The 40-ft long MicroBooNE detector is a 170 ton (total volume) liquid-argon (LAr) time projection chamber (TPC). It is currently the largest LArTPC operating in the U.S.
The liquid argon serves as the neutrino target. This is desirable since it is dense (40% denser than water), inert, and relatively cheap compared to other noble liquids. The argon must be kept extremely cold (87K) to remain in liquid form and be extremely pure for the ionization electrons to drift across the TPC volumes so that their signals can be recorded.
The TPC consists of a cathode plane on one side, a field-shaping cage around the drift perimeter, and three planes of wires on the opposite end to record the signals from the drifting ionization electrons. The cathode plane is powered to a very high voltage (roughly -100 kV) to create an electric field across the TPC volume. The ionization electrons will travel through this field and their signals measured by the three wire planes. Each plane is offset by 60 degrees from the others providing spacial reconstruction ability in the y-z plane. Knowing when the charge reaches the wires allows for determination of the x component.
Further timing information will be provided by a photomultiplier tube (PMT) array measuring the prompt scintillation light produced during the excitation or ionization of argon atoms.
The MicroBooNE detector was filled with liquid argon in the summer of 2015. The argon was successfully purified using the MicroBooNE filtration, recirculation, and purification system. MicroBooNE saw the first cosmic ray tracks in the TPC in August 2015 and started collecting neutrino beam data in October 2015.
The MicroBooNE time projection chamber (TPC) was assembled at Fermilab in 2012-2013, sealed in the cryostat at the end of 2013, and installed in the Liquid Argon Test Facility (LArTF) in the Booster neutrino beamline in June 2014. If you wish to go into more details about the MicroBooNE detector, please check our paper on the Design and Construction of the MicroBooNE Detector.
View more interesting photos of the assembly effort along with more MicroBooNE Photos.
Inside the MicroBooNE LArTPC
Click the image below to enter the MicroBooNE detector!
Time Projection Chamber (TPC) Wires inspection
In April 2015, several photos of the sense-wire planes were taken from the inside of the cryostat, via a clever camera-mirror-lighting arrangement. This survey was conducted to inspect the TPC for damage such as breakage or sagging, after the transportation of the vessel.
View the TPC Wires Survey photos or learn more about the design and operation of a setup with a camera and adjustable mirror to inspect the sense-wire planes.