Speaker
Description
In view of the J-PARC program of upgrades of the beam power, the T2K collaboration is preparing upgrades of the neutrino beamline and near detector, ND280, towards an increase of the exposure aimed at establishing leptonic CP violation at 3 σ level for a significant fraction of the possible δCP values. To reach this goal, the upgrade of the ND280 has been aimed at reducing the overall statistical and systematic uncertainties to the needed level, better than 4%.
The upgraded detector comprises the totally active Super-Fine-Grained-Detector (SuperFGD), two High Angle TPC (HA-TPC) and six TOF planes. The SuperFGD, a highly segmented scintillator detector, acting as a fully active target for the neutrino interactions, is a novel device, with dimensions of ~2x1.8x0.6 m3 and a total mass of about 2 tons. It consists of about 2x106 small scintillator cubes each of 1 cm3. Each cube is covered by a chemical reflector making it optically separated from each other and has three holes in x, y and z directions. The signal readout from each cube is provided by wavelength shifting fibers inserted in these holes and connected to micro-pixel avalanche photodiodes MPPCs. The total number of channels will be ~60,000. We have demonstrated that this detector, providing three 2D projections, has excellent PID, timing and tracking performance, including a $4 \pi$ angular acceptance, especially important for short proton and pion tracks.
The HA-TPC will be used for 3D track reconstruction, momentum measurement and particle identification. These TPCs, with overall dimensions of 2x2x0.8 m3, will be equipped with 32 resistive Micromegas. The thin field cage (3 cm thickness, 4% rad. length) will be realized with laminated panels of Aramid and honeycomb covered with a kapton foil with copper strips. The 34x42 cm2 resistive bulk Micromegas will use a 500 kOhm/square DLC foil to spread the charge over the pad plane, each pad being approximately 1 cm2. The front-end cards, based on the AFTER chip, will be mounted on the back of the Micromegas and parallel to its plane.
The TOF, consisting of cast plastic scintillator readout by MPPC, will reach a time resolution of 150 ps.
In this talk we will report on the design of these detectors, their performance, the results of the test beam and the plan for the construction.
