KATRIN - Karlsruhe Tritium Neutrino Experiment -

measuring sub-eV neutrino masses

G. Drexlin, FZ Karlsruhe

for the KATRIN Collaboration

International Europhysics Conference on High Energy Physics EPS-HEP

Aachen, July 17-23, 2003

International Collaboration: 60 people, 12 institutions, 5 countries (CZ, D, RU, UK, US)

U Bonn – JINR Dubna* – Daresbury Lab – FH Fulda – U & Forschungszentrum

Karlsruhe – U Mainz – NPI Rez – RAL – UW Seattle – UW Swansea – INR Troitsk

- motivation

- major components : molecular tritium sources, spectrometers

- sensitivity & project schedule

Motivation I : particle physics

valididate or largely rule out models

w. quasi-degenerate mass eigenstates

Mixings and mass splittings by -oscillation studies,

fundamental -mass scale by ß-decay and 0ßß

KATRIN sensitivity

Science objectives of KATRIN

perform high resolution & high statistics

measurement of ß-spectrum

close to 18.6 keV endpoint of T2

mi [

eV]

Motivation II : cosmology

role of ‘s as hot dark matter –

fix or constrain m ()

S.W. Allen et al, astro-ph/0306386m = 0.7 eV (best fit)

Cosmological limits for m

are model-dependent:

D.N. Spergel et al, astro-ph/0302209

m < 0.69 eV (95%CL)

need lab measurement!

Science objectives of KATRIN

perform high resolution & high statistics

measurement of ß-spectrum

close to 18.6 keV endpoint of T2

status of present tritium experiments

Troitsk Mainz

gaseous T2-source quench-condensed solid T2-source

both experiments have reached their intrinsic limit of sensitivity

analysis 1994-99, 2001 analysis 1998/99, 2001

electrostatic retarding spectrometers with magnetic adiabatic collimation

see previous talk by Christine Kraus

experimental observable in ß-decay is m

aim : improve m by one order of magnitude (2 eV 0.2 eV )

requires : improve m by two orders of magnitude (4 eV2 0.04 eV2 )

problem : count rate close to ß-end point drops very fast (~E3)

last 10 eV : 2 x 10-10 / last 1 eV : 2 x 10-13 of total ß-activity

• improve statistics :

- stronger tritium source (factor 80) (& larger analysing plane, Ø=10m)

- longer measuring period (~100 days ~1000 days)

• improve energy resolution :

- large electrostatic spectrometer with E=1 eV (factor 4 improvement)

- reduce systematic errors :

- better control of systematics, energy losses (reduce to less than 1/10)

2

2

scaling factors for next-generation experiment

10 m 20 m 5 m 25 m 5m

KATRIN Layout

KATRIN will be located

on the site of FZK at

Tritium Laboratory Karlsruhe

TLK is worldwide unique,

for ITER tritium fuel cycle

TLK

1010 ß-decays/s

Main spectrometer – industrial design study

Stainless steel vessel ( Ø = 10 m & l = 22 m ) on HV potential,

minimisation of background rate : p < 10-11 mbar (XHV!)

main technological challenge of KATRIN,

addressed recently at X-VAT Workshop, Bad Liebenzell, April 2003

KATRIN Sensitivity

MC spectra for 3 years

with (bg) = 10 mHz:

statistical accuracy for

optimised measuring

point distribution:

(m2) = 0.013 eV2

m() < 0.146 eV (90%CL)

m() < 0.160 eV (95%CL)

all systematic errors :

(m2) = 0.011 eV2

statistical & systematic

errors contribute ~ equally

KATRIN Sensitivity

m() < 0.2 eV (90% CL)

no -mass signal –

KATRIN sensitivity :

evidence for-mass signal –

KATRIN discovery potential :

m() = 0.35 eV (5)

m() = 0.30 eV (3)

MC spectra for 3 years

with (bg) = 10 mHz:

1 2 3

3

2 1

KATRIN time schedule

1/2001 first presentation at internat. workshop Bad Liebenzell

6/2001 formal founding of KATRIN Collaboration

9/2001 submission of Letter of Interest (hep-ex 0109033)BMBF funding astroparticle physics

5/2002 International KATRIN review panel, UK joins Collaboration

2002-03 background studies, R&D works, design optimisation

5/2002 International KATRIN review panel, UK joins Collaboration

2003 Proposal submission, pre-spectrometer tests,tender for transport section & cryo supply,

KATRIN - hardware status

pre-spectrometer: first major KATRIN system component

will be operational soon with 2 superconducting magnets

vacuum and electromagnetic tests, background studies

inspection of weld seams

KATRIN time schedule

1/2001 first presentation at internat. workshop Bad Liebenzell

6/2001 formal founding of KATRIN Collaboration

9/2001 submission of Letter of Interest (hep-ex 0109033)BMBF funding astroparticle physics

5/2002 International KATRIN review panel, UK joins Collaboration

2002-03 background studies, R&D works, design optimisation

5/2002 International KATRIN review panel, UK joins Collaboration

2003 Proposal submission, pre-spectrometer tests,tender for transport section & cryo supply,

2003/04 funding applications & reviews: HGF, DOE, PPARC, RAS

2004-06 set up of T2 loop, transport section, spectrometer, detector

2006/07 commissioning of major components

2007 first measurements of entire system

Conclusions

KATRIN – a next generation tritium ß-decay experiment:

the only model-independent kinematic measurement with

sensitivity to sub-eV neutrino masses

- no signal: m< 0.2 eV (90% CL.) sensitivity

- signal : m = 0.35 eV @ 5 discovery potential

0.30 eV @ 3

first substantial funding: construction works have started !

tight project schedule with aim for first measurements 2007