Probing Neutrino Masses Using Frequency Techniques J. A. Formaggio - - PowerPoint PPT Presentation

• J. A. Formaggio

Massachusetts Institute of Technology

(for the Project 8 Collaboration)

Probing Neutrino Masses Using Frequency Techniques

Outline:

• 1. Scientific Motivation
• 2. Principle of Technique
• 3. Status of Project

Outline:

• 1. Scientific Motivation
• 2. Principle of Technique
• 3. Status of Project

The Sudbury Neutrino Observatory

SNO KamLAND

KamLAND

Super-Kamiokande Super-Kamiokande M I N O S

M I N O S

Body of Evidence

The phenomena of neutrino

• scillations is now

firmly established.

Solar Atmospheric

Camilieri, Lisi, Wilkerson Ann. Rev. 57 (2008). Fogli et al, arXiv:1205.5254 (hep-ph)

sin2 (θ13) = 0.0241 ± 0.0025

sin2 (θ12) = 0.307 ± 0.016 ∆m2

12 = (7.54 ± 0.26) × 10−5 eV2

sin2 (θ23) = 0.386 ± 0.022 ∆m2

23 = (2.43 ± 0.09) × 10−3 eV2

Reactor & Long Baseline

What do we learn?

mν > 2 eV (eV scale, current) Neutrinos ruled out as primary dark matter candidate mν > 0.2 eV (degeneracy scale) Impact on cosmology and 0νββ reach mν > 0.05 eV (inverted hierarchy) Resolve hierarchy if null result mν > 0.01 eV (normal hierarchy) Oscillation limit; possible CνB detection

Direct Probes

3H ➟ 3He+ + e- + νe

Beta decay allows a kinematic determination of the neutrino mass No dependence on cosmological models or matrix elements

The KATRIN Experiment

Error Budget and Sensitivity

Neutrino Mass Goals

Discovery: 350 meV (at 5σ ) Sensitivity: 200 meV (at 90% C.L.)

Δmβ,stat2 = 0.018 eV2 Δmβ,sys2 = 0.017 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(mv

2) 0

0.01 eV2

Can we push further?

• KATRIN will achieve 200 meV scale.

Can direct measurements push lower to the 50 meV scale?

• Any future experiment needs to be

able to (a) have a better scaling law for increased target mass and (b) improve its energy resolution.

KATRIN Sensitivity

10 meters across 10-11 mbar vacuum

Probing Neutrino Masses Using Frequency Techniques

Outline:

• 1. Scientific Motivation
• 2. Principle of Technique
• 3. Status of Project

“Never measure anything but frequency.”

• I. I. Rabi
• A. L. Schawlow
• B. Monreal and J. Formaggio, Phys. Rev D80:051301

Frequency (GHz) 25.6 25.8 26 26.2 26.4 26.6 26.8 27 27.2 Power (arb. units) 1 2 3 4 5 6

E = 17572 eV Theta = 1.565

Simulation run (105 events)

rare high-energy electrons many overlapping low-energy electrons

signal

Project 8

Source ≠ Detector

“Never measure anything but frequency.”

• I. I. Rabi
• A. L. Schawlow

B field T2 gas

ω(γ) = ω0 γ = eB K + me

• Use cyclotron

frequency to extract electron energy.

• Non-destructive

measurement of electron energy.

• B. Monreal and J. Formaggio, Phys. Rev D80:051301

Frequency Approach

3H → 3He+ + e− + ¯

νe

The Concept

Coherent radiation emitted can be collected and used to measure the energy of the electron in a non- destructive manner.

ω(γ) = ω0 γ = eB K + me

Cyclotron Frequency Radiative Power Emitted

• Uniform B field
• Low pressure T2 gas.
• Antenna array for

cyclotron radiation detection.

Ptot(k, ) = 1 4⇡✏0 2e2!2 3c 2

k

1 − 2

B field

T2 gas

• B. Monreal and J. Formaggio
• Phys. Rev. D80:051301 (2009).

The Spectrum

• Look at a simulated

tritium spectrum watched by a synthetic array (evenly spaced antennas over 10 meter uniform field).

• Low energy electrons

dominate at higher frequencies.

• Rare, high energy

electrons give a clean signature near endpoint.

Unique Advantages:

• Source = Detector
• Frequency measurement
• Full spectrum sampling

Count Rate, Background, Resolution

For a background (b) and a count rate (r), the optimum energy window (ΔE) to count in is: The best useful resolution with molecular tritium is then ΔE ~ 2.35*0.36 = 0.9 eV . For a given r, we then know the target level of background.

∆E = (2b r )1/3

!!= 0.36 eV

With molecular T2, the rovibrational width of the ground state molecular ion limits the effective resolution

σ = 0.36 eV

Decay Rate

The total rate of decays scales inversely as the frequency squared: Arbitrarily selecting 100 MHz we get a cavity volume of about 8 m3 and a gross decay rate therein of 4.4 x 108 Bq. However there are two acceptance factors, one for the useful active volume inside the cavity, the other for the solid angle to trap an

• electron. Together these factors might be 0.01 – 0.1.

To this level of precision, it looks feasible to reach 200 meV , except for the noise.

r = fgeom ∆Ω 4π nC(2πc)3 τmω3

c

η

Background

• M. Leber calculated the cosmic ray delta intensity for KATRIN

(about 3 Ci of tritium), for a background of about 0.01 Hz In Project 8, assuming the same source strength, this background is 3 x 10-10 Hz/ eV near the endpoint!

Resolution

The energy resolution is related to the frequency resolution by the following relation. The magnetic field must be uniform to at least this level. The emission interrupted after a random time gives a Lorentzian line width.

This time scale also sets the trapping time for electrons. A magnetic bottle is necessary to ensure adequate observation & photon collection.

Magnetic Bottle

dω ω = − T T + m0c2 dT T

∆ω = Γ = 1 τ

A Phased Approach

Given the novelty of the project, we are pursuing a phased approach toward neutrino mass measurements:

• 1. Phase I Goals: Single electron detection.
• 2. Phase II Goals: T-He mass difference
• 3. Phase III Goals: Mass sensitivity to 0.2-2 eV range
• 4. Phase IV Goals: Mass sensitivity pushed down to inverted scale

We have commenced Phase I, we are designing Phase II

Antenna Options

Two possible options for cyclotron detection being explored: 1. A resonant microwave cavity containing tritium.

• In this case the Doppler shift is

eliminated, but the volume of the cavity, and hence the source strength, is related to the operating frequency. 2. A non-resonant chamber surrounded by receiving antennas.

• The Doppler shift is present, but the size
• f the volume, and hence the source

strength, is not directly related to the

• perating frequency.

B e i n g u s e d i n P h a s e I

Neutrino Mass Sensitivity

Parameters and statistical sensitivities for resonant-cavity experiments at various cyclotron frequencies.

Source strength, resolution and background help determine the activity and frequency needed to achieve a given neutrino mass sensitivity. Table on right shows mass sensitivity versus cyclotron frequency. Does not correspond to the phased approach, only a guide.

Neutrino Mass Sensitivity

Parameters and statistical sensitivities for non resonant-cavity experiments at 10 GHz cyclotron frequency.

Source strength, resolution and background help determine the activity and frequency needed to achieve a given neutrino mass sensitivity. Table on right shows mass sensitivity versus cyclotron frequency. Does not correspond to the phased approach, only a guide.

Probing Neutrino Masses Using Frequency Techniques

Outline:

• 1. Scientific Motivation
• 2. Principle of Technique
• 3. Status of Project

Main Superconducting Magnet 1 T field (27 GHz) 10 G Trapping coil

Use 0.93 Tesla field, where signal occurs at ~26 GHz with quadrupole trapping coil. System monitors field in-situ using DPPH ESR and Hall probe monitoring. Overall stability of prototype

ΔB B ~1×10−5

Magnetic Environment

Magnetic field monitoring

ESR Measurement

Magnetic Monitoring

Magnet Cooling

Use 0.93 Tesla field, where signal occurs at ~26 GHz with quadrupole trapping coil. System monitors field in-situ using DPPH ESR and Hall probe monitoring. Overall stability of prototype

ΔB B ~1×10−5

Dual waveguide prototype

Monolithic assembly inserted into 2-in diameter vertical bore of 1 T s.c. magnet. Source gas flows directly through waveguide fiducial volume. Cyclotron power transported in both directions to low- noise 26 GHz amplifiers loaned by NRAO. Signal mixed down to lower frequency (250 MHz bandwidth) and fully digitized.

Prototype Status

Project 8 Waveguide Prototype

BPF

Cryogenic Rack-mounted 1st (HF) Receive Stage

WR-42 waveguide with electron source

40-50 cable (~6 dB loss) K-connector interface at top

• f insert

Directional Coupler RF (26 GHz) IF (1.5 GHz)

24.5 GHz DRO 25-27 GHz 25 dB 30 dB

Used to examine signal with SA during digitizer use

To LF Rx Stage

2nd (LF) Receive Stage

Directional Coupler

500-2200 MHz signal generator 20 dB

To digitizer From HF Rx stage

20 dB 20 dB 1 2 3 4 5 6 7

HPF LPF

0.07 - 1000 MHz DC – 81 MHz 20 dB 20 dB 8 9 10 11 12 13 14 15 16

Fundamental cyclotron signal at 26 GHz is mixed down with 24.5 GHz

• scillator, and again with 500+ MHz oscillator resulting in signals

~100 MHz, digitized at 500 MHz 8-bit sampling rate for ~10 hours continuously and without dead-time.

The signal from our waveguide prototype is expected to be a short- lived “chirp” from a trapped electron.

Expected Signal

Did preliminary test run in January 2013. System with greater monitoring

• f vacuum, temperature, and

calibration of fields. Using power and frequency- time (e.g. Wigner-Valle) techniques to amplify signal- to-noise. Analysis is on-going and future data taking expected to continue.

January Run

• M. Bahr, B. LaRoque, M. Leber, B. Monreal

University of California, Santa Barbara

• J. Formaggio, D. Furse, N. Oblath

Massachusetts Institute of Technology

• J. Kofron, L. McBride, R.G.H. Robertson, Leslie Rosenberg, Gray Rybka

University of Washington, Center for Experimental Nuclear Physics and Astrophysics

• R. Bradley

National Radio Astronomy Observatory

• R. Patterson

California Institute of Technology

D.M. Asner, J. Fernandes, A.M. Jones, J.F. Kelly, B.A. VanDevender

Pacific Northwest National Lab

• T. Thuemmler

Karlsruhe Institute of Technology

Shepard Doelman, Alan Rogers

Haystack Observatories

Thank you for your attention

Additional Slides

PLANCK

• Planck alone can push

neutrino limits down to the sub-eV level.

• However, high dependence on

modeling and priors used.

WMAP PLANCK

PLANCK

Cosmological Limits

Komatsu et al 2010 Gonzales- Garcia arXiv: 1006.3795v2 (and many

• thers)

Current Limits

Planck

Planck + Weak Lensing

• Current sensitivity depends
• n model complexity
• CMS + LSS + HST + SNIa

(current limit)

Σ mν < 0.44-0.76 eV

• Planck Alone

(expected 2013)

Σ mν < 0.38-0.84 eV

• Planck + Weak Lensing

(expected 2020)

Σ mν < 0.07-0.09 eV

Can KATRIN be Scaled?

Source Strength

(T2 column density near max)

Size

(Next diameter iteration: 300 m!) Rot-vibrational states of T2

A Phased Approach

• Experiment sub-divided into different phases, moving toward neutrino mass measurements.
• Phase I: Use 30 GHz waveguide and NRAO receivers, detect 83mKr monochromatic lines.
• Phase II: Move down to 2.2 GHz (cavity or waveguide). Prepare to use 3H.
• Phase III: Move down to 100 MHz, SQUID amplifiers, 30 K operating temperature.
• Phase IV: Move to atomic 3H measurement, 4 K cavity.

Preliminary Milestones

2012 2013 2014 2015 2016 2017 2018

Analysis 1 Analysis 2

Planck: Construction Running KATRIN:

I: Proof of concept II: Tritium III: Neutrino Running

Project 8: