The Upgraded ND280 Near Detector: Impact on T2K and the Road to Hyper-Kamiokande

by Ms Merlin Varghese (IFAE, Spain)

Tuesday 6 Jan 2026, 14:30 → 15:30 Asia/Kolkata

A-304 and Zoom

The Tokai to Kamioka (T2K) experiment in Japan is a long-baseline neutrino oscillation experiment designed to measure CP violation in the leptonic sector. A key ingredient in this programme is the near detector ND280, which constrains neutrino flux and interaction systematics. To improve its acceptance for high-angle tracks and low-momentum particles, ND280 has recently undergone a major upgrade, including a novel scintillator tracker, acting as a neutrino target, the Super Fine-Grained Detector (SFGD), and, in addition, a Time-of-Flight (ToF) system and two High-Angle Time Projection Chambers (HA-TPCs).

In the talk, I will focus on the detector aspects of the ND280 upgrade, with particular attention to the HA-TPCs. These chambers employ a lightweight composite field cage to minimise passive material while maximising active volume and an Encapsulated Resistive Anode Micromegas (ERAM) readout that improves robustness and stability without degrading spatial resolution. I will present results from the first performance studies with the fully upgraded ND280 at J-PARC, including spatial and momentum resolution, drift-direction studies, and electric-field behaviour.  The upgraded ND280 will be used as a near detector of Hyper-Kamiokande (HK), the successor of T2K, starting data taking in 2028. The importance of ND280 for HK will be discussed briefly, including a possible additional upgrade of ND280, ND280++, for the HK era.