“Status of direct neutrino mass measurements” Florian Fränkle, Institute for Nuclear Physics (IKP) , Karlsruhe Institute of Technology (KIT) KIT – University of the State of Baden-Wuerttemberg and www.kit.edu National Research Center of the Helmholtz Association
Outline Introduction Neutrino masses Single β -decay experiments 163 Ho electron capture experiments Status and outlook Summary 2 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
Introduction Neutrinos are massive particles, but so far there are only upper (< 2 eV)* and lower limits ( > 0.01 eV) Absolute neutrino mass scale is one of the big open questions in particle physics, astrophysics and cosmology Different approaches to determine neutrino mass: direct measurements neutrino mass 0 νββ decay cosmology * J. Beringer et al. (Particle Data Group), Phys. Rev. D86, 010001 (2012) and 2013 partial update for the 2014 edition 3 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
Neutrino masses Neutrino flavour eigenstates are ν e U e1 U e2 U e3 m 1 ν µ related to neutrino mass eigenstates U µ 1 U µ 2 U µ 3 m 2 = ν τ U τ 1 U τ 2 U τ 3 m 3 by the lepton mixing matrix (PMNS) Neutrino oscillations are sensitive to mass ordering the differences between the squares ν e of neutrino masses: 2 ν µ m ν τ +0.12 ∆ m atm. = (2.32 ) × 10 -3 eV 2 * 2 -0.08 ∆ m sol. = (7.5 ± 0.2) × 10 -5 eV 2 * 2 2 2 m 3 m 2 ∆ m sol. 2 ∆ m atm. 2 Two mass ordering scenarios 2 m 1 2 m 2 ∆ m atm. 2 possible ∆ m sol. 2 2 m 3 The value of the lightest neutrino 2 ? ? m 1 mass is unknown 0 normal inverted * J. Beringer et al. (Particle Data Group), Phys. Rev. D86, 010001 (2012) and 2013 partial update for the 2014 edition 4 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
Neutrino mass and single β -decay Fermi theory of β -decay: β -decay: n → p + e - + ν e Neutrino mass influences energy spectrum of β -decay observable: electrons Neutrino mass β -spectrum for tritium: determination via precise measurement of the spectral shape close to the endpoint Model independent method 5 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
MAC-E filter M agnetic A diabatic C ollimation combined with an E lectrostatic Filter Combines high luminosity with high energy resolution transmission transmission ideal filter: MAC-E filter: energy resolution: magnetic moment: E t = 1 1 B ∆ E = A E µ = const t B B max 0 0 energy energy E 0 E 0 + ∆ E E 0 p e θ B 6 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
The KATRIN experiment KA rlsruhe TRI tium N eutrino experiment goal: measure neutrino mass with a sensitivity of 200 meV ~ 70 m Pre-Spectro- Differential and meter Main Spectrometer Detector Windowless Gaseous Cryogenic Pumping sections Tritium Source tritium β -decay β -electron energy analysis of β -electrons counting transport of trans- decay rate: 10 11 1/s resolution 0.93 eV @ 18.6 keV mitted tritium retention pressure < 10 -10 mbar T 2 pressure: β -electrons (factor > 10 12 ) 10 -3 to 10 -6 mbar 7 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
KATRIN – Windowless Gaseous Tritium Source August 19 th , 2014 longitudinal source profile 3.6 Tesla T 2 T 2 T 2 pumping injection pumping Stability of T 2 density profile of 10 -3 (function of T 2 injection rate, purity, beamtube temperature T B stability and homogeneity, pump rate) T B stability in prototype experiment 10× better than specified* Tritium loop processes 1.4 × 10 16 Bq tritium / day (same scale as ITER) WGTS currently under construction, delivery to KIT next year (summer) * S. Grohmann et al. “The thermal behaviour of the tritium source in KATRIN”, Cryogenics, V. 55–56, 2013, p. 5–11, DOI: 10.1016/j.cryogenics.2013.01.001 8 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
KATRIN – pumping sections Differential pumping Cryogenic pumping T 2 Ar frost stainless steel T 2 partial pressure reduction T 2 partial pressure reduction (10 5 ) via differential pumping (10 7 ) via cryosorption of T 2 on Magnetic guiding of β -electrons argon frost Concept successfully tested* Removal of positive ions Currently under construction, Commissioning end of this year delivery beginning of next year * F. Eichelhardt et al. "First Tritium Results of the KATRIN Test Experiment Trap" Fusion Science and Technology 54 (2008), Nr. 2, p. 615-618 9 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
KATRIN – Spectrometer & Detector Section (SDS) Angular selective Main spectrometer electron source detector First SDS commissioning measurements in autumn 2013 Main spectrometer successfully operated at -18.6 kV Spectrometer pressure ~ 10 -10 mbar Transmission characteristics of main spectrometer as expected Initial background rate ~ 1 cps (benchmark 0.01 cps) 2nd commissioning phase: test active & passive background reduction 10 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
Project 8 Simulated spectrum (10 5 T 2 decays)* antenna array electron T 2 B ω eB ω γ = γ = 0 ( ) + E m e Idea: Measure β -spectrum via coherent cyclotron radiation emitted by an energetic electron in a magnetic field Frequency of emitted radiation independent of electron pitch angle Θ New form of nondestructive spectroscopy * B. Monreal, J.A. Formaggio, PHYSICAL REVIEW D 80, 051301(R) (2009), DOI: 10.1103/PhysRevD.80.051301 11 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
Project 8 – phase I * * gas lines expected signal (simulation) * ( 83m Kr) waveguide electron trapping magnet (~ 1T) Prototype system for “proof of principle” test Goal: detect single electrons from 83m Kr Measurement phase finished, data analysis ongoing * Noah Oblath, „The Project 8 Experiment“, KATRIN Analysis Workshop 2014 12 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
Project 8 – phase I results * cyclotron radiation emission from single, mildly relativistic electrons has been observed experimentally for the first time! * D.M. Asner et al. „Single electron detection and spectroscopy via relativistic cyclotron radiation “ http://arxiv.org/abs/1408.5362 13 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
MARE – ( M icrocalorimeter A rrays for a R henium E xperiment ) AgReO 4 crystal (0.5 mg) MARE-1 @ Milano-Bicocca* β -decay neutrino ∆ E = 28 eV @ 1.5 keV ‡ counts ‡ Cl K α calorimeter Si K α thermometer 200 thermal link, Al K α readout 100 heat sink (< 1 K) 0 0.5 1.0 1.5 2.0 2.5 3.0 energy [keV] Calorimeter ideally measures all the energy released in the decay (except neutrino energy), source = detector 187 Re: T 1/2 = 4.3 ×10 10 yr, Q-value = 2.47 keV Investigate different techniques: Si thermistors, transition edge sensor, magnetic microcalorimeter, microwave kinetic inductance detector MARE also investigates the possibility to use 163 Ho electron capture * A. Nucciotti, Meudon Workshop 2011, 8-10 JUNE 2011, ‡ E. Ferri, “The status of the MARE experiment with 187 Re and 163 Ho isotopes” TAUP 2013 14 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
Neutrino mass and electron capture Electron capture: p + e - → n + ν e Neutrino mass affects the de-excitation energy spectrum Calorimetric measurement of atomic de-excitation (x-rays, Auger electrons, Coster-Kronig transitions) * * 163 Ho T 1/2 : 4570 yr Q (EC) : 2.56 keV * Loredana Gastaldo, “Status of Holmium-based Neutrino Mass Measurements” Neutrino 2014, Boston 15 26.08.2014 Florian Fränkle, “Status of direct neutrino mass measurements” Institute for Nuclear Physics (IKP) XIIth International Conference on Heavy Quarks & Leptons 2014, Mainz, Germany
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