Abstract
The nuclear emulsion target of the CHORUS detector was exposed to the wide-band neutrino beam of the CERN SPS of 27 GeV average neutrino energy from 1994 to 1997. In total, about 100 000 charged-current (CC) neutrino interactions with at least one identified muon were located in the emulsion target and fully reconstructed, using newly developed automated scanning systems. Charmed particles were searched for by a program recognizing particle decays. The observation of the decay in nuclear emulsion makes it possible to select a sample with very low background and minimal kinematical bias. In all, 2013 CC interactions with a charmed hadron candidate in the final state were selected and confirmed through visual inspection. The charm production rate induced by neutrinos relative to the CC cross-section is measured to be σ(νμN→μ−CX)/σ(CC)=(5.75 ± 0.32(stat)±0.30(syst))%. The charm production cross-section as a function of neutrino energy is also obtained. The results are in good agreement with previous measurements. The charm-quark hadronization produces the following charmed hadrons with relative fractions (in %): fD0=43.7±4.5, fΛc+=19.2±4.2, fD+=25.3±4.2 and fDs+=11.8±4.7.
Highlights
Took advantage of the spatial resolution of nuclear emulsion to distinguish the charm decay vertex from the primary neutrino interaction vertex
The disadvantage of the low statistics generally obtained in emulsion experiments (122 charm events observed in E531) has been overcome in the CHORUS experiment [16] by using a massive (770 kg) nuclear emulsion target and automated emulsion scanning [17, 18]
The CHORUS experiment took data from 1994 to 1997 in the CERN Wide Band Neutrino Beam [19], which essentially consisted of muon neutrinos
Summary
The CHORUS experiment was designed to investigate neutrino oscillation by searching for ντ appearance in the SPS wide-band neutrino beam at CERN through direct observation of τ decay in nuclear emulsions. The emulsion target, of 770 kg total mass, is segmented along the beam direction in four stacks of 1.4 × 1.4 m2 transverse area and about 3 cm thickness. It is equipped with highresolution trackers made out of three interface emulsion sheets and a set of scintillating fibre tracker planes that provide predictions of particle trajectories into the emulsion stack with an accuracy of about 150 μm in position and 2 mrad in angle. The muon spectrometer provides the charge and momentum of muons and provides a rough measurement of the leakage of hadronic showers out of the calorimeter. Several planes of scintillator hodoscopes are used for triggering the data acquisition system [21]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
