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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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Outline

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


Basic idea calorimetric detection
Basic Idea: Calorimetric Detection

x-ray, γ-ray, e-,

WIMP, etc.

Choice of thermometers

NTD, TES, MQC etc.


Why low temp detectors

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


What to measure
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


Ntd sensor
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)


Transition edge sensor tes

(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 


Magnetic quantum calorimeter mqc

Kα

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


Cryogenic massive detectors
Cryogenic massive detectors

ROSEBUD, Tolyo-DM, ORPHEUS, MACHe3, etc.


Detection of signals for wimps

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


Phonon signals
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


Neutrinoless decay
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


Direct search for neutrino mass

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


Ltds at kriss

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


Absolute measurement of radioactivity

55Fe, 3H, or other sourcein 4π geometry

Absolute measurement of radioactivity

(Future work at KRISS)

No loss in source and detector

Absolute measurement


High resolution eds

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


Ltds in the underground lab at yangyang
LTDs in the underground lab at Yangyang?

Certainly possible !

We are open for new ideas and people !


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