthermore, a new generation of experiments to search for ( e ) $ oscillations, with a sensitivity at least an order of magnitude larger than CHORUS and NOMAD, is being actively discussed [3,4,5,6,7,8].…”