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Direct Measurements of the Neutrino Mass

Direct Measurements of the Neutrino Mass. Klaus Eitel Forschungszentrum Karlsruhe Institute for Nuclear Physics klaus.eitel@ik.fzk.de. Direct Measurements of the Neutrino Mass. neutrino masses in particle physics & cosmology (mass scenarios, n ´s as HDM) micro-calorimeters

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Direct Measurements of the Neutrino Mass

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  1. Direct Measurements of the Neutrino Mass Klaus Eitel Forschungszentrum Karlsruhe Institute for Nuclear Physics klaus.eitel@ik.fzk.de Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  2. Direct Measurements of the Neutrino Mass • neutrino masses • in particle physics & cosmology • (mass scenarios, n´s as HDM) • micro-calorimeters • (Mibeta: 187Re in AgReO4) • electrostatic spectrometers • (Mainz, Troitsk, KATRIN) Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  3. neutrino masses and schemes „normal“ mass hierarchy m1<m2<m3 quasi-degenerate first task: decide n mass scenario hierarchical Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  4. neutrino masses and cosmology r [% of rcr] second task: decide whether n contribute as Hot Dark Matter 1087n´s per flavor from BB! (without n annihilation; astro-ph/0404585) Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  5. Neutrino Mass Measurements Strategies cosmology & structure formation astrophysics: SN ToF measurements 0nbb decay: b decay kinematics: microcalorimeters MAC-E spectrometers NEMO3 76Ge @ LNGS ´90-´03 (71.7 kg×y) 2nbb D.N. Spergel et al: Smn < 0.69 eV (95%CL) S.W. Allen et al: Smn = 0.56 eV (best fit) |mee|=0.44+0.13-0.2 eV 187Re 3H SuperK, SNO, OMNIS + grav.waves: potential for ~1eV sensitivity? Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  6. b – decay kinematics phase space determines energy spectrum transition energy E0 = Ee + En (+ recoil corrections) dN/dE = K × F(E,Z) × p × Etot × (E0-Ee) × [ (E0-Ee)2 – mn2]1/2 theoretical b spectrum near endpoint experimental observable 1 0.8 0.6 0.4 0.2 0 • strong source (high count rate near E0) • small endpoint energy E0 • excellent energy resolution • long term stability • low bg rate rel. rate [a.u.] mn = 0eV mn = 1eV -3 -2 -1 0 Ee-E0 [eV] Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  7. b – decay kinematics and 0nbb decay • b-decay kinematics0nbb decay • direct n mass determination only possible for Majorana n´s • if n masses are not resolved • average neutrino mass coherent sum of mass EV´s m2(ne) = S |Uei2| m(ni)2mee(n) = | S |Uei|2 eia(i)m(ni)| incoherent sum, real average, partial cancellation possible since 0 ≤ |Uei2| ≤ 1 (not fully since SNO says: no max. solar mixing) m2(ne)vs. mee(n):complementary information, differences due to Dirac neutrino CP-phases Problems with nuclear matrix elements Other processes (right-handed currents, Susy-particles, ...) Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  8. m calorimeters for 187Re b decay • neutrino mass measurement with • array of 10 AgReO4 crystals • lower pile up • higher statistics • MIBETA experiment • (Milano, Como, Trento) • M.Sisti et al, NIM A520(2004)125 • A.Nucciotti et al, NIM A520(2004)148 • C. Arnaboldi et al, PRL 91, 16802 (2003) • MANU2 experiment • (Genoa) • F. Gatti, Nucl. Phys. B • (Proc.Suppl.) 91 (2001) 293) E0 = 2.46 keV Top ~ 70-100mK Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  9. m calorimeters for 187Re b decay Kurie plot of 6.2 ×106187Re b decay events above 700 eV • fit with function • free fit parameters: • b endpoint energy • mn2 • b spectrum normal. • pile-up amplitude • background level Mibeta Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  10. 187Re b decay endpoint and mn E0 = 2465.3 ± 0.5stat± 1.6syst eV (8751 h*mg, NIMA520, 2004) = 2466.1 ± 0.8stat± 1.5syst eV (4485 h*mg, PRL91,2003) mn2 = -112 ± 207 ± 90 eV2 mn< 15 eV (90%CL) future: proposal for a new calorimeter expt. with ~2-3 eV sensitivity foreseen 2007 (?) F. Gatti (n´04): 0.5g Re 1–1.7 eV sensitivity expected fit range: 0.9 to 4 keV fit function Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  11. principle of an electrostatic filter with magnetic adiabatic collimation (MAC-E) Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  12. principle of an electrostatic filter with magnetic adiabatic collimation (MAC-E) adiabatic magnetic guiding of b´s along field lines in stray B-field of s.c. solenoids: Bmax = 6 T Bmin = 3×10-4 T energy analysis by static retarding E-field with varying strength: high pass filter with integral b transmission for E>qU Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  13. magnetic spectrometers & MAC-E filters Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  14. latest results from the MAINZ experiment frozen T2 on HOP graphite T=1.86K A=2cm2, d~130ML (~45nm) 20mCi activity spectr.: l=2m, Ø=0.9m DE=4.8eV condensed T2 film  neighbour excitations W.Kolos et al., PRA37(1988): anex=5.9%; e=14.6eV Mainz 1998-2001: anex=(5±1.6±2.2)% with e=16.1eV C. Kraus, Eur.Phys.J. C33, s01 (2004), n´04 free fit for anex, mn2 for last 170eV 1994-2001 improvements in systematics: • roughening of T2 film • inelastic scattering • self charging of T2 film Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  15. From current to future experiments Mainz: Troitsk: mn2 = -1.2(-0.7)± 2.2 ± 2.1 eV2 mn2 = -2.3 ± 2.5 ± 2.0 eV2 mn < 2.2(2.3) eV (95%CL) mn < 2.05 eV (95%CL) C. Weinheimer, Nucl. Phys. B (Proc. Suppl.) 118 (2003) 279 V. Lobashev, Nucl.Phys. A719 (2003) 153c C. Kraus, Eur.Phys.J. C33 (neighbour excit´s self-consistent) (allowing for a step function near endpoint) • aim: improvement of mn by one order of magnitude (2eV  0.2eV ) •  improvement of uncertainty on mn2 by 100 (4eV2  0.04eV2) • statistics: • stronger Tritium source (>>1010b´s/sec) • longer measurement (~100 days  ~1000 days) energy resolution: • DE/E=Bmin/Bmax  spectrometer with DE=1eV  Ø 10m UHV vessel Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  16. The KArlsruhe TRItium Neutrino Experiment Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  17. KATRINlocation at FZKarlsruhe KATRIN ~70 m beamline, 40 s.c. solenoids Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  18. Windowless Gaseous Tritium Source at Tritium Laboratory Karlsruhe single WGTS solenoid (l=1m) WGTS parameters: total length l = 10m, inner diam. Ø = 90mm, Bsource = 3.6T, isotopic purity > 95% T2 T = (27± 0.03)K (l=10m) Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  19. WGTS source characteristics pinj = 3.0 × 10-3 mbar ( at T=27K) qinj = 1.85 mbar l/s = 1020 mol./s = 4.7 Ci/s (~ 40g T2 per day if no closed loop) isotopic purity (±2‰) monitored by Laser Raman spectroscopy Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  20. electrostatic spectrometers tandem design electrostatic pre-filtering & analysis of tritium ß-decay electrons ~1010b´s/sec ~103b´s/sec ~10 b´s/sec (qU=E0-25eV) pre-spectrometer main spectrometer fixed retarding potential ≈ 18.45kV variable retarding potential 18.5 – 18.6 kV Ø = 1.7m; length = 3.5m Ø = 10m; length = 24m DE ≈ 60 eV DE = 0.93 eV (18.575keV)  detailed el.-magn. design! Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  21. KATRIN Main Spectrometer • stainless steel vessel (Ø=10m & l=24m) on HV potential • minimisation of bg  UHV: p ≤ 10-11 mbar  „massless“ inner electrode system Mainz V results 2.8mHz inner electrode installed in Mainz spectrometer for background tests UHV requirements: outgassing < 10-13 mbar l/s inner surface ~ 800m2 volume to pump ~ 1500m3 intrinsic det. bg 1.6mHz Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  22. Detector concept the prespectrometer detector: prototype of KATRIN main detector PIN diode array segmented PIN-diode 44 x 44 mm² 64 segments 5x5 mm², bonded onto ceramics with FET stage T-structure multipixel PIN diode 8x8 Pin-Diode from Canberra SemiConductors backside of UHV flange, with board for 64 preamps 64 channel FET stage Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  23. KATRIN sensitivity & discovery potential design optimisation ´01 ´03  statistical accuracy on mn2 LoI 9/2001 Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  24. KATRIN sensitivity & discovery potential design optimisation ´01 ´03  statistical accuracy on mn2 2× stronger gaseous source (Ø=75mm Ø=90mm) required Ø=10m spectrometer) isotopic T purity 70%  95% LoI 9/2001 LoI 9/2001 Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  25. KATRIN sensitivity & discovery potential design optimisation ´01 ´03  statistical accuracy on mn2 2× stronger gaseous source (Ø=75mm Ø=90mm) required Ø=10m spectrometer) optimised measuring point distribution (~5 eV below E0) LoI 9/2001 reference Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  26. KATRIN sensitivity & discovery potential design optimisation ´01 ´03  statistical accuracy on mn2 2× stronger gaseous source (Ø=75mm Ø=90mm) required Ø=10m spectrometer) optimised measuring point distribution (~5 eV below E0) active background reduction by inner electrode system, low background detector (needs further detailed tests) LoI 9/2001 reference Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  27. KATRIN - systematic uncertainties unaccounted variances s2 lead to shift of m2: 1. inelastic scatterings of ß´s inside WGTS requires dedicated e-gun measurements, unfolding techniques for response fct. 2. HV stability of retarding potential required: ~ppm level precision HV divider (PTB), monitor spectrometer beamline 3. fluctuations of WGTS column density required < 0.1% stability rear detector, Laser-Raman spectroscopy, T=30K stabilisation, e-gun measurements 4. WGTS charging due to remaining ions (MC: f<20mV) inject low energy meV electrons from rear side, diagnostic tools available 5. final state distribution reliable quantum chem. calculations a few contributions with each Dm2n≤ 0.007 eV2 Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  28. KATRIN sensitivity & discovery potential expectation: after 3 full beam years ssyst~sstat mn = 0.35eV (5s) mn = 0.3eV (3s) 5s discovery potential mn < 0.2eV (90%CL) sensitivity Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  29. status of hardware activities pre-spectrometer pre-spec detector assembly differential pumping section WGTS Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

  30. conclusions & outlook • absolute neutrino mass of prime importance • microcalorimeter (MIBETA 187Re): mn<15eV(90%CL)  2eV in 2007? • MAC-E spectrometers (Mainz, Troitsk) mn<2.3eV(95%CL) (sensitivity limit) • KATRIN sensitivity mn<0.2eV(90%CL) discovery potential mn=0.35eV at 5s design optimized; first components; commissioning in 2008 Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004

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