Min Kyu Lee ( 이민규 )Kyoung Beom Lee ( 이경범 )Yong-Hamb Kim ( 김용함 )

Low Temperature Detectors

2006 Workshop on the Underground Experiment at YangyangTEXONO-KIMS collaboration meeting

LTD 2

OutlineOutline

• Basic idea – Calorimetric detection, Why? What?

• Sensors – NTD, TES, MQC

• Massive detectors– Search for WIMPs, 0ν-ββ, ν mass

• LTDs at KRISS– Future plan

LTD 3

Basic Idea: Calorimetric DetectionBasic Idea: Calorimetric Detection

x-ray, γ-ray, e-, WIMP, etc.

Choice of thermometers NTD, TES, MQC etc.

LTD 4

Why Low Temp. Detectors?Why Low Temp. Detectors?

• High resolution • Low threshold

NIST

Al-Ag TESSi(Li)

Low heat capacity dielectric ~ T3

240g sapphire (CRESST-I) ~ 580 eV at 10 mK, 99% efficiency

LTD 5

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

LTD 6

NTD SensorNTD Sensor(Neutron Transmuted Doped Ge Thermistors)

• Near metal-insulator transition

• R(T) : 1 M100 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)

LTD 7

Transition Edge Sensor (TES)Transition Edge Sensor (TES)

• Superconducting strip at Tc

(W, Ir/Au, Mo/Au, Mo/Cu,

Al/Ag, etc.)

• RN : 10 m1

(2004)

ΔE = 2.4 eV @ 6 keV

LTD 8

Magnetic Quantum Calorimeter (MQC)Magnetic Quantum Calorimeter (MQC)

Magnetic material (Au:Er, Ag:Er, Bi2Te3:Er)in loop of a dc SQUID

ΔE = 3.4 eV @ 6 keV99 % quantum efficiency

Brown-Heidelberg Au:Er (2003)

Kα

Kβ

LTD 9

Cryogenic massive detectorsCryogenic massive detectors

EDELWEISS-I Ge 1 kg Ch/Ph NTD 1996 Modance

EDELWEISS-II Ge 10 kg Ch/Ph NTD,NbSi 2005 Modance

CDMS-I Ge, Si 1 kg, 250 g Ch/Ph NTD 1996 Stanford

CDMS-II Ge, Si 7 kg, 1.4 kg Ch/Ph TES 2003 Soudan

CRESST-I Al2O3 1 kg TES 1999 Gran Sasso

CRESS-II CaWO4 10 kg L/Ph TES 2003 Gran Sasso

CUORICINO TeO2 40 kg NTD 2003 Gran Sasso

CUORE TeO2 750 kg NTD ~2007 Gran Sasso

Name Target Mass Discrim Thermometer Start Location

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

LTD 10

Detection of signals for WIMPsDetection of signals for WIMPs

Nuclear recoil on electron recoil bkg

Phonon

Light

Charge

Different Ch/Ph or L/Ph ratio for electron recoils and neutron recoils

Event by event discrimination

Ene

rgy

in c

harg

e ch

anne

l (ke

Vee

)

Energy in phonon channel (kev)

electr

on re

coils

(γ‘s)

nuclear recoils (

neutrons)

Ene

rgy

in li

ght c

hann

el (

keV

ee)

Energy in phonon channel (kev)

electr

on re

coils

(e- s,

γ‘s)

nuclear recoils (neutrons)

CRESST

CaWO4

LTD 11

Phonon signalsPhonon signals

Phonon down conversion 1. Very high energy phonon (not stable)

2. 20 ~ 50 K phonon (stable)

Anharmonic decay

3. Thermal phonon distribution

Inelastic surface scatteringInelastic impurity scattering

~ ns

~ 10 μs

Athermal signals

Thermal signals

Size and shape of athermal signals also provide discrimination for surface events

LTD 12

Neutrinoless Neutrinoless ββββ decay decay

U, Th contaminations on Cu give 50% bkg of ββ region (tested some ideas for surface event rejection)

COURE (750 kg TeO2) being built

COURICINO: 40 kg of TeO2 + NTD130Te : 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)

LTD 13

Direct search for neutrino massDirect search for neutrino mass

rel.

Rat

e (a

.u.)

-3 -2 -1 0 Ee-E0 (eV)

1

0.8

0.6

0.4

0.2

0

m = 0 eV

m = 1 eV

E0 = 2.46 keV

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

Theoretical β spectrum near endpoint

LTD 14

LTDs at KRISSLTDs at KRISS

• MQC: We own the sensors (900 ppm Au:Er).

• TES: Ti/Au bilayer (DMRC & KRISS)

Temperature (K)

Res

ista

nce

(Ω)

Ti/Au (15/50 nm)Jan19/2006

Sensors

LTD 15

Absolute measurement of radioactivity Absolute measurement of radioactivity (Future work at KRISS)

No loss in source and detectorAbsolute measurement

55Fe, 3H, or other source in 4π geometry

LTD 16

High resolution EDS High resolution EDS

e-

detector

cryostat

sample

x-ray optics

x-ray window

(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

Long term goal: resolution 3 eV at 6 keV count rate 10,000/s quantum efficiency 90% up to 6 keV

LTD 17

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

Certainly possible !

We are open for new ideas and people !