Neutrino Physics

1. Neutrino Physics Shafagh Datsjani Farahani Seminar on: “Noble Prize in Neutrino Physics” 4.1.2005

2. Neutrinos • Øno electrical Charge. hardly interacting with matter (difficult to detect) • Very light particles ( Mne<2.2 eV, Mnm<170 keV, Mnt<15MeV)?????? • Spin 1/2

3. Neutrinos play an important role in : Subatomic physics Cosmology Astrophysics Test of “Standard Model” carry up to 99% of energy Released in type 2 Supernova explosions information core of our sun.

4. Brief History • 1931” Wolfgang Pauli”. prediction radioactive decay • 1934 “Fermi” Theory:explanation of observed results. ”Neutrino” • 1959 “Fred Reines and Clyde Cowan”:discovery of Neutrinos. • 1962 discovery of Muon Neutrino at Brookhaven and at CERN

5. Brief History • 1968 first experimental detection of solar neutrinos.”solar neutrino problem” • 1978 discovery of Tau Particle at SLAC. • 1988 the Nobel Prize to Melvin Schwartz,Jack Steinberger,Leon M.Lederman:

6. Neutrino Sources • Atmospheric Neutrinos • Super Nova Neutrinos • Sun:Solar Neutrinos. • Artificial Sources: Reactors,accelerators,collider,synchrotrons…

7. Violation of Parity and Charge Conjugation in Meson Decay • 1956” at BNL”,Lee and Yang: Tau and Theta Puzzle Discussion • no evidence for parity conservation by the week force. • 1957 Christmas Wu reported large Parity Violation in Decay of Co (60)

8. Lepton Number • Reactor: n p+e+ne • Evidence:p+ne n+e+ L= 0+(-1) L=0+(-1) L=-1+0 L=1+0(not possible) Cl37+ ne Ar37+e Cl37+ ne Ar37+e (no) n+ne p+e

9. Brookhaven Experiment • Explanations about the absence of mg+e with Two Neutrinos types .[Lee & Yang,1960]: • If ne=nm there should be equal numbers of Electrons and Muons produced.

10. to produce the pions was the newly completed Alternate Gradient Synchrotron (A.G.S.) at the Brookhaven National Laboratory. Schwartz,Lederman and Steinberger(1988 noble prize)

11. Brookhaven Experiment Protons Time structure, gate detector Synchrotron Be-Target Mesons Mesons Decay tunnel Detector & shielding

12. Brookhaven Experiment • collision of Proton beam & Beryllium target Pions • Detector is located after the steel wall. • Effective use of beam gate the detector on the burst of pions when the target was struck.

13. Mesons Kaons decay is a major contributor for neutrino energies greater than about 1.2 GeV. • K m+-+n/n-

14. Weak Interactions We can divide the weak interactions in three classes: • 1. leptonic reactions • 2. semi lepton reactions • 3. hadronic weak reaction

15. Scattering of neutrinos and nucleons Weak Neutral Current neutrino Muon Charged Current Hadron state nucleon

16. Structure of the charged weak current

17. Z0 boson First Observation • On 30 April 1983 ,UA1 Experiment @ CERN. @SPS,collision high E Proton and antiproton • Weak Force Uncharged carrier • Quark in proton anti- quark in antiproton “annihilation “.Total E convert to M of Z0:E=MC2 • M of Z0 around 91.2 GeV.Z0 lighter Particles. “Characteristic signature”in Detector

18. Z0 Boson • Electron –positron carry mass of Z0 converted back to energy. Yellow tracks. • Z0 Decay into Muons *penterating* • A photon can be emitted from one of muons.which may produce a pair of muons.`

21. NBB & WBB • Two hadrons beam forming options: • 1)conventional so called narrow band beam • 2)achromatic Van der Meer horn focused wide band beam

24. NBB & WBB • Neutrino spectra made by these are different • WBB high intensity ,steep energy fall off,substational contamination of wrong sign neutrinos • NBB lower intensity ,flat energy dependence in contribution from each if two decays,small wrong sign background,energy of neutrino can be known subject to a twofold p - k dichotomy if the decay angle is known.

25. Atmospheric Neutrinos • Collision of primary cosmic rays. • Shower of hadrons pions. Kaons • Pions Muon electro neutrino Muon Neutrino Detection Super Kamiokande

27. Super Kamiokande Kamiokande stands for Kamioka Neutrino Detector Experiment (originally it was Kamioka Nucleon Decay Experiment - the project was first intended to look for proton decay

28. Super Kamiokande:cherenkov light detector • Detection Hydrogen Oxygen 50000 tons of highly purified water Located in north-central Japan @ depth of 2700 M water equivalent. • Neutrino flavor lepton final state • E<1 GeV Neutrino: • react by Quasi-elastics scattering • only lepton visible in final state.

29. Super Kamiokande • Higher energy neutrino: • The final state Muon or Electron accompanied by a Pion • Numerous hadrons(deep inelastic scattering) • 1998 announced evidences for neutrino oscillation

32. Cherenkov Light Fuzzy due to electromagnetic shower Sharpcollapse angle if beta<1

34. KEK and K2K KEK: Japanese national high energy physics laboratory K2K stands for KEK to Kamiokande ,Japan-Korea-US collaborative 250 Km away

35. Neutrino beamline apparatus & detector layout

36. Near detector

37. Neutrino oscillations n1 q n2

38. This is true in vacuum for all cases, is true in matter for nm nt but may be modified for oscillation involving ne which travel through matter. In super kamiokande the zenith angle indicates maximal nm nt mixing with Dm2 in the vicinity of 2 to 2.5 * 10-3 eV2.

39. Tau Neutrinos • 1975 discovery of Tauns by Perl and colleagues at Stanford ,17 times heavier than Muon. • Tauns born in Steel Short lifetime short travel distance Emulsion directly after steel plates • 21 July,2000,@Donut Higher energy than@Brookhaven. • Donut uses *Tungsten beam Dump.shielding

40. DONUT Experiment

41. Three charged tracks emerge from a collision between a nt and a nucleus in one of the steel plates: The 4.5-mm track shown red is a tau lepton that decays into a roughly 4-GeV electron (green) plus two unseen neutrinos. The two gray tracks are presumably hadrons. The striated bar indicates the steel (blue), plastic (yellow), and emulsion (white) layers of the target. Dots indicate tracks found in the 100-mm-thick emulsion layers.

43. Special scanning stations with computer controlled cameras -> 3D images of particle tracks

44. Summary • Neutrinos exist in three classes with different small masses. • Neutrinos mix with each other • The unconventional properties of the Neutrinos are in the current interest of important experiments (K2K and Donut) • The mass of the Neutrino is still unresolved and its determination will have important consequences for theories of supernova explosions and for the beginning of the universe.

45. Index • Web sites: • Super kamiokande. • Kek. • Nobleprizes.org • Fermilab • physics today • ….. .

46. Standard Modle

47. Max E was 30 GeV 15 GeV minimize background of energetic muons

48. Neutrino beam • Neutrino beam: • 1)production of secondary hadrons. • 2)momentum selection and focusing of the hadrons. • 3)passage of the beam through decay region,long enough to permit fraction of hadrons to decay • 4)absorption of the hadrons and muons that are produced along with neutrinos in a shield of adequate thickness

49. Atmospheric Neutrinos Flux ratio of 2 to 1 for: Muon Neutrinos/Electro Neutrinos. Cosmic rays with E>10 GeV not deflected much with Magnetic field. Cosmic rays arrive @ earth Isotropically. Prediction flux of atmospheric Neutrinos for equal Angles should be equal. A=Up-Down/Up+Down=0.296+-0.048(sta)+-0.01(sys)measured for *Muonneu* and predicted was zero. A for *Electro neu*zero

50. Super Kamiokande • Background: • Natural radioactivity in surrounding rocks and water. • cosmic rays. • Detector underground