NEUTRINO MASS a long wait for a little weight STUART FREEDMAN MEMORIAL SYMPOSIUM BERKELEY, JAN 11, 2014 Hamish Robertson, University of Washington.
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NEUTRINO MASS a long wait for a little weight STUART FREEDMAN MEMORIAL SYMPOSIUM BERKELEY, JAN 11, 2014 Hamish Robertson, University of Washington Neutrinos oscillate, have mass SNO KamLAND Super-Kamiokande 2 What is the neutrino mass scale? Particle Physics Cosmology NEUTRINO MASS FROM BETA SPECTRA With flavor mixing: mixing from oscillations neutrino masses mass scale 4 MASS LIMITS FROM TRITIUM 5 Hamish Robertson, Stuart Freedman, Tom Bowles, Carol Bowles, Karl-Erik Bergkvist. Erice 1980. (from Tom) 6 Tom Bowles, Carol Bowles, Stuart Freedman, Hamish Robertson, Erice 1980. (from Tom) 7 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 8 CURRENT STATUS: Mainz: solid T2, MAC-E filter C. Kraus et al., Eur. Phys. J. C40, 447 (2005) Troitsk: gaseous T2, MAC-E filter V. Aseev et al., PRD 84 (2011) 112003 Together:… mv < 1.8 eV (95% CL) 9 MASS AND MIXING PARAMETERS Oscillation m212 7.54+0.21-0.21 x 10-5 eV2 m322| 2.42+0.12-0.11 x 10-3 eV2 mi > 0.055 eV (90% CL) 12 34.1+0.9-0.9 deg 23 39.2+1.8-1.8 deg 13 9.1+0.6-0.7 deg sin213 0.025+.003-.003 Kinematic < 5.4 eV (95% CL)* Marginalized 1-D 1- uncertainties. *C. Kraus et al., Eur. Phys. J. C40, 447 (2005); V. Aseev et al. PRD 84 (2011) 112003. Other refs, see Fogli et al. 1205.5254 10 At Karlsruhe Institute of Technology unique facility for closed T2 cycle: Tritium Laboratory Karlsruhe KATRIN TLK A direct, modelindependent, kinematic method, based on β decay of tritium. ~ 75 m long with 40 s.c. solenoids 11 First measurement, UIE = 700V, electron gun source. July 12, 2013. ~0.4 eV 12 Measuring something and getting it wrong? 13 A WINDOW TO WORK IN Molecular excitations Energy loss 14 KATRIN’S UNCERTAINTY BUDGET 2 σ(mv ) 0 0.01 eV2 Statistical Final-state spectrum T- ions in T2 gas Unfolding energy loss Column density Background slope HV variation Potential variation in source B-field variation in source Elastic scattering in T2 gas σ(mv2)total= 0.025 eV2 mv< 0.2 eV (90 % CL) 15 WHAT IS THE BRANCHING RATIO FOR T2 → 3HeT+? Source TH T2 Experiment Theory Snell Wexler 0.932 ± 0.019 0.895 ± 0.011 --- --- 0.945 ± 0.006 0.36 Need a test of the final-state theory for KATRIN and Project 8 Tritium Recoil-Ion Mass Spectrometer (TRIMS) time of flight (s) ´10-6 Mass 3 1 0.9 10 15 20 25 30 35 40 45 50 measured ion energy (keV) Mass 6 5 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 MASS RANGE ACCESSIBLE KATRIN starting 2016 Present Lab Limit 1.8 eV K. Abazajian, CF5 Summary 18 LEPTONS TeV QUARKS t τ GeV c μ MeV s d u e keV eV νh meV νm νl ?? b MASS RANGE ACCESSIBLE KATRIN starting 2016 Present Lab Limit 1.8 eV 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. σ(mv)2 ~ 0.38 eV2 Size of experiment now: Diameter 10 m. Next diameter: 300 m! Source T2 column density near max Rovibrational states of THe+, HHe+ molecule CYCLOTRON RADIATION FROM TRITIUM BETA DECAY (B. Monreal and J. Formaggio, PRD 80:051301, 2009) Radiated power ~ 1 fW 25.5-GHz waveguide cell Working on the UW prototype SIGNAL IS A RISING “CHIRP” IN FREQUENCY PROJECT 8: A PHASED APPROACH PROJECT 8 SENSITIVITY 25 NEUTRINO MASS LIMITS FROM BETA DECAY NEUTRINO MASS: SOME MILESTONES Construction Running KATRIN: Project 8: Proof concept Prototype Phase I Planck: Analysis 2 2013 2014 2015 2016 2017 2018 2019 27 Stuart Freedman, Steve Elliott, Hamish Robertson. Spanish coast 1992. Photo by John Wilkerson. 28 29 CAPTURE OF RELIC NEUTRINOS PTOLEMY project 30 CAPTURE OF RELIC NEUTRINOS PTOLEMY project n e + 3H ® 3He + e 31 PTOLEMY Experimental Layout Tritium Source Disk (Surface Deposition) High Field Solenoid Low Field Region Long High Uniformity Solenoid (~2T) ~50-150eV below Endpoint E0+30kV E0-18.4keV E0 e- Accelerating MAC-E filter Accelerating (De-accelerating Potential Potential Potential) Cryogenic Calorimeter (~0.1eV) 0-1keV (~150eV) RF Tracking (38-46 GHz) Time-of-Flight (De-accelerating Potential) 32 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 T2 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 FIRST PLANCK ANALYSIS (MARCH 2013) Planck XVI WP = WMAP Polarization data AL = weak lensing parameter τ = optical depth at recombination “…Planck lensing likelihood favours larger Σm than the temperature power spectrum.” CYCLOTRON RADIATION FROM TRITIUM BETA DECAY 25.5-GHz waveguide cell (B. Monreal and J. Formaggio, PRD 80:051301, 2009) NEUTRINOLESS DOUBLE BETA DECAY Depends on mv but not a `direct’ measurement 1 sigma W. Rodejohann, 1206.2560 ELECTRON CAPTURE HOLMIUM EXPT (ECHO) 187 J.F. Wilkerson 38 ELECTRON CAPTURE HOLMIUM EXPT (ECHO) 187 J.F. Wilkerson 39 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