Performance of High-Angle Time Projection Chambers in the T2K Near Detector Upgrade

Performance of High-Angle Time Projection Chambers in the T2K Near Detector Upgrade Matteo Feltre, on Behalf of T2K HA-TPC Group University and INFN, Padova XXI Workshop on Neutrino Telescopes Padova, Italy, September 29th – October 3rd, 2025 Overview 1. T2K Experiment 2. ND280 Upgrade 3. HA-TPC components 4. HA-TPC performance M. Feltre, NeuTel 2025 2 The T2K Experiment T2K is a long-baseline neutrino experiment from J-PARC to Super-Kamiokande Main goals and results: •𝝂𝝁disappearance 𝜽𝟐𝟑,𝚫𝒎𝟐𝟑 𝟐 •𝝂𝒆appearance and comparison with ഥ 𝝂𝒆 𝜽𝟏𝟑,𝜹𝑪𝑷 Upgrades: •MR beam power reached 840 kW, expecting to reach up to 1.3 MW •Upgrade of Near Detector ND280 to decrease systematics Goal: improve sensitivity to 𝜹𝑪𝑷 M. Feltre, NeuTel 2025 3 𝝂𝝁 𝝂𝝁 𝝂𝝁 𝝂𝝁𝝂𝒆 𝝂𝒆 Upgraded Detector Configuration: 1. Super Fine Grain Detector (sFGD): Segmented target of cubic scintillators (1 cm side) 2. Two High Angle TPCs (HA-TPC): Placed at high angles respect to beam direction 3. Time of Flight (ToF): Six planes of scintillators to reduce the background Near Detector ND280 Upgrade Critical points: 1. Improve acceptance for tracks with high angle w.r.t. beam direction 2. Low efficiency in reconstructing hadronic parts of interactions ND280 Upgrade goals: •Overall systematic uncertainty to 4% (from 6%) •Near detector for Hyper-K from 2028 M. Feltre, NeuTel 2025 4 High Angle Time Projection Chambers (HA-TPC) Requirements: 1. Momentum resolution σp p<10% at 1 GeV/c → neutrino energy estimation 2. Energy resolution 𝝈(dE dx)<10% → PID of electrons and muons 3. Low material budget walls 1. Field Cage •Thin walls and less space subtracted to active volume 2. Resistive MicroMegas ERAM: Encapsulated Resistive Anode MicroMegas •Charge spread on resistive layer to enhance spatial resolution •Spark protection M. Feltre, NeuTel 2025 5 Operating conditions: •T2K gas Ar:CF4:iC4H10 =95:3:2 •Overall dimension ∼2.0 ×0.8 × 1.8 m3 •Drift length 1 m •Electric field uniformity <10−3 at 15 mm from walls Innovative aspects: Installation of HA-TPC in ND280 at J-PARC HA-TPCs installation Neutrino data since May 2024 Top HA-TPC Bottom HA-TPC Side view of full ND280 event display M. Feltre, NeuTel 2025 6 HA-TPC characterization and performance M. Feltre, NeuTel 2025 7 HA-TPCs require the understanding of several aspects in order to offer optimal performances: 1. ERAMs characterization 2. Electric field characterization 3. Monitoring of gas purity 1. Several test beam campaigns on prototypes and on ERAMs 2. Cosmic rays data taking at CERN and J-PARC on the final HA-TPCs Prototype and full-scale HA-TPCs were tested with: 1. Charged track interaction in gas 2. Primary electron drift 3. Readout signal modeling Evaluation of HA-TPCs performances 1. Spatial reconstruction 2. dE/dx Simulation of the detector: 1 Signal has same time scale as shaping time O(100 ns) 2D diffusion equation 𝜌 𝑟,𝑡 = 𝑅𝐶 4𝜋𝑡exp −𝑟2𝑅𝐶 4𝑡 Electrical model of the sensor FEE response function 4 2 3 Resistive MicroMegas Sensors (ERAMs) mesh M. Feltre, NeuTel 2025 8 Primary electrons create avalanches in the amplification gap ERAM response characterization was performed at CERN on a test bench with a 55-Fe source ERAMs Validation and Characterization From the measurements performed on the test bench, three parameters are estimated: 1. RC 2. Gain 3. Resolution Plots summarize the 3 properties of each pad in every ERAM for •identification of defects •choosing the final detectors for HA-TPCs Different DLC batch Imprints of stiffeners Shorter amplification gap M. Feltre, NeuTel 2025 9 Candle plots Red dashed lines represent different production campaigns HA-TPC Simulation and Reconstruction Ratio of 𝑄1/𝑄0 close to the anode for vertical tracks: M. Feltre, NeuTel 2025 16 Tracks divided over distance from leading pad centre Drift region x<10 cm: •Diffusion effects are expected to be negligible •Overall agreement when lowering the RC measured parameters by 20% in simulations Considering the whole drift distance: •Small underestimation persists in simulation Current efforts are dedicated to improve signal formation modeling Work in progress Work in progress Work in progress Work in progress Spatial resolution Performances of HA-TPCs are evaluated by looking at their residuals with respect to the helix fit of the track 𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙𝑠= 𝑦𝑟𝑒𝑐 −𝑦𝑓𝑖𝑡 2+ 𝑧𝑟𝑒𝑐 −𝑧𝑓𝑖𝑡 2−𝑅 Spatial resolution is defined as the width of the gaussian fit of the residuals distribution Spatial resolution v. drift distance beam cosmic Spatial resolution v. angle on ERAM plane M. Feltre, NeuTel 2025 17 Work in progress Work in progress Work in progress Work in progress σ∼400 μm Considering tracks with a drift distance 500-550 mm: Momentum Resolution 𝜎𝑝𝑡 𝑝𝑡=𝜎𝑦𝑧 𝑚𝑝𝑡𝐺𝑒𝑉 𝑐 𝑒 𝐵 𝑇 𝑙2𝑚2720 𝑁𝑝+4 Spatial and momentum resolution are related thanks to the Gluckstern equation A linear trend in resolution is expected from the equation 𝜎𝑝𝑡 𝑝𝑡∝𝑝𝑡 Horizontal tracks Vertical tracks M. Feltre, NeuTel 2025 18 Work in progress Work in progress Momentum resolution is defined as 𝑝𝑟𝑒𝑐𝑜−𝑝𝑡𝑟𝑢𝑒 𝑝𝑡𝑟𝑢𝑒 and reported as a function of 𝑝𝑡𝑟𝑢𝑒 Energy Loss per unit of Length (dE/dx) The reconstruction of dE/dx combined with momentum information is crucial for obtaining a good Particle Identification Energy loss estimation is performed by considering a track as a continuous linear density For a linear track: 𝜌1𝐷 𝑧,𝑦,𝑡;𝑝0,𝑝1,𝜆 = 𝜆 2𝜋𝜎exp − −𝑦+𝑝1∗𝑧+𝑝0 2 2 1+𝑝12𝜎2 𝑄𝑝𝑎𝑑 𝑡 =නන 𝑝𝑎𝑑𝜌1𝐷 𝑦,𝑧,𝑡 𝑑𝑦𝑑𝑧 𝑑𝐸 𝑑𝑥 𝑒𝑣𝑒𝑛𝑡 =σ𝑝𝑎𝑑𝑑𝐸𝑝𝑎𝑑 σ𝑝𝑎𝑑𝑑𝑥𝑝𝑎𝑑 The total charge on a pad is given by the charge density over its area: The total energy loss over the track length is given by the sum of pads contribution Good agreement between data and MC M. Feltre, NeuTel 2025 19 Work in progress Work in progress dE/dx resolution dE/dx resolution v. Momentum dE/dx resolution v. track length The evaluation of dE/dx resolution is performed by: 1. Binning data in momentum slices 2. Each slice was fitted with a gaussian and the ratio 𝜎 𝜇 is extracted 3. Range 300 MeV/c – 500 MeV/c is considered Events from beam and cosmic datasets are reported 𝜎 𝜇𝑐𝑜𝑠𝑚𝑖𝑐𝑠 = 9.2±0.1 % 𝜎 𝜇𝑏𝑒𝑎𝑚 = 6.5±0.3 % The resolution satisfies the requirements in the region of interest of the detector M. Feltre, NeuTel 2025 20 Work in progress Work in progress Work in progress The realization of HA-TPCs required the design, prototyping, construction, validation and characterization of their components since 2018 Both detectors were successfully installed at J-PARC by May 2024 HA-TPCs performances were evaluated using cosmic rays and neutrino beam data at J-PARC Comparisons between data and MC show a reasonable agreement achieving: •Spatial resolution better than 800 μm •dE/dx resolution better than 10% meeting their design performance targets HA-TPCs are expected to continue their operations as a part of Hyper-K long baseline program! Conclusions Paper in preparation! M. Feltre, NeuTel 2025 21 Thanks for your attention! M. Feltre, NeuTel 2025 22