Kinematic Mass Measurements (Part I) Amherst Center for Fundamental Physics Dec 14 th 2015 Joseph A. Formaggio MIT 1
Neutrino mass measurements have a long history in physics, predating the Standard Model itself. It should therefore be no surprise that our quest to understand this fundamental property continues; both for its own right as well as its theoretical implications.
We have learned one thing in this time. “Grande” is ruled out. And so is “Zero”. 3
2015 Nobel Prize in Physics Arthur B. McDonald Takaaki Kajita (Sudbury Neutrino Observatory) (Super-Kamiokande)
The legacy… n ν X M = m ν ,i i Cosmological Measurements n ν X h m 2 U 2 ei m ν ,i | 2 ββ i = | i Beta Decay Mass (eV) 0 νββ Measurements n ν | U ei | 2 m 2 X h m β i 2 = ν ,i i Beta Decay Measurements Lightest Neutrino Mass (eV)
The legacy… • The neutrino mass scale remains one of the essential “unknowns” of the Standard Model. Knowledge of neutrino masses can have a • significant impact on many different arenas, including cosmology, the mass hierarchy, sterile neutrinos, and even relic neutrino detection. m ν > 2 eV (eV scale, current) Ruled out by β -decay experiments Neutrinos ruled out as dark matter Next goal of future β -decay Beta Decay Mass (eV) experiments m ν > 0.2 eV (degeneracy scale) Impact on cosmology and 0 νββ reach m ν > 0.05 eV (inverted hierarchy) Resolve hierarchy if null result m ν > 0.01 eV (normal hierarchy) Oscillation limit; possible C ν B detection Lightest Neutrino Mass (eV)
Direct Probes Electron Energy | U ei | 2 q ˙ X E 2 0 − m 2 N ∼ p e ( K e + m e ) 0.2 count rate ν i i 0.15 z 0.1 0.05 0 3 H ➟ 3 He + + e - + ν e 0 5 10 15 20 25 kinetic energy (keV) Beta Decay A kinematic determination of the neutrino mass No model dependence on cosmology or nature of mass
Techniques for the 21 st Century Frequency Spectroscopy Calorimetry (Project 8) (KATRIN) (HOLMES, ECHO & NUMECS) Radio-frequency Technique highly Magnetic Adiabatic spectroscopy for beta decay advanced. Collimation with Electrostatic Filtering New experiment(s) R&D phase (new results) planned to reach State-of-the-Art technique ~eV scale. T 2 → (T · 3 He + ) + e − + ¯ 3 He + + e − + ¯ 163 Dy ∗ + ν e 3 H → 163 Ho + e − → ν e ν e
Spectroscopic: MAC-E Filter MAC-E Filter Technique KATRIN adiabatic transformation of e - momentum Inhomogeneous magnetic guiding field. Retarding potential acts as high-pass filter High energy resolution T 2 → (T · 3 He + ) + e − + ¯ ν e ( Δ E/E = B min /B max = 0.93 eV)
The KATRIN Setup 10 11 Bq “Windowless” gaseous T 2 Source Detector High resolution (High field) Tritium retention System electrostatic filter system (High Field) (10 7 tritium flow reduction) (3G low field) μ e μ e μ e μ e μ e 10 11 e - / second 1 e - / second Adiabatic transport ensures high retention of phase space for decay ∆ E = B min → 0 . 93 eV E B max Energy resolution scales as the ratio of minimum / maximum fields
All components of the experiment, including the source, now on site and being commissioned. Main spectrometer commissioned and provides more precise spectrometer of its kind.
Spectrometer Commissioning Precision high voltage system Ultra high vacuum High precision Full detector system electron gun system Summer 2013 saw “first light” from the KATRIN. Spectrometer and detector system fully integrated. Allowed for test of transmission function and background levels.
Transmission Function Background Rates At -18.6 keV, better than Background rate of order Hz 100 meV resolution (radon-dominated) Sharpest transmission function Greater reduction of for a MAC-E filter backgrounds to come Commissioning showed excellent behavior of MAC-E Filter response.
Projected 2 ) 0 0.01 eV 2 σ (m v Sensitivity 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 Neutrino Mass Goals Discovery: 350 meV (at 5 σ ) Sensitivity: 200 meV (at 90% C.L.) Data taking to commence in 2016.
Can we push further? • Can direct measurements push to the inverted hierarchy scale? 10 meters across • To do so, they must have better scaling law. 10 -11 mbar vacuum Ruled out by β -decay experiments Beta Decay Mass (eV) KATRIN Sensitivity σ (m v ) 2 ~ 0.38 eV 2 Source column Rovibrational states density at max Lightest Neutrino Mass (eV) of THe +
s Γ H m 2 ˙ N ∼ ( Q EC − E C ) 2 X X | U ei | 2 ν i B H ψ 2 2 π 1 − H (0) ( E EC − E H ) 2 + Γ 2 ( Q EC − E C ) 2 H i H 4 ν e m ν = 0 eV 163 Ho m ν = 1 eV 163 Ho + e - ➟ 163 Dy * + ν e 163 Dy* 163 Dy * ➟ 163 Dy + E.C. isotope New kid on the block: Electron Capture 16
Challenges: Advantages & Challenges Detector Response Source Activity Calorimetry Δ E FWHM < 10 eV N ev > 10 14 to reach τ risetime < 1 µs sub-eV level • Experimental Challenges: • Advantages: Fast rise times to avoid pile-up Source = detector effects. No backscattering Good energy resolution & No molecular final state effects. linearity 183 Dy ∗ + ν e 163 Ho + e − → Self-calibrating Sufficient isotope production 17
New results! SHIPTRAP Calorimetry Latest results with Penning traps show improved resolution on the Ho-Dy mass difference. 183 Dy ∗ + ν e 163 Ho + e − → 10.1103/PhysRevLett.115.062501 18
Their Predecessor AgReO 4 MARE MARE provides the first β decay measurement of 187 Re using calorimetry Calorimetry 19
The ECHo Experiment Technology: • The ECHo experiment uses metallic magnetic calorimeters to achieve Counts per 2 eV goals. • Fast rise times and good energy resolutions and linearity demonstrated. • Endpoint measured at Metallic Magnetic 2.80 + 0.08 keV . Calorimeters 20
The HOLMES Experiment HOLMES (Italy) transition edge sensors / MKIDs Technologies: Superconducting Resonators NuMECS (USA) TES thermometer transition edge sensors Transition Edge Sensors 21
Project 8 “Never “Never measure measure anything but anything but frequency.” frequency.” Source ≠ Detector Coherent radiation emitted can be collected and used to measure the energy of I. I. Rabi I. I. Rabi A. L. Schawlow A. L. Schawlow the electron in non- destructively. • Use cyclotron Simulation run eB frequency to extract (10 5 events) ω ( γ ) = ω 0 γ = electron energy. 6 Power (arb. units) K + m e 5 many overlapping • Non-destructive rare high-energy low-energy electrons electrons measurement of 4 electron energy. 3 E = 17572 eV Theta = 1.565 B field 2 signal T 2 gas 1 0 Frequency Approach 25.6 25.8 26 26.2 26.4 26.6 26.8 27 27.2 Frequency (GHz) 3 He + + e − + ¯ 3 H → ν e B. Monreal and JAF, Phys. Rev D80:051301 B. Monreal and J. Formaggio, Phys. Rev D80:051301
Electron Energy 0.2 Unique count rate Beta spectrum Advantages 0.15 0.1 • Source = Detector 0.05 (no need to separate the electrons from the tritium) Cyclotron Frequency 0 0 5 10 15 20 25 kinetic energy (keV) eB ω ( γ ) = ω 0 • Frequency Measurement γ = K + m e (can pin electron energies to well-known frequency standards) • Full Spectrum Sampling (full differential spectrum measured at once, large leverage for stability and statistics) Beta (frequency) spectrum
� 2 2 e 2 ! 2 1 k 0 P tot ( � k , � ) = …and 4 ⇡✏ 0 3 c 1 − � 2 (Free) Radiative Power Emitted Challenges • Power Emitted Less than 1 fW of power radiated (depends on antenna geometry) is challenging. • Confinement Period Simulation of electron motion in magnetic bottle One needs time to make sufficiently accurate measurement (> 10 μ s). Employ magnetic bottle for trapping. • Full Spectrum The full spectrum is available. Fortunately, linearity of frequency space helps separate regions of interest. Simulation of beta (frequency) spectrum
Project 8 Collaboration J. Formaggio, D. Furse*, N. Oblath, P. Mohanmurthy*, E. Zayas* Massachusetts Institute of Technology T. Thuemmler K. Heeger, P. Slocum Karlsruhe Institute of Technology Yale University S. Doelman, A. Rogers, L. de Viveros, B. LaRoque*, M. Leber, B. Monreal Haystack Observatories University of California, Santa Barbara P. J. Doe, M. Fertl, J. Kofron*, R.G.H. Robertson, L. Rosenberg, G. Rybka University of Washington, Center for Experimental Nuclear Physics and Astrophysics D.M. Asner, J. Fernandes, A.M. Jones, J.F . Kelly, B.A. VanDevender Pacific Northwest National Lab * indicates graduate student
Initial Demonstration: 83m Kr 86d 83 Rb ε 17824.35±0.75 eV conversion electron 1.83h 83m Kr 1/2- 17.8 7/2+ 32.1 9.4 Tritium endpoint 9/2+ 154ns 83 Kr 7/2+ 9.4 stable 83 Kr 9/2+ atom K-ion Conversion electrons at 17.8, 30 and 32 keV. Phase I : Use mono-energetic source to determine single electron detection. Use of standard gaseous 83m Kr source allows quantification of energy resolution and linearity.
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