Technical challenges for the new T2K High Angle TPCs2

Technical challenges for the new T2K High Angle TPCs 2 October 2025 Stefano Levorato on behalf of the T2K ND280 upgrade group XXI Workshop on Neutrino Telescopes | Sep. 29th, 2025 to Oct. 3rd, 2025 | Palazzo del Bo, Centro Culturale San Gaetano, Padua Italy | S. Levorato Outlook 2 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato •The T2K ND280 experiment •The ND280 upgrade project •The motivations •The upgrade •The High Angle Time Projection Chambers (HATPC) •A short detector description •The Encapsulated Resistive Anode Micromegas (ERAM) •Construction •Quality assessment •HATPCs performace •Conclusions Super-K J-PARC Long-baseline neutrino experiment from J-PARC to Super-Kamiokande The T2K experiment and the role of ND280 3 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato High intensity, 0.6 – 2.2 GeV 𝜈𝜈μ beam produced at J-PARC (Tokai) → 𝜈𝜈 or 𝜈𝜈 mode by changing the horn polarity Neutrinos detected at the Near Detector (ND280) and at the Far Detector (Super-Kamiokande) •𝜈𝜈e and 𝜈𝜈e appearance → determine θ13 and δCP •Precise measurement of 𝜈𝜈μ disappearance → θ23 and |Δm232| Near Detector complex at 280 meters from the target Several detectors installed to monitor the beam reduce systematic uncertainties in oscillation analyses, and measure 𝜈𝜈 and 𝜈𝜈 crosssections ND to measure un-oscillated beam flux and ν cross sections The T2K experiment and the role of ND280 4 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato High intensity, 0.6 – 2.2 GeV 𝜈𝜈μ beam produced at J-PARC (Tokai) → 𝜈𝜈 or 𝜈𝜈 mode by changing the horn polarity Neutrinos detected at the Near Detector (ND280) and at the Far Detector (Super-Kamiokande) •𝜈𝜈e and 𝜈𝜈e appearance → determine θ13 and δCP •Precise measurement of 𝜈𝜈μ disappearance → θ23 and |Δm232| Near Detector complex at 280 meters from the target Several detectors installed to monitor the beam reduce systematic uncertainties in oscillation analyses, and measure 𝜈𝜈 and 𝜈𝜈 crosssections ND to measure un-oscillated beam flux and ν cross sections Results from the T2K experiment by Sophie King First results from T2K's upgraded near detector by Gioele Reina Latest neutrino cross-section results from T2K Ellen May Sandford Neutron Production in Neutrino-Nucleus Interactions with T2K Asit Srivastava The ND280 experiment: the upgrade 5 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato •Reduced angular acceptance 𝜈𝜈 events, mostly reconstructing forward going tracks entering the TPCs •Low efficiency to reconstruct low momenta protons New detectors to extend acceptance for tracks at high angles Detector installed inside UA1/NOMAD magnet (0.2 T) Super-K acceptance ND280: the upgrade detectors 6 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Timing characterization for T2K ND280Upgrade SuperFGD detector by Gioele Reina Super Fine-Grained Detector for improved neutrino interaction measurements in T2K Wataru Okinaga-san ND280: upgrade completed! Top-HATPC installed in the end of April 2024 7 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Top HATPC SFGD Bottom HATPC TOF TOF ND280: upgrade completed! Top-HATPC installed in the end of April 2024 8 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Top HATPC SFGD Bottom HATPC TOF TOF Installation of the Detectors of the ND280 upgrade successfully completed in May 2024! The ND280 experiment: High Angle TPC highlights 9 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato •The HATPC detector •Detector construction highlights •Encapsulated Resistive Anode Micromegas (ERAMs) •The realization of the 50 ERAM sensors •The ERAM characterization •Detector response, signal • HATPC performance The ND280 experiment: High Angle TPC highlights 16 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato INNER VOLUME OUTER VOLUME Internal Twaron layer Aramid fabric for optimal mechanical support while maintaining low budget materials and insulating properties The ND280 experiment: High Angle TPC highlights 17 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato External layers Additional Twaron layers and Aluminum shielding INNER VOLUME OUTER VOLUME The ND280 experiment: High Angle TPC highlights 18 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Data: Max deformation of large faces: ∼50 μm mbar Max deformation of small faces: ∼8μm mbar Almost linear in the studied pressure range Simulation: Max deformation of large faces: ∼50 μm mbar Central cathode only partially constrains flanges deformation Deformation due to underor over-pressure on field cage walls that might influence the direction of electric field The ND280 experiment: High Angle TPC highlights 19 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Particular attention was dedicated to the insulating properties of the inner materials: •Strip foil •Additional Kapton layers •Inner Twaron layer •Resins to assess: 2. Volumetric resistivity 1. Surface resistivity The ND280 experiment: High Angle TPC highlights 20 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 1. Surface resistivity 2. Volumetric resistivity Match with the expected values from an insulating material! HATPC, Electric Field studies 21 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato The HATPC geometry has been integrated in COMSOL – Multiphysics Detailed Electric Field maps have been computed  fed to the reconstruction routines of ND280 software package Electric Field deviations from the ideal condition are present along the cathode and anode edges Introduce distortions in the reconstruction of the track Electric Field Biasing Effect The ND280 experiment: High Angle TPC highlights 22 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato •The HATPC detector •Detector construction highlights •Encapsulated Resistive Anode Micromegas (ERAMs) •The realization of the 50 ERAM sensors •The ERAM characterization •Detector response, signal • HATPC performance ERAM: MicroMegas with DLC resistive foil 23 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Resistive layer enables charge spreading → space resolution below 500µm with larger pads → less FEE channels (lower cost) → improved resolution at small drift distance (where transverse diffusion cannot help) Resistive layer prevents charge build-up and quench sparks → enables operation at higher gain → no need for spark protection circuits for ASICs → compact FEE → max active volume Resistive layer encapsulated and properly insulated from GND → Mesh at ground and Resistive layer at +HV → improved field homogeneity → reduced track distortions → better shielding from mesh and DLC → potentially better S/N ERAM Module breakout 24 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato  Very compact Electronics parallel to the detector 8 + 8 ERAMs per HATPC Charge spread on low resistivity foil 25 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Charge Spreading 2D telegraph eqn. solution time scale is driven by RC Gaussian spread Final ERAM layout choice for series production: Considering pads of 11x10 mm2 parameters -400 kΩ/□ DLC resistivity – low resistivity -150 µm thickness glue – Cdlc-pad/gnd ~ O(20pF)  RC ~ O(100ns/mm2) Trade-off optimal charge spread VS spark protection Gain not affected by resistivity (transparency to induced signals is guaranteed) Reconstructing X-rays Q: the importance of QC 32 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Production steps: tough! (needed long tuning) 1) Selecting DLC foil resistivity -Large variations from DLC provider -Stable values only after annealing 2) Gluing steps by Pressing -DLC to PCB -Stiffener to DLC-PCB RC map of ERAMS on bottom HATPC EP1 ns/mm2 ERAM with DLC-PCB gluing issue Gain map of ERAM OK 1µm mesh-DLC gap variation => 10% variation in gain up 20% RC variation over same ERAM Extraction of RC and Gain maps from X-rays 33 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Converted X-ray impact point position is also fitted accurate maps of Gain and RC Use of the method for the extraction of ERAM GAIN and RC Use for detailed studies of charge diffusion and ERAM response at fine PAD position level Indications are that the lower resistivity the better the performance (eg space resolution) Extraction of RC and Gain maps from X-rays 34 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Converted X-ray impact point position is also fitted accurate maps of Gain and RC Use of the method for the extraction of ERAM GAIN and RC Use for detailed studies of charge diffusion and ERAM response at fine PAD position level Indications are that the lower resistivity the better the performance (eg space resolution) ERAM Series production: a summary table 35 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Energy resolution RC distribution Gain distribution @350V The ND280 experiment: High Angle TPC highlights 36 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato •The HATPC detector •Detector construction highlights •Encapsulated Resistive Anode Micromegas (ERAMs) •The realization of the 50 ERAM sensors •The ERAM characterization •Detector response, signal • HATPC performance TPC detector stability from Assembly to Operation 37 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Low resistivity DLC O(~400kΩ/□) [after annealing] features •Optimal charge spread → uniform response across pad (combined with C ~ O(20pF/cm2) •Fast Q removal and Effective Protection against sparks included at moderate rates ~ O(1kHz) tracks crossing pads •Leakage currents at level of few nA in normal conditions (no beam) Challenging installation conditions → high sensitivity to dust → low H2O level (100ppm) before HV on 0.8 ÷ 2 sparks/day → Confirmed by the detector operation at T2K ERAM response – Signal and noise model 38 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Main ingredients Avalanche signal measured with fast electronics on bulk micromegas Electron signal (too fast for our shaping times) Ions signal (slow) FEE Response Function In the time scale of our shaping time O(100ns) Charge spread is properly described by Electrical model of the sensor 2 1 3 4 Note: Of course, gas transport properties (L, T diffusion) have to be accounted for Solutions of 2D diffusion eqn. Noise: stability of the installed detector 39 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Noise in module 0 has been stable between September 23 and June 24 All the Erams are quasi-identical but one, Eram 27, due its higher capacitance  the excellent uniformity of the electronics and of the mechanical definition of the glue layer driving the detector capacitance Noise: stability of the installed detector 40 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Previous conclusions supported by the noise detailed model included in the MC for Simulation of charge deposition in events Reconstructing charge deposition 41 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Use of the model for Reconstructing the charge deposition Due to square shape of ERAM pads, the classical method (PRF+clustering) works OK only for tracks with horizontal or vertical direction (wrt pads coordinates) Better methods use solutions of telegraph equation in order to 1) compute the pattern templates for charge diffusion on DLC 2) calculate the overall expected signal waveform per each pad 3) find the best matching with the recorded waveforms Its computationally heavy  different approximations are used for different analysis 1) X-rays analysis – ERAM characterization 2) Measurement of dE/dx – Particle Identification 3) Track reconstruction – momentum measurement Conclusions 48 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Two new TPCs have been installed in ND280 at JPARC -Very stable operations in commissioning and technical runs -Neutrino Data already collected! Restarting in mid November! Resistive MM with encapsulated anode ERAM - First time use of an encapsulated resistive Micromegas in a High Energy running experiment -Low resistivity & optimal charge spread & no sparks effects -Series production allowed several detailed studies -The ERAM technology is complex and delicate to produce as are all the resistive MPGDs. The expertise and excellent partnership with the CERN/PCB workshop enabled a high yield (~80%) of high-quality production -New algorithms for square pads exploiting detailed response model under development -Detector performance, still preliminary but very promising! Conclusions 49 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Two new TPCs have been just installed in ND280 at JPARC -Very stable operations in commissioning and technical runs -Neutrino Data already collected! Restarting in mid November! Resistive MM with encapsulated anode ERAM - First time use of an encapsulated resistive Micromegas in a High Energy running experiment -Low resistivity & optimal charge spread & no sparks effects -Series production allowed several detailed studies -The ERAM technology is complex and delicate to produce as are all the resistive MPGDs. The expertise and excellent partnership with the CERN/PCB workshop enabled a high yield (~80%) of high-quality production -New algorithms for square pads exploiting detailed response model under development -Detector performance, still preliminary but very promising! Spare Just in Case 50 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 51 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Reconstruction of charge deposition 2/2 Charge on DLC spreads along any direction including track direction «longitudinal correlation» across primary pads within our electronics shaping time scale requires a dedicated signal formation model Reconstructing Q along tracks: Waveform Sum 52 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato OK for almost H & V tracks Q missing for inclined tracks Simple method based on Sum of waveforms(t) (WS) over pads in a cluster Reconstructing Q along tracks: Crossed Pad (XP) 53 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 1) Reconstruct tracks and consider only pads crossed (XP) by the track (primary pads) 2) Reconstruct original (ion induced) charge (Q) for each XP (given the track parameters there) by Q = A x (Q/A) – where A is recorded amplitude on XP and rescaling ratio (Q/A) from Look Up tables (LUT) LUTs build from model: original Q is distributed linearly over the segment for each XP so that solutions of diffusion equations can be used 1) No clustering => potentially more accurate method because reconstructing full induced charge on primary pads 2) «dilution of ion signal» on a XP pad, due to charge spread over the pad is correctly taken into account 3) «longitudinal correlation» among adjacent XP pads, due to charge spread along track direction is accounted for 4) Fast method though based on model templates (long time is to generate LUTs …) Reconstructing Q along tracks: Crossed Pad (XP) 54 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Building the rescaling ratio Q/A ratio 4D LUTs via model dE/dx preliminary results: (WS) and (XP) methods 55 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato dE/dx (4GeV electrons) – comparison of WF and XP methods on Test Beam data (DESY) dE/dx preliminary results: (XP) method 56 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato dE/dx via XP method on Test Beam data (CERN PS T10) Reconstructing Q along tracks 57 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato For the reconstruction of the charge along the tracks two methods - Waveform Sum (WS) - Crossed Pad (XP) Compare the performance of the two methods for dE/dx extraction 64 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Reconstructing tracks: trajectory fitting 65 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato LogQ Method based on clustering & Log[Qprimary /Qsecondary] •logQ method to reconstruct position in each cluster •Helix fit performed on those reconstructed positions Full Waveform fit Method – based on model & no clustering 1) Use all the pads associated to a track (Qmax values) to define a (v,u) local frame 2) Distribute “arbitrary” point charges along v axis separated by ∆v (5mm) the Q per each point is a free parameter 3) Diffusion model to predict the waveform generated by point charges in surrounding pads 4) Move all points along the u axis to minimize the chi-square difference between measured waveforms and templates RungeKutta method to fit (u0, du/dv, q/p, t0, dv/dt) GAIN, RC 66 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Detailed R measurement (dedicated probe) 67 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato R inhomogeneities in the sputtering are clearly visible in the direction perpendicular to the drum rotation axis. A dedicated probe has been built to perform a fine measurement of the surface resistivity. Will be soon complemented with the comparison with the data extracted from X-ray analysis 68 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Conclusions 69 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Two new TPCs have been just installed in ND280 at JPARC -Very stable operations in commissioning and technical runs -Firs Neutrino Data taking just completed, restarting in October 2024 Field cages -High ratio active/passive volume -Highly effective insulation & E field uniformity -Composite material technology exploited at the limit of the technology Resistive MM with encapsulated anode -Low resistivity & optimal charge spread & no sparks effects -Series production allowed several detailed studies -The ERAM technology is complex and delicate to produce as are all the resistive MPGDs. The expertise and excellent partnership with the CERN/PCB workshop enabled a high yield (~80%) of high-quality production -New algorithms for square pads exploiting detailed response model under development HATPC: features, challenges, constrains and solutions 70 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Mechanics and Electric Field uniformity •Min dead space & max active volume in the dipole magnet Rectangular shape & thinnest walls & field shaping electrodes incorporated into the walls • Electric field uniformity better than 10-3 @1cm from walls  Mechanical accuracy: inner surfaces planarity & parallelism ~ O(0.2mm/m)  Shaping Electrode design: Field and Mirror copper strip layers on two sides of a Kapton foil •Low material budget walls  lightweight & lowest Z & robust (self supporting) Electrical insulation Constrains •HV insulation mantle R > 1TOhm and volume resistivity, HV geometry: several cm paths for charge from -HV strips to GND shielding (cathode flanges) insulating materials: very high resistivity & dielectric strength HATPC: features, challenges, constrains and solutions 71 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Building process: hand lay-up of composite materials on a Mould & polymerization in autoclave at high Pressure •Autoclave dimensions  Field Cage comprising two halves (symmetrical flanges at central cathode position) •Hand layup & large dimensions  several hours per process step  very long pot life for epoxy resin •Mechanical accuracy of geometry  resin curing at low T < O(40ºC) Materials of choice •lamination materials: Aramid polymers for peels (Twaron) and for honeycomb (Nomex paper) •epoxy resin limited choice: Resoltech 1054 combined with quality control against contaminants (moisture, …) •high insulation layers: Kapton •box skeleton material: high quality laminated G10 The ND280 experiment: High Angle TPC highlights 72 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato •Field Cage (FC) •Assembly and layout •Production •Characterization and Quality Assessment •Mechanical • Electrical •Encapsulated Resistive Anode Micromegas (ERAMS) •Production of 50 sensors •Characterization •Detector response, signal and impact on reconstruction •Impact on HATPC performance Field Cage: walls stack up layout 73 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Wall cross-section Inner surface Outer surface Wall thickness ~ 40 mm ~ 2% radiation length Alu (shielding) Field Cage building, assembling & characterization at NEXUS Kapton Layer + inner Twaron + G10 Skeleton 80 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Gluing G10 structural skeleton and casting resin on flanges for ensuring gas tightness •G10 skeleton gluing •Curing 40C in clean room •Casting low viscosity resin on top flange sealing flange to laminated layers •Autoclave curing at 40C Flanges & Bars by ORVIM company (TV, Italy) Field Cage building, assembling & characterization at NEXUS Kapton Layer + inner Twaron + G10 Skeleton + HC + Ext Twaron 81 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato •Flipping the box top-bottom •Resin casting on second flange •Curing at 40C in autoclave •Second Twaron peel lamination •Curing at 40C in autoclave •Gluing Nomex Honeycomb •Curing at 40C in oven Post-curing at 40C in oven (lasting as long as possible) Outer Twaron peel lamination Field Cage machining and final QC at Nexus 82 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Precision machining of cathode and anode flanges and surfaces finishing Back to NEXUS company for •Mould removal •Very fine polishing of flanges •Correction of defects (eg bubbles) Shipment to CERN Vallmoll – Spain The ND280 experiment: High Angle TPC highlights 83 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato •Field Cage (FC) •Assembly and layout •Production •Characterization and Quality Assessment •Mechanical • Electrical •Encapsulated Resistive Anode Micromegas (ERAMS) •Production of 50 sensors •Characterization •Detector response, signal and impact on reconstruction •Impact on HATPC performance Field Cage assembling, characterization at CERN 84 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Vertical assembly of two Field Cages into HATPC Field Cage assembling, characterization at CERN 85 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 1) He leak tested sniffer (air + 30mbar of He) 2) Tested against gas density changes -He Over-pressure (+20mbar) -Air Under-pressure (-20mbar) Gas density corrected for Volume variation (due to Pin - Pout) = 𝑃𝑃𝑃𝑃𝑃𝑃(𝑡𝑡) 𝑇𝑇𝑃𝑃𝑃𝑃(𝑡𝑡)/𝑇𝑇𝑃𝑃𝑃𝑃(0)1−∆𝑉𝑉 𝑉𝑉0 (Pin −Pout) Several T,P,RH sensors Inside FC => Overall Leak < 10-3 mbar L / s Gas leakages qualification Field Cage assembling, characterization at CERN 86 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Mechanical qualification Comparison with FEM models in fair agreement with •load tests •deformation vs pressure Field Cage assembling, characterization at CERN 87 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Mechanical qualification Comparison with FEM models in fair agreement with •load tests •deformation vs pressure Field Cage assembling, metrology at Nexus 88 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Tolerances and specifications at a level better than 300µm/m for planes parallelism and orthogonality and better than ISO1302-N8 for waviness are respected with few localized acceptable exceptions Reached limits of composite material technique Large dimensions and hand lay-up Field Cage assembling, metrology at CERN 89 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Measured internal geometry after assembly agrees with nominal CAD with pull better than 300µm with few localized, acceptable exceptions Near Detector impact on Oscillation Analysis ND280 limitations ND280 Upgrade improvements Mantle resistance ERAM Production - about 50 detectors Crucial steps in production (needed tuning) 1) Selecting DLC foil resistivity -Large variations from DLC provider -Value stable after annealing 2) Gluing steps by Pressing -DLC to PCB -Stiffener to DLC-PCB X-rays Test Bench at CERN was fundamental to 1) Qualify, characterize and calibrate all prototypes and series ERAMs 2) support the development of detailed ERAM response model Field Cage assembling, characterization at CERN Gas contamination from Field Cage – other contaminants ERAM Series Production experience Effect of gas density on (gas) GAIN Effect of humidity on (gas) GAIN Fine grain scan GAIN as a function of Pad positio Reconstructing tracks dE/dx dE/dx – comparison of SWF and XP methods on Test Beam data (4GeV electrons, DESY) Reconstructing tracks – pattern recognition •Time and charge definition for each hit •Waveform multipeak search in order to differentiate vertices and crossing trajectories •Merging between different ERAMs and End Plates XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 2.10.2025 112/20 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 2.10.2025 113/20 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 2.10.2025 114/20 Although a-C:H and ta-C belong to the same material family, they are not produced by the same coating process. a-C:H is achieved by PECVD (Plasma Enhanced Chemical Vapor deposition) in a gaseous environment. Whereas ta-C is produced by PVD-arc (Physical Vapor deposition arc) from a solid carbon target. PVD-arc technology enables the production of a ta-C coating with a higher percentage of sp3 hybridization without hydrogen and providing a higher hardness. XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 2.10.2025 115/20 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 2.10.2025 116/20 Both experiments individually prefer normal ordering and δCP~- π/2, T2K prefers upper octant, SK prefer lower octant We performed Bayesian and Frequentist analyses → frequentist analyses shown today The CP-conserving value of the Jarlskog invariant is excluded with a significance between 1.9 and 2 σ XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 2.10.2025 117/20 R inhomogeneities in the sputtering are clearly visible in the direction perpendicular to the drum rotation axis. XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 2.10.2025 118/20 And this matches the resistivity direct measurement (C is very well constrained by the thickness of insulator) R inhomogeneities in the sputtering are clearly visible in the direction perpendicular to the drum rotation axis. The ND280 experiment: High Angle TPC highlights 119 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato •Field Cage (FC) •Assembly and layout •Production •Characterization and Quality Assessment •Mechanical • Electrical •Encapsulated Resistive Anode Micromegas (ERAMS) •Production of 50 sensors •Characterization •Detector response, signal and impact on reconstruction •Impact on HATPC performance An outsider: Field Cage 0 ? Electrical Issues, what we understood… and learnt Insulation issue in full scale FC0 prototype 120 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Insulation issue in full scale FC0 prototype 121 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Strip to strip V drop disuniformity Buried resistive layer: electrical model 128 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato R K V(x) Glue prepreg. Resin impregnated Twaron layer Cathode -10kV Kapton 50µm Kapton 25µm Anode 0V Center FC Buried resistive layer I1(0)+I3(0)=I1(L) –I3(L) I2(0)=I3(0) I2(L)=-I3(L) Symmetry 𝒅𝒅𝒅𝒅𝟑𝟑(𝒙𝒙=𝑳𝑳/𝟐𝟐) 𝒅𝒅𝒙𝒙 =0 (middle of the cage) Kirchhoff law 𝑻𝑻𝒅𝒅𝒅𝒅𝟑𝟑(𝒙𝒙) 𝒅𝒅𝒙𝒙 +𝐑𝐑𝐑𝐑𝐑𝐑 𝐱𝐱 − 𝐊𝐊𝐑𝐑𝟐𝟐 𝐱𝐱=𝟎𝟎 𝒅𝒅𝐑𝐑𝐑𝐑𝐱𝐱 𝒅𝒅𝒙𝒙 +𝐑𝐑𝟑𝟑𝐱𝐱=𝟎𝟎 𝒅𝒅𝐑𝐑𝟐𝟐𝐱𝐱 𝒅𝒅𝒙𝒙 −𝐑𝐑𝟑𝟑 𝐱𝐱=𝟎𝟎 Transmission line model I1(x) T I2(x) Constraints [K]=Ωm, [T]=Ω/□,[R]= Ω Buried resistive layer: electrical model results 129 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Glue prepreg. Resin impregnated Twaron layer Cathode -10kV Kapton 50µm Kapton 25µm Anode 0V Center FC Buried resistive layer - 5kV - 5kV - 5kV - 1kV - 3kV - 4kV - 6kV - 7kV - 9kV R K V(x) Kirchhoff law 𝑻𝑻𝒅𝒅𝒅𝒅𝟑𝟑(𝒙𝒙) 𝒅𝒅𝒙𝒙 +𝐑𝐑𝐑𝐑𝐑𝐑 𝐱𝐱 − 𝐊𝐊𝐑𝐑𝟐𝟐 𝐱𝐱=𝟎𝟎 𝒅𝒅𝐑𝐑𝐑𝐑𝐱𝐱 𝒅𝒅𝒙𝒙 +𝐑𝐑𝟑𝟑 𝐱𝐱=𝟎𝟎 𝒅𝒅𝐑𝐑𝟐𝟐𝐱𝐱 𝒅𝒅𝒙𝒙 −𝐑𝐑𝟑𝟑 𝐱𝐱=𝟎𝟎 Transmission line model I1(x) T I2(x) Constraints The electric field in the active volume is non uniform Due to the spurious voltage divider formed in parallel to the regular one Buried resistive layer: electrical model results 130 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato m m uA uA Anode kV kV Buried resistive layer: fit to the data 131 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato 25µm Kapton Breakdown observed at values much lower than datasheet Buried resistive layer: electrical model results 132 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato m m uA uA Anode kV kV Early Stage Later Stage Final layout, materials and procedures fixed for the series production 133 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato Key points to avoid failures - no resin contamination !!! Note: usually glues and resins are the weakest points - Interpose between strips and Twaron layers a “thick” layer of insulator featuring -High resistivity ρv > 1015 Ωcm -Dielectric strength > 150kV/mm Final layout of the stack: minimal changes to design •new strip foil w/ thicker Kapton coverlay 50µm + 25µm glue (produced at CERN, gluing in vacuum with press) •3 layers of Kapton: 125µm + 50µm resin each (to be laminated on the back of strip foil on the mold) thickness Kapton+Resin ~0.5mm → “vertical R” below 1 strip O(10TΩ) @ 10kV Materials: Same insulating materials (Kapton + Aramid) and same resin (Resoltech) Production procedure and enhanced countermeasures and QC •Minimize moisture trapped in wall layers: drying in oven Kapton & Twaron just before use •QC epoxy contamination -> proper control of mixing and de-gassing process (new mixing / degassing tools and QC) and … avoid antistatic spray… •QC electrical resistivity measurements after each early step in the production ND280: installations at J-PARC 134 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato N280: commissioning at JPARC with cosmics 135 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato -Detector commissioning with and without magnetic field -Alignment runs -New software deployment -New T2K gas system commissioning for both vertical and horizontal TPCs N280: ν technical runs in December 2023 and February 2024 physics run 136 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato The T2K run schedule: beam upgrade 137 2.10.2025 XXI Workshop on Neutrino telescopes | Sep.29th - Oct.3rd 2025; Padua, Italy | S. Levorato ν beam @ J-PARC: dedicated upgrade of the MR facility to reach the 1.3 MW beam power Steady improvements to reach 1.3 MW by 2027 with an increase T2K statistics ~ a factor of 3 by 2027 December 2023 → Beam power increased from 500 to 760 kW stable mode 800 kW reached in 2024 for the first run with the fully upgraded ND280 Expect to select 20k 𝜈𝜈μ CC0pi interactions in the superFGD for 0.2e21 POT (1 month)