The Ultimate Neutrino Detector Adam Para, Fermilab Experimental Seminar, SLAC, M

The Ultimate Neutrino Detector Adam Para, Fermilab Experimental Seminar, SLAC, M www.phwiki.com

The Ultimate Neutrino Detector Adam Para, Fermilab Experimental Seminar, SLAC, M

Jeffers, Michael, Contributing Writer has reference to this Academic Journal, PHwiki organized this Journal The Ultimate Neutrino Detector Adam Para, Fermilab Experimental Seminar, SLAC, March 28, 2006 Outline Liquid Argon Time Projection Chamber: a mature technology Neutrino oscillations opportunities with the NuMI beam Liquid Argon detector as long as the NuMI off-axis experiment ‘Other’ physics with the LAr detector Liquid Argon Time Projection Chamber Proposed in May 1976 at UCI (Herb Chen, FNAL P496). R&D enthusiastically endorsed by the PAC 50 L/100 L prototypes at UCI in addition to Caltech, Fermilab prototype (Sam Segler/Bob Kephart) 10 ton prototype at Los Alamos (Herb Chen, Peter Doe) BARS spectrometer operating in Protvino (2 x 150 ton) (Franco Sergiampietri, S. Denisov) 25 years of pioneering ef as long as ts at CERN in addition to INFN (Carlo Rubbia + countless others) + advances in technology 50 l prototype in WANF beam 3 ton prototype, 10 m3 prototype 300 ton detector operating in Pavia 600 ton under commissioning in LNGS

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Many years of intense R&D 300‘000 kg LAr = T300 Leading to a large detector Inside in addition to outside

It works! Time Projection Chamber I A: signal amplitude (dE/dx) t1 : rise time (track angle, diffusion) t2: fall time (front-end electronics) B : baseline Uni as long as m electric field: (t-T0) = vdrift (x-xwire) a 2D projection ‘only’ TPC II: the second/(third) coordinate A ‘traditional’ TPC: a set of pads behind the sense wire. Liquid Argon: add a plane(s) of grids in front of the collection wires Arrange the electric fields/wire spacing as long as a total transparency [Bunneman, Cranshaw,Harvey, Can. J. Res. 27 (1949) 191] Detect the signal induced by passing electrons, thus giving additional coordinates [Gatti, Padovini, Quartapelle,Greenlaw,Radeka IEEE Trans. NS-26 (2) (1979) 2910] Signals are strongly correlated: the arrival time in addition to charge (module electronics noise)

TPC III: Induction wires signal in real life Front-end electronics/pulse shaping determines the actual wave as long as m: room as long as optimization Front-end electronics issues Signal to noise: Signal = 5,500 e d (in mm) JFET, shaping time ~ 1msec: ENC = 500 + 2.6 C (C –detector capacitance) Optimize detector design (wire spacing, cable length) Better technology SiGe Bipolar Cold vs warm (reliability vs feed-throughs, cables, noise) Signal size: how many electrons per 1 cm of a track (dE/dx)mip = 2.13 MeV/cm, Wion = 23.6 eV (dQ/dx)0 = 90000 e/cm (dQ/dx)measured = R(dQ/dx)0 R – recombination factor: Electric field Ionization density scintillation Experiment: (dQ/dx) ~ 55,000 e/cm@400-500 V/m

Drifting electrons over long distance (3m) Electron mobility 500 cm2/Vs Vdrift = f(E). Use E= 500 V/cm HV across the drift gap = 150 kV Vdrift = 1.55 mm/msec tdrift = 2msec Diffusion Diffusion coefficient, D=4.8 cm2/s sd2= 2Dt = 9.6t, sd= 1.4 mm as long as 3 m drift Number of collisions/sec ~1012 2×109 collisions along the longest path ‘none’ of them must ‘eat’ an electron Concentration of electronegative (O2) impurities < 10-10 Measuring argon purity below 0.1 ppb Best commercial O2 gauge: least count 0.2 ppb (not bad at all, but not good enough) How do you know that there are no other impurities, not detectable with your purity ,monitors, which absorb electrons (remember MarkII ) Electron lifetime detector Carugno,Dainese,Pietropaolo,Ptohos NIM A292 (1990) 580: Extract electrons from a cathode Drift over a certain distance Measure charge along the path Argon purification: liquid in addition to gas phase Re-circulate liquid/gaseous argon through st in addition to ard Oxysorb/Hydrosorb filters (R20 Messers-Griesheim GmBH) ICARUS T600 module: 25 Gar m3/hour/unit 2.5 Lar m3/hour Argone purity/electron lifetime in real life Impurities concentration is a balance of Purification speed tc Leaks Fin(t) Outgassing A, B For a T600 module: asymptotic purity/lifetime > 13 msec Argon purity, lessons as long as a very large detector Long electron lifetimes (~10ms)/drift distances (>3m) appear achievable with commercial purification systems The main source of impurities are the surfaces exposed to the gaseous argon Increasing the ratio of liquid volume to the area of gaseous contact helps (dilution) Increasing the ratio of cold/warm surfaces helps (purification) Material selection/h in addition to ling (high vacuum technology) is the key In the meantime Neutrino Physics has become a major source of excitement/surprises: Neutrinos have mass. First glimpse of physics beyond the St in addition to ard Model Neutrino mixing. Why so different from quark mixing CP violation in the lepton sector Origin of matter-antimatter asymmetry in the Universe Neutrino experiments will be a significant component of our future physics program Hint: we have a (super) beam.

What do we want to know AD2006 1. Neutrino mass pattern: This Or that 2. Electron component of n3 (sin22q13) 3. Complex phase of s() CP violation in a neutrino sector () baryon number of the universe n2 n1 n3 mass “Normal” mass hierarchy n1 n2 n3 “Inverted” mass hierarchy Dm2atm Dm2sun Off-axis NuMI Experiment NuMI neutrino beam: exists since Feb. 2005 Off-axis ‘narrow b in addition to ’ beams minimize NC background NuMI: intense neutrino (nm) beam from Fermilab to Minnesota Initial motivation: precise determination of Dm2. First results this Thursday! ‘Current’ motivation: ne appearance experiment NuMI Opportunity Two amplitudes contribute One amplitude proportional to q13 Relative phase, CP violating, d changes sign from neutrinos to antineutrinos Matter effects have different sign as long as different mass hierarchies

Untangling the physics Experiment measures two numbers: Pnu in addition to Pnubar Distance from the origin: q13 Distance from the diagonal: CP violation in addition to mass hierarchy All effects of the same order Ambiguities possible if q13 small Physics potential of the NuMI beam (Mena+Parke,hep-ph/0505202) To first order the physics potential of an off-axis experiment is determined by a product: NpxMxe Possible detectors: Liquid Scintillator calorimeter (NOvA) – e = 0.24 Liquid Argon TPC (FLARE) – e = 0.9 Three scenarios: S/M/L A Quest as long as sin22q13 Dependence on mass hierarchy in addition to CP phase precludes unambiguous interpretation of a possible null result in terms of a limit on sin22q13. Limits of 1×10-2 (2×10-3) achievable with S (L) detectors but it offers an increase of sensitivity beyond 10-4 level ! (some luck required)

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Real Challenges: Mass Hierarchy in addition to CP violation Required: sin22q13>0.01 + favorable value of d. Required amount of luck diminishes as the size of the experiment/beam intensity increases Experimental Challenge Maximize Mxe Where: M – detector mass e – efficiency as long as identification of ne CC events While maintaining h>20/ e (to ensure NC bckg < 0.5 ne CC bckg) Where h is the rejection factor as long as NC events with observed energy in the signal region Why is it hard to achieve high e Y-distribution – electron energies ranging from 0 to En Low(er) electron energies emitted at large angles Why is it hard to achieve high h p0’s produced in the hadronic shower, early conversions in addition to /or overlap with charged hadrons Coherent p0 production ne identification in LAr TPC Good particle identification using purely topological in as long as mation Excellent spatial granularity an important asset High detection efficiency. The key: possibility to identify high-y events (low energy electrons at large angles) Good NC background rejection Very fine longitudinal sampling: gamma conversions clearly separable from the primary vertex (often) Very good transverse graularity: gamma conversions clearly separable from charged tracks (often) Very good energy resolution: gamma conversions identifiable through dE/dx at the origin (usually) Detector Per as long as mance Blind scan of fully simulated detector (GEANT 3): electron neutrino CC identification efficiency = 81+-7% while NC background < 20% of the intrinsic nue component of the beam Questions: can one build such a detector can one af as long as d such a detector Legacy of ICARUS ( in addition to other R&D ef as long as ts) One can drift electrons in argon over distance of several meters in argon purified with the st in addition to ard commercial purifiers HV systems (power supply, noise filter, feedthrough, field shaping cage) can be made to operate reliably with voltages up to 150 kV Low noise electronics can be built (commercial!) in addition to operated with adequate S/N ratio as long as detector capacitances up to ~ 600 pF as long as signals at the level of 15,000 electrons Challenges Are there any elements of technology which are not really yet demonstrated, or does one need some further R&D What is a realistic cost estimate of a (~fully) engineered detector Accelerator neutrino experiment is given, how realistic is a perspective of a surface-based nucleon decay/ supernova experiment A very real possibility of a major savings in money in addition to much shorter timescale as long as an experiment Conclusions Newly developed technology of liquid argon imaging calorimetry offers a very attractive ( in addition to diversified) physics opportunities to establish/enrich our physics program We can make a Great Leap Forward by learning in addition to using the technology developed by/ as long as ICARUS 50 kton class Lar calorimeter in northern Minnesota/southern Canada is a very attractive avenue to take a lead in studies of neutrino oscillations in the US in addition to establish this technology

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