The KATRIN experiment M. Beck Institut Für Kernphysik Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-str Münster Motivation The Experiment Principle, Set-up, Status Summary

The Neutrinomass Experimental detection of neutrino oscillations  Neutrinos have got mass How large is m( e ), what is the mass hierarchy?  -Oscillations 7,3  eV 2 <  m 12 2 < 9.3  eV 2 solar 1,6  eV 2 <  m 23 2 < 3.6  eV 2 atm.  There is a  with m i  0,009eV and one with m j  0,05eV 2.0  -decay  m( e )   0,4 eVto be confirmed 3.Tritium  -decay m( e ) 2 = -0,6  2,2  2,1 eV 2 Mainz  m( e )  2,3eV (95%) 4.Cosmology  m i  O(1eV)

The Neutrinomass Planned sensitivity of KATRIN:0,2eV Detection limit 0,3eV (3  ) / 0,35eV (5  )

Tritium  Decay: 3 H  3 He + + e - + e Tritium  -Decay Superallowed E 0 = 18.6 keV t 1/2 = 12.3 a dN/dE = K F(E,Z) p E tot (E 0 -E e )  |U ei | 2 [ (E 0 -E e ) 2 – m( i ) 2 ] 1/2

The KATRIN experiment Being set-up at the Forschungszentrum Karlsruhe KArlsruhe TRItium Neutrinoexperiment

Principle: MAC-E Filter Solid angle: Up to 2  Adiabatic:  =E  /B=const. Resolution:  E/E=B min /B max B max = 6T B min  3  T  E  1eV

The Tritium-Source: WGTS WGTS: Windowless Gaseous Tritium Source Purpose: Tritium source with high and uniform intensity Properties:  = 9cm/L = 10m/B = 3,6T  /  = 0,1%,  T = 0,1K !!! Gas purity 95±1% T2 !!! T 2 -flow: 4,7Ci/s !!! p(T 2 ) max = 4  mbar Column density 5  T 2 /cm  -decays/s

conzept: 2-Phasen Neon (sied. Flüssigkeit) 2-phase Neon beam pipe Cu Tritium heater s.c. Helium vessel Kr The Tritium-source: WGTS Pressure regulation tested successfully: testexperiment TILO (  constant at ‰ im level) Status: Ordered

The transport section Purpose: - Transport of the  -Electrons to the spectrometers - Prevent the transport of T 2 (Reduction of the flux of T 2 by to mbar l/s!!!) Differential pumping sections DPS1-F, DPS2-F Cryopumping sections CPS1-F, CPS2-F

The transport section Status: DPS2-F under construction TRAP-experiment: cryosorption is working Cryopumping: Cryosorption on Ar-snow Testexperiment TRAP: DPS2-F

The prespectrometer Purpose: MAC-E filter for the suppression of  -electrons with E  <18,4keV Fixed retardation potential of 18,4kV  = 1,7m/L = 4,2m, B max = 4,5T, B min = 0.025T Reduction of electron-flux   E  70-80eV

The prespectrometer at FZK Since end of 2003 at the Forschungszentrum Karlsruhe

The prespectrometer at FZK Wire electrode NEG (10000l/s) Status: Vaccuum tests successfull: p < mbar EMD-test in progress since July 2006

The main spectrometer Purpose: MAC-E filter for the precision measurement of the endpoint region of the Tritium  -spectrum Variable retardation potential 18,5-18,6kV  =10m/L=23m, B max = 6T, B min = 3  T vacuum < mbar !!!  E  1eV

An end section Deggendorf,

The spectrometer tank Deggendorf, June 2006

The wire elctrode

The wire electrode 5 x 20 cylinder 3 x 20 large cone 1 x 10 small cone Sum: 240 moduls!

The wire electrode Single module: ca m x 1.80 m 2 combs connected via 4 C-profiles „Combs of stainless steel“: Cut by water or laser

The wire electrode C-profile Comb 1. layer Ø 0.3 mm 2. layer Ø 0.2 mm 70 mm 25 mm Prototype, U Münster Prototype in Münster

The detector Purpose: Position sensitive detection of the electrons Status: Under development Segmented Si-PIN diode Detector of prespectrometer

Schedule First components already set up at FZK: Prespectrometer → vacuum- and EMD-tests Installation of the main spectrometer at FZK planned for end of 2006 (Mass-)production of the wire electrode modules in Münster in 2007 → installation end of 2007 Test measurements with a Krypton-source (U Münster) at the main spectrometer in 2008 Installation of the Tritium-source in 2008 Tritium measurements will start in 2010 Work on the building for the main spectrometer at FZK

Summary The aim of KATRIN is to search for the neutrino mass in the region 0,2-2eV → distinguish between hierarchical and degenerate mass models → cosmologically relevant For the specifications see KATRIN design report 2004 FZKA Scientific Report 7090 The main components are under construction Measurements with KATRIN will start in 2010