MARE (microcalorimeter array for a rhenium experiment) Massimiliano Galeazzi for the MARE collaboration

OUTLINE INTRODUCTION A Rhenium Experiment Cryogenic Microcalorimeters Precursors to MARE (MANU & MIBETA) MARE I (m < 1-2 eV) Status of MARE I in Milan/Wisconsin Status of MARE I in Genoa/Miami MARE II (m < 0.1-0.2 eV) Requirements Rhenium vs. Holmium Technology Development CONCLUSIONS

OUTLINE INTRODUCTION A Rhenium Experiment Cryogenic Microcalorimeters Precursors to MARE (MANU & MIBETA) MARE I (m < 1-2 eV) Status of MARE I in Milan/Wisconsin Status of MARE I in Genoa/Miami MARE II (m < 0.1-0.2 eV) Requirements Rhenium vs. Holmium Technology Development CONCLUSIONS

A RHENIUM EXPERIMENT Direct measurement of the electron neutrino mass by studying the beta decay of 187Re with cryogenic microcalorimeters. Radioactive source embedded in the microcalorimeter absorber Calorimetric Experiment (all the energy, except the neutrino’s, is measured) All events are detected Rhenium is the beta isotope with the lowest known endpoint energy (2.47 keV) Fully complementary to a tritium experiment (different isotope AND different experimental technique) Expected sensitivity of MARE ~ 0.1-0.2 eV/c2 4

CRYOGENIC MICROCALORIMETERS FALL TIME (Depends on C, G, Bias Power) RISE TIME (Depends on Absorber) 5

RESISTIVE SENSORS Thermistors TES Very high resistance Negative “low” sensitivity FET readout TES Very low Resistance Positive “high” sensitivity SQUID readout 6

NON-RESISTIVE SENSORS A. Fleischmann et al., LTD13 7

BETA ENVIRONMENTAL FINE STRUCTURE (BEFS) MANU & MIBETA MANU: Re single crystal with NTD Ge thermistors MIBETA: AgReO4 with Si implanted therimostors END POINT  2465.3±0.5(stat)±1.6(syst) eV 2470±1(stat)±4(syst) eV HALF LIFE  4.32±0.02(stat)±0.01(syst) 1010 yrs 4.12±0.02(stat) ±0.11(syst)1010 yrs MASS  mn < 15 ev/c2 mn < 26 ev/c2 BETA ENVIRONMENTAL FINE STRUCTURE (BEFS) HEAVY NEUTRINOS 8

OUTLINE INTRODUCTION A Rhenium Experiment Cryogenic Microcalorimeters Precursors to MARE (MANU & MIBETA) MARE I (m < 1-2 eV) Status of MARE I in Milan/Wisconsin Status of MARE I in Genoa/Miami MARE II (m < 0.1-0.2 eV) Requirements Rhenium vs. Holmium Technology Development CONCLUSIONS

MARE I m < 2 eV/c2 1010 events - 300 sensors Milano / Como / IRST / Wisconsin / NASA/GSFC 8 arrays of Si:P thermistors with AgReO4 absorbers energy resolution 25 eV @ 2.6 keV Genoa / Miami / Florida / Lisbon Ir TES with Re crystal absorbers Energy resolution <10 eV 10

MARE I - MILAN Single crystal of silver perrhenate (AgReO4) as absorber mass ~ 500 mg per pixel (Ab~ 0.3 decay/sec) regular shape (600x600x250 mm3) low heat capacity due to Debye law 6x6 array of Si thermistors (NASA/GSFC) pixel: 300x300x1.5 mm3 high energy resolution developed for X-ray spectroscopy 600 µm Si support 300 mm 11

MARE I - MILAN calibration spectrum Top=85 mK Mn Ka Al Ka Ca Ka Cl Ka Ca Ka Ca Kb Ti Ka Ti Kb Mn Ka Mn Kb Top=85 mK DE = 33 eV@ 2.6 keV tR ~ 500 ms Araldit / ST2850 12

Araldit or ST1266 thermistor/spacer MARE I - MILAN FIRST 11 CRYSTALS Thermal coupling: ST2850 spacer/absorber Araldit or ST1266 thermistor/spacer 13

MARE I - MILAN SUMMARY The first phase of MARE-1 in Milan is getting ready to start at the end of September with 72 channels With 72 channels a sensitivity on neutrino mass of about 5 eV can be achieved in two years Based on these preliminary results, a decision concerning funding of the deployment of the remaining 6 arrays can be made 14

MARE I - GENOA Single crystal of pure Re as absorber Ir TES on Si3N4 membrane Gold thermal link between absorber and TES Energy Resolution ~10 eV FWHM Re TES Metal contact TES O 15

MARE I - GENOA Ir TES on Si3N4 membrane Re crystal on top of TES Al leads for TES 16

The first phase of MARE-1 in Genoa is starting in September MARE I - GENOA SUMMARY The first phase of MARE-1 in Genoa is starting in September Single SQUID readout for the initial detectors SQUID multiplexing available by the end of the year Expected sensitivity of ~0.2 eV in 2 years of data taking 17

OUTLINE INTRODUCTION A Rhenium Experiment Cryogenic Microcalorimeters Precursors to MARE (MANU & MIBETA) MARE I (m < 1-2 eV) Status of MARE I in Milan/Wisconsin Status of MARE I in Genoa/Miami MARE II (m < 0.1-0.2 eV) Requirements Rhenium vs. Holmium Technology Development CONCLUSIONS

MARE 19

MARE SENSITIVITY 20

MARE REQUIREMENTS EXPERIMENTAL CONSTRAINS Statistics Unresolved pileup Energy Resolution Energy calibration Background BEFS 21

MARE REQUIREMENTS REQUIRED EXPERIMENTAL PARAMETERS 22

MARE REQUIREMENTS Sources of Uncertainty 23

CURRENT STATUS OF MARE The full MARE experiment is still in the R&D phase and multiple options are being evaluated. In particular: TECHNOLOGY ISOTOPE 163Ho 187Re TES MagCal 24

RHENIUM VS. HOLMIUM finite neutrino mass causes a kink at the end-point similarly to beta spectra 25

RHENIUM VS. HOLMIUM Advantages of a Ho experiment: tunable source activity independent on the absorber mass Minimization of the absorber mass to the minimum required by the full absorption of the energy cascade  resolution less dependent on the activity Rise-time less of 10 us for SiN suspended detector Higher Counting rate per detector Self calibrating experiment Easiest way to reach higher count rate with presently better performing detectors 26

RHENIUM VS. HOLMIUM The necessary statistics for a Ho experiment depends on the exact value of the IB endpoint energy, but should be comparable to that of a Re experiment 27

RHENIUM VS. HOLMIUM In the past the Genoa group made a tentative experiment to verify the feasibility of a measurements Ho-163 Cl solution from ISOLDE (E Laesgaard) after a tentative made by INR-Moscow (purification failed) Final result was an admixture of fine salt grain onto a Sn matrix The final energy resolution was not satisfactory NTD thermistor Salt grains in Sn matrix (absorber) 28

RHENIUM VS. HOLMIUM 100 eV at 2 keV 40 eV at 6 keV cal line Broad, non-Gaussian MI line 8% disagreement on energy line measured with respect to the expected. However 4 lines resolved: MI,MII,NI,NII and a preliminary analysis gives Q=2.80+/-0.05 keV. More recently implantation tests have been done at ISOLDE (CERN), but first sample contains high level of radioactive impurities 29

MARE The full MARE experiment is still in the R&D phase and multiple options are being evaluated. In particular: ISOTOPE TECHNOLOGY 187Re 163Ho TES MagCal 30

TES PERFORMANCE TES development at NASA/GSFC 31

MAGNETIC CALORIMETER DEVELOPMENT A. Fleischmann et al., LTD13 32

MAGNETIC CALORIMETER DEVELOPMENT A. Fleischmann et al., LTD13 33

Re-Ir TES detectors (Genoa, Miami) CURRENT WORK ON MARE Re-Ir TES detectors (Genoa, Miami) AgReO –Si array (Milan-Wisconsin-Goddard) MUX Readout (PTB-Genoa) Kinetic Inductance Sensor (Como-IRST-Trento) Magnetic Calorimeter (Heidelberg) Semi-analytical modeling for experimental design (Milan) GEANT simulation and data Analysis ( U.Florida- Miami) Ho-163 (Genoa-Goddard-Miami-Lisbon, Heidelberg) TES physics (Lisbon-Miami) Production and study of E.C. isotopes (GSI) 34

DETECTOR READOUT 10,000-50,000 Channels SINGLE CHANNEL READOUT (wiring, power consumption) SQUID MULTIPLEXING Time division Multiplexing Frequency division multiplexing Microwave Multiplexing SQUID MULTIPLEXING Time division Multiplexing Frequency division multiplexing Microwave Multiplexing 35

Genoa-PTB development of frequency MUX readout READOUT MULTIPLEXING Genoa-PTB development of frequency MUX readout PTB SQUID under test at Genoa 36

NIST development on MUX readout READOUT MULTIPLEXING NIST development on MUX readout Time Domain Multiplexing Microwave Multiplexing 37

UNIFORMITY OF IRIDIUM THIN FILMS 3 4 6 12 17 4” 14 3 2 4 9 10 38

FULL SCALE REALISTIC SIMULATION GOALS OF THE SIMULATION Geant Monte Carlo to simulate the individual Re decays and create an event list containing relevant event parameters such as energy, time, and position (within the microcalorimeter). Numerical solver to model the non-linear response and noise of the microcalorimeter. Optimal filter analysis of the simulated pulses to generate a "data-like" beta spectrum. GOALS OF THE SIMULATION Understanding the systematics of the experiment Optimization of the experimental design (size of the absorbers, number of detectors, detectors parameters, etc.) Improve the analysis procedure (by incorporating, for example, the unidentified pileup spectrum in the fitting procedure) 39

SIMULATION TEST RUN Unidentified pileup Effect of the decay position in the absorber Efficiency and systematics of the analysis tools Background events originating from radioactive decays in the surrounding cryostat material 8x108 events 1 mg detector 40

THE BIG CHALLENGES ABSORBER PHYSICS FABRICATION RHENIUM ISOTOPE GENERATION ISOTOPE IMPLANT RHENIUM HOLMIUM 41

CONCLUSION 1) MARE I development is finished and should start taking data in September (1-2 yrs of data taking) 2) MARE II is a challenging experiment, but feasible. Technology ready and mature. In the next 2-3 years a decision on the isotope and detector technology should be made and a prototype detector built. Full development could start immediately after that (if funding is available both in the US and Europe) 3) MARE will provide fully complementary results to KATRIN