ArgoNeuT is a joint NSF/DOE R&D project at Fermilab to expose a small-scale liquid argon time projection chamber (LArTPC) to the NuMI neutrino beam. Data-taking is presently under way and is expected to continue through March 2010. Event images are available in the Images section.
Liquid argon detectors are an exciting class of neutrino experiments because they can provide bubble chamber quality images and excellent background rejection. In these detectors, neutrinos passing through a large volume of argon interact with an argon atom, producing light and ionization particles. An electric field within the detector causes these charged particles to drift through the volume of argon, leaving a path of ionization electrons. As they drift, the ionization electrons induce current in two wire planes and are collected at a third plane. Measurement of the signals created within the wires, the position of the wires within the planes, the drift velocity of the ionization particles, and time of drift (from scintillation light or elsewhere) provides all the information needed for 3D reconstruction of the event.
ArgoNeuT's neutrino source is the NuMI (Neutrinos at the Main Injector) beam. The beam passes through the MINOS (Main Injector Neutrino Oscillation search) near and far detectors, positioned at 1 km and 735 km from the target at Fermilab. ArgoNeuT is located at Fermilab upstream of the MINOS near detector, and is calibrated using muons that traverse the chamber and penetrate several layers into MINOS.
ArgoNeuT supplies valuable information about both low energy neutrino interactions and underground detector operations. By taking measurements in the .1 to 10 GeV range, the test provides the first ever data for low energy neutrino interactions within a LArTPC, paving the way for construction of larger detectors. ArgoNeuT also serves as a stepping stone to larger detectors by providing experience in operating underground argon recirculation, trigger, and readout systems.
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