NEUTRINO MASS

STUART FREEDMAN MEMORIAL SYMPOSIUM

BERKELEY, JAN 11, 2014

Hamish Robertson, University of Washington

a long wait for a little weight

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Neutrinos oscillate, have mass

Super-Kamiokande

KamLAND

SNO

Particle Physics Cosmology

What is the neutrino mass scale?

NEUTRINO MASS FROM BETA SPECTRA

neutrino massesmixing

With flavor mixing:

from oscillations mass scale

4

5

MASS LIMITS FROM TRITIUM

6Hamish Robertson, Stuart Freedman, Tom Bowles, Carol Bowles, Karl-Erik Bergkvist. Erice 1980. (from Tom)

7Tom Bowles, Carol Bowles, Stuart Freedman, Hamish Robertson, Erice 1980. (from Tom)

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Magnetic spectrometers showed no kink. But they had shape correction factors.

"Contrary to intuition, a nullresult is not inherently more reliable than a positive one.”

J.J. Simpson

Grabowski spectrometer

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)

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MASS AND MIXING PARAMETERS

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) < 5.4 eV (95% 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

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

Oscillation Kinematic

TLK

KATRINAt Karlsruhe Institute of Technology

unique facility for closed T2 cycle:

Tritium Laboratory Karlsruhe

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A direct, model-independent, kinematic method, based on β decay of tritium.

~ 75 m long with 40 s.c. solenoids

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~0.4 eV

First measurement, UIE = 700V, electron gun source.July 12, 2013.

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Measuring something and getting it wrong?

A WINDOW TO WORK INMolecular excitations

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Energy loss

KATRIN’S UNCERTAINTY BUDGET

StatisticalFinal-state spectrum

T- ions in T2 gasUnfolding energy loss

Column densityBackground slope

HV variationPotential variation in source

B-field variation in sourceElastic scattering in T2 gas

σ(mv2) 0 0.01 eV2

σ(mv2)total= 0.025 eV2

15mv< 0.2 eV (90 % CL)

WHAT IS THE BRANCHING RATIO FOR T2 → 3HeT+?

Source Experiment Theory

Snell Wexler

TH 0.932 ±

0.019

0.895 ±

0.011

---

T2 --- 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)

MASS RANGE ACCESSIBLE

PresentLab Limit1.8 eV

starting2016

KATRIN

18K. Abazajian, CF5 Summary

e

μ

τ c

s

ud

t

b

νh

νm

νlmeV

eV

keV

MeV

GeV

TeVLEPTONS QUARKS

??

MASS RANGE ACCESSIBLE

PresentLab Limit1.8 eV

starting2016

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 T2 column density near max

Next diameter: 300 m!

σ(mv)2 ~ 0.38 eV2

(B. Monreal and J. Formaggio, PRD 80:051301, 2009)

Radiated power ~ 1 fW

CYCLOTRON RADIATION FROM TRITIUM BETA DECAY

Working on the UW prototype25.5-GHz waveguide cell

SIGNAL IS A RISING “CHIRP” IN FREQUENCY

PROJECT 8: A PHASED APPROACH

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PROJECT 8 SENSITIVITY

NEUTRINO MASS LIMITS FROM BETA DECAY

2013 2014 2015 2016 2017 2018 2019

Analysis 2

Planck:

Construction Running

KATRIN:

Phase IProof concept Prototype

Project 8:

NEUTRINO MASS: SOME MILESTONES

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28Stuart Freedman, Steve Elliott, Hamish Robertson. Spanish coast 1992. Photo by John Wilkerson.

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CAPTURE OF RELIC NEUTRINOS

PTOLEMY project

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CAPTURE OF RELIC NEUTRINOS

PTOLEMY project

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PTOLEMY Experimental Layout

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Tritium Source Disk(Surface Deposition)

High Field Solenoid

Long High Uniformity Solenoid (~2T)

AcceleratingPotential

MAC-E filter(De-accelerating

Potential)

AcceleratingPotential

RF Tracking(38-46 GHz)

Time-of-Flight(De-accelerating

Potential)

CryogenicCalorimeter

(~0.1eV)

Low FieldRegion

e-

E0-18.4keV

0-1keV(~150eV)

E0

E0+30kV

~50-150eVbelow

Endpoint

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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.

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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 …

Planck XVI

WP = WMAP Polarization dataAL = weak lensing parameterτ = optical depth at recombination

“…Planck lensing likelihood favourslarger Σm 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, 1206.2560

Depends on mv but not a `direct’ measurement

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ELECTRON CAPTURE HOLMIUM EXPT (ECHO)

187

J.F. Wilkerson

39J.F. Wilkerson

187

ELECTRON CAPTURE HOLMIUM EXPT (ECHO)

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NEUTRINO MASS PHYSICS IMPACT

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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)