1. Cryogenic Particle Detectors in Rare event Searches
International Workshop on Double Beta Decay
Cryogenic Particle Detectors
in Rare event Searches
Oct

2. LTD people at KRISS (Daejeon, 大田)
(Korea Research Institute of Standards and Science)
Jang, Yong Sik
Kim, Il Hwan
Kim, Min Sung
Kim, Yong-Hamb
Yuryev, Yury
Lee, Kyoung Beum
Lee, Hwa Yong
Lee, Min Kyu
Lee, Sang Jun

3. Introduction to cryogenic particle detectors
Outline
Introduction to cryogenic particle detectors
Why? How? What?
Sensors (Thermistors, TES, MMC)
Search for rare events in underground labs
Measurement chains
CUORE (cryostat, shielding)
Detector development at KRISS
x-ray sensors, Q spectrometry
Prospective R & D for 0ν

4. Basic idea: Calorimetric detection
Energy absorption  Heat (Temperature)
, , , etc.
Thermometer
Absorber
Thermal link
Heat sink < 100 mK
Choice of thermometers
Thermistors (doped Ge, Si)
TES (Transition Edge Sensor)
MMC (Metallic Magnetic Calorimeter )
STJ, KID etc.

5. Why cryogenics? Advantages of using cryogenic calorimeters
Extreme sensitivity of energy resolution (ΔE/E < 1/1000)
Ultra low energy threshold ( < 1 eV)
Active for Charge, Light, Phonon(Temperature) chains
NIST
Al-Ag TES
Si(Li)
(NIST 2006)
(KRISS 2007)
(NIST 2007)

6. What to measure?
eV ~ MeV
from K. Irwin’ 2008

7. Thermistors Neutron transmuted doped Ge thermistors
Ion implantation doped Si thermistors
Near metal-insulator transition
R(T) : 1 M ~100 M
Operated with conventional electronics
Slow due to poor coupling between conduction electrons and lattice of the thermistor
NASA GSFC

8. Transition Edge Sensor (TES)
(초전도상전이센서)
Superconducting strip at Tc
(W, Ir/Au, Mo/Au, Mo/Cu,Al/Ag, etc.)
RN : 10 m ~1 
Proximity effect : Tunable Tc (20~200mK)
Voltage Bias  negative feedback
working
point

9. Metallic Magnetic Calorimeter (MMC)
(자기양자센서)
Field coil
Magnetic material (Au:Er) in dc SQUID
Au:Er(10~1000ppm)
weakly-interacting paramagnetic system
metallic host: fast thermalization ( ~ 1ms)
junctions
5 mT  Δε = 1.5 eV
1 keV  109 spin flips
g = 6.8
U. of Heidelberg

10. Different sensors for rare event searches
Thermistor
TES
MMC
Fast, Most sensitive
MUX possible
Narrow working temp.
High-tech. fab.
Conventional electronics
Absorber friendly
Slow at low temp.
Joule Heating
Fast, Wide working temp.
Absorber friendly
MUX being developed
I of 167Er

11. Search for rare events in underground labs
Outline
Introduction to cryogenic particle detectors
Why? How? What?
Sensors (Thermistors, TES, MMC)
Search for rare events in underground labs
Measurement chains
CUORE (cryostat, shielding)
Detector development at KRISS
x-ray sensors, Q spectrometry
Prospective R & D for 0ν

12. Solid detectors for rare events
Detector Requirement
Massive (spin optional) for WIMPs
Contain isotopes of interest for 0νββ
Low internal background
Low threshold, high resolution
Active background rejection
Thermometer
Thermometer
Light
detector
Charge
collector
Scintillator
Semiconductor

13. Measurement Chains in LTDs
Measurement methods
(Charge, Light, Phonon(Temperature))
“Low temperature favorable”
examples
CRESST, ROSEBUD
Events
Light
Charge
Phonon
COURE
CDMS, EDELWEISS

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

15. Neutrinoless  decay with LTD
Double Beta Decay with two neutrinos
(Rare Spontaneous Nuclear Transition)
Double Beta Decay with no neutrino e-
Calorimetric Detection
Source = Detector
- Neutrino is only allowed
to escape from the bulk
- 100% detection efficiency

16. COURICINO toward CUORE
COURICINO (40.7 kg of TeO2 + NTD Ge)
130Te : candidate for 0ν
natural abundance (34%)
Transition energy (2.53 MeV)
5cm
(2006)
COURE (741 kg TeO2) plans to start data taking
in 2011

17. CUORE cryostat

18. Shielding for CUORE

19. Detector development at KRISS
Outline
Introduction to cryogenic particle detectors
Why? How? What?
Sensors (Thermistors, TES, MMC)
Search for rare events in underground labs
Measurement chains
CUORE (cryostat, shielding)
Detector development at KRISS
x-ray sensors, Q spectrometry
Prospective R & D for 0ν

20. First signal at KRISS for rare events
2006/06 S.C. Kim
6 keV from 55Fe
Counts
5×5×0.5 mm3 Si
with Ti/Au TES
WIMP, ν, 0νββ etc.
Signal size (a.u.)
Clear appearance of 6 keV x-rays
Important demo. toward massive detectors

21. Detector development at KRISS
TES
MMC
Au:Er Si
field coil
SQUID loop
18 eV FWHM
55Fe spectrum
Measured with MMC
2007/11, S.J. Lee
Mn Ka2
Mn Ka1

22. 4 measurement for alpha decay
radionuclides in 4 geometry
Au foil absorber
40~100 m
Au:Er ( 50 m×30 m)
1.4 mm
SQUID
No loss in source and detector
Absolute activity
Decay energy (Q)

23. 241Am decay
241Am Np
decay
(Q= keV)
241Am
244Cm

24. Identification of Pu isotopes
“Q spectrum”
Each alpha emitter
 One peak
238Pu
241Am
Clear identification of 239Pu, 240Pu
7.9 keV FWHM achieved
239Pu
240Pu

25. Two detection channels phonon + light
R & D with CaMoO4 at KRISS
Scintillating Detectors for 0ν at Low temperatures
Two detection channels phonon + light
Si or Ge
TES
Additional light sensor
CaMoO4
Phonon sensor
w. TES or MMC

26. First trial with CaMoO4 241Am ~ 500 m thick brass crystal size
~ 1 cm  1 cm  0.7 cm
base temperature : 13 ~ 100 mK

27. Full spectrum typical signal gamma peak alpha peak time (s) ~1/64
5.5 MeV alpha signal
alpha peak
60 keV gamma pileups
time (s)
~1/64

28. Gamma and Alpha spectrum of 241Am
60 keV region
5.5 MeV region
three
major
peaks
60 keV added
1.8 keV
11.2 keV
11.2 keV FWHM for alpha’s from 241Am source (13 keV by ORTEC)
60 keV gamma pileups
Too big alpha signals (factor of 3)
1.8 keV FWHM for 60 keV gamma
Mo x-ray escape peak
Measured together with 5.5MeV alpha

29. For 3 MeV source, ΔE of 1.7 keV is achievable w. current setup.
Baseline noise
Noise spectrum from optimal filtering method
For 3 MeV source, ΔE of 1.7 keV is achievable w. current setup.
With
- Mono-energetic source
- Good energy linearity
- Temperature stability in time
FWHM = 1/1750

30. Now and near future  TES CaMoO4 Phonon sensor Crystal size: ~ 20 cm3
Crystal size: 1 cm1 cm0.7 cm
Energy resolution
3 MeV 
Energy resolution
2 ~12 keV @ 5.5 MeV
Additional light sensor (Quenching)
Non-thermal phonons (Shaping)
Si or Ge
TES
CaMoO4
Phonon sensor

31. Comparison with COURE COURE prospect Crystal (abundance) 130TeO2 (34%)
Ca100MoO4 (9.6%) Q
2530 keV
3034 keV
Phonon sensor
NTD Ge
MMC or TES
B.G. Rejection
TBA (none)
Light
ΔE at Q
5~7 keV
Mass
741 kg
Location
Gran Sasso
Start
2011
1~3 keV ??

32. Cryogenic particle detectors ??
Cryogenic is hard !!
Consider refrigerator, heat load, SQUID, etc.
Limit size, wires, shield, etc.
Cryogenic is not impossible.
Benefits are too good to ignore.
Limits are not known, to be explored

33. Thank you (감사합니다)