Novel hermetic detector for KAPAE
Transcript of Novel hermetic detector for KAPAE
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Novel hermetic detector for KAPAE
Darkness on the table
HyeoungWoo Park, D. W. Jung, J. Jegal, H.J. KimKyungpook National University
2021.08.09
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Introduction of KAPAE
Design of KAPAE Detector
KAPAE Phase I
KAPAE Phase II
Summary
1Contents
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Introduction
KAPAE
▪ KNU Advanced Positronium Annihilation Experiment (KAPAE)
e+
e-
Electron-Positron Pair
- Quasi-stable bound state
- Create energetic photons
(𝑚𝑒+ +𝑚𝑒−= 1.022 MeV)
Physics
- QED verification- New Physics (invisible decay…)
Eur. Phys. J. D (2018) 72: 44
Searching for light dark matter
through Positronium decay
PHYS. REV. D 97, 092008 (2018)
First search for invisible decays of
orthopositronium confined in a vacuum cavity
Application
- Positron Emission Tomography (PET)
2
HW Park
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Positronium
▪ Unstable hydrogen-like atoms (𝑀𝑝 ⟶𝑚𝑒+)
▪ The spin state of Ps can be calculated using the hydrogen atom model
▪ Positronium (Ps)
- Singlet spin state (para-Positronium, p-Ps)
- Triplet spin state (ortho-Positronium, o-Ps)
e+
e-
|0,0 >=1
2↑↓−↓↑
Singlet Spin State (p-Ps)
e+
e-
Triplet Spin State (o-Ps)
|1,0 >=1
2↑↓+↓↑
|1,1 >=↑↑ , |1, −1 >=↓↓
γ Energies = 511 keV γ Energies < 511 keV
[𝒔 = 𝟏][𝒔 = 𝟎]
Introduction3
HW Park
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Introduction4
Positronium
▪ Parity: Flip in sign of spatial coordinates
→ 𝑃𝜓 𝑥 = 𝜓 −𝑥 , 𝑃2𝜓 𝑥 = 𝜓 𝑥 → 𝑃 = ±1
▪ Antiparticle & particle pair intrinsic parity : 𝑃𝑝 ∙ 𝑃𝑝 = −1
▪ 𝑃 = (−1)𝑙+1
▪ 𝐶 = (−1)𝑙+𝑠
para-Positronium
▪ The ground state 𝑙 = 0, 𝑠 = 0
▪ 𝐶 = +1
▪ Photon 𝐶 = (−1)𝑛
- Singlet decay = even photon (2, 4, 6 …)
▪ Lifetime = 125 ps
ortho-Positronium
▪ The ground state 𝑙 = 0, 𝑠 = 1
▪ 𝐶 = −1
▪ Photon 𝐶 = (−1)𝑛
- Triplet decay = odd photon (3, 5, 7 …)
▪ Lifetime = 142 ± 0.02 𝑛𝑠
HW Park
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Introduction5
HW Park
New Physics
▪ Invisible Exotic Decay (Mirror world, Extra dimensions …)
▪ Visible Exotic Decay (Standard model verification, axion)
Milli-charged particles
- The grand unified theory (GUT) model
- Electric charge particles (”shadow” photon <<<< e-)
Γ(o−𝑃𝑠 → 𝑋 ത𝑋) =𝛼5𝑄𝑋
2𝑚𝑒
6∙ 𝑘 ∙ 𝐹(
𝑚𝑋2
𝑚𝑒2)
Mirror world
- The mirror universe model
- Vibration of o-Ps and mirror o-Ps
Br(o−𝑃𝑠 → invisible) =2(2𝜋𝜀𝑓)2
Γ2 + 4(2𝜋𝜀𝑓)2
Br =9𝜋
4 𝜋2 − 9∙1
𝛼2∙𝜋
16
𝑚0 − Ps
𝑘
2
≈ 3 × 104𝑚0 − Ps
𝑘
2
Extra dimensions
- k > 2.7 TeV
o−𝑃𝑠 → 𝛾∗ → additional dimension(s)
Axion
- Light pseudoscalar
o−Ps → 𝛾𝑋
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Introduction6
HW Park
ETH Zurich (Switzerland)
APEX (U.S.A.)Triangle Universities Nuclear Laboratory
J-PET (Poland)The Jagiellonian University
KAPAE (Korea)Kyungpook Nat'l Univ.
ICEPP (Japan)Univ. of Tokyo
- Invisible decay study - Plastic + BGO + PMT- 2.1 × 10-8 at 90% C.L.
- CPT study- NaI + PMT
- CPT study- Plastic + PMT
- Plastic + SiPM (ver. II) - BGO + SiPM- CPT study ± 0.000142 at 90%CL- Invisible upper limit sensitivity 1.79 × 10-8 at 90% CL
- CP & CPT study- Plastic + NaI + PMT
Recently Other Research
< 2016< 2006
< 2011
< 2020
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Introduction7
HW Park
▪ Discrete symmetries of positronium
▪ CPT violation in lepton sector
▪ CPT violation forbidden
CPT-Violation
*Vetter P and J Freedman S 2003 91 263401
𝐶𝑐𝑝𝑡 = 0.0026 ± 0.0031 *
𝐴 =𝑁+ − 𝑁−𝑁+ +𝑁−
𝐶𝑐𝑝𝑡 = ൗ𝐴 𝑃
𝑃 = 0.41 (22Na)
The Ps rest frame
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Design of KAPAE Detector8
HW Park
Gamma detection & Dual readout
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Design of KAPAE Detector9
HW Park
Design of hermetic novel detector
▪ Compact size & multichannel (fine segmentation)
▪ 192 BGO crystals + 8 endcap BGO crystals = 200 BGO crystals
8 Endcap BGO crystals (50 x 7.5 x 7.5 mm3)
192 BGO crystals(150 x 7.5 x 7.5 mm3)
14
14
192 BGO crystals(150 x 7.5 x 7.5 mm3)
8 Endcap BGO crystals (50 x 7.5 x 7.5 mm3)
Side4 endcap 4 endcap
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Design of KAPAE Detector10
HW Park
Design of hermetic novel detector
▪ 196 SiPM Channels → Dual readout (392 chaanels)
▪ New concept of positron trigger (expected to improve trigger efficiency)
196 SiPM channels
196 SiPM channels
Trigger DAQ
N2
Trigger part
1 channel SiPM
Sealing film
Plastic scintillator
Reflector
22Na point source
Aerogel
Plastic gas chamber
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Mid
TCB
N2
Darkbox
Opticalcable
USB 3.0
Design of KAPAE Detector11
HW Park
3D CAD design
Customized 22Na on trigger
Detector is here
Plat cable
KAPAE phase I65 MHz DAQ & 2ns TCB
SiPM & BGO optimization
85 90 95 100 105 110 115 1200
10
20
30
40
50
Light Output (ADC channel)
Variation of light output
Mock up & Partial assembly
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KAPAE Phase I12
HW Park
Geant4 Simulation
▪ Event distributions of BGO location
3D & 2D graph Energy spectrum at different locations
Edge BGO
Center BGO
Total events
641,904,669430,967 (0.06%)
3,291,906 (0.5%)
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KAPAE Phase I13
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Channel Mapping
▪ SiPM locations
≠ Board number
≠ Cable number
≠ Channel number
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KAPAE Phase I14
HW Park
Single photoelectron calibration
▪ Pedestal & background estimation
▪ Single photoelectron ~ 40 channels
Single photon energy
SiPM Manual :::: 50 kHz /mm2 x 6.07 x 6.07 mm2 = 1.842 MHz
Result of measurement single photon rate :::: 2.589 MHzSingle photon noise
0 20 40 60 80 100 120 140100
200
300
400
500
600
First
Pe
ak P
ositio
n (
AD
C c
ha
nn
el)
Peak Sum Width (ns)
First Peak Position
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KAPAE Phase I15
HW Park
▪ Positron trigger signal
- 5.9 x 104 Hz positron signal measurement
- DAQ firmware (Max rate = 2.5 x 104 Hz)
▪ BGO gamma signal
- ER 20 ~ 35 % at 511 keV (FWHM)
▪ 673 photon/MeV (single photon calculation)
~ ER 25 %
Trigger & Gamma spectrum
Energy (MeV)
Even
t N
um
ber
Geant4
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KAPAE Phase I16
HW Park
Pedestal & Temperature monitoring
Monitoring
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KAPAE Phase I17
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Energy correction
▪ BGO Left (ER 33%) + Right (ER 38%) → BGO Total (ER 26%) → Correction (ER 25%)
▪ Adding adjacent BGO energy (ER 63% → 33%)
- Compton effect, Crosstalk (electronics, optical), Misalignment
▪ Time correction → leading edge time discrimination
Energy & Time correction
Time correction
Before correction After correction
Tim
e in
terv
al(p
osi
tro
n–
gam
ma)
Tim
e in
terv
al(p
osi
tro
n–
gam
ma
)
Tim
e in
terv
al(p
osi
tro
n–
gam
ma
)Ti
me
inte
rval
(po
sitr
on–
gam
ma
)
Gamma energy (MeV) Gamma energy (MeV)
Positron energy (ADC channel) Positron energy (ADC channel)
Trigger time correction
BGO time correction
Before After
Before After
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KAPAE Phase I18
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Schematic of o-Ps decay
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KAPAE Phase I19
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3 Gamma selection
▪ Total Energy Sum = 1.022 MeV
▪ Time Cut > 10 ns (exclude 1.274 MeV & p-Ps annihilation)
Case of energy deposit position Total energy cut
Sum of Energy (Hit count == 3)
Z axis
1.27 MeV escape
1.27 MeV
1.27 MeV
2 gamma 3 gamma
1.27 MeV
KAPAE data
Geant4 data
Energy (MeV)
Eve
nt N
um
be
r
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KAPAE Phase I20
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KAPAE Server
▪ Raw data = 200 TB → After 1st sorting = 41 TB (3 month)
▪ Storage server and multiple cores for data processing
▪ 41 TB / 768(Byte/event) = 5.332131 x 1010 events → 4% 3gamma select → 2.14 x 109
64 Core Workstation (x2) + GPU DATA Server (476 TB)
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KAPAE Phase I21
HW Park
Kinematic Fit
▪ 4 constraint kinematic fitting ( BGO attenuation: 0.96 cm-1→ 𝜃 value is loss )
▪ The kinematic fitting ROOT code has been converted to Python code
Energy kinematic fitting result 𝜑 kinematic fitting result
Energy (keV)
Eve
nt N
um
be
r
𝜑 (degree)
Eve
nt N
um
be
r
KAPAE data
Fitting data
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KAPAE Phase I System intensification22
HW Park
Focus on CPT violation
▪ Rotate the positron trigger direction 90 degrees → 𝜃 value is not required
▪ Enhancing the nitrogen environment → 3 𝜸 efficiency improvement
Current KAPAE Phase I System (𝜃 value is required) Trigger rotation
1 channel SiPM
Sealing film
Plastic scintillator
Reflector
22Na point source
Aerogel
Plastic gas chamber
Increase Aerogel
Space
Rotation
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KAPAE Phase I System intensification23
HW Park
Focus on CPT violation
▪ Only XY projection data is sufficient to search CPT Violations
Upgrade KAPAE Phase I System (𝜃 value is not required)
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KAPAE Phase I System intensification24
Jin Jegal
Deep learning
▪ CNN Deep learning (KAPAE Phase I Geant4 simulation data)
▪ Positronium annihilation reconstruction (x2 improvement in accuracy)
CNN Deep learning
Plan to apply to
real data analysis
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25
Design & Simulation
▪ Invisible upper limit sensitivity
▪ KAPAE phase II (Minimize dead area, Thicker BGO system)
KAPAE phase I → 1.778 × 10-8 at 90% CL, KAPAE phase II → 1.728 × 10-9 at 90% CL
3D design & GEANT4 simulation
KAPAE Phase II DW Jung
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26
KAPAE phase I Trigger upgrade
KAPAE phase II (Design & Simulation)
Deep learning CPT Violation
Invisible Decay
- CPT Violation sensitivity
± 0.000142 at 90%CL
→ ± 0.000086 at 90%CL
- Invisible upper limit
1.778 × 10-8 at 90% CL
- Invisible upper limit
sensitivity
1.778 × 10-8 at 90% CL
→ 1.728 × 10-9 at 90% CL
0.0073 % → 0.000069%
Zero deposit events improve
Summary HW Park
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Thank You !
27
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BACK UP
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Design of KAPAE Detector29
HW Park
The concept of detector for KAPAE
▪ Positronium = Electron + Positron
- Positron → 𝛽+ decay (22Na)
- Electron → aerogel
▪ Trigger signal
→ Plastic scintillator
1 channel SiPM
Sealing film
Plastic scintillator
Reflector
22Na point source
Aerogel(e- donor)
e+
e+
e+
Positron Energy loss
e+e-
e-
e-
e-e-
e-
e-
e-
e-
e-
e-
e-
Positroniumformation
1 channel SiPM
Sealing film
Plastic scintillator
Reflector
Aerogel(e- donor)
e+
e+
Positron generate Scintillation light
e+e-
e-
e-
e-
e-
e-e-
e-
e-
e-
Positroniumformation
Reflector improves collection efficiency
SiPM direct light collection
e-
e- e-
Generation of trigger signal
Positronium formation in aerogel
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KAPAE Phase I30
HW Park
Light loss in KAPAE
▪ Near coincidence events check
▪ 44.9% light loss at other side direction light (BGO optimization ER = 12% → KAPAE 20~35%)
Near coincidence events The other side coincidence events
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KAPAE Phase I31
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Analysis of preliminary data
▪ Accidental 𝛾-ray → exponential fitting include constant term
- Lifetime: 62.4 ± 0.25 ns in air & 111.7 ± 8.44 ns in N2
Positronium decay time
0 20 40 60 80 100 120 140 160 180 200 2200
20
40
60
80
100
120
140
Po
sitro
niu
m d
eca
y tim
e (
ns)
Fitting start time (ns)
Nitrogen
Air
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KAPAE Phase I32
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▪ Optimization of peak sum width
- BGO decay time 300 ns
- Peak sum width (PSW) = 1000 ns
Analysis of preliminary data
0 200 400 600 800 1000 1200 1400
0.0
0.2
0.4
0.6
0.8
1.0
No
rmaliz
atio
n
Peak Sum Width (ns)
Measurment
Calculation 300 ns
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KAPAE Phase I33
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Analysis of preliminary data
▪ Accidental 𝛾-ray → exponential fitting include constant term
- Lifetime: 62.4 ± 0.25 ns in air & 111.7 ± 8.44 ns in N2
Positronium decay time
0 20 40 60 80 100 120 140 160 180 200 2200
20
40
60
80
100
120
140P
ositro
niu
m d
eca
y tim
e (
ns)
Fitting start time (ns)
Nitrogen
Air
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3434
Results
Analysis of preliminary data
▪ 3 𝛾 events selection
- Detector efficiency → 0.86 % 511 keV gamma loss
▪ - BGO Compton
- 3 𝛾 deposit at 3BGO crystal = 34.8%
Hit count
Geant4 Simulation data analysisEv
ent
Nu
mb
er
3 Gamma
→ 3 hit < 34.8%
The number
of hit
Compton
Events
0.4 ~ 0.5
MeV select
Adjacent
Events
Sum
0.4 ~ 0.5
MeV select
1 62.78% 51.89% 84.76% 70.34%
The
number
of hit
Compton
Events
Adjacent
Events
Sum
Total 100.00% 100.00%
0 0.86% 0.86%
1 62.78% 84.77%
2 30.65% 13.37%
3 5.29% 0.36%
4 0.57% -
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3535
Results
Analysis of preliminary data
Comparison of Geant4 and measurement data (3 gamma)
Hit count
Even
t N
um
ber
Hit count
Even
t N
um
ber
Geant4 simulation
Measurement
Only 3gamma
annihilation
+ 1.274 MeV
Hit count
Even
t N
um
ber 2 + 3gamma
annihilation
+ 1.274 MeV
Geant4 Simulation
KAPAE data
The number
of hit
Simulation
Events
Measurement
Events
1 2.94% 1.00%
2 6.77% 7.94%
3 13.83% 14.87%
4 18.54% 23.99%
5 19.80% 24.28%
6 16.87% 14.57%
7 11.24% 6.47%
8 5.96% 2.89%
9 2.62% 1.70%
10 0.97% 1.09%
11 0.33% 0.63%
12 0.09% 0.32%
13 0.02% 0.14%
14 0.01% 0.07%
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3636
Results
Analysis of preliminary data
▪ 3 gamma events selection
- BGO Hit Count > 3 (include Compton scattering)
- Total Energy Sum = 1.022 MeV
- Time Cut = 160 ns ~ 800 ns (exclude 1.274 MeV & p-Ps annihilation)
- Accidental gamma depress
KAPAE data
Geant4 data
Energy (MeV)
Eve
nt N
um
be
r
Sum of Energy (Hit count == 3)
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3737
Partial Assembly Results
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3838
Conclusion
Summary
▪ Development of a Hermetic Novel Detector for KAPAE
▪ The new concept of trigger part offers high performance of positron trigger efficiency
- KAPAE trigger maximum counting rate 59 kHz
- 20 times better than ETH Zurich trigger counting rate 3.2 kHz
▪ CPT asymmetry sensitivity is ± 0.000058 at 90% C.L. (confidence level)
- 5.5 times improvement over reported papers.
▪ Invisible upper limit sensitivity is 1.79 × 10-8 at 90% C.L. for new physics
- 2.1 × 10-8 at 90% C.L. (ETH Zurich)
▪ Positronium decay time increase under N2 condition
▪ Geant4 simulation include 3 gamma annihilation
▪ Python based → machine learning▪ CPT violation study
▪ Invisible decay
▪ PET medical application
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3939
Pick-off process
Pick-off Process
e+
e-
e-Other electron
in the surrounding
atom or ion
Pick-off
ortho-Positronium
Pick-off process
Γ𝑝𝑖𝑐𝑘−𝑜𝑓𝑓 = 4𝜋𝑟02𝑐𝜌0𝑍𝑒𝑓𝑓𝑃0
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4040
SiPM (SensL spec.)
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4141
Time leading edge problem
Time discrimination methods: (a) Leading edge, (b) peak, (c) center of gravity, (d) inflection, (e) constant fraction.
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4242
511 keV Hit of BGO