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Basic idea Calorimetric detection, Why? What? Sensors NTD, TES, MQC Massive detectors Search for WIMPs, 0 ν - ββ , ν mass LTDs at KRISS Future plan. Outline. Basic Idea: Calorimetric Detection. x-ray, γ - ray, e - , WIMP, etc. Choice of thermometers NTD, TES, MQC etc.

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  1. Basic idea Calorimetric detection, Why? What? Sensors NTD, TES, MQC Massive detectors Search for WIMPs, 0ν-ββ, ν mass LTDs at KRISS Future plan Outline

  2. Basic Idea: Calorimetric Detection x-ray, γ-ray, e-, WIMP, etc. Choice of thermometers NTD, TES, MQC etc.

  3. High resolution Low threshold Al-Ag TES Si(Li) NIST Why Low Temp. Detectors? Low heat capacity dielectric ~ T3 240g sapphire (CRESST-I) ~ 580 eV at 10 mK, 99% efficiency

  4. What to measure? • WIMP: CDMS, CRESST, EDELWEISS, etc. • Nutrinoless double beta decay: COURICINO(COURE) • Direct measument of neutrino mass: MANU, MARE • X-ray astronomy: Constellation-X, XEUS, Astro-E2 • Solar neutrino detector: HERON • Energy Depressive x-ray spectroscopy • Single photon counting: IR, visible, UV, etc. • Bio-molecules: time-of-flight mass spectrometry x-ray absorption spectroscopy

  5. NTD Sensor (Neutron Transmuted Doped Ge Thermistors) • Near metal-insulator transition • R(T) : 1 M ~100 M • Operated with conventional electronics • 4.5 eV at 6 keV (Alessandrello et. al. prl. 1999) • Slow due to poor coupling between conduction electrons and lattice of the thermistor • E dependent resistance • Radioactive contamination (68Ge, 3H)

  6. (2004) ΔE = 2.4 eV @ 6 keV Transition Edge Sensor (TES) • Superconducting strip at Tc • (W, Ir/Au, Mo/Au, Mo/Cu, • Al/Ag, etc.) • RN : 10 m ~1 

  7. Kα Kβ Magnetic Quantum Calorimeter (MQC) Magnetic material (Au:Er, Ag:Er, Bi2Te3:Er) in loop of a dc SQUID Brown-Heidelberg Au:Er (2003) ΔE = 3.4 eV @ 6 keV 99 % quantum efficiency

  8. Cryogenic massive detectors ROSEBUD, Tolyo-DM, ORPHEUS, MACHe3, etc.

  9. CaWO4 electron recoils (e-s, γ‘s) CRESST Energy in light channel (keVee) nuclear recoils (neutrons) Energy in phonon channel (kev) electron recoils (γ‘s) Energy in charge channel (keVee) nuclear recoils (neutrons) Energy in phonon channel (kev) Detection of signals for WIMPs Nuclear recoil on electron recoil bkg Light Charge Phonon Different Ch/Ph or L/Ph ratio for electron recoils and neutron recoils Event by event discrimination

  10. Phonon signals Phonon down conversion 1. Very high energy phonon (not stable) Anharmonic decay ~ ns 2. 20 ~ 50 K phonon (stable) Athermal signals Inelastic surface scattering Inelastic impurity scattering ~ 10 μs 3. Thermal phonon distribution Thermal signals Size and shape of athermal signals also provide discrimination for surface events

  11. Neutrinoless ββ decay COURICINO: 40 kg of TeO2 + NTD 130Te : candidate for 0ν-ββ natural abundance (34%) high transition energy (2.53 MeV) Source ≡ Detector (neutrino is the only allowed to escape from the bulk) U, Th contaminations on Cu give 50% bkg of ββregion (tested some ideas for surface event rejection) COURE (750 kg TeO2) being built

  12. 1 0.8 0.6 0.4 0.2 0 rel. Rate (a.u.) E0 = 2.46 keV mn= 0eV mn= 1eV -3 -2 -1 0 Ee-E0(eV) Direct search for neutrino mass Theoreticalβ spectrum near endpoint Source ≡ Detector (neutrino is the only allowed to escape from the bulk) Published results: < 15 eV(90 C.L.) Milano MIBETA (AgReO4) < 26 eV(95 C.L.) Genova MANU (metallic Re) Future plan MARE phase I (MANU II, 2006~2009), goal < 2 eV TES or MQC phase II (2010~2015), goal < 0.2 eV, TES or MQC

  13. MQC: We own the sensors (900 ppm Au:Er). TES: Ti/Au bilayer (DMRC & KRISS) Ti/Au (15/50 nm) Jan19/2006 Resistance (Ω) Temperature (K) LTDs at KRISS Sensors

  14. 55Fe, 3H, or other sourcein 4π geometry Absolute measurement of radioactivity (Future work at KRISS) No loss in source and detector Absolute measurement

  15. x-ray optics e- detector sample cryostat x-ray window High resolution EDS (Future work at KRISS) Long term goal: resolution 3 eV at 6 keV count rate 10,000/s quantum efficiency 90% up to 6 keV

  16. LTDs in the underground lab at Yangyang? Certainly possible ! We are open for new ideas and people !

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