About Detectors Alberto Marchionni, Fermilab  Next challenges in neutrino physics call for larger and specialized detectors  How to extrapolate from past & present neutrino detectors to what we need for the future ones ?  beam optimization (superbeams, off-axis, factories,…) is a key element to simplify the detectors  not every detector technology of the past is fit for future applications  Water Cherenkov detectors  Sampling, tracking calorimeters  Liquid Argon TPC’s  Conclusions

The Physics Roadmap  The next generation of neutrino experiments will focus on  to e transitions to find out about   13  normal or inverted mass hierarchy  possibility of CP violation in the leptonic sector  We want to be sensitive to oscillation probabilities down to few   Experiments, at least in a first phase, will be statistics limited

Beam-Detector Interactions  At which distance and which energy ?  flux  1/L 2  oscillation probability  sin 2 (1.27  m 2 L/E)  Which energy ? 1 st, 2 nd,… oscillation maximum ?  dependence of cross section on energy  sensitivity to matter effects  A limit: how many protons can I get ?  Neutrino beam optimization to reduce background  use a narrow energy beam (off-axis concept) to reduce NC background and beam e intrinsic background  use a neutrino factory and look for wrong sign muons  use of beta-beams  sensible choices will make the detector easier to build and operate

Different strategies L(km)/n 1 (GeV) 2 (GeV) 3 (GeV) E < 1 GeV (KEK/JPARC to SuperK, CERN to Frejus 0.3 < E < 3 GeV (NuMI off-axis) 0.5< E < 5 GeV (C2GT, BNL to ?) n=oscillation peak  m 2 =2.5  eV 2  JPARC mostly quasi-elastic, 1   NuMI few  ’s, range out Different detectors 

Scaling violations Florence Dome, span 42 m, masonry structure Oita sports park “Big Eye” dome, span 274 m, steel structure Millennium Dome, Greenwich, London, span 365 m, cable structure

Super-Kamiokande 39 m 42 m 50,000 ton water Cherenkov detector (22.5 kton fiducial volume)

Hyper-Kamiokande ~1,000 kt Candidate site in Kamioka Good for atm. proton decay L=500 m 10 subdetectors

MINOS Far Detector  2 sections, each 15m long  8m Octagonal Tracking Calorimeter  486 layers of 2.54cm Fe  4cm wide solid scintillator strips with WLS fiber readout  25,800 m 2 active detector planes  Magnet coil provides  1.3T  5.4kt total mass  Fully loaded cost ~$6 M/kton

MINOS Detector Technology Detector module with 20 scintillator strips MUX boxes route 8 (1 in Near Detector) fibers to one MAPMT pixel

e Interactions in MINOS? e CC, E tot = 3 GeV energy Detector Granularity: Longitudinal: 1.5X 0 Transverse: ~R M NC interaction  NC interactions energy distributed over a ‘large’ volume  e CC interactions (low y) electromagnetic shower short and narrow most of the energy in a narrow cluster

How to improve e signal/background: choice of the beam NuMI off-axis beam NuMI low energy beam These neutrinos contribute to background, but not to the signal  spectrum NC (visible energy), no rejection e background e (|U e3 | 2 = 0.01)

A Detector for NuMI off-axis  Physics requirements  very large mass  identify with high efficiency e charged interactions  good energy resolution to reject e ’s from background sources  e background has a broader energy spectrum than the potential signal  provide adequate rejection against  NC and CC backgrounds  e/  0 separation fine longitudinal segmentation, smaller than X 0 fine transverse segmentation, finer than the typical spatial separation of the 2  ’s from  0 decay  e/ ,h separation (electrons appears as “fuzzy” tracks)  optimized for the neutrino energy range of 1 to 3 GeV  detector on surface, must be able to handle raw rate and background from cosmic rays  fine granularity, low/medium Z tracking calorimeter

Towards a detector choice  Design challenges  large fiducial mass at low unit cost  aim to reduce the cost/kton by ~3 with respect to MINOS  fine granularity, low/medium Z tracking calorimeter  operating in a relatively remote location: rugged, robust, low level of upkeep and maintenance  A monolithic detector as tracking calorimeter ?  Large (  10 kTon) LAr TPC, as evolution from the ICARUS design  A sampling detector as tracking calorimeter ?  several examples on a smaller scale in the past: CHARM, CHARMII, ….  choice of absorber structure and active detector modules

Detectors under consideration for NuMI off-axis  A sampling, tracking calorimeter detector of 50 kton  proposed absorber is manufactured wood sheets, either particleboard (from wood “sawdust”) or Oriented Strand Board (from wood chips) structural strength can be produced in sheets of sizes up to ~ 2.4m  8.5m  2.5cm density ~ 0.7 g/cm 3 availability of industrial strength fastening systems, high strength adhesives, cartridge loaded screw guns,… low cost: ~ $290/ton, production plants in Minnesota  proposed active detector elements Liquid scintillator as the baseline technology Glass Resistive Plate Chambers as backup

Liquid scintillator detector  50 kton sampling calorimeter detector, comprised of 42 kton of wood particleboard as absorber and 7 kton of mineral-oil based liquid scintillator as active detector, contained in segmented PVC extrusions of 1 kton total mass  1/3 X 0 longitudinal granularity, 4 cm transverse granularity  made up of 750 planes, 29.3 m wide, 14.6 m high and 22.9 cm thick, arranged to provide alternating horizontal and vertical views, for a total length of m  the liquid scintillator is contained in segmented titanium dioxide loaded PVC extrusions 14.6 m long, 1.2 m wide and 2.86 cm thick, with 4 cm transverse segmentation  the scintillation light in each cell will be collected by a looped 0.8 mm  wavelength-shifting plastic fiber  light from both ends of the fiber will be directed to a single pixel on an avalanche photodiode (APD)  540,000 analog readout channels

Assembly of the liquid scintillator detector Each stack is equivalent to 7 layers of particle board and one layer of PVC extrusion containing liquid scintillator Stack: size 48’  8’  9” weight ~ 5 tons The detector consists of 750 planes. Each plane is made out of 12 stacks. 48’ 8’ 29.3 m 14.6 m

Readout of the liquid scintillator detector The APD readout combines the advantages over PMT of lower cost and much higher quantum efficiency Manifold to collect fibers from the ends of scintillator cells to an optical connector WLS fiber Emission spectra for L= m Hamamatsu 32- channel APD array Pixel size 1.8  1.8 mm 2 Sizeable number of photoelectrons/MIP: ~30 photoelectrons for an interaction at the far end of a looped fiber. With FNAL SVX4 electronics and APD cooling expect S/N ~ 5:1

5 planes of stacked modules 17.1 m 19.5 m 200 m Aluminum end-frames Steel end-frames Glass RPC detector  50 kton detector made of 1200 modules, stacked in an array made of 75 planes along the beam direction, each plane being 2 modules wide and 8 high  Each module, 8.5m  2.4m  2.6m with a weight of 42 tons, consists of 12 vertical planes of absorber interleaved with a detector unit consisting of a double plane of RPC’s  Walls of modules are supported from the floor and are not connected to each other  Modules within each wall are interlocked with the help of corner blocks as used in standard shipping container

Glass RPC detector units  The low rate environment of a neutrino experiment makes it possible to use glass RPC’s with strip readout as active detectors  They can provide 2-dimensional position information from every plane of detectors  Very large induced signals processed by simple discriminators  measurement of the event limited to recording of “hits”  RPC chambers,  m 2, are composed of 2 parallel glass electrodes, 3 mm thick, kept 2 mm apart by Noryl spacers placed every 15 cm  2 planes of RPC’s, each made of 3 RPC’s, are sandwiched between 2 particleboards, used as readout boards  Both surfaces of both particleboards are laminated with thin copper foil. Foils on inner surfaces are cut into strips  Each detector unit has 192 vertical strips and 64 horizontal ones  horizontal strips are 3.7 cm wide, vertical ones 4.34 cm wide  3.7  10 6 digital channels

Fuzzy track = electronClean track = muon Electron/  appearance RPC detector simulation

NC -  tracks NC background RPC detector simulation gap

Simulation results  4  pot/yr, 5 year run  50 kton RPC detector, 85% fiducial mass  positioned at a distance=735 km, offset=10 km   m 2 =2.5  10 -3, sin 2 (2  13 )=0.1, no matter effects or CP included SignalBackgrounds Beam e  NC  CC Reconstructed events before cuts After cuts Efficiency/Bckg fraction 33.5%5.2     Figure of merit: S/  B=214.5/  49.6=30.4

ICARUS: a Liquid Argon Imaging Detector  Working principle:  Ionization chamber filled with LAr, equipped with sophisticated electronic read- out system (TPC) for 3D imaging reconstruction, calorimetric measurement, particle ID.  Absolute timing definition and internal trigger from LAr scintillation light detection Drifting Ionizing Track e-e- light A. Rubbia

Neutrino physics with a Large LArTPC  The ideal detector for a neutrino factory/off-axis a’ la NuMI  Excellent pattern recognition capabilities and energy determination  High efficiency for electron identification and excellent e/  0 rejection   identification via kinematic reconstruction  lepton charge determination if in a magnetic field

LAr Cryostat (half-module) 20 m 4 m View of the inner detector ICARUS T300 Prototype

Iron yoke Coil Cryostat Field shaping electrodes Wire chamber Cathode A large magnetized LAr TPC LANNDD: Liquid Argon Neutrino and Nucleon Decay Detector F. Sergiampietri, NuFact’01  = 40 m H = 40 m 8  5 m drifts 70 kTon active LAr mass

Detector chambers structure F. Sergiampietri, NuFact’01  # wire chambers: 4 CH1,CH4 W=26.8 m, H=40 m CH2,CH3 W=39.2m, H=40 m  readout planes/chamber: 4 0 o, 90 o stainless steel 100  m wires at a 3 mm pitch screen-grid planes/chamber: 3  total # wires (channels):  # cathode planes: 5

R&D on a Large LAr TPC  R&D items to face  Engineering of a large cryostat  Engineering of wire chambers  HV feedthroughs up to 250 kV  Argon purity  Working conditions under high hydrostatic pressure HV= kV T max drift = ms

My personal conclusions  Different “baselines & energies” have different detector requirements  given the importance of the physics measurements, which could possibly lead to the discovery of CP violation in the leptonic sector, measurements with different detectors are important and different baselines are somewhat complementary  Water Cherenkov detectors are a well established technology  a factor 20 increase in mass is being considered  A large effort is underway to develop large (~50 kton) sampling, tracking calorimeters  R&D is crucial to verify the choice of technology  Impressive results from ICARUS 300 ton prototype  LAr technology is mature to proceed with the construction of a few kton detector  LAr technology could be considered for  10 kton detector  Lots of room for new, clever ideas, … but we need to move up to be ready to fully exploit the facilities that we have now  we are in the lucky situation where a series of upgrades in beamlines/detectors could lead us to important physics discoveries