F. GattiTAUP2007, Sendai, MARE an experiment for the calorimetric search of m  with sub eV sensitivity F.Gatti On the behalf of the Collaboration University and INFN of Genoa TAUP, Sendai, Sep. 14th 07

F GattiTAUP 2007, Sendai, MARE: Microcalorimeter Arrays for a Rhenium Experiment Proposal of a direct measurement of neutrino mass (MARE) with sub eV sensitivity. MARE want to exploit the true calorimetric method in conjunction with the eV energy resolution of the cryogenic detectors. MARE want to achieve a model independent measurement MARE is foreseen to develop the research program trough different phases: MARE I: R&D and test experiment with eV sensitivity MARE II: fixing the technology and measurement in the sub eV ( ~0.1 eV) range.

F GattiTAUP 2007, Sendai, MARE: Microcalorimeter Arrays for a Rhenium Experiment Università di Genova and INFN Genova,Italy Goddard Space Flight Center, NASA, Maryland, USA GSI, Darmstadt, Germany Kirkhhof-Institute Physik, Universität Heidelberg, Germany Università dell'Insubria,Italy Univ. Milano-Bicocca and INFN Milano-Bicocca, Italy NIST, Boulder, Colorado, USA ITC-irst, Trento and INFN Padova,Italy PTB, Berlin, Germany University of Maryland, Maryland, USA University of Miami, Florida, USA University of Florida, Gainesville, Florida, USA Università Roma “L a Sapienza” and INFN Roma I, Italy SISSA, Trieste, Italy University of Wisconsin, Madison, Wisconsin, USA

F GattiTAUP 2007, Sendai, Calorimetric beta spectroscopy The source is embedded in the detector  Advantages : Measurement of whole energy of the decay E i =  i +  i  dN(  ) = A  i w i  i     d   no model dependent corrections for atomic and molecular final states.  no correction for nuclear recoil energy and for electron energy losses. Disadvantages : Beta Source inside the detector  all spectrum must be acquired: but interesting area proportional to only  m c 2  E     Re 187 : lowest Q ~ 2.5 keV.  Re 187 :  m c 2  E    ~1/400 of H 3  dN/A  Re-187 Os  ß i,

F GattiTAUP 2007, Sendai, An exemple of ¨rhenium microcalorimeter¨ Absorber Re single crystal (99.99% purity) typical dim. 300x300x300 μm surfaces cleaned to optical level annealed at 1300ºC in UHV 63% of 187- Re Thermistor Ir-Au TES on Si Electrical & Heat link Al -1% Si wires 15 μm diam., 1mm length Thermal contact High purity epoxy

F GattiTAUP 2007, Sendai, How the detector works TES R vs T MnK  1,2 energy spectrum

F GattiTAUP 2007, Sendai, Short History In 1985 the use of Re in cryogenic detectors has been proposed by S.Vitale (Genoa) In 92: first calorimetric observation of the 187-Re beta decay 96-99: achieved performance for execution of a first log run eV fwhm 30 eV fwhm

F GattiTAUP 2007, Sendai, Other type of

F GattiTAUP 2007, Sendai,

F GattiTAUP 2007, Sendai, known sources of systematics The absorber modulates the E endpoint : E endpoint = (Q-m e ) – (e  -E Fermi )-  B lattice Atomic long term metastable excited states: <7x10-5 Absorber thermal efficiency: in superconducting Re: ~ 1 down to 90 mK detector response function (energy dependence, shape,...): material dependent, good absorber show gaussian like funct. and approx flat energy dependence condensed matter effects: BEFS observed in Re and AgReO4  improve data and modeling 187Re decay spectral shape: improve F(Z,E) and S(E) energy dependent background: low energy emission in the surrounding materials and radioactivity to be pile-up and rejection efficiency investigation with MC methods other analysis artifacts under investigation with MC methods energy surface escape: < 10-4

F GattiTAUP 2007, Sendai, Sensitivity: analytic formula vs MC MARE I MARE II

F GattiTAUP 2007, Sendai,

F GattiTAUP 2007, Sendai,

F GattiTAUP 2007, Sendai,

F GattiTAUP 2007, Sendai, MARE II: Detector and read-out technologies Mo/Au TES at GFSC/NASA Electron-beam deposited Tc ~ 0.1 K Noise-mitigating normal-metal stripes Absorbers joined to TES in micro- fabrication “Mushroom” shaped to cover the gaps Emphasis on absorbers needed for Constellation-X reference design 0.25 mm pitch (TES is 0.13 mm wide) 92% fill factor 95% QE at 6 keV Bi Cu nitride

F GattiTAUP 2007, Sendai, MARE II: Detector and read-out technologies GSFC/NASA Group

F GattiTAUP 2007, Sendai, MARE II: Detector and read-out technologies Study of the optimal detector concept (Genoa Group) Improve risetime  direct contact Absorber-TES Improve resolution  minimization of not useful materials Provide a design fully compatible with usual planar lithography tech.  large scale integration Re SiO TES Suspended SiN menbrane Re TES Metal contact Re Genoa Group

F GattiTAUP 2007, Sendai, MARE II: Detector and read-out technologies M T 'Curie' KαKα Trigger level Characterization with 55 Fe-Source: energy resolution  E FWHM = 2.7 eV resolving power 2200 Kα1Kα1 Kα2Kα2 non-linearity at 6keV: < 0.8% Heidelberg Group

F GattiTAUP 2007, Sendai, MARE II: Detector and read-out technologies NIST

F GattiTAUP 2007, Sendai, MARE II: Detector and read-out technologies sciencepixelsMUXInstitute Funded Experiments ACT CMB/SZ3000 TDM (NIST/UBC) APEX-SZ CMB/SZ330 FDM (Berkeley) CLOVER CMB-Pol 1500 TDM (NIST/UBC) EBEX CMB-Pol 1200 FDM (Berkeley) LABOCA Sub-mm 288 TDM (Jena/MPI) SAFIRE/SOFIA Sub-mm 1000 TDM (NIST/GSFC) SCUBA-2 Sub-mm TDM (NIST/UBC) SPT CMB/SZ 1000 FDM (Berkeley) Future Experiments PolarBeaR CMB-Pol 1200 FDM (Berkeley) MKID-cam/CSO Sub-mm 1600 MKID (JPL/CIT) 6m Russian Tele (RAS) Sub-mm128 FDM (RAS) SPIDER CMB-Pol2000 TDM (NIST/UBC) Constellation-X X-ray1000 TDM (NIST/GSFC) XEUS X-ray1000 FDM (SRON/VTT) NeXT X-rayTBD FDM (ISAS) EURECAX-ray964FDM(SRON/ISAS) MARE II -mass 50000FDM(INFN)

F GattiTAUP 2007, Sendai, A possible sensitivity scenario for MARE II

F GattiTAUP 2007, Sendai, Eletron Capture Decay provides another tool for calorimetric mass measurements 163Ho is the most suited, The end point of the highest capture line is sensitive to mass ( A De Rujula, 1983). Implanted 163Ho is a source with tunable activity independent form the absorber masses Minimization of the absorber mass  minimum required by the full absorption of the energy cascade  resolution less dependent from the activity Different systematics than 187 Re  increase confidence level A further possibility: not only 187Re

F GattiTAUP 2007, Sendai,

F GattiTAUP 2007, Sendai, Concluding remarks vMass07: “if Katrin don’t see signal … we need to go at 5x10-2 eV!” vMass07:“ cosmology can set new constraints on the mass in the ten year … but a laboratory measurement is needed, as in the case of neutrino oscillation at the reactor (Kamland) respect to the astrophysical evidence.” Thermal detectors can achieve resolution of the 1 eV in a short time and can be used for a very high statistics experiment  expected sensitivity in the KATRIN range or better, in future. EC decay is considered as second tool The overall technology is not fully tested for application to beta decay  an huge effort of a large community is needed  new collaborators are welcome