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FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Study of Future 3D Calorimetry Based onLYSO or LaBrCe Crystals for High Precision
Physics
Patrick [email protected]
Paul Scherrer Institut
Zurich PhD Seminar9.10.2019
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 1 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Overview
1 A Brief Introduction
2 A Word on the Simulation
3 Simulation Results
4 Conclusions Towards a Prototype
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 2 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
The Quest of High Precision Particle Physics
Find evidence for BSM physics in testing SM predictions to anunprecedented accuracy.
Charged Lepton Flavour Violation [1, 2]
Looking for decays like µ→ eγ, µ→ eee etc.
Prohibited by the SM, highly suppressed by light neutrinos.
Predicted by some BSM theories.
The Legendary Needle in the Haystack: µ→ eγ [3, 4]
Signal
µe
γ
BR(µ→ eγ) > 6 · 10−14 ???
Radiative Muon Decay
µeνe
νµγ
Accidental Background
µeνe
νµγ
Racc ∝ R2µ ·∆E2
γ ·∆Pe ·∆Θ2eγ ×∆teγ
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 3 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Measuring Energy Deposits
Calorimetry
Measure the energy a particle deposits in the detector. If it islarge enough, the total energy of the particle will be deposited.
Scintillator
Scintillators emit visible light when hit by high energy radiation.The number of photons is roughly proportional to the energydeposit inside the scintillator.
Silicon Photo-Multipliers (SiPMs)
Semiconducting device to detect optical photons. They consistof thousands of pixels - each of them can be fired by a singlephoton.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 4 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
The Idea in General
Scintillator
Quartz
SiPMs
PCB
Carbon Fibres
Goal: Detect Photons of O(50 MeV)
Build a calorimeter by attaching SiPMs to a scintillator.
Thin SiPMs allow readout on front and back.
Use granularity for geometrical reconstruction.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 5 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
What kind of Scintillator to use?
Selection of Scintillating Materials
Densityρ (g/cm3)
Light YieldLY
(ph/keV)
Decay Timeτ (ns)
RadiationLenthX0 (cm)
LaBr3(Ce) 5.08 63 16 2.1LYSO 7.1 27 41 1.21NaI(Tl) 3.67 38 245 2.59BGO 7.13 9 300 1.12
Properties
Light Yield: Amount of visible light emitted per energy depositDecay Time: Time scale on which the light gets emittedRadiation Length: Depth scale on which the energy is deposited
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 6 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
The MC Simulation
GEANT4 based using custom code for:
SiPM
Include approximate geometry. Create active area physicalvolume, not single pixels
Determine pixel hit based on mathematical formula.
Include quantum efficiency check.
Waveform Generation
Use real SiPM and DAQ response to 1 photoelectron.
Sum detected photons passing dead time check, add noise.
Extract charge and time for each channel.
Time extraction on each side on sum of waveforms.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 7 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Crystal Sizes Investigated
”Available”
These crystal sizes were promised by industry:LaBr3(Ce) 20 cm length, 9 cm diameterLYSO 16 cm length, 7 cm diameter
”Large”
Crystals with increased diameter:LaBr3(Ce) 20 cm length, 15 cm diameterLYSO 16 cm length, 15 cm diameter
”Ultimate”
Crystals with 10 Moliere radii and 15 radiation lengths:LaBr3(Ce) 31.5 cm length, 46 cm diameterLYSO 17 cm length, 40 cm diameter
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 8 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Variable Estimation Algorithms
Charge: Sum integrated charge over all channels
Qtot =∑
qi
Time: Estimate from front and back times tf , tb (next slide)
t =(n− 1)tf + (n+ 1)tb − L/c(n2 + n)
2n
Position: Estimate from times ti, charges Qi and theiraveraged position xi
x = axxf + bxxb + cx
z = az ln(Qf ) + bz ln(Qb) + cztf + dztb + ez
Parameters trained on the first 10 % of each configuration.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 9 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Time Extraction Algorithms
3 3.5 4 4.5 5 5.5 6 6.5 7 (in ns)
0t
0
200
400
600
800
1000
1200
1400
1600
coun
ts Time Reconstruction (All) = 0.0310(3) nsσ
Time Reconstruction (Square) = 0.0428(3) nsσ
Time Reconstruction (Intense) = 0.0419(3) nsσ
Time Reconstruction (First) = 0.0395(3) nsσ
Time Reconstruction (Sum) = 0.0260(2) nsσ
Low Noise
LYSO crystal(R = 3.5 cm, L = 16 cm)
All: average over allchannelsSquare: average over thechannels in a squarearound the one with themost chargeIntense: average over the10 channels with the mostcharge.First: average over the 10first channelsSum: Sum up allwaveforms on each side,then take CF
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 10 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Time Extraction Algorithms
3 3.5 4 4.5 5 5.5 6 6.5 7 (in ns)
0t
0
100
200
300
400
500
600
700
800
coun
ts Time Reconstruction (All) = 0.339(4) nsσ
Time Reconstruction (Square) = 0.0736(6) nsσ
Time Reconstruction (Intense) = 0.0716(6) nsσ
Time Reconstruction (First) = 0.0641(5) nsσ
Time Reconstruction (Sum) = 0.0517(4) nsσ
Medium Noise
LYSO crystal(R = 3.5 cm, L = 16 cm)
All: average over allchannelsSquare: average over thechannels in a squarearound the one with themost chargeIntense: average over the10 channels with the mostcharge.First: average over the 10first channelsSum: Sum up allwaveforms on each side,then take CF
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 11 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Noise Effects
800 900 1000 1100 1200 1300 1400 1500 1600
310×
q(a.u.)
0
20
40
60
80
100
120
140
coun
tsLow Noise (0.5 pe)
= 0.0167(5) µ/σMed Noise (5 pe)
= 0.0168(5) µ/σHigh Noise (10 pe)
= 0.0171(4) µ/σ
Charge
3 3.2 3.4 3.6 3.8 4 4.2 4.4 4.6 4.8 5t_0 (ns)
0
100
200
300
400
500
600
700
800
coun
ts
Low Noise (0.5 pe) = 0.0260(2) nsσ
Med Noise (5 pe) = 0.0517(4) nsσ
High Noise (10 pe) = 0.0855(6) nsσ
Time
40− 30− 20− 10− 0 10 20 30 40 x (mm)∆
0
50
100
150
200
250
300
coun
ts Low Noise (0.5 pe) = 2.38(5) mmσ
Med Noise (5 pe) = 2.37(6) mmσ
High Noise (10 pe) = 2.46(5) mmσ
x Difference
40− 30− 20− 10− 0 10 20 30 40 z (mm)∆
0
20
40
60
80
100
120
140
160
180
coun
ts Low Noise (0.5 pe) = 4.42(8) mmσ
Med Noise (5 pe) = 5.29(14) mmσ
High Noise (10 pe) = 5.7(2) mmσ
z Difference
min
oreff
ect
min
oreff
ect
sign
ifica
nt
effec
tob
serv
able
effec
t
LYSO crystal (R = 3.5 cm, L = 16 cm)
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 12 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Simulations of Available Sizes
800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800310×
q (a.u)
0
50
100
150
200
250
300
350
400
450
Cou
nts
(a.u
.)
Charge
D = 7 cm, L = 16 cm, LYSO = 1.69(6) % µ/σ
:Ce3
D = 9 cm, L = 20 cm, LaBr = 2.52(8) % µ/σ
40− 30− 20− 10− 0 10 20 30 40 z (mm)∆
0
100
200
300
400
500
600
700
Cou
nts
(a.u
.)
z Resolution
D = 7 cm, L = 16 cm, LYSO = 4.39(8) mm σ
:Ce3
D = 9 cm, L = 20 cm, LaBr = 4.17(8) mm σ
Significant differences only for charge resolution. Explainedby larger energy leakage through lateral side in LaBr3(Ce).
Time resolution around 30 ps
Position resolution around 3 mm perpendicular to thecrystal axis
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 13 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Spread Out Photons
Consider photons spread out over the whole front face:
800 900 1000 1100 1200 1300 1400 1500
310×
q (a.u.)
0
20
40
60
80
100
120
140
160
180
200
Cou
nts
(a.u
.)Uncut
= 2.67(12) %µ/σMC Truth Cut
= 0.402ε = 2.06(10) % µ/σRec. Pos Cut
= 0.400ε = 2.13(11) % µ/σSkewness Cut
= 0.438ε = 2.06(10) % µ/σUnspread (scaled)
= 1.69(6) %µ/σ
Charge
Reduced charge/energy resolution due to lateral events.Recover to some extend by applying appropriate cuts.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 14 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Geometrical Cuts
MC Truth CutUse true position of first interaction as recorded by MCsimulation. Select events with some distance from theborder.
Reconstructed CutUse the reconstructed (x, y)-Position to reject events closeto the border.
Skewness CutAnalyse the radial distribution of the collected charge.Reject events below a certain skewness - most chargecollected on the outer region with distinct tail towards thesmaller radii.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 15 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Increasing the Size
800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800310×
q (a.u)
0
200
400
600
800
1000
1200
1400
1600
1800
Cou
nts
(a.u
.)
Charge
D = 7 cm, L = 16 cm, LYSO = 1.69(6) % µ/σ(Ce)
3D = 9 cm, L = 20 cm, LaBr = 2.52(8) % µ/σD = 15 cm, L = 16 cm, LYSO = 0.444(10) % µ/σ
(Ce)3
D = 15 cm, L = 20 cm, LaBr = 0.94(3) % µ/σ
Better energy resolution for larger diameters.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 16 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Ultimate Crystals
1000 2000 3000 4000 5000 6000310×
q (a.u)
0
200
400
600
800
1000
1200
Cou
nts(
a.u.
)
Charge
LYSO (R = 20 cm, L = 17 cm) + sensL = 0.242(4) %µ/σ
LYSO (R = 20 cm, L = 17 cm) + Hamamatsu = 0.334(5) %µ/σ
LaBrCe (R = 23 cm, L = 31.5 cm) + sensL = 0.196(4) %µ/σ
LaBrCe (R = 23 cm, L = 31.5 cm) + Hamamatsu = 0.304(5) %µ/σ
Time resolution O(30 ps), Position resolution O(5 mm).
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 17 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Industry Issues
”Available” LYSO crystal has defects ...
800 900 1000 1100 1200 1300 1400 1500 1600310×
q (a.u)
0
20
40
60
80
100
120
140
160
180
200
220
240
Cou
nts
(a.u
.)
Charge
D = 7 cm, L = 16 cm = 1.68(5) % µ/σ
D = 7.5 cm, L = 10 cm = 1.78(7) % µ/σ
Closest size: 7.5 cm diam., 10 cm length.No significant decrease in performance.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 18 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Summary
Resolutions
LaBr3(Ce) LYSOEnergy (%) 2.5 / 0.9 / 0.3 1.7 / 0.4 / 0.3Time (ps) 28 / 30 /39 26 / 28 /36x Position (mm) 3 / 3.7 /5.7 2.4 / 3.0 / 3.6z Position (mm) 4 / 4.8 /5.4 4.4 / 5 / 6
Values refer to available/large/ultimate crystals.
Conclusion
Light yield is not the limiting factor for the resolutions.
LYSO performs better due to higher density.
Spread out irradiation worsens resolution, geometrical cutsallow some recovery.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 19 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
Next Steps
Simulation
Mostly done.
Further runs using the detailed information about theprototype.
Refine analysis algorithms in the final configuration.
The Prototype
Selection based on simulations:
LYSO crystal with 10 cm length and 7.5 cm diameter.
Hamamatsu MPPC S13360-6025PE
Confirming final orders with industry. Assembly to follow soon.
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 20 / 20
FutureLYSO/LaBrCeCalorimetry
P. Schwendi-mann
Introduction
Simulation
Results
Prospects
References and Further Reading
References
[1] A. M. Baldini et al. arXiv:1812.06540v1 [hep-ex]
[2] G. Cavoto et al. Eur. Phys. J. C 78 (2018), 37
[3] A. M. Baldini et al. (MEG II Collaboration)arXiv:1301.7225v2 [physics.ins-det]
[4] A. M. Baldini et al. (MEG II Collaboration)Eur. Phys. J. C 78 (2018), 380
Further Reading
A. Papa, P. Schwendimann, NIM A 936 (2018), 130
P. Schwendimann (PSI) Future LYSO/LaBrCe Calorimetry Zurich PhD Seminar, 9.10.19 21 / 20