NEUTRINO MASS STUART FREEDMAN MEMORIAL SYMPOSIUM BERKELEY, JAN 11, 2014 Hamish Robertson, University of Washington a long wait for a little weight

2 Neutrinos oscillate, have mass Super-Kamiokande KamLAND SNO

Particle Physics Cosmology What is the neutrino mass scale?

NEUTRINO MASS FROM BETA SPECTRA neutrino masses mixing With flavor mixing : from oscillationsmass scale 4

MASS LIMITS FROM TRITIUM 5

6 Hamish Robertson, Stuart Freedman, Tom Bowles, Carol Bowles, Karl-Erik Bergkvist. Erice (from Tom)

7 Tom Bowles, Carol Bowles, Stuart Freedman, Hamish Robertson, Erice (from Tom)

8 Magnetic spectrometers showed no kink. But they had shape correction factors. "Contrary to intuition, a null result is not inherently more reliable than a positive one.” J.J. Simpson Grabowski spectrometer

CURRENT STATUS: Mainz: solid T 2, MAC-E filter C. Kraus et al., Eur. Phys. J. C40, 447 (2005) Troitsk: gaseous T 2, MAC-E filter V. Aseev et al., PRD 84 (2011) Together:… m v < 1.8 eV (95% CL) 9

MASS AND MIXING PARAMETERS  m x eV 2  m 32 2 | x eV 2 mimi > eV (90% CL)< 5.4 eV (95% CL)*  deg  deg  deg sin 2  Marginalized 1-D 1-  uncertainties. *C. Kraus et al., Eur. Phys. J. C40, 447 (2005); V. Aseev et al. PRD 84 (2011) Other refs, see Fogli et al OscillationKinematic

TLK KATRIN At Karlsruhe Institute of Technology unique facility for closed T 2 cycle: Tritium Laboratory Karlsruhe 11 A direct, model- independent, kinematic method, based on β decay of tritium. ~ 75 m long with 40 s.c. solenoids

12 ~0.4 eV First measurement, U IE = 700V, electron gun source. July 12, 2013.

13 Measuring something and getting it wrong?

A WINDOW TO WORK IN Molecular excitations 14 Energy loss

KATRIN’S UNCERTAINTY BUDGET Statistical Final-state spectrum T - ions in T 2 gas Unfolding energy loss Column density Background slope HV variation Potential variation in source B-field variation in source Elastic scattering in T 2 gas σ(m v 2 ) eV 2 σ(m v 2 ) total = eV 2 15 m v < 0.2 eV (90 % CL)

WHAT IS THE BRANCHING RATIO FOR T 2 → 3 HeT + ? SourceExperimentTheory SnellWexler TH0.932 ± ± T2T ± Need a test of the final-state theory for KATRIN and Project 8 Tritium Recoil-Ion Mass Spectrometer (TRIMS)

MASS RANGE ACCESSIBLE Present Lab Limit 1.8 eV starting 2016 KATRIN

18 K. Abazajian, CF5 Summary

e μ τ c s u d t b νhνh νmνm νlνl meV eV keV MeV GeV TeV LEPTONSQUARKS ??

MASS RANGE ACCESSIBLE Present Lab Limit 1.8 eV starting 2016 KATRIN

THE LAST ORDER OF MAGNITUDE If the mass is below 0.2 eV, how can we measure it? KATRIN may be the largest such experiment possible. Size of experiment now: Diameter 10 m. Rovibrational states of THe +, HHe + molecule Source T 2 column density near max Next diameter: 300 m! σ(m v ) 2 ~ 0.38 eV 2

(B. Monreal and J. Formaggio, PRD 80:051301, 2009) Radiated power ~ 1 fW CYCLOTRON RADIATION FROM TRITIUM BETA DECAY Working on the UW prototype 25.5-GHz waveguide cell

SIGNAL IS A RISING “CHIRP” IN FREQUENCY

PROJECT 8: A PHASED APPROACH

PROJECT 8 SENSITIVITY 25

NEUTRINO MASS LIMITS FROM BETA DECAY

Analysis 2 Planck: ConstructionRunning KATRIN: Phase I Proof concept Prototype Project 8: NEUTRINO MASS: SOME MILESTONES 27

28 Stuart Freedman, Steve Elliott, Hamish Robertson. Spanish coast Photo by John Wilkerson.

29

CAPTURE OF RELIC NEUTRINOS PTOLEMY project 30

CAPTURE OF RELIC NEUTRINOS PTOLEMY project 31

32 Tritium Source Disk (Surface Deposition) High Field Solenoid Long High Uniformity Solenoid (~2T) Accelerating Potential MAC-E filter (De-accelerating Potential) Accelerating Potential RF Tracking (38-46 GHz) Time-of-Flight (De-accelerating Potential) Cryogenic Calorimeter (~0.1eV) Low Field Region e-e- E keV 0-1keV (~150eV) E0E0 E 0 +30kV ~50-150eV below Endpoint

PTOLEMY SUMMARY 100 g of tritium (1 MCi) on 12-m diameter disk. Relic capture rate ~ 10/year without local clustering. Also presumably able to measure mass, active and sterile. Transition-edge sensor array to provide basic 0.1-eV resolution. Tagging with RF cyclotron radiation a la Project 8. Necessary to understand quantum effects of binding of T 2 on surface. 33

INPUTS 1.Present laboratory limit 1.8 eV (90% CL) from Mainz and Troitsk experiments on tritium 2.KATRIN experiment under construction. 3.Project 8 in proof-of-concept phase. 4.Cosmological inputs driven by Planck, SPT, ACT, Sloan … 34

Planck XVI WP = WMAP Polarization data A L = weak lensing parameter τ = optical depth at recombination “…Planck lensing likelihood favours larger Σ m than the temperature power spectrum.” FIRST PLANCK ANALYSIS (MARCH 2013)

(B. Monreal and J. Formaggio, PRD 80:051301, 2009) CYCLOTRON RADIATION FROM TRITIUM BETA DECAY 25.5-GHz waveguide cell

NEUTRINOLESS DOUBLE BETA DECAY 1 sigma W. Rodejohann, Depends on m v but not a `direct’ measurement

ELECTRON CAPTURE HOLMIUM EXPT (ECHO) J.F. Wilkerson

39 J.F. Wilkerson 187 ELECTRON CAPTURE HOLMIUM EXPT (ECHO)

NEUTRINO MASS PHYSICS IMPACT 40

SUMMARY Direct mass measurements are largely model independent: Majorana or Dirac No nuclear matrix elements No complex phases No cosmological degrees of freedom One experiment in construction (KATRIN); 2015 start. Three experiments in R&D (Project 8, ECHo, PTOLEMY) 41