cryogenic phonon-scintillation detectors with pmt readout ... · cryogenic phonon-scintillation...
TRANSCRIPT
Cryogenic phonon-scintillation detectors with PMT readout for rare
event search experiments Junsong Lin
(with Hans Kraus, Vitaliy Mikhailik and Xiaohe Zhang)
19/02/2016 UCLA Dark Matter Conference Junsong Lin1
Credit: Hamamatsu Photonics K.K.
Outline
Motivation
Experimental setup
Results
2
In this talk:Phonon detector ↔ calorimeter ↔ heat detector
Photon detector ↔ scintillation detector↔ light detector
19/02/2016 UCLA Dark Matter Conference Junsong Lin
Motivation
319/02/2016 UCLA Dark Matter Conference Junsong Lin
Motivation
419/02/2016 UCLA Dark Matter Conference Junsong Lin
Motivation
519/02/2016 UCLA Dark Matter Conference Junsong Lin
Motivation
6
Lower threshold
19/02/2016 UCLA Dark Matter Conference Junsong Lin
Motivation
7
More exposure
19/02/2016 UCLA Dark Matter Conference Junsong Lin
Motivation
8
More exposure
See Florian Reindl’s
talk for update19/02/2016 UCLA Dark Matter Conference Junsong Lin
Phonon-scintillation detector (CRESST for example )
9
Phonon detector- deposit energy; Light detector - discrimination Light detector with TES practical difficulty (performance range,
manufacture and operate) PMT might be more scalable (mature, consistent, robust, easy to
use…)
Image credit: CRESST collaboration Image credit: Raimund Johann Strauβ Ph.D. thesis
19/02/2016 UCLA Dark Matter Conference Junsong Lin
CaWO4
PMT and calorimeter @ milli-Kelvin temperature
10
Detectors inside NOSV
copper housing
Dilution refrigerator
Similar to PMT used in XENON 100
Pt underlay for milli-Kelvin usage. Decrease QE
Hamamatsu R8520-06-PT
with Pt underlay
QE: 15%-20%
19/02/2016 UCLA Dark Matter Conference Junsong Lin
Credit: Hamamatsu Photonics K.K.
Experimental setup – detectors
LBNL11
CaMoO4 or CaWO4
19/02/2016 UCLA Dark Matter Conference
PMT – High voltage and readout
12
Only a few volt AC outside cryostat
Avoid high voltage feedthrough
19/02/2016 UCLA Dark Matter Conference Junsong Lin
Cockcroft–Walton generator
13
Voltage divider generates too much heat
19/02/2016 UCLA Dark Matter Conference Junsong Lin
Typical event (122 keV γ)
100X difference in time
Fast response in light channel
– good for coincidence
– background reduction
14
-0.5 0.0 0.5 1.0 1.5 2.0 2.5
-6
-4
-2
0
2
Light signal
Sig
na
l , m
V
Time, ms
-50 0 50 100 150 200 250
-15
-10
-5
0
Phonon signal
Sig
nal ,
mV
Time, ms
19/02/2016 UCLA Dark Matter Conference Junsong Lin
Phonon channel spectrum
15
0 50 100 150 2000
200
400
600
800
Co
un
ts/k
eV
Energy, keV
FWHM = 0.97 keV
CaMoO4
0 50 100 150 2000
200
400
600
800
1000
Co
un
ts/k
eV
Energy, keV
FWHM = 2.17 keV
CaWO4
57Co source: 122 keV (91%) and 136 keV (9%) 𝛾
Tungsten escape peaks
100Mo for 0𝜐2𝛽 decay
19/02/2016 UCLA Dark Matter Conference Junsong Lin
(0.79%)
(1.8%)
Photon channel spectrum
16
0 50 100 150 200 2500
20
40
60
80
100
120
140
Co
un
ts
Number of Photons
CaWO4
0 50 1000
20
40
60
80
100
120
140
160
180
200
Co
un
ts
Number of Photons
CaMoO4
57Co source
CaWO4 better fit the PMT. More photons, better 𝜎 𝐸
19/02/2016 UCLA Dark Matter Conference Junsong Lin
FWHM: 19.9% at 122 keVFWHM: 29.7% at 122 keV
Correlation – phonon and photon channel
17
0 50 100 150 2000
50
100
150
200
250
300
Lig
ht
de
tecto
r, n
um
be
r o
f p
ho
ton
s
Phonon detector, keV
CaWO4
0 50 100 150 2000
20
40
60
80
100
CaMoO4
Lig
ht
de
tecto
r, n
um
be
r o
f p
ho
ton
s
Phonon detector, keV
Coincidence
Two channel readout mode (discrimination)
19/02/2016 UCLA Dark Matter Conference Junsong Lin
Light yield plot (discrimination)
18
Light yield = 𝑝ℎ𝑜𝑡𝑜𝑛 𝑛𝑢𝑚𝑏𝑒𝑟
𝑘𝑒𝑉(normalised to electron recoil)
Light detector comparison. (especially <40 keV)• Not accounting for non-proportionality
Digital readout, no baseline noise
19/02/2016 UCLA Dark Matter Conference
Future improvements
𝑁𝑑𝑒𝑡𝑒𝑐𝑡𝑒𝑑 = 𝑁𝑠𝑐𝑖𝑛𝑡𝑖𝑙𝑎𝑡𝑒𝑑 ⋅ 𝜂𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛 ⋅ 𝜂𝑞𝑢𝑎𝑛𝑡𝑢𝑚
• Scintillator
• Crystal shapes, surface conditions
• Relative position and orientation
• Reflecting foils, supporting strings
• Two PMTs?
• PMT
19
Estimation, 𝑁𝑠𝑐𝑖𝑛𝑡𝑖𝑙𝑎𝑡𝑒𝑑 ≈ 28ph/keV, 𝜂𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛≈35% , 𝜂𝑞𝑢𝑎𝑛𝑡𝑢𝑚≈ 15%
19/02/2016 UCLA Dark Matter Conference Junsong Lin
ConclusionsColdest PMT in the world (@13 mK)
Work along with calorimeter well
Two channel mode with good discrimination power
Mature, scalable, consistent and robust solution
Applicable to dark matter and 0𝜐2𝛽 decay
2019/02/2016 UCLA Dark Matter Conference
Acknowledgment
• We thank the EDELWEISS collaboration, in particular Xavier-Francois Navick (CEA, Saclay), for providing the NTD-Ge sensor used in this study.
21Junsong Lin19/02/2016 UCLA Dark Matter Conference
Backup slides
Image credit: Hamamatsu Photonics K.K.
Cooldown procedure – He exchange gas
EXTRASIL is a brand of synthetic silica.
Hyodo, S.I.; Nagai, A., Helium permeation through glass
at low temperatures, Journal of the Faculty of
Engineering, University of Tokyo, Series A, Vol 18, 1980
Concern: Helium permeation into PMTFreeze out? Warm operation?
Cool down procedure:1. Nitrogen fill2. Helium fill3. 1 K stage4. Circulation 3He/4He
Luminescence spectrum and PMT response spectrum
CaWO4 (1), ZnWO4 (2) and CaMoO4 (3) @ T = 8 K for excitation with 31 eV VUV
photons Typical spectral response of R8520-406 (similar to model of PMT in this work )
V. B. Mikhailik and H. Kraus
DOI: 10.1002/pssb.200945500
Credit: Hamamatsu Photonics K.K.
PMT specifications
PMT Parameter Description / ValueSpectral response 200 mm – 650 mmWindow material Synthetic silica
PhotocathodeBialkali with Pt
underlay,20.5 mm × 20.5 mm
Dynode10-stage metal
channel dynode
Maximum supply voltage900 V
(between anode and cathode)
Average anode current 0.1 mAGain (at 25 °C) 1.0 × 106
Hamamatsu R8520-06 PMT. Note that the PMT is made to order, therefore some of the
listed values are only for reference.
Credit: Hamamatsu Photonics K.K.