F. Gatti TAUP2007, Sendai, 14.9.07

MARE an experiment for the calorimetric search of mwith sub

eV sensitivity

F.GattiOn the behalf of the Collaboration

University and INFN of GenoaTAUP, Sendai, Sep. 14th 07

F Gatti TAUP 2007, Sendai, 14.9.07

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 Gatti TAUP 2007, Sendai, 14.9.07

MARE: Microcalorimeter Arrays for a Rhenium Experiment

Università di Genova and INFN Genova,ItalyGoddard Space Flight Center, NASA, Maryland, USA

GSI, Darmstadt, GermanyKirkhhof-Institute Physik, Universität Heidelberg,

GermanyUniversità dell'Insubria,Italy

Univ. Milano-Bicocca and INFN Milano-Bicocca, ItalyNIST, Boulder, Colorado, USA

ITC-irst, Trento and INFN Padova,ItalyPTB, Berlin, Germany

University of Maryland, Maryland, USAUniversity of Miami, Florida, USA

University of Florida, Gainesville, Florida, USAUniversità Roma “L a Sapienza” and INFN Roma I, Italy

SISSA, Trieste, ItalyUniversity of Wisconsin, Madison, Wisconsin, USA

F Gatti TAUP 2007, Sendai, 14.9.07

Calorimetric beta spectroscopy

The source is embedded in the detector

Advantages:Measurement of whole energy of the decay Ei=i+i

dN() = A i wi idno 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 mc2 E

Re187 : lowest Q ~ 2.5 keV.

Re187: mc2 E ~1/400 of H3

dN/A

Re-187

Os

ßi,

F Gatti TAUP 2007, Sendai, 14.9.07

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 contactHigh purityepoxy

F Gatti TAUP 2007, Sendai, 14.9.07

How the detector works

TES R vs T MnK1,2 energy spectrum

F Gatti TAUP 2007, Sendai, 14.9.07

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

1992 1996660 eV fwhm 30 eV fwhm

F Gatti TAUP 2007, Sendai, 14.9.07

Other type of

F Gatti TAUP 2007, Sendai, 14.9.07

F Gatti TAUP 2007, Sendai, 14.9.07

known sources of systematics•The absorber modulates the Eendpoint:

Eendpoint = (Q-me ) – (e-EFermi)-Blattice

•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 Gatti TAUP 2007, Sendai, 14.9.07

Sensitivity: analytic formula vs MC

MARE I

MARE II

F Gatti TAUP 2007, Sendai, 14.9.07

F Gatti TAUP 2007, Sendai, 14.9.07

F Gatti TAUP 2007, Sendai, 14.9.07

F Gatti TAUP 2007, Sendai, 14.9.07

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 Gatti TAUP 2007, Sendai, 14.9.07

MARE II: Detector and read-out technologies

GSFC/NASA Group

F Gatti TAUP 2007, Sendai, 14.9.07

MARE II: Detector and read-out technologies

Study of the optimal detector concept (Genoa Group)

Improve risetime direct contact Absorber-TESImprove resolution minimization of not useful materialsProvide a design fully compatible with usual planar lithography tech. large scale integration

Re

SiOTES

SuspendedSiN menbrane

Re

TES

Metal contact

Re

Genoa Group

F Gatti TAUP 2007, Sendai, 14.9.07

MARE II: Detector and read-out technologies

totC

E

T

MT

T

MM

M

T

'Curie'

Kα

Trigger level

Characterization with 55Fe-Source:

energy resolution EFWHM = 2.7 eV

resolving power 2200

Kα1

Kα2

non-linearity at 6keV: < 0.8%

HeidelbergGroup

F Gatti TAUP 2007, Sendai, 14.9.07

MARE II: Detector and read-out technologies

400400

50005000

100100 100100

100100 100100

5000050000

NIST

F Gatti TAUP 2007, Sendai, 14.9.07

MARE II: Detector and read-out technologies

  science pixels MUX Institute

Funded Experiments        

ACT CMB/SZ 3000 TDM (NIST/UBC)

APEX-SZ CMB/SZ 330 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 12800 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-mm 128 FDM (RAS)

SPIDER CMB-Pol 2000 TDM (NIST/UBC)

Constellation-X X-ray 1000 TDM (NIST/GSFC)

XEUS X-ray 1000 FDM (SRON/VTT)

NeXT X-ray TBD FDM (ISAS)

EURECA X-ray 964 FDM (SRON/ISAS)

MARE II -mass 50000 FDM (INFN)

F Gatti TAUP 2007, Sendai, 14.9.07

A possible sensitivity scenario for MARE II

F Gatti TAUP 2007, Sendai, 14.9.07

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 2565 2570 2575 2580 2585

0

1

2

3

x10-5

[d

W/(

dE

cW)]

1/2 /

eV

-1/2

m10 eV

m=2 eV

m=0 eV

E / eV

22

2222

HC

occC EE

mEQEQMdE

dW

A further possibility: not only 187Re

F Gatti TAUP 2007, Sendai, 14.9.07

F Gatti TAUP 2007, Sendai, 14.9.07

Concluding remarks Petcov @ vMass07: “if Katrin don’t see signal … we need to go at

5x10-2 eV!” www.ge.infn.it/~numass

Pastor @ 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.” www.ge.infn.it/~numass

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