ASTROPHYSICAL NEUTRINOS IN SUPER- KAMIOKANDE ERIN O’SULLIVAN DUKE UNIVERSITY UNIVERSITY OF VIRGINIA HEP SEMINAR DECEMBER 2, 2015 1 Wednesday, December 2, 15
2 Wednesday, December 2, 15
NEUTRINO TIMELINE 1899: Beta decay is discovered Beta Decay A continuous energy spectrum was observed 3 Wednesday, December 2, 15
NEUTRINO TIMELINE 1930: Pauli proposes the neutrino 1899: Beta decay is discovered Wolfgang Ernst Pauli (1900 – 1958) 4 Wednesday, December 2, 15
NEUTRINO TIMELINE 1930: Pauli proposes the neutrino 1959: First measurement 1899: Beta decay of the (anti)neutrino is discovered 5 Wednesday, December 2, 15
NEUTRINO TIMELINE 1930: Pauli proposes the neutrino 1959: First measurement 1899: Beta decay of the (anti)neutrino is discovered Plan A: Detonate a nuclear bomb (El Monstro) 6 Wednesday, December 2, 15
NEUTRINO TIMELINE 1930: Pauli proposes the neutrino 1959: First measurement 1899: Beta decay of the (anti)neutrino is discovered Plan B: Set up a detector near a nuclear reactor Neutrino detector at Savannah River, a nuclear facility in Augusta, GA Photodetectors Scintillator Water 7 Wednesday, December 2, 15
NEUTRINO TIMELINE 1930: Pauli proposes the 1962: The muon neutrino neutrino is discovered 1959: First measurement 1899: Beta decay of the (anti)neutrino is discovered Melvin Schwartz Leon Lederman Jack Steinberger (1932 – 2006) (1922 – ) (1921 – ) A spark chamber measures a muon produced from a neutrino interaction 8 Wednesday, December 2, 15
NEUTRINO TIMELINE 1930: Pauli proposes the 1962: The muon neutrino neutrino is discovered 1959: First measurement 1899: Beta decay 2000: The tau neutrino is of the (anti)neutrino is discovered discovered Tau neutrinos Tau neutrinos produced through produce taus in the tau decays detector 9 Wednesday, December 2, 15
NEUTRINO TIMELINE 2006: Z boson decay 1930: Pauli proposes the 1962: The muon shows that there is only neutrino neutrino is discovered 3 neutrino flavours 1959: First measurement 1899: Beta decay 2000: The tau neutrino is of the (anti)neutrino is discovered discovered 10 Wednesday, December 2, 15
NEUTRINOS: LIGHT NEUTRAL LEPTONS 11 Wednesday, December 2, 15
Super-Kamiokande 12 Wednesday, December 2, 15
THE SUPER- KAMIOKANDE DETECTOR • Located near Toyama, Japan • 22.5 kton fiducial volume • Optically separated into inner and outer volumes • 11,146 20“ PMTs (ID) + 1885 8” PMTs (OD) 13 Wednesday, December 2, 15
SUPER-KAMIOKANDE RUN PERIODS SK-I SK-I SK-I (1996-2001) SK-II (2003-2005) SK-I SK-I SK-I SK-I • Ended with an accident • Surviving phototubes + that destroyed ~7000 of spares (about half the the phototubes original photocoverage) SK-III (2005-2008) SK-IV (2008-present) • Refurbish detector to the • New DAQ system which original photocoverage of had a larger dynamic range SK-I for PMT charge 14 Wednesday, December 2, 15
SUPER-KAMIOKANDE PHYSICS GOALS Solar neutrinos Supernova neutrinos Atmospheric neutrinos Proton decay 15 Wednesday, December 2, 15
DETECTING NEUTRINOS IN WATER 16 Wednesday, December 2, 15
PARTICLE ID IN SUPER- KAMIOKANDE 17 Wednesday, December 2, 15
NEUTRON TAGGING IN SUPER-KAMIOKANDE •In SK-IV, we record events 500 microseconds from a trigger • Search for 2.2 MeV gamma from neutron capture on Hydrogen • Efficiency ~20% 18 Wednesday, December 2, 15
Atmospheric Neutrinos 19 Wednesday, December 2, 15
ATMOSPHERIC NEUTRINOS Atmospheric neutrinos are produced from protons in our atmosphere 20 Wednesday, December 2, 15
ATMOSPHERIC NEUTRINO OSCILLATIONS Pions produce a set ratio of neutrinos in cosmic ray 1998: Super-Kamiokande published a interactions paper (Phys. Rev. Lett. 81 (1998) 1562-1567) that showed: ≃ 2 - the ratio they measure is less than 2 (R data /R expected ≃ 0.6) - the discrepancy was dependent on neutrino path length (neutrinos entering the bottom of the detector vs. the top of the detector) - that the missing neutrinos were muon type neutrinos The paper concluded that the behaviour fit all the hallmarks of neutrino oscillation and they calculated a best fit value for ν μ → ν τ mixing parameters 21 Wednesday, December 2, 15
CLASSIFYING ATMOSPHERIC EVENTS Roger Wendell Neutrino 2014 22 Wednesday, December 2, 15
CLASSIFYING ATMOSPHERIC EVENTS Roger Wendell Neutrino 2014 23 Wednesday, December 2, 15
ATMOSPHERIC NEUTRINOS AS A BACKGROUND FOR ASTROPHYSICAL NEUTRINOS 24 Wednesday, December 2, 15
Astrophysical Neutrinos 25 Wednesday, December 2, 15
SOURCES OF ASTROPHYSICAL NEUTRINOS Known sources Sun Supernovae GRBs Active galactic nuclei Supernova remnants Magnetars 26 Wednesday, December 2, 15
ASTROPHYSICS WITH ICECUBE 27 Wednesday, December 2, 15
ASTROPHYSICS WITH ICECUBE Bert Ernie Big Bird Highest energy neutrinos ever measured 1 PeV Aug 2011 1.1 PeV Jan 2012 2.2 PeV Dec 2012 Any significant clustering? Not yet, need more statistics. 28 Wednesday, December 2, 15
ASTROPHYSICS WITH ANTARES Antares(2015(arXiv:(1402.6182( 29 Wednesday, December 2, 15
WHERE DOES SK FIT IN? - SK is mainly sensitive to Southern hemisphere events (unlike IceCube). This includes the Galactic centre. - SK is more sensitive to the lower energy (tens of GeV) than either IceCube or Antares Antares(2015(arXiv:(1402.6182( 30 Wednesday, December 2, 15
SOLAR NEUTRINOS Produced in the thermonuclear reactions in the Sun pp chain CNO cycle 31 Wednesday, December 2, 15
SOLAR NEUTRINOS IN SK BOREXINO (pep) all solar BOREXINO (pp) ( 7 Be) BOREXINO ( 8 B) Homestake SK+ +SK+SNO SNO (CNO) ( 8 B) 32 Wednesday, December 2, 15
SUPERNOVA NEUTRINOS Neutronization burst Infall p + e- n + ν e Cooling Accretion n + e+ p + ν e p + e- n + ν e e + + e- ν ¡+ ¡ν 33 Wednesday, December 2, 15
SUPERNOVA NEUTRINOS IN (S)K 34 Wednesday, December 2, 15
SUPERNOVA NEUTRINOS IN (S)K 35 Wednesday, December 2, 15
SUPERNOVA NEUTRINOS IN (S)K 35 Wednesday, December 2, 15
OTHER EXOTIC SOURCES GRBs Supernova remnants Active galactic nuclei Magnetars 36 Wednesday, December 2, 15
HOW CAN YOU SEARCH FOR ASTROPHYSICAL NEUTRINOS? • Step%1:%Pick%a%search%direc1on% • Step%2:%Define%a%cone%of%8°%around%the%search% direc1on.%(This%is%large%enough%to%encompass%the% expected%spread%of%events%from%a%single%astro% source.%)% • Step%3:%Record%number%of%events%in%the%search% cone,%along%with%their%characteris1cs%(angle%from% search%direc1on,%showering/nonshowering).% • Step%4:%Perform%max%likelihood%calcula1on%(more% about%this%later).% • Step%5:%Choose%another%search%direc1on.%Thrane% 2009%used%0.5°%steps.% 37 Wednesday, December 2, 15
HOW CAN YOU SEARCH FOR ASTROPHYSICAL NEUTRINOS? ! Describes&a& Total&Probability& Signal&strength& background&event& P!!!=!!α!S!+!(1)α)!B! Describes&a& signal&event& α&is&the&probability&an&event&is&due&to&signal& 38 Wednesday, December 2, 15
HOW CAN YOU SEARCH FOR ASTROPHYSICAL NEUTRINOS? ' n Showering/ ! o SK#Period# * nonshowering# c e r i d Event'direc*on' ' S=S(θ|m,n,dec)S( h θ' c r a e S Point'spread'func*on' Allows&you&to&characterize&the&signal&as& clustered&events&(vs.&background&events& which&are&more&diffuse)& 39 Wednesday, December 2, 15
HOW CAN YOU SEARCH FOR ASTROPHYSICAL NEUTRINOS? ! SK#Period# S=S(θ|m,n,dec)S(n|m,dec)S(m)! Prob&of&obs.&showering/ Point&spread&func>on& nonshowering&event&type&(n)& Allows&you&to&characterize&the&signal&in& energy&(if&you&assume&signal&events&are& higher&in&E&8>&more&chance&of&showering)& 40 Wednesday, December 2, 15
HOW CAN YOU SEARCH FOR ASTROPHYSICAL NEUTRINOS? Prob%of%obs.%event% ! in%SK%phase%m% S=S(θ|m,n,dec)S(n|m,dec)S(m)! Prob&of&obs.&showering/ Point&spread&func0on& nonshowering&event&type&(n)& Allows&you&to&consider&rela1ve&live1mes&of& SK&phases&(assumes&constant&source&that& would&be&visible&over&all&phases)& 41 Wednesday, December 2, 15
HOW CAN YOU SEARCH FOR ASTROPHYSICAL NEUTRINOS? ! Total&Probability& Signal&strength& Describes&a&background&event& P!!!=!!α!S!+!(1)α)!B! Describes&a&signal&event& Likelihood)to)see)N) ! events)with)those) characteris3cs) L!=!P poisson! Π i N! P(α)!!! 42 Wednesday, December 2, 15
HOW CAN YOU SEARCH FOR ASTROPHYSICAL NEUTRINOS? P poisson % Π i N$ P(α)$$$ This%is%the%final%likelihood%func2on!%Now%vary%α% between%0%and%1%to%maximize%the%likelihood.%%% 43 Wednesday, December 2, 15
HOW CAN YOU SEARCH FOR ASTROPHYSICAL NEUTRINOS? ! Λ=2log(L(α fi,ed )/L(α=0))!! This%is%final%test%sta,s,c%that%determines% how%much%more%likely%our%fi6ed%α%is% compared%with%the%background%only% scenario ! % 44 Wednesday, December 2, 15
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