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Neutrinos

Neutrinos. Beck Róbert Fizikus MSc II. ELTE TTK. Topics. Basic information about neutrinos Past experiments Neutrino oscillation Recent and future experiments. What is a neutrino ?. „ small neutral one ” in Italian Electrically neutral , elementary subatomic particle

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Neutrinos

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  1. Neutrinos Beck Róbert Fizikus MScII. ELTE TTK

  2. Topics • Basic informationaboutneutrinos • Pastexperiments • Neutrinooscillation • Recent and futureexperiments

  3. What is a neutrino? • „smallneutralone” in Italian • Electricallyneutral, elementarysubatomicparticle • Notyetmeasured, butnon-zeromass • Speedveryclosetospeed of light • Interactions: • Weakinteraction • Gravity (negligible)

  4. History of theneutrino • Existenceproposed: 1930, Pauli • Negativebetadecay • Detected: Cowan-Reines 1956 • Reactorproducedantineutrinos • Detectedγphotonsfrompositronannihilation (scintillator) • Detectedneutronswithcadmium • Crosssection:

  5. History of theneutrinotypes • 1962 Lederman, Schwartz, Steinberger: muonneutrino (AGS) • 1975 tauparticles, taudecayobserved – StarnfordLinearAcceleration Center • 2000 tauneutrino’sinteractiondirectlydetected (DONUT) • Muon and taudecay, inanalogytobetadecay • No interactionbetweentheseatfirst; SM: no mass

  6. Historicalneutrinoexperiments • Homestakeexperiment 1970-1994 • 1478 m underground (goldmine) • Raymond Davis, John Bahcall, UPenn • 380 m3 perchloroethylene • Heliumbubbledthroughtocollecttheradioactive argon • 1/3 of neutrinofluxpredictedfrom Sun model

  7. Historicalneutrinoexperiments • Kamiokande (1983-) • Cerenkov-detector • Hugearray (1000) of photomultipliertubes • Verygooddirectionaldetection • 3000 t of water • 1/2 of neutrinofluxpredictedfrom Sun model • Super-Kamiokande (1996-) • 50 000 t of water, 11 200 PMTs • Inner and outerdetectorlayers • Implosion of 6600 tubesin 2001

  8. Historicalneutrinoexperiments • Sudburyneutrinoobservatory (1999-2006) • Usesheavywater (1000 t) • Cerenkov-detectorwith 9600 PMTs • Also: neutron capture • Deuterium: 6 MeV gamma (smallcross sec.) • Lightwater: 2 MeV gamma (largecross sec.) • Neutralcurrentdetectionarray (NCD) • 3He filledstrings

  9. Historicalneutrinoexperiments • CC: νe • NC: νe, vμ, vτ • Homestake: CC, 1/3 flux • Kamiokande: CC + 1/6 NC, 1/2 flux • SNO: CC, CC + 1/6 NC, NC • Insidethe Sun: onlyνearecreated • Yet: allthreeflavoursarrivetoEarth

  10. Neutrinooscillation • Experimentallyprovedin 2001 by SNO • Neutrinotypes: threeflavours • Theycantransmuteintoeachotherwhilepropagatingthroughspace • Non-zeromass • Flavoreigenstates != masseigenstates • TheoryproposedbyPontecorvo (1957) • Quantitativelyby Maki, Nakagawa, and Sakata (1962); expandedbyPontecorvo (1967)

  11. Neutrinooscillation • Differenceinmass: mass-statephasespropagateatdifferentrates • Macroscopiccoherencelength • Pontecorvo-Maki-Nakagawa-Sakata lepton mixing matrix

  12. Neutrinooscillation • Pontecorvo-Maki-Nakagawa-Sakata lepton mixing matrix • Masseigenstatepropagation: planewave • Ultrarelativisticcase:

  13. Neutrinooscillation • 3 Θangles, 3 Δm mass-differences • δ, α1,2parametersunknown • Alsosign of Δm32 • Solar, atmospheric, reactor, beamneutrinooscillation • Differentenergies • Differentcircumstancessuitedformeasuringdifferentparameters • Mikheyev–Smirnov–Wolfensteineffect • Electronschangepropagationeigenstateenergylevelsduetoweakinteractions

  14. Otheropenquestions • What is withhelicity? • Onlyleft-handedneutrinos, right-handedantineutrinosobserved • Counterpartseitherveryheavy (seesaw), ordonottake part inweakinteraction (sterile) • Origin of mass • Majoranamass? • Higgs-fieldinteraction (shouldinvolvebothhandedparticles)?

  15. Recentneutrinoexperiments • OPERA - Oscillation Project with Emulsion-tRacking Apparatus (2008-) • CERN neutrinostoGranSasso project • Designedfordirectobservation of tauneutrinos • Beam (pulses) of muonneutrinos • Detector: 150 000 bricks of emulsionmaterial, interleavedwithscintillatorcounters and lead plates, followedby a magneticspectrometer • Real-timetagging of interestingbricks • 2010, 2012: tauevents

  16. Recent neutrino experiments • OPERA tau observations • To be continued, by Ági

  17. Neutrinosfasterthanthespeed of light? • High-precision GPS, atomicclocks • Proton pulse, detectedneutrinostimestamped • Allelectroniclatencies had to be takeninto account • Distance: geodesy, globalcoordinatesystem • Maximum likelihood fit of signalshapes • Loosefiberopticcable • Icarus, Borexino, LVD (, OPERA) GranSassodetectorsusingthe CNGS beamreportedneutrinospeedsconsistentwiththespeed of light

  18. Recent neutrino experiments • IceCube South Pole Neutrino Observatory • Location: Amundsen-Scott South Pole Station, Antarctica • Why there? • Interacting material (ice) already in place • Ice easy to drill into (unlike rock) – with specialized hot water drills • Detectors lowered into the holes • Better shielding from noise sources than anywhere else • Completed in 2010

  19. Recent neutrino experiments • IceCube South Pole Neutrino Observatory • Detectors: Digital Optical Modules, DOMs • 86 strings, 60 detectors per string • They detect Cherenkov radiation • Spacing, calibration: TeV energy neutrinos • Angular resolution < 2 degrees • Supplementary detectors • IceTop • Deep CoreLow-EnergyExtension (<100 GeV)

  20. Recent neutrino experiments • IceCube South Pole Neutrino Observatory • Detection targets • Electrons: contained within detector, no source direction -> energy studies only • Taus: double-bang to distinguish from e-, distance between DOMs -> PeV energy; none discovered • Muons: good sensitivity, source direction detection • Main source: cosmic rays, not muon-neutrinos, going downwards, rejected • Going upwards through the Earth: caused by muon-neutrinos • Generated by cosmic rays hitting the other side of the Earth • Astronomical sources

  21. Recent neutrino experiments • IceCube South Pole Neutrino Observatory • Experimental targets • Extraterrestrial high-energy neutrino point sources • Neutrino astronomy • Neutrino flux map of the northern hemisphere • Gamma ray burst-neutrino coincidence • Neutrino oscillation measurements • Measure the θ23 mixing angle of the PMNS matrix • WIMP dark matter annihilation in the Sun • Cosmic ray composition, energies • Difference between IceTop and IceCube events • Milky Way supernova rays vs black hole jets (higher E)

  22. Recent neutrino experiments • IceCube South Pole Neutrino Observatory • Results • Too few high-E neutrinos found – inconsistent with GRB fireball model, new background flux limit • Atmospheric muon neutrino into tau neutrino oscillation measurement at high energies (30 GeV, Deep Core) • No excess WIMP-related neutrino flux found, upper limit for the annihilation rate; in the Sun and the GC • No neutrino point sources found above noise fluctuation • Cosmic ray composition, energy spectrum • Other flux limits, experimental concept, background study articles

  23. Sources • Wikipedia • OPERA website • CNGS website • Fermilab website • IceCubewebsite • Dr. Csótó Attila: Fejezetek a mag- és részecskefizikából coursenotes • http://profmattstrassler.com • Othervariouswebpages

  24. Thankyouforyourattention!

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