MARE Microcalorimeter Arrays for a Rhenium Experiment COLLABORATION:

1. The MARE experiment on direct measurement of neutrino massDaniele PergolesiUNIVERSITY and INFN of Genova

2. MARE Microcalorimeter Arrays for a Rhenium Experiment COLLABORATION: INFN sez. Genova and Università di Genova, Dipartimento di Fisica, ITALY NASA Goddard Space Flight Center, USA Universität Heidelberg, Kirchhoff-Institut für Physik, GERMANY Università dell’Insubria, Dipartimento di Fisica e Matematica, ITALY INFN sez. Milano and Università di Milano-Bicocca, Dipartimento di Fisica, ITALY ITC-IRST, Trento, ITALY University of Wisconsin, Physics Department, USA + NIST Boulder USA, Miami University USA, PTB Berlin GERMANY

3. SUij|ni |ni = Scientific motivations: What does the oscillations tell us? - Neutrino has a mass - neutrino is in a coherent superposition of three different states: nenmnt - natmospheric∆m232≈ 2⋅10-3 eV2 (SK + CHOOZ) - nsolar∆m122≈ 7⋅10-5 eV2 (SNO + KAMland) - Approx measurment or constraints on the elements of the mixing matrix: What we do not know: - Mass hierarchy: - The absolute mass scale - Neutrino is a Majorana or a Dirac particle? inverted normal Degenerate hierarchy when m1 ≈ m2 ≈ m3

4. Neutrino mass scale determination: Present status • Neutrinoless double beta decay - 0νββ:mne< 0.35 eV (Heidelberg—Moscow 76Ge) • mne< 0.2÷1.1 eV (CUORICINO 130Te) • mne = 0.1÷0.9 eV (Klapdor: : 76Ge reanalysis) • Cosmology:Σmni< 0.42eV (CMB+SDSS+SN) • Single b-decay:mne< 2.2eV (Troitsk, Mainz electrostatic spectrometer) • All of these techniques are model dependent: • 0νββ needs to assume that neutrino is a Majorana particle • In an electrostatic spectrometer the b source is outside the detector and the deconvolution from the data of the response function of the spectrometer is complicated (systematic problems with final state corrections, energy loss in the source) • Future perspectives for electrostatic spectrometer: KATRINmne< 0.2eV in 2010. • Direct sub-eV determination (model independent with different systematic) needed!!

5. The so-called direct neutrino mass measurement, or its upper limit determination, can be obtained by means of microcalorimeter with internal b source (Re). Only the neutrino energy escapes the detection and the total decay energy minus the energy carried away by the neutrino is measured. What is effectively measured, is the neutrino energy in the form of a missing energy at the end-point of the b-decay spectrum. The lifetime of the excited molecular or atomic states is negligible with respect to the detector time response (i.e. no loss of energy stored in excited states). Good knowledge of the detector response function allows the reconstruction of the theoretical spectral shape. Re is a very efficient absorber for microcalorimeter at the typical working temperature of about 100mK.

6. MARE Microcalorimeter Array for a Renium Experiment Direct measurement of neutrino mass studying the 187Re b-decay spectrum MANU MIBETA MANU2 MIBETA2 MARE phase1 MARE phase2

7. End-point =(2470 ± 1 stat ± 4 sys) eV • Half-life = (4.12 ± 0.02stat ± 0.11sys) 1010 y • mn2 = - 462 +579–679 eV2/c4 • mn < 26 eV/c2 95% CL, < 19 eV/c2 90% CL • First observation of the Beta Environmental Fine Structure (BEFS) MANU: Results Fine structure of the residual microcalorimetric measurement of 187Re b-decay spectrum

8. MIBETA:results Q = 2465.3  0.5 stat  1.6 sys eV Mb2 = -112  207 stat  90 sys eV2 t½ = 43.2  0.2 stat  0.1 sys Gy Mb< 15.0 eV (90% c.l.)

9. MANU and MIBETA phases II MARE phase I Aims: sensitivity range between 1 and 2 eV MARE phase1 will provide, for the very first time, the opportunity of checking the results obtained with the electrostatic spectrometer

10. MARE phase1 MIBETA2 Options and perspectives MIBETA2: MC simulation 1010 events needed to reach the required sensitivity

11. MARE phase1 MANU2 statistical sensitivity • MANU2Key Features: • 300 microcalorimeters with rhenium • single crystal absorber • Required DE: 5-10 eV FWHM @ 6KeV • TES sensors (Ir/Au – g Al\Ag) • operating at about 100mK • Testing no-SQUID readout electronics

12. First test of MANU2 single pixel Amplitude 2560mV rise time 100ms (10-90 %) Pile-up discrim. time 50ms • Ir\Au TES on high purity Si substrate operating at about 80 mK. • Re crystal: (400x470x54) mm3 • Signal amplified (x10) at room T, bandwidth (1-1000)Hz and read out by DC-SQUID Energy resolution at 6KeV RMS noise 1.2mV

13. MARE phase2 TES-MC MMC ? • From MARE phase1 results: • Scaling up to hundreds of channels • Optimization of single channel performances • Study of the sources of systematic uncertainties • Precise understanding of the Re b-decay spectrum (BEFS) Requirements: neutrino mass Stat. Sens. of 0.2eV (90%C.L.) New generation detector: faster rise time (order of msec),energy resolution of about 5eV FWHM in the energy range of interest) • Read-out electronics: multiplexed SQUID • Very big number of channels (order of 5 104) • for Mtot ≈ 1Kg, requires detector modularity

14. MARE phase2 MC simulation of the sensitivity of MARE phase2 (from the Milano Group)

15. 2 eV 0.2 eV 20 eV 1990 1995 2000 2005 2010 2015 2.2 eV MAINZ 20-10 eV KATRIN TROITZK 2.2 eV spettrometri magnetici spettrometri elettrostatici Spettrometri Calorimetri 26 eV MANU MARE Sandro Vitale 1985 187Re 15 eV MIBETA 20 eV 2 eV 0.2 eV 1995 2005 1990 2000 2010 2015 KATRIN v.s. MARE in sub-eV n mass search MARE phase2 will be the only available way to confirm or disprove KATRIN results From A. Giuliani, Insubria University