The KATRIN Neutrino Mass Experiment Diana Parno Carnegie Mellon University Lake Louise Winter Institute 23 February 2017

The Neutrino Mass Scale Lightest n mass m1 (eV/c2) Neutrino mass mi (eV/c2) Normal hierarchy Lower bound on m2, m3 from oscillation Upper bound from b decay KATRIN design ? (quasidegenerate regime) (Mainz, Troitsk) Diana Parno -- KATRIN Neutrino Mass Experiment

Diana Parno -- KATRIN Neutrino Mass Experiment From T2 to mnb Extract m2nb from fit to spectral shape near endpoint 3H 3He e- ne Almost model-independent mnb = 0 eV mnb = 1 eV 2x10-13 decays in last eV Q = 18.6 keV Diana Parno -- KATRIN Neutrino Mass Experiment

KArlsruhe TRItium Neutrino Intense T2 source (1011 decays/second) Spectrum analysis with electromagnetic filter Design resolution 0.93 eV Design mnb sensitivity: 0.2 eV/c2 at 90% confidence level Leopoldshafen November 2006 Diana Parno -- KATRIN Neutrino Mass Experiment

Putting It All Together 1 e-/sec 103 e-/sec Gaseous T2 source 3He e- ne 3H 1011 e-/sec Electron transport Detect bs Analyze b energy V Monitor energy threshold Diana Parno -- KATRIN Neutrino Mass Experiment

Spectrometer Background 2015 commissioning revealed high backgrounds ~50x higher than design value (10 mcps) Primary mechanism: 210Po decay in wall Secondary particles via sputtering Rydberg atoms (H*) enter flux tube H* ionized via blackbody radiation Low-energy e- created in flux tube! Diana Parno -- KATRIN Neutrino Mass Experiment

Mitigating High Backgrounds Reduction ideas (early) Optimize scanning Enlarge analysis window Increase Bmin Slide from Kathrin Valerius, Marco Kleesiek Diana Parno -- KATRIN Neutrino Mass Experiment

First Light Major milestone: e- transport from rear section to detector KIT Illuminate rear wall Magnetically guide photoelectrons along 70m beamline First all-KATRIN commissioning rdb instruments KIT Last beamline valve opens 14 October 2016 Diana Parno -- KATRIN Neutrino Mass Experiment

Molecular Final-State Distribution Electronic excitations in T atoms Excitations in T2 gas Electronic: 20 eV Vibrational: ~0.1 eV Rotational: ~0.01 eV Beta spectrum depends on excitation energies Vk and probabilities Pk Diana Parno -- KATRIN Neutrino Mass Experiment

Describing T2 Final States Precise ab initio calculations Uncertainty hard to estimate Enters directly into analysis Fackler et al., PRL 55 (1985) 1388 Saenz et al., PRL 84 (2000) 242 Binding energy (eV) Relative probability (%/eV) Calculation LANL mn2 LLNL mn2 1985 -147(79) eV2 -130(25) eV2 2000 (est.) 20(79) eV2 37(25) eV2 Bodine, DSP, Robertson, PRC 91, 035505 (2015) KATRIN needs sFSD to 1% New calculations Initial-state source characterization TRIMS experiment to resolve historical discrepancy Diana Parno -- KATRIN Neutrino Mass Experiment

Some Recent Technical Results Trapping of 220Rn on LN2-cooled copper baffle Hannen et al., Astropart. Phys. 89 (2017) 30 E – qU (eV) Transmission probability Drexlin et al., Vacuum 138 (2017) 165 Sojourn time (s) Baffle temperature (K) Deconvolution method for energy loss in source Diana Parno -- KATRIN Neutrino Mass Experiment

Diana Parno -- KATRIN Neutrino Mass Experiment 2017: A Busy Year Right now: Analysis of commissioning data (up to late 2016) Maintenance, upgrades, software work preparing for: Summer/Fall 2017: System commissioning with 83mKr, H2, and D2 Late 2017: First tritium data And beyond: Early mass results (final sensitivity: 3 beam yrs) Sterile neutrino searches Searches for physics beyond the Standard Model Diana Parno -- KATRIN Neutrino Mass Experiment

Light Neutrino, Bright Future KATRIN has constructed its entire beamline Successful electron transport across 70m Novel background source identified Countermeasures under development Commissioning and systematics studies underway Gearing up for tritium data soon Diana Parno -- KATRIN Neutrino Mass Experiment

The KATRIN Collaboration Carnegie Mellon University Max Planck Institut für Kernphysik, Heidelberg University of Applied Science, Fulda Case Western Reserve University University of Bonn Nuclear Physics Institute of the ASCR University of Mainz CEA/Saclay Complutense University of Madrid University of Münster Massachusetts Institute of Technology University of North Carolina Institute for Nuclear Research, Troitsk Max Planck Institute for Physics, Munich University of Washington Karlsruhe Institute for Technology University of Wuppertal Technical University of Munich Lawrence Berkeley National Lab Primary support from Helmholtz Association; BMBF; DOE Office of Science DE-FG02-97ER41020; Helmholtz Alliance for Astroparticle Physics; Grant Agency for Czech Republic Diana Parno -- KATRIN Neutrino Mass Experiment

T2 Spectroscopy: MAC-E Filter Measure integral spectrum with moving threshold Magnetic Adiabatic Collimation + Electrostatic filter Electrodes T2 source Detector Troitsk (at INR) Mainz Analyzing plane pe (without E field) Diana Parno -- KATRIN Neutrino Mass Experiment

internal radioactivity 40K, … external radioactivity Background Sources Slide from Florian Fränkle vessel wire electrodes e H H* H- internal radioactivity cosmic muons 210Pb, … µ a g NR e BBR field emission e H2 FPD Penning discharge e e insulator processes H+ UV 219Rn g baffle 40K, … external radioactivity Various processes can contribute to the spectrometer background Spectrometer backgrounds were investigated in detail during two measurement phases (SDS1 & SDS2) Diana Parno -- KATRIN Neutrino Mass Experiment