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International Europhysics Conference on High
Energy Physics EPS-HEP Aachen, July 17-23, 2003
G. Drexlin, FZ Karlsruhe for the KATRIN
Collaboration
KATRIN - Karlsruhe Tritium Neutrino Experiment -
measuring sub-eV neutrino masses

• motivation
• major components molecular tritium sources,
  spectrometers
• sensitivity project schedule

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
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Science objectives of KATRIN perform high
resolution high statistics measurement of
ß-spectrum close to 18.6 keV endpoint of T2
KATRIN sensitivity
Motivation I particle physics valididate or
largely rule out models w. quasi-degenerate
mass eigenstates
mi eV
Mixings and mass splittings by n-oscillation
studies, fundamental n-mass scale by ß-decay
and 0nßß
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Science objectives of KATRIN perform high
resolution high statistics measurement of
ß-spectrum close to 18.6 keV endpoint of T2
Motivation II cosmology role of ns as hot
dark matter fix or constrain mn (Wn)
Cosmological limits for Smn are model-dependent
D.N. Spergel et al, astro-ph/0302209
Smn lt 0.69 eV (95CL)
S.W. Allen et al, astro-ph/0306386
Smn 0.7 eV (best fit)
need lab measurement!
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status of present tritium experiments
see previous talk by Christine Kraus
Troitsk
Mainz gaseous T2-source
quench-condensed solid
T2-source
electrostatic retarding spectrometers with
magnetic adiabatic collimation
analysis 1994-99, 2001
analysis 1998/99, 2001
both experiments have reached their intrinsic
limit of sensitivity
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scaling factors for next-generation experiment
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• experimental observable in ß-decay is mn
• aim improve mn by one order of magnitude
  (2 eV 0.2 eV )
• requires improve mn by two orders of magnitude
  (4 eV2 0.04 eV2 )
• problem count rate close to ß-end point drops
  very fast (dE3)
• 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, Ø10m)
• - longer measuring period (100 days 1000
  days)
• improve energy resolution
• large electrostatic spectrometer with DE1 eV
  (factor 4 improvement)

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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
10 m
20 m
5 m
25 m
5m
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1010 ß-decays/s
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Main spectrometer industrial design study
Stainless steel vessel ( Ø 10 m l 22 m ) on
HV potential, minimisation of background rate
p lt 10-11 mbar (XHV!)
main technological challenge of KATRIN,
addressed recently at X-VAT Workshop, Bad
Liebenzell, April 2003
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KATRIN Sensitivity
MC spectra for 3 years with G(bg) 10 mHz
statistical accuracy for optimised measuring
point distribution s(mn2) 0.013 eV2
m(n) lt 0.146 eV (90CL) m(n) lt 0.160 eV
(95CL)
all systematic errors s(mn2) 0.011 eV2
statistical systematic errors contribute
equally
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KATRIN Sensitivity
MC spectra for 3 years with G(bg) 10 mHz
no n-mass signal KATRIN sensitivity
m(n) lt 0.2 eV (90 CL)
evidence for n-mass signal KATRIN discovery
potential
m(n) 0.35 eV (5s)
m(n) 0.30 eV (3s)
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n3 n2
n1
n1 n2 n3
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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 Internatio
nal KATRIN review panel, UK joins Collaboration
2002-03 background studies, RD works,
design optimisation 5/2002 International
KATRIN review panel, UK joins Collaboration
2003 Proposal submission, pre-spectrometer
tests, tender for transport section cryo
supply,
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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
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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 Internatio
nal KATRIN review panel, UK joins Collaboration
2002-03 background studies, RD 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
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Conclusions

• KATRIN a next generation tritium ß-decay
  experiment
• the only model-independent kinematic measurement
  with
• sensitivity to sub-eV neutrino masses
• - no signal mn lt 0.2 eV (90 CL.)
  sensitivity
• signal mn 0.35 eV _at_ 5s
  discovery potential
• 0.30 eV _at_ 3s
• first substantial funding construction works
  have started !
• tight project schedule with aim for first
  measurements 2007