Study of the Cluster Splitting Algorithm In EMC Reconstruction
Transcript of Study of the Cluster Splitting Algorithm In EMC Reconstruction
![Page 1: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/1.jpg)
Study of the Cluster Splitting Algorithm In EMC
ReconstructionQing Pu1,2 , Guang Zhao2 , Chunxu Yu1, Shengsen Sun2
1Nankai University2Institute of High Energy Physics
PANDA Collaboration Meeting, 21/19/3/2021
1Qing Pu
![Page 2: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/2.jpg)
OutlineΓIntroduction
ΓStudy of the cluster-splitting algorithm
ΓLateral development measurement
ΓSeed energy correction
ΓReconstruction checks
ΓSummary
2Qing Pu
![Page 3: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/3.jpg)
Introductionβ’ Cluster-splitting is an important algorithm in EMC reconstruction.β’ The purpose of the cluster-splitting is to separate clusters that are close to each other. β’ In this presentation, we improve the cluster-splitting algorithm in the following ways:
β’ Update the lateral development formulaβ’ Correct the seed energy
3Qing Pu
Cluster-splitting for a EmcCluster Angles between the 2Ξ³ from pi0
Cluster splitting is important for high energy pi0
![Page 4: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/4.jpg)
4
1. Cluster finding: a contiguous area of crystals with energy deposit.
2. The bump splittingl Find the local maximum: Preliminary split into seed crystal informationl Update energy/position iteratively
l The spatial position of a bump is calculated via a center-of-gravity method
l The crystal weight for each bump is calculated by a formula.
MakeCluster ExpClusterSplitter
EmcDigi EmcCluster
2DLocalMaxFinder
EmcBump
Bump Splitting
Qing Pu
EMC reconstruction overview
![Page 5: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/5.jpg)
π€! =(πΈ"##$)!exp(β β2.5π! π %)
β&(πΈ"##$)&exp(β2.5π& β π %)
5
l Initialization:Place the bump center at the seed crystal.
l Iteration:1.Traverse all digis to calculate π€π.
Qing Pu
π or π : different seed crystalsπ ": Moliere radiusπ#: distance from the shower center to the target crystal
(πΈ"##$)'
(πΈ"##$)(
β¦
π1π2
π3ππ
(π€1, π€2, π€3, β¦ , π€π)
(πΈ"##$)!
The Cluster splitting algorithm
(πΈ"##$))
2. Update the position of the bump center.
3. Loop over 1 & 2 until the bump center stays stable within a tolerance of 1 mm or the number of iterations exceeds the maximum number of iterations.
the target crystalthe seed crystalthe shower center
![Page 6: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/6.jpg)
π€! =(πΈ"##$)!exp(β β2.5π! π %)
β&(πΈ"##$)&exp(β2.5π& β π %)
6
l Initialization:Place the bump center at the seed crystal.
l Iteration:1.Traverse all digis to calculate π€π.
2. Update the position of the bump center.
3. Loop over 1 & 2 until the bump center stays stable within a tolerance of 1 mm or the number of iterations exceeds the maximum number of iterations.
Qing Pu
π or π : different seed crystalsπ ": Moliere radiusπ#: distance from the shower center to the target crystal
(πΈ"##$)'
(πΈ"##$)(
β¦
π1π2
π3ππ
(π€1, π€2, π€3, β¦ , π€π)
the target crystalthe seed crystalthe shower center
(πΈ"##$)!
Energy for the target crystal: πΈ456789
The Cluster splitting algorithm
The πΈ456789 is calculated using the lateral development formula
(πΈ"##$))
![Page 7: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/7.jpg)
7
The lateral development (old PandaRoot)Energy deposition from a seed:
πΈ*+,-#* = πΈ"##$exp(β β2.5 π π .)
Qing Pu
πΈ*+,-#*πΈ"##$
= exp(β β2.5 π π .) , π . = 2.00 ππ
exp(β β2.5 π π ')
β’ Since exp does not fit the data well, we try to improve the formula.
Γ Gamma (0~6GeV)
Γ Events 10000
Γ Geant4
Γ Generator: Box
Γ Phi(0, 360)
Γ Theta(22, 140)
E tar
get/
E see
d
Etarget/Eseed
![Page 8: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/8.jpg)
8Qing Pu
The lateral development (new measurement)Define the lateral development:
π π =πΈ*+,-#*πΈ"/01#,
πΈ"/01#, is the total energy of the single-particle shower.
π
πΈ"/01#,
πΈ*+,-#*The lateral development π π can from obtained Geant4 simulation.
In this measurement the crystal dimension is considered
Control sample:Γ Gamma (0ο½6GeV)
Γ Geant4
Γ Phi(0, 360)
Γ Events 10000
Γ Generator: Box
Γ Theta(22, 140 )
the target crystalthe shower center
![Page 9: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/9.jpg)
9Qing Pu
ParametrizationThe function form used for fitting:
π π = π2exp βπ'π .
π π , π(π) = π β π(πexp[βπ
π)π .
3%]
Where π2, π', π(, π) and π4 are parameters.
β’ These parameters may depend on the detector geometry.
Γ Gamma (1GeV)
Γ Events 10000
Γ Geant4
Γ Generator: Box
Γ Phi(0, 360)
Γ Theta(70.8088, 72.8652 )
E tar
get/
E sho
wer
π2 represents the energy of the seed
![Page 10: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/10.jpg)
QingPu 10
π'(πΈ5 , π) π((πΈ5 , π) π)(πΈ5 , π) π4(πΈ5 , π)
π) = πΆ exp βππΈ5 + ππ( = π΅ exp βππΈ5 +π
π4 = π· exp βππΈ5 + π
π' = π΄exp βπ πΈ5 + β
Energy dependency
π΄ = π6(π) π = π7(π) β = π/(π)π΅ = π8(π) π = π9(π)
πΆ = π:(π) π = π;(π)π· = π<(π) π = π=(π) π = π>(π)
Theta dependency
π = π%(π)
π = π?(π)
β’ Assuming no phi-directed dependency.
Parametrization (II)
β’ The characteristic of the cluster has dependency on the energy and the detectorgeometry
β’ We consider the dependency of the parameters on energy and polar angle
![Page 11: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/11.jpg)
11Qing Pu
Parameters (energy dependency)
Fitting function:
π) = πΆ exp βππΈ5 + ππ( = π΅ exp βππΈ5 +π
π4 = π· exp βππΈ5 + π
π' = π΄exp βπ πΈ5 + β
Range of simulated samples: β’ Theta Range4: 32.6536 ~ 33.7759
β’ Phi0~360
![Page 12: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/12.jpg)
12Qing Pu
Parameters (angle dependency)
π' =π΄exp βπ πΈ5 + β
π( =π΅ exp βππΈ5 +π
![Page 13: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/13.jpg)
13Qing Pu
Fitted parameters of the lateral development
Fitting Result:
π' πΈ5 , π = β0.9006 β ππ₯π β3.093 β πΈ5 + 5.048 β 10@A β π β 88.71 ( + 3.085
π( πΈ5 , π = 5.546 β 10@) β πΈ5 + 0.9225
π) πΈ5 , π = β8.560 β 10@4 β πΈ5 β 1.569 β 10@A β π β 85.84 ( + 0.7162
π4 πΈ5 , π = β2.857 β ππ₯π β1.148 β πΈ5 + 2.105 β 10@4 β π β 80.76 ( + 4.717
( π .= 2.00 ππ)
Energy dependency Angle dependency
πΈ*+,-#*πΈ"##$
= exp{βπ'π .
π π, π(, π), π4 } π(π) = π β π(πexp[βπ
π)π .
3%]
![Page 14: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/14.jpg)
14Qing Pu
Seed energy correction
β’ In the old PandaRoot, the seed energy is used to calculate the πΈ*+,-#* = πΈ"##$Γπ(π)
β’ If the shower center does not coincide with the crystal center, πΈ"##$ needs to be corrected
r or π"##$:the distance from the center of the Bump to the geometric center of the crystal.
π
πΈ*+,-#*
πΈ"##$
ππΈ"##$
πΈ*+,-#*
π!""#πΈ"/01#,
Old PandaRoot version Updated version
the target crystalthe seed crystalthe shower center
the target crystalthe seed crystalthe shower center
![Page 15: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/15.jpg)
15Qing Pu
Seed energy correctionIn the new update, πΈ*+,-#* can be calculated by the lateral development f(r):
πΈ*+,-#* = πΈ"/01#,Γπ(π)πΈ"/01#,, which is not available in the reconstruction algorithm, can be related to the πΈ"##$ :
πΈ"/01#, =πΈ"##$π(π"##$)
In the end, πΈ*+,-#* can be calculated as ( 'B(,&''()
as the correction factor) :
πΈ*+,-#* =πΈ"##$π(π"##$)
Γπ(π)
r or π"##$:the distance from the center of the Bump to the geometric center of the crystal.
π
πΈ*+,-#*
πΈ"##$
ππΈ"##$
πΈ*+,-#*
π!""#πΈ"/01#,
Old PandaRoot version Updated version
the target crystalthe seed crystalthe shower center
the target crystalthe seed crystalthe shower center
![Page 16: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/16.jpg)
16Qing Pu
Splitting efficiency
Control sample:Γ di-photon (0ο½6GeV)
Γ Events 10000
Γ Geant4
Γ Generator: Box
Γ Phi(0, 360)
Γ Theta(22, 140 )
π5: The distance between two shower centers
πππ‘ππ =π"3E!**!?-π*0*+E
Γ100 (%)
![Page 17: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/17.jpg)
17Qing Pu
Energy resolution (di-photon)
Range of simulated samples:β’ Energy0.5~6 GeV
β’ Theta 67.7938 ~ 73.8062 {deg}
β’ Phi0.625 ~ 7.375 {deg}
Energy resolution of di-photon
β’ The angle between two photons < 6.75 (deg)
![Page 18: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/18.jpg)
18Qing Pu
Energy resolution (di-photon)
Range of simulated samples:β’ Energy0.5~6 GeV
β’ Theta Range12: 70.8088 ~ 72.8652
β’ PhiSquare area calculated according to theta
Energy resolution of di-photon
d: the distance between shower centers
![Page 19: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/19.jpg)
19Qing Pu
Energy resolution (pi0)Invariant mass resolution of pi0
Range of simulated samples:β’ Energy0.5~5 GeV
β’ Theta 22~140 (deg)
β’ Phi0~360 (deg)
![Page 20: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/20.jpg)
Summary
β’ The lateral development of the cluster using Geant4 simulation is measuredβ’ Lateral development with the crystal dimension is considered
β’ Energy and angle dependent is considered
β’ Seed energy is corrected while applying the lateral development in cluster-splitting
β’ Several checks are done in reconstruction, includingβ’ Splitting efficiency
β’ Energy resolution for di-photon samples
β’ Mass resolution for pi0 samples
β’ Improvements are seen with the new algorithm. Will finalizing the code.
Qing Pu 20
![Page 21: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/21.jpg)
QingPu 21
Backup
![Page 22: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/22.jpg)
22Qing Pu
The seed energy dependency
β’ For the same π, F)*+,')F&''(
depends on π"##$ .
Consider two cases where the photon hits the seed at different positions:
πππ π1: π πΈ*+,-#* πΈ"##$
πππ π2: π πΈ*+,-#* πΈ"##$|| || X
πΈ*+,-#* = πΈ"##$exp(β β2.5 π π .)π
πΈ"##$
πΈ*+,-#*
π!""#β
β‘
the target crystalthe seed crystalthe shower center
![Page 23: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/23.jpg)
23Qing Pu
The detector geometry dependency
π π / π π"##$ = π2exp[β3-G.π π ]/ π2exp[β
3-G.π(π"##$)] = exp{β 3-
G.π π β π π"##$ }
π π = π2exp[βπ'π .
π π ] π(π) = π β π(πexp[βπ
π)π .
3%] (π . = 2.00 ππ)
πΈ*+,-#*πΈ"##$
= exp{βπ'π .
π π, π(, π), π4 β π π"##$ , π(, π), π4 } π ππ€:πΈ*+,-#*πΈ"##$
= exp(βππ .
π)
According to the definition of π π :
![Page 24: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/24.jpg)
24Qing Pu
!!!!!!π' π( π) π4 πA πH πI'πI2
Range 1
πJ
Range 2 Range 23
Γ Gamma (0.2, 0.3, 0.4β¦0.9 GeV)
Γ Events 10000
Γ Geant4
Γ Generator: Box
Γ Phi(0, 360)
Γ Theta(Range1, Range2,β¦ ,Range23)
Γ Gamma (1, 1.5, 2, 2.5β¦6 GeV)
Γ Events 10000
Γ Geant4
Γ Generator: Box
Γ Phi(0, 360)
Γ Theta(Range1, Range2,β¦ ,Range23)
< 1πΊππ β₯ 1πΊππ
Control sample
![Page 25: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/25.jpg)
25Qing Pu
Control sample
Range1: 23.8514 ~ 24.6978Range2: 26.4557 ~ 27.3781Range3: 29.4579 ~ 30.4916Range4: 32.6536 ~ 33.7759Range5: 36.1172 ~ 37.3507Range6: 39.9051 ~ 41.2390Range7: 44.2385 ~ 45.7355Range8: 48.8451 ~ 50.4459Range9: 53.7548 ~ 55.4790Range10: 59.0059 ~ 60.8229Range11: 64.7855 ~ 66.7591
Range12: 70.8088 ~ 72.8652Range13: 77.0506 ~ 79.1942Range14: 83.4997 ~ 85.6749Range15: 90.2068 ~ 92.4062Range16: 96.8200 ~ 99.0099Range17: 103.361 ~ 105.534Range18: 109.793 ~ 111.893Range19: 116.067 ~ 118.019Range20: 121.838 ~ 123.686Range21: 127.273 ~ 129.033Range22: 132.400 ~ 134.031Range23: 137.230 ~ 138.679
Theta(deg):
Phi: 0~360
![Page 26: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/26.jpg)
26Qing Pu
Fitting results
π π = π2exp βπ'π .
π π, π(, π), π4 οΌπ(π, π(, π), π4) = π β π(πexp[βπ
π)π .
3%]
Fitting function:
Range12; 0.5 GeV Range12; 1 GeV
![Page 27: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/27.jpg)
27Qing Pu
Fitting results
π π = π2exp βπ'π .
π π, π(, π), π4 οΌπ(π, π(, π), π4) = π β π(πexp[βπ
π)π .
3%]
Fitting function:
Range12; 3 GeV Range12; 6 GeV
![Page 28: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/28.jpg)
28Qing Pu
Angle dependency of parameters
π) =πΆ exp βππΈ5 + π
π4 =π· exp βππΈ5 + π
![Page 29: Study of the Cluster Splitting Algorithm In EMC Reconstruction](https://reader034.fdocuments.in/reader034/viewer/2022042405/625df6b60a8e78760a577de8/html5/thumbnails/29.jpg)
29Qing Pu
Energy resolution (pi0)
The angle between the two photons produced by the decay of pi0 changes with its momentum: