Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 Direct Measurements of the Neutrino Mass Klaus Eitel Forschungszentrum Karlsruhe Institute for Nuclear Physics

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 neutrino masses in particle physics & cosmology (mass scenarios, ´s as HDM) micro-calorimeters (Mibeta: 187 Re in AgReO 4 ) electrostatic spectrometers (Mainz, Troitsk, KATRIN) Direct Measurements of the Neutrino Mass

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 neutrino masses and schemes „normal“ mass hierarchy m 1 <m 2 <m 3 hierarchical quasi-degenerate first task: decide mass scenario

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

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10,  decay:  decay kinematics: microcalorimeters MAC-E spectrometers cosmology & structure formation astrophysics: SN ToF measurements Neutrino Mass Measurements Strategies 3H3H NEMO3 76 LNGS ´90-´03 (71.7 kg×y) |m ee |= eV D.N. Spergel et al:  m < 0.69 eV (95%CL) S.W. Allen et al:  m = 0.56 eV (best fit) SuperK, SNO, OMNIS + grav.waves: potential for ~1eV sensitivity? 187 Re 2 

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 phase space determines energy spectrum transition energy E 0 = E e + E  (+ recoil corrections) experimental observable  – decay kinematics  strong source (high count rate near E 0 )  small endpoint energy E 0  excellent energy resolution  long term stability  low bg rate E e -E 0 [eV] rel. rate [a.u.] theoretical  spectrum near endpoint m = 0eV m = 1eV dN/dE = K × F(E,Z) × p × E tot × (E 0 -E e ) × [ (E 0 -E e ) 2 – m 2 ] 1/2

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004  – decay kinematics and 0  decay  -decay kinematics0  decay direct mass determination only possible for Majorana ´s if masses are not resolved  average neutrino masscoherent sum of mass EV´s m 2 ( e ) =  |U ei 2 | m( i ) 2 m ee ( ) = |  |U ei | 2 e i  (i) m( i ) | incoherent sum, real average, partial cancellation possible since 0 ≤ |U ei 2 | ≤ 1(not fully since SNO says: no max. solar mixing) m 2 ( e ) vs. m ee ( ): 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  calorimeters for 187 Re  decay neutrino mass measurement with array of 10 AgReO 4 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, (2003) MANU2 experiment (Genoa) F. Gatti, Nucl. Phys. B (Proc.Suppl.) 91 (2001) 293) E 0 = 2.46 keV T op ~ mK

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 fit with function free fit parameters:   endpoint energy  m 2   spectrum normal.  pile-up amplitude  background level  calorimeters for 187 Re  decay Kurie plot of 6.2 × Re  decay events above 700 eV Mibeta

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, Re  decay endpoint and m 187 Re  decay endpoint and m m 2 = -112 ± 207 ± 90 eV 2 m < 15 eV (90%CL) future: proposal for a new calorimeter expt. with ~2-3 eV sensitivity foreseen 2007 (?) F. Gatti ( ´04): 0.5g Re 1–1.7 eV sensitivity expected E 0 = ± 0.5 stat ± 1.6 syst eV (8751 h*mg, NIMA520, 2004) = ± 0.8 stat ± 1.5 syst eV (4485 h*mg, PRL91,2003) fit range: 0.9 to 4 keV fit function

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

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

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

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

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

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

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

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 Windowless Gaseous Tritium Source at Tritium Laboratory Karlsruhe single WGTS solenoid (l=1m) WGTS parameters: total length l = 10m, inner diam. Ø = 90mm, B source = 3.6T, isotopic purity > 95% T 2 T = (27± 0.03)K (l=10m)

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 WGTS source characteristics p inj = 3.0 × mbar ( at T=27K) q inj = 1.85 mbar l/s = mol./s = 4.7 Ci/s (~ 40g T 2 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 electrostatic spectrometers tandem design electrostatic pre-filtering & analysis of tritium ß-decay electrons ~10 10  ´s/sec ~10 3  ´s/sec ~10  ´s/sec (qU=E 0 -25eV) pre-spectrometer main spectrometer fixed retarding potential ≈ 18.45kVvariable retarding potential 18.5 – 18.6 kV Ø = 1.7m; length = 3.5m Ø = 10m; length = 24m  E ≈ 60 eV  E = 0.93 eV (18.575keV)  detailed el.-magn. design!

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 KATRIN Main Spectrometer  stainless steel vessel (Ø=10m & l=24m) on HV potential  minimisation of bg  UHV: p ≤ mbar  „massless“ inner electrode system UHV requirements: outgassing < mbar l/s inner surface ~ 800m 2 volume to pump ~ 1500m 3 inner electrode installed in Mainz spectrometer for background tests intrinsic det. bg 1.6mHz 2.8mHz Mainz V results

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

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 KATRIN sensitivity & discovery potential design optimisation ´01  ´03  statistical accuracy on m 2 LoI 9/2001

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

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, × stronger gaseous source (Ø=75mm  Ø=90mm) required Ø=10m spectrometer) optimised measuring point distribution (~5 eV below E 0 ) design optimisation ´01  ´03  statistical accuracy on m 2 LoI 9/2001 reference KATRIN sensitivity & discovery potential

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, × stronger gaseous source (Ø=75mm  Ø=90mm) required Ø=10m spectrometer) optimised measuring point distribution (~5 eV below E 0 ) active background reduction by inner electrode system, low background detector (needs further detailed tests) LoI 9/2001 reference design optimisation ´01  ´03  statistical accuracy on m 2 KATRIN sensitivity & discovery potential

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 2004 KATRIN - systematic uncertainties 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:  <20mV) inject low energy meV electrons from rear side, diagnostic tools available 5. final state distribution reliable quantum chem. calculations unaccounted variances  2 lead to shift of m 2 : a few contributions with each  m 2 ≤ eV 2

Klaus Eitel, Forschungszentrum Karlsruhe IDM 2004, Edinburgh, September 6-10, 5 KATRIN sensitivity & discovery potential m < 0.2eV (90%CL) m = 0.35eV (5  ) m = 0.3eV (3  ) sensitivity discovery potential expectation: after 3 full beam years  syst ~  stat

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

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