The Design, Operation, and Experience with the ND280 Neutrino Detector Blair Jamieson (UBC) for the T2K collaboration ANT 2010 Santa Fe, NM Sept 16-19, 2010

Blair Jamieson ANT2010 Sept 16-19, The T2K Collaboration Canada TRIUMF U. Alberta U. B. Columbia U. Regina U. Toronto U. Victoria York U. France CEA Saclay IPN Lyon LLR E. Poly. LPNHE Paris Germany U. Aachen ~500 members, 61 Institutes, 12 countries Italy INFN, U. Roma INFN, U. Napoli INFN, U. Padova INFN, U. Bari Japan ICRR Kamioka ICRR RCCN KEK Kobe U. Kyoto U. Miyagi U. Edu. Osaka City U. U. Tokyo Poland A. Soltan, Warsaw H.Niewodniczanski, Cracow T. U. Warsaw U. Silesia, Katowice U. Warsaw U. Wroclaw Russia INR S. Korea N. U. Chonnam U. Dongshin U. Sejong N. U. Seoul U. Sungkyunkwan STFC/RAL STFC/Daresbury USA Boston U. B.N.L. Colorado S. U. Duke U. Louisiana S. U. Stony Brook U. U. C. Irvine U. Colorado U. Pittsburgh U. Rochester U. Washington Spain IFIC, Valencia U. A. Barcelona Switzerland U. Bern U. Geneva ETH Zurich United Kingdom Imperial C. London Queen Mary U. L. Lancaster U. Liverpool U. Oxford U. Sheffield U. Warwick U.

Blair Jamieson ANT2010 Sept 16-19, Tokai To Kamioka Experiment: T2K Plan for Talk: ● Introduction to T2K long-baseline experiment ● Description of the near detector components ● ND280 installation and operation ● Performance of detectors ● Thoughts on future near detectors

Blair Jamieson ANT2010 Sept 16-19, Core T2K Measurements; e Appearance ● P( ν μ ν e ) depends on angle θ 13 ● Chooz limit sin 2 13 <0.17 ● Predicted T2K sensitivity is >10 times improvement over current limits (for 5 years of full power running = 3.75MW x 10 7 s) ● T2K aim for 150kW x 10 7 s by summer 2011 (~3x10 20 pot) – sin ~0.05

Blair Jamieson ANT2010 Sept 16-19, Core T2K Measurements : ν μ Disappearence Plan: ● Measure the unoscillated ν μ energy spectrum at ND280 ● Measure the oscillated ν μ energy spectrum at Super-K – Using CCQE interaction mode in both cases ● Comparisons of near/far spectrum spectrum allows for precise extraction of ν μ disappearance Plots of predicted CCQE energy spectra at Super-K, for different values of m 2 x 5 years

Blair Jamieson ANT2010 Sept 16-19, GeV Neutrino Interactions; Background Considerations Interaction background processes: Largest ν μ background to CCQE ν μ measurements at Super-K is CCπ + ν μ/e + N → μ - /e - + N + π + comparable size to CCQE Largest ν μ backgrounds to ν e search at Super-K are intrinsic nu-e, and NC π 0 ν μ/e + N → ν μ/e + N + π 0 Only π 0 →γγ detected in final state γ and e - are indistinguishable Important to measure at near detector T2K Charged Current Cross Sections

Blair Jamieson ANT2010 Sept 16-19, Overview of T2K Experiment T2K Concept: ● Produce a beam of neutrinos using the JPARC proton beam. ● Measure the neutrino flux, lepton flavour content and interaction dynamics at the near detector, before any oscillations have occurred. ● Collaborate with NA61 to constrain beam production uncertainty ● Measure flux and lepton flavour content at far detector (Super-K); ● Combining together this information we can derive new measurements of neutrino oscillation parameters.  120m0m280m 295 km 2.5 o Super-Kamiokande Proton Beamline Near Detector

Blair Jamieson ANT2010 Sept 16-19, T2K Off-axis Beam ● T2K uses a novel off-axis neutrino beam (idea developed at TRIUMF). – Super-K and ND280 are located 2.5 O off-axis from direction of proton beamline. ● The off-axis beam results in a quasi- monochromatic beam in the energy range of our oscillation maximum. – Also means less backgrounds from higher energy neutrinos. Off-axis beam technique (Ref: BNL-E889 proposal)

Blair Jamieson ANT2010 Sept 16-19, T2K Status 3 0 GeV continuous running achieved ● T2K has largely finished all construction and started taking data during – Have seen our first neutrinos! ● 50kW stable running

Blair Jamieson ANT2010 Sept 16-19, T2K Near Detectors – Physics Role To achieve T2K sensitivity, we require accurate/precise measurements of unoscillated beam. This will be provided by a pair of neutrino detectors at 280m: ● INGRID : on-axis – beam profile monitoring ● ND280 : off-axis – energy spectum (flux x cross section) – Intrinsic beam e – NC 0

Blair Jamieson ANT2010 Sept 16-19, Near Detector - INGRID ● On-axis detector measures beam profile – Large mass ~ 10k daily – Position resolution ~ 7cm (3mm proton beam shift) – Beam angle accuracy goal of 1 mrad ● 16 modules of scintillator planes interleaved with 6.5 cm iron planes. ~8m direction Beam is well centered

Blair Jamieson ANT2010 Sept 16-19, ND280 Detector - Off-Axis Tracker Section: 2 FGDs (Fine Grained Detectors): ● Thin, wide scintillator planes. ● Provides active target mass. 3 TPCs (Time Projection Chambers): ● Excellent measurements of charged particles from FGD and P0D. P0D ( 0 Detector): Scintillators planes interleaved with lead/brass and water layers; optimized for gamma detection. SMRD (Side Muon Range Detector): Scintillator planes in magnet yoke. Detect muons from inner detector. direction ECAL: Scintillator planes with radiator. Measure EM showers from inner detector. Refurbished the UA1 Magnet. Operate with 0.188T field. Inner volume ~ 3.5m x 3.6m x 7m.

Blair Jamieson ANT2010 Sept 16-19, Core ND280 Measurements; Tracker CC- ● Charged-Current Quasi-Elastic: + n -> - + p ● Super-K oscillation analysis uses this interaction mode for disappearance measurement; accurate/precise measurement before oscillation is essential. ● Tracker optimized for this measurement: – Thin FGDs and P0D provide target mass for interaction. – TPCs provide superior momentum measurement and PID. p TPC FGD Second FGD and P0D have water targets; allows for cleaner extrapolation to water-based Super- K. Simulated event in Tracker

Blair Jamieson ANT2010 Sept 16-19, Core ND280 Measurements; Tracker CC- e ● There is a non-negligible e component in the T2K neutrino beam, before any oscillations. Must be accurately measured in order to not bias Super-K e appearance measurement. ● Measurement depends strongly on TPC/ECAL PID ability to distinguish the rare e interactions from the much more common interactions.

Blair Jamieson ANT2010 Sept 16-19, ● Neutral-Current 0 + N -> + N + 0 ● Important background to Super-K e appearance (ie. if SK misses one from 0 ) ● P0D 11 ton target mass, layers of: – Lead/brass radiators – Water layers (3 tons) – Scintillator ● P0D + ECAL optimized for measurement of gammas from 0 Pi0 Detector One of 4 supermodules

Blair Jamieson ANT2010 Sept 16-19, Side Muon Range Detector ● Instrumented magnet for : – Sand muon veto, Cosmic trigger – CCQE muon range

Blair Jamieson ANT2010 Sept 16-19, ECAL ● Downstream ECAL in place since beginning of running ● Barrel ECALs all built and now being installed into ND280 ● Layers of scintillator bars and brass radiator ● Use for both: – sand muon rejection, and – detecting gammas for 0 analysis, and – detecting bremstrahlung in e measurement DS ECAL e-e- FGD TPC DSECAL One of barrel ECAL Scintillator Geometry 4cm1cm

Blair Jamieson ANT2010 Sept 16-19, Detector Details: TPC TPC overview: ● Excellent tracking and particle identification for charged tracks. ● Momentum resolution 1GeV/c ● Point resolution ~700m at full drift Mechanical construction: ● Inner box constructed from copper-clad G10; outer box from aluminum/rohacell. ● Designed, fabricated and assembled at TRIUMF TPC inner box

Blair Jamieson ANT2010 Sept 16-19, TPC MEGAS: ● First production of “bulk” MEGAS: – Pad size: 6.9 x 9.7 mm 2. – Number of pads: ● 12 MEGAS per end: 72 total MEGAS TPC Electronics: ● ~100,000 TPC readout channels. ● Signal readout using AFTER chip; based on a 511-deep switched capacitor array (FGD uses same). ● Data transfer by fibre optics.

Blair Jamieson ANT2010 Sept 16-19, Micromegas Bulk MM cost (PCB+mesh+integration+connectors) ~ 10k€ / m 2 ● Gain 1500 (mesh at -350V) ● Gain Uniformity 2.8% over module 7.3% over all 72 modules ● E/E = 9.0% with 5.9keV 55Fe x-ray, similar with cosmic rays ● E/E uniform to 6% over active area ● ~9m 2 of active area with ~10 5 channels, only 10 dead channels ● 0.1 Sparks / hour at -350 V ● Non-flammable gas mixture ● Low transverse diffusion ~250 m/cm ● Drift velocity ~7.5cm/s ● Minimized gas impurities (mainly O2) >30m attenuation length

Blair Jamieson ANT2010 Sept 16-19, TPC Gas System: ● Inner (drift) volume gas: 95:3:2 Ar:CF 4 :isobutane ● Outer (buffer) volume of CO 2 ● PLC for safe gas delivery, control and data acquisition ● Two small TPCs 55 Fe, 90 Sr src monitor gain, drift velocity TPC Laser: ● Laser data (in combination with magnetic field measurements), will allow for understanding of momentum scale at 2% level. ● Also useful for checking gain and v drift. Laser flash illuminating pattern of dots and strips on central cathode.

Blair Jamieson ANT2010 Sept 16-19, TPC laser dot position measurements ● Left shows apparent movement of dots from B-field off to on for the downstream-most TPC ● Below shows reconstructed dot position minus survey position ● Adequate resolution for understanding E,B distortions Largest line is 5mm movement

Blair Jamieson ANT2010 Sept 16-19, TPC Performance ● Plots show the TPC dE/dx as a function of momentum – 2D Histogram shows results for tracks from real neutrino events. – Lines are predicted values. – Upper plot is negatively charged particles; lower plot is positively charged. ● Plots demonstrate impressive TPC particle identification capabilities. Negatively charged tracks Positively charged tracks

Blair Jamieson ANT2010 Sept 16-19, Detector Details: FGD ● Five scintillator based subdetectors: INGRID, P0D, FGD, ECAL, SMRD. Describing FGD as example

Blair Jamieson ANT2010 Sept 16-19, Detector Configuration and Number of Channels

Blair Jamieson ANT2010 Sept 16-19, Multi-Pixel Photon Counters MPPC is array of Si diodes, just above breakdown V Output is sum of charges from pixel avalanches Insensitive to magnetic fields ND280 is using ~50,000 MPPCs First large-scale use of these devices Hamamatsu MPPC Active area: 1.3x1.3 mm 2 Number of pixels: 667 x50 x1000

Blair Jamieson ANT2010 Sept 16-19, MPPC Characterization Characterization High dark noise rates: ~0.5MHz. Cross-talk/afterpulsing. Recovery effects. All quantities depend strongly on temp and over-voltage. Typical operating voltage ~70V. Aging/Stability Have tested MPPCs at elevated T (~80C) with no obvious ill-effects. First year of operation with MPPCs has been very positive; few-to-none have failed. Simulation ● Developing simulation to account for all characteristics. ND280 group has been working hard on testing and characterizing new MPPCs.

28 Preparing detectors for installation The building where detectors were handled in Tokai had less infrastructure than Fermilab or CERN. Japanese law: any motorized device capable of lifting as much as a paper clip is considered a crane, and has to be operated by a licensed professional. Loophole: manually operated hoists, no matter how much they lift, are not cranes, and are unregulated.

Blair Jamieson ANT2010 Sept 16-19, Installation of ND280 P0D TP C FG D DSECAL FG D TP C ● Involved installing and removing scaffolding to connect all services ● Detectors “dropped” into place by crane ● Survey of detector locations FGD Water supply P0D Water supply

Blair Jamieson ANT2010 Sept 16-19, Neutrino Event Displays ● Top display is a clean CC interaction ● Bottom display is more complicated DIS interaction

Blair Jamieson ANT2010 Sept 16-19, ND280 Neutrino Results; Event Timing ● Plots show the times for hits from beam triggers. ● 6 bunch structure of J-PARC proton beam is seen. ● FGD Timing resolution ~1ns (can tell direction of tracks crossing two FGDs) FGDFGD

Blair Jamieson ANT2010 Sept 16-19, FGD Neutrino Rate Check ● FGD neutrinos simple selection: – >4 time-clustered hits in beam window – No hits in upstream-most FGD layers – Hits must be in consecutive, unbroken layers ● Other sub-detectors have similar simple selection schemes. Tracker Neutrino Candidate ● Below shows # of interactions / time, normalized by protons on target ● Consistent with flat, as expected

Blair Jamieson ANT2010 Sept 16-19, Future Plans for T2K ● Final elements of ND280 detector going to be installed over this summer. ● Plan in place for continual increase of JPARC beam power. ● Major focus is now on calibration, reconstruction and analysis.

Blair Jamieson ANT2010 Sept 16-19, Thoughts on future near neutrino detectors ● ND280 Arrangement is working well, and if LBNE chooses water cherenkov far detector, ND280-like would be good choice – Live scintillator target in front of TPCs for ● good momentum and charge determination ● particle ID – Use of MPPCs for compactness, insensitivity to magnetic fields, and high photo detection efficiency – Include water layers to extrapolate to far water detector – Having nearly hermetic surrounding ECAL is important for vetoing sand muons ● If LBNE uses LAr far detector, it probably makes sense to make the near detector LAr also

Blair Jamieson ANT2010 Sept 16-19, Conclusions ● T2K plans to publish first physics result at end of year ● Aim is for 150kW x 10 7 s by summer 2011 ● sin sensitivity ~0.05 ● High statistics in near detectors

Blair Jamieson ANT2010 Sept 16-19, Backup

Blair Jamieson ANT2010 Sept 16-19, Hadron production & NA61 31GeV/c p on T2K replica target ● Hadrons produced at a given momentum and angle ● Horns focus a subset of these down the decay volume. So neutrino flux depends on: ● Secondary beam geometry ● Hadron distribution off target ● Reinteractions of p, pi in target Modelling hadron production is hard: T2K will use data from NA61 (SHINE) ● Uses thin and T2K replica targets

Blair Jamieson ANT2010 Sept 16-19, Review of Optical Transition Radiation Optical Transition radiation (OTR) is emitted when a charged particle crosses a boundary between media with different dielectric constants  Characteristic angle 1/γ Use of the optical transition radiation for beam diagnostics is a novel approach which is becoming increasingly popular within the particle accelerator community Ai r

Blair Jamieson ANT2010 Sept 16-19, Super-K: NCπ O Background NCπ O events produce two photons from π O decay. ● Photons convert to e + /e - pairs that produce e-like Cherenkov rings. ● If the other photon goes undetected, becomes a background to ν e appearance. ● This is why it is important to measure rate of NCπ O events in near detector. SK electron-lik e

Blair Jamieson ANT2010 Sept 16-19, FGD Neutrino Event Profile ● Plot shows the distribution of vertices for FGD neutrino candidates. ● More events near bottom; expected because the proton beam center is below off-axis detector. Direction of neutrino beam center.

Blair Jamieson ANT2010 Sept 16-19, Japan Proton Accelerator Research Complex (JPARC) Bird’s eye photo in January of 2008 Neutrino Beams (to Kamioka) JFY2009 Beams Main ring JFY2008 Beams 3 GeV Synchrotron CY2007 Beams Linac

Blair Jamieson ANT2010 Sept 16-19, JPARC Status ● Completion of JPARC 30 GeV Main Ring occurred in ● Achieved 100kW (single shot) and ~50 kW (continuous) beam intensity this summer. – JPARC has now entered annual summer shut-down; first year of data taking is finished. ● Final design intensity for first phase of JPARC is 750 kW. Bird’s eye photo in January of 2008

Blair Jamieson ANT2010 Sept 16-19, Protons Delivered to T2K ● Number of delivered of protons to T2K: 3.28×10 19 (Jan-June, 2010)

Blair Jamieson ANT2010 Sept 16-19, GeV Neutrino Interactions GeV Neutrinos are detected through a variety of processes. Signal mode for our measurement is Charged Current Quasi-Elastic (CCQE): ν μ/e + n → μ - /e - + p Allows flavor tagging of the neutrino via the charged lepton. Dominant process at T2K oscillation maximum. T2K Charged Current Cross Sections Note: Figure does not Include recent MiniBooNE CCQE result arXiV: v1

Blair Jamieson ANT2010 Sept 16-19,

Blair Jamieson ANT2010 Sept 16-19, TRIUMF M11 Beamtest ● After assembly, the TPC and FGD detectors were tested in the M11 beamline at TRIUMF (in 2008 and 2009). – Similar tests were done for the DsECAL at CERN in ● The M11 tests were an important part of the final integration of the many components of the detectors; in particular, was critical for developing and validating our electronics and DAQ. TPCFGD Example M11 event M11-specific G4 simulation, as well as default Tracker simulation.

Blair Jamieson ANT2010 Sept 16-19, TRIUMF M11 Beamtest Results ● Mixed M11 beam was important for TPC and FGD calibration; for instance: – Tests of non-linearity corrections. – Detailed study of energy loss in FGD for particles of different momentum. Example M11 Event R. Tacik P. Kitching

Blair Jamieson ANT2010 Sept 16-19, Time difference between FGDs ● Distinguish direction of a track by the relative time difference between FGD1 and FGD2 ● The two clusters correspond to downward-going tracks that hit either FGD1 first or FGD2 first

Blair Jamieson ANT2010 Sept 16-19, Deposited photoelectron yield vs. path length of track in FGD

Blair Jamieson ANT2010 Sept 16-19, TPC laser targets for p.e. calibration Array of Al Dots on Cathode UV laser Multiplexed To 18 locations To cover cathode ● Al targets emit p.e. when flashed with UV light ● Center of target measured from survey and with charge collected at readout ● Distortions of track shape for pe full drift can be measured

Blair Jamieson ANT2010 Sept 16-19, TPC Operations ● Nearly 100% live fraction during beam time – only off time due to either low voltage or MM HV trip -- quickly recovered ● Monitored gain, gas density, gas quality, drift velocity, many voltages and currents

Blair Jamieson ANT2010 Sept 16-19, FGD Electronics and DAQ ● MPPC signals are readout by a set of custom electronics cards designed and built at TRIUMF: – Front End Board to digitize signal (using TPC AFTER ASIC). – Crate Master Board to provide zero- suppression and transfer data off-magnet. – Data Concentrator Card to collect data and transfer to PC. ● MIDAS system for data readout and slow control monitoring provided by DAQ group.