Presentation is loading. Please wait.

Presentation is loading. Please wait.

Absolute neutrino mass determination with the experiment KATRIN F. Glück (on behalf of the KATRIN collaboration) Johannes Gutenberg-Universität, Mainz.

Similar presentations


Presentation on theme: "Absolute neutrino mass determination with the experiment KATRIN F. Glück (on behalf of the KATRIN collaboration) Johannes Gutenberg-Universität, Mainz."— Presentation transcript:

1 Absolute neutrino mass determination with the experiment KATRIN F. Glück (on behalf of the KATRIN collaboration) Johannes Gutenberg-Universität, Mainz

2 Neutrino mass value important for: particle physics, astrophysics, cosmology Information for neutrino mass: neutrino oscillation experiments direct kinematical measurements neutrinoless double beta decay supernovae cosmological observations (galaxy redshift, microwave background radiation)

3 Neutrino oscillation results: 1.At least 2 neutrino masses are finite; lepton mixing matrix has large off-diagonal elements 2.SNO, KAMLAND:  m 12 2 ≈7·10 -5 eV 2, θ 12 ≈33° 3. SuperKamiokande:  m 23 2 ≈ 2.5·10 -3 eV 2, θ 23 ≈45°  → m ν (max) ≈ 50 meV m 1 => m 2, m 3 No information about absolute mass scale (m 1 ) !

4 neutrino masses and schemes „normal“ mass hierarchy m 1

5 0  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 

6 Neutrino mass limit from cosmology: -free-streaming of neutrinos in universe (because of their small interaction) -massive neutrinos: gravitational effect, they can reduce the matter density fluctuations -large neutrino mass → no small scale structure in universe -neutrino mass limit from cosmology is model dependent (correlations with many other parameters)

7 m  eVm  eV m  eVm  eV Ma ’96

8 large scales small scales ~900 Mpc ~90 Mpc 2dFGRS analysis & -mass limit redshifts for 32 point galaxy power spectrum  2 = 32.9

9 Cosmology: -masses from WMAP & 2dFGRS & Ly  WMAP galaxies with =0.11 Combined result : m < 0.23 eV (95 % CL.) CMBR Powerspectrum of CMBR a challenge for KATRIN ?! How are these results derived, and are they realistic? astro-ph/

10 2dFGRS analysis & -mass limit adding priors for cosmological parameters Inference of neutrino mass depends on priors for Hubble parameter h, baryon density  b h 2,  tot, flat prior on 0.1 <  m < 0.5

11 WMAP results- a critical review 3 main lines of criticism: - ‚Massive attack‘ on  CDM: the role of H 0 and the need for  and their influence on   (Rowan-Robinson & Sarkar) - The role of priors and combination of different data sets (Hannestad, Elgaroy & Lahav) - Systematic problems of the WMAP result itself at large and small scales, compatibility with BBN, the role of the  CDM model (PL-  CDM or RSI-  CDM)

12

13 need lab experiments with sub-eV mass sensitivity

14 Double  decay normal (2  ) neutrinoless (0  ) needed:a)  ν  (Majorana) b) helicity flip: m( )  0 or other new physics _ Heidelberg Moscow (enriched 76 Ge) Z  E

15 Evidence for 0  at Heidelberg Moscow Exp.? „Single-Side-Events“ erwartete Position  T 1/2 0 = ( ) y  m ee = ( ) eV  m( e ) = ( ) eV  (fast) degenerierte  ? Nearly same data as earlier (54kgy: 8/ /2000), but now asumptions of peaks in [2000,2080] keV:  background level is lower fit only [2032,2046] keV with background and peak  peak at 0  signal position (2039 keV) Klapdor-Kleingrothaus et al., MPLA 37 (2001) 2409 (s.also comments: hep-ex/ , hep-ph/ , hep-ph/ ) New, data up to 2003: 72 kgy, with new data selection, new calibration Klapdor-Kleingrothaus et al., PL B586 (2004) 198  Peak at (5) keV (expected: (50) keV) Multi-Gauss. Fit: 4.2  significance for 0  T 1/2 0 = ( ) y  m ee = eV (99.7% C.L.) single side events expected peak position

16 If 0νββ due to light Majorana neutrino: τ 0ν -1 ~ m ee 2 · M 0ν 2 (1) m ee = Σ i U ei 2 m i ν (2) τ 0ν → m i ν model dependent, because of: -nuclear matrix element -sign (complex phase) of U ei 2 -possibility for beyond Standard Model mechanism of 0νββ process (supersymmetry, …) → Eq. 1 not valid any more Possible: present HM signal confirmed, but hierarchical neutrino masses ( m i ν < 0.2 eV) Test by KATRIN !

17 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

18  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) E 0 = 2.46 keV T op ~ mK

19 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

20 187 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 (?) 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 Flavio Gatti (Genoa): 0.5g Re  1—1.7eV sensitivity expected Expt. Under construction

21 average neutrino mass Need: very high energy resolution & very high luminosity &  MAC-E-Filter very low background Direct determination of m ν by tritium β decay tritium  decay: 3 H  3 He + +e - + e _ } super allowed E 0 = 18.6 keV t 1/2 = 12.3 a

22 magnetic spectrometers & MAC-E filters

23 Principle of the MAC-E-Filter Magnetic Adiabatic Collimation + Electrostatic Filter (A. Picard et al., Nucl. Instr. Meth. 63 (1992) 345) ● Two supercond. solenoids compose magnetic guiding field ● Electron source (T 2 ) in left solenoid ● e - in forward direction: magnetically guided ● adiabatic transformation:  = E  /B = const.  parallel e - beam ● Energy analysis by electrostat. retarding field  E = E  B min /B max = E  A s,eff /A analyse  4.8 eV (Mainz)

24 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

25 The Mainz Neutrino Mass Experiment Mainzer -Gruppe 2001: J. Bonn B. Bornschein* L. Bornschein* B. Flatt Ch. Kraus B. Müller** E.W. Otten J.P.Schall Th. Thümmler** Ch. Weinheimer** *  FZ Karlsruhe **  Univ. Bonn ● T 2 film at 1.86 K ● quench-condensed on graphite (HOPG) ● 45 nm thick (  130ML), area 2cm 2 ● thickness determination by ellipsometry tilded solenoids new cryostat

26

27 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 < 2.1 eV (95%CL) C. Weinheimer, Nucl. Phys. B (Proc. Suppl.) 118 (2003) 279V. Lobashev, private communication C. Kraus, EPS HEP2003 (neighbour excitations self-consistent)(allowing for a step function near endpoint)

28 The KArlsruhe TRItium Neutrino Experiment Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft

29 transport magnet s spectrometer solenoi ds e - /s 10 3 e - / s Pre and main spectrometer Main spectrometer ● Energy resolution:  E = 0.93 eV ● high luminosity: L = A Seff  /4  = A analyse  E/(2E) = 20 cm 2 ● Ultrahigh vacuum requirements (Background) p < mbar ● „simple“ construction: vacuum vessel at HV = electrode + „massless“ screening electrode ● industry study Pre spectrometer: ● Transmission of electron with highest energy only (10 -7 part in last 100 eV)  Reduction of scattering probaility in main spectrometer  Reduction of background ● only moderate energy resolution required:  E = 50 eV ● Test of new ideas (XHV, shape of electrodes, avoid and remove of trapped particles,...)

30 KATRIN Main Spectrometer  stainless steel vessel (Ø=10m & l=22m) 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

31 Detector

32

33

34 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

35

36 design optimisation ´01 -´03 - tritium purity by tritium laboratory (>95%) - 2× stronger gaseous source (Ø=75mm  Ø=90mm) requires 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) reference Statistical uncertainty LoI

37 5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

38 Systematic uncertainties any not accounted variance  2 leads to negative shift of m 2 :  m 2 = -2  2 1. inelastic scatterings of ß´s inside WGTS - requires dedicated e-gun measurements, unfolding techniques for response fct. 2. fluctuations of WGTS column density (required < 0.1%) - rear detector, Laser-Raman spectroscopy, T=30K stabilisation, e-gun measurements 3. HV stability of retarding potential on ~3ppm level required - precision HV divider (PTB), monitor spectrometer beamline 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 Systematic uncertainties a few contributions with each:  m 2  eV 2 }

39 Status and schedule of Katrin 2001Presentation of project to community (Bad Liebenzell Workshop) Foundation of KATRIN collaboration Letter of Intent (hep-ex/ ) First, but significant funds by BMBF, FZ Karlsruhe 2002Very positive report of International Review Panel 2003X-Vat Workshop in Bad Liebenzell Background investigations at Mainz Setup of pre spectrometer at FZK 2004Reviewing, proposal and funding Setup of major KATRIN components: WGTS, transport system, main spectrometer, detector 2008 Commissioning at start of data taking with complete setup

40 Status of hardware components

41 Setup of pre-spectrometer at FZ Karlsruhe s

42 Electric screening by „massless“ wire electrode  e-e- Secondary electrons from wall/electrode by cosmic rays, environmental radioactivity,... wire electrode on slightly more negative potential U-  U U  test installation at Mainz

43 total background rate: 2.8mHz detector background rate 1.6mHz Mainz V (2004- PhD thesis: B. Flatt/Mz New record ! April 04 KATRIN pre spectrometer First realisation: Mainz III Electric screening by „massless“ wire electrode

44 Summary KATRIN: ● A large tritium  decay neutrino mass experiment at FZ Karlsruhe performed by a strong international collaboration with sub-eV sensitivity (<0.20 eV) ● probes in a unique model independent way: degenerate and cosmologically relevant neutrino masses ● complementary to oscillation experiments, 0 , cosmology  key experiment w.r.t. neutrino mass scale


Download ppt "Absolute neutrino mass determination with the experiment KATRIN F. Glück (on behalf of the KATRIN collaboration) Johannes Gutenberg-Universität, Mainz."

Similar presentations


Ads by Google