Recent Discoveries in Neutrino Physics

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1 Recent Discoveries in Neutrino Physics Experiments with Reactor Antineutrinos Karsten Heeger

2 Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

3 Standard Model and Particle Physics Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

4 Neurinos have been with us since the Early Universe

5 Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

6 Why neutrinos? Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

7 Fig: Murayama neutrinos are the most abundant particles in the Universe besides photons Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

8 330 neutrinos/cm 3. One billion more neutrinos than protons. Fig: Murayama neutrinos are the most abundant particles in the Universe besides photons Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

9 Heavy Elements: 0.03% Ghostly Neutrinos: ~0.3% Matter in the Universe Stars: 0.5% Free Hydrogen and Helium: 4% Dark Energy: 70% Dark Matter: 25% neutrinos are highly abundant but with little mass What is their nature? What is the role of neutrinos in the Universe? Why is there only matter in the Universe?

10 Neutrinos and the Early Universe c at T ~ 1 MeV (~ 1 sec) neutrinos decouple relic neutrino spectrum left over at T < 100 kev deuterium formation, followed by BBN n+p d+γ at T < 1 ev (380,000 yrs) photons decouple, cannot break up atoms no more free charges to scatter photons Universe becomes transparent p+e - H+γ

11 Neutrinos and the Early Universe c 380,000 yrs now

12 s Massive Neutrinos Play a Role in Large Scale Structure of the Universe Even small neutrino mass influences power spectrum of galaxy correlations Neutrinos that are more massive cause more clustering on large scales. Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

13 The Big Questions in Neutrino Physics Are neutrinos their own antiparticles? What is the absolute neutrino mass? Is there CP violation? Where did all the antimatter go?

14 Neutrinos from the Big Bang ~330 neutrinos per cm proton per cm 3 Supernova Neutrinos Atmospheric Neutrinos High Energy Cosmic Neutrinos Geo Neutrinos Accelerator&Reactor Neutrinos Solar Neutrinos

15 Neutrino Energies Big-Bang neutrinos ~ ev Neutrinos from the Sun "< 20 MeV depending of their origin. Atmospheric neutrinos" ~ GeV Antineutrinos from nuclear reactors < 10.0 MeV Neutrinos from accelerators up to GeV (10 9 ev)

16 History of the Neutrino Pauli, 1930 N N + e - electrons! some nuclei emit Chadwick, 1914 Fermi, 1934

17 First Proposal For Direct Detection of Neutrino

18 Nuclear Reactors as a Neutrino Source Reactors are intense and pure sources of νe B. Pontecorvo Natl.Res.Council Canada Rep. (1946) 205 Helv.Phys.Acta.Suppl. 3 (1950) 97

19 Reactor Antineutrinos > 99.9% of νe are produced by fissions in 235 U, 238 U, 239 Pu, 241 Pu pure νe source

20 Reactor Antineutrinos rule of thumb: ~ 1 event per day per ton of LS per GWth at 1km

21 1953: Project Poltergeist Experiment at Hanford

22 Hanford Experiment inverse beta decay ν e + p e + + n Reines, Cowan 300 liters of liquid scintillator loaded with cadmium

23 Hanford Experiment inverse beta decay ν e + p e + + n Reines, Cowan 300 liters of liquid scintillator loaded with cadmium

24 Hanford Experiment inverse beta decay ν e + p e + + n Reines, Cowan 300 liters of liquid scintillator loaded with cadmium shielding and background reduction is important

25 The First 70 Years of Neutrino Physics 3 ν flavors Upper limits on m ν from kinematic studies. Massless ν (ad hoc assumption in SM)

Birth of Neutrino Astrophysics 1938 " Bethe & Critchfield " p + p 2 H + e + + ν e 1947 " Pontecorvo,1949 Alvarez " propose neutrino detection through " 37Cl + ν e 37 Ar + e - Light Element Fusion

26 Birth of Neutrino Astrophysics 1938 " Bethe & Critchfield " p + p 2 H + e + + ν e 1947 " Pontecorvo,1949 Alvarez " propose neutrino detection through " 37Cl + ν e 37 Ar + e - Light Element Fusion Reactions p + p 2 H + e + + ν e p + e - + p 2 H + ν e 99.75% 0.25% 2H + p 3 He + γ 85% ~15% ~10-5 % 3He + 3 He 4 He + 2p 3He + p 4 He + e + +ν e 3He + 4 He 7 Be + γ 1960 s Ray Davis builds chlorine detector. John Bahcall, generates first solar model calculations and ν flux predictions % 7Be + e - 7 Li + γ +ν e 7Li + p α + α 0.02% 7Be + p 8 B + γ 8B 8 Be* + e + + ν e to see into the interior of a star and thus verify directly the hypothesis of nuclear energy generation in stars... (Bahcall, 1964)

27 Cl-Ar Solar Neutrino Experiment at Homestake ν e + 37 Cl 37 Ar + e SSM only sensitive to ν e

28 Sudbury Neutrino Observatory 2092 m to Surface (6010 m w.e.) PMT Support Structure, 17.8 m cm PMTs ~55% coverage within 7 m Acrylic Vessel, 12 m diameter 1000 Tonnes D 2 O Experiment that measures 5300 Tonnes H 2 O, Outer Shield ν e and ν e,µ,τ separately. Urylon Liner and Radon Seal Solar model-independent measurement.

29 Sudbury Neutrino Observatory

30 Construction of the Sudbury Neutrino Observatory

Charged-Current constrained 1.5 Neutrino Signal (SSM/BP00) 1.0 0.5 SSM 5.3 σ 0.

31 The Solution to the Solar Neutrino Problem: Neutrinos Change Flavor 2.0 Neutral Current (NC) Elastic Scattering (ES) Charged Current (CC) CC Neutral-Current shape Elastic Scattering Charged-Current constrained 1.5 Neutrino Signal (SSM/BP00) SSM 5.3 σ 0.0 CC shape unconstrained ν e + ν µ +ν τ Total Neutrino flux ν e (ν µ +ν τ ) ν e Electron Neutrino flux Results from SNO, /3 of initial solar ν e are observed at SNO to be ν µ,τ

32 Neutrinos Oscillate between Three Flavors Electron neutrino Muon neutrino Tau neutrino

33 Neutrino Oscillation Fermi, 1934 Neutrino States First Mass States Mass states Second First Weak States Weak states Second First Second First Second ν 1 ν 2 ν e ν µ Time Evolution ν 2 ν µ sinθ cosθ ν ν e e a = cos 1 sin 2 ν e b = sin 1 θ + cos 2 θ ν 1 Pure ν µ µ cosθ sinθ ν ( = ) =( )( ν 1 1 ν ) cosθ 2 ν e cosθ sinθ ν µ 2sinθ cosθ ν µ 2sinθ ν 2 Pure ν µ µ Pure ν µ ν 2 2 ν 1 Pontecorvo, Time, t Time, t L P i i = sin 2 2θ sin Δm 2 E

34 Neutrino Mixing Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

Neutrino Oscillation KamLAND 2003 Survival Probability 1 0.8 0.6 0.

35 Neutrino Oscillation KamLAND 2003 Survival Probability Data - BG - Geo ν e Expectation based on osci. parameters determined by KamLAND L 0 /E νe (km/mev)

36 Neutrino Mixing how much? Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

37 Measuring θ13 at Daya Bay Near Far νe νe,x νe,x near 1.1 distance L ~ 1.5 km far θ13 N osc /N no_osc θ 13 detector 1 detector Baseline (km)

38 Nuclear Reactors in the World

95 GW th ) Hong Kong All 6 reactors are in commercial operation Adjacent to mountains; convenient to

39 Daya Bay Nuclear Power Plant Daya Bay Lind Ao Ling Ao II Daya Bay A Powerful Neutrino Source Among the top 5 most powerful reactor complexes in the world, producing 17.4 GW th (6 x 2.95 GW th ) Hong Kong All 6 reactors are in commercial operation Adjacent to mountains; convenient to construct tunnels and underground labs with sufficient overburden to suppress cosmic rays Reactors produce ~ antineutrinos/sec/gw

40 Daya Bay Experiment Layout RPCs outer and inner water shields (IWS and OWS) automated calibration units (ACU) AD Gd-LS target concrete antineutrino detectors (AD)

41 Daya Bay Experiment Layout Hall 3: began 3 AD operation on Dec. 24, 2011 Hall 2: began 1 AD operation on Nov. 5, Hall 20112: began 1 AD operation on Nov. 5, 2011 Hall 1: began 2 AD operation on Sep. 23, Hall : began 2 AD operation on Sep. 23, 2011

42 Antineutrino Detector Assembly detector assembly in pairs Jan 2010

43 Antineutrino Detector Installation - Near Hall Karsten Heeger, Univ. of Wisconsin NUSS, July 13, 2009

Predicted (sin 2 13 = 0) 2 Predicted (sin 2 13 = 0.

44 Antineutrino Rate vs. Time Detected rate strongly correlated with reactor flux expectations IBD rate (/day) EH1 Predicted (sin 2 13 = 0) 2 Predicted (sin 2 13 = 0.089) Measured 2 D1 off IBD rate (/day) EH2 L2 on L1 off L1 on L4 off IBD rate (/day) 100 EH Dec 27 Jan 26 Feb 25 Mar 26 Apr 25 Run time Predicted Rate assumes no oscillation. Normalization is determined by fit to near detector data.

45 Rate Deficit & Near/Far Ratio N detected / N expected sin EH1 EH2 θ EH Weighted Baseline [km] sin 2 2θ 13 = ± (stat) ± (syst) Most precise measurement of sin 2 2θ13 to date.

46 One of 10 Breakthroughs of the Year 2012 Science Magazine

47 The Big Questions in Neutrino Physics Neutrino mass and mixing # # Evidence for Physics beyond Standard Model Are neutrinos their own antiparticles? What is the absolute neutrino mass? Is there CP violation? Where did all the antimatter go?

Recent Discoveries in Neutrino Oscillation Physics & Prospects for the Future

Recent Discoveries in Neutrino Oscillation Physics & Prospects for the Future Karsten M. Heeger Lawrence Berkeley National Laboratory 8 7 6 5 4 3 2 1 SNO φ ES SNO φ CC SNO φ NC SSM φ NC 0 0 1 2 3 4 5 6