1. Single Particle Geant4 simulation for the sPHENIX PRESHOWER
OUT LINE
Motivation of PRESHOWER
Parameter of Preshower
Result of earlier study
γ/pi separation
e/pi separation
Efficiency and Rejection
Energy resolution
K.L.I.Nagashima, K.Shigaki
Hiroshima University, Japan
Special Thanks
Y.Akiba, C.Pinkenburg
Hello,
My name is Kazua longiland Nagashima,Hiroshima university.
I would like to talk about perfoermance study of preshower.
I’m studying preshower using geant4 simulation.
I report the current states of preshower performance study.
Here is Outline.
First of all, I will talk about motivation of preshower.
And then.
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

2. Motivation of PRESHOWER
γ/π0 Separation
High pT p0 RAA up to 40 GeV/c
Direct Photon
γ-jet correlation
e/π Separation
High pT electrons (c,b)
Upsilon measurements
This figure is sPHENIX barell of MIE version.
Preshower is shown yellow and located out of Tracking detecter.
(But not determined,That Preshower is located in or out of solenoid.
(In the simulation of this time,Preshower is located out of solenoid.
Motivation of preshower is some two major.
The first is γ/pai0 separation.
It means separation 2γ from high Pt pi0.
As a result,pai0 Raa up to 40 GeV/c.
And Direct Photon measurements.
The second is e/pi separation.
It means separation high pt electron and charged pion.
If we can separate electrons and charged pions, Charm,Bottom and Upsilon will be able to be measured well.
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

3. Parameter of Preshower
Incident Particle
π+_0.1 GeV
Parameter of preshower
・1Layer
・radius = 90 cm
・Absorber ＝ Tungsten
-thickness = 0.84 cm (2.4 length)
・Readout ＝ Silicon
-thickness = cm
This figure is sample of geant4 simulation on sPHENIX frame work .
Yellow ring is Preshower and Blue ring is solenoid.
And Emcal and Hcal.
I injected 0.1GeV charged pion.
My analysis is MIE version.
Parameter of preshower is 1layer,…....
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

4. Result of earlier study of geant4 simulation
Incident Particle
e- = 5 GeV
π+ = 5 GeV
Incident particle is π0 [42.8GeV]
Decay channel π0 -> 2γ
There figures are results of earlier study of geant4 simulation.
Left figure shows separating 2γ from high pt pi0.
Horizontal axis is η, and Vertical axis is deposited energy.
In case of incident particle is 40 GeV pi0,
It is possible to distinguish two photon by reducing the size of Preshoewr cell.
Because Shower scarcely occurs by reducing the thickness of Preshower.
Right figure shows the two particle resolution of electron and charged paion.
Horizontal axis is Total measured energy mean Preshower and Emcal measured energy, and Vertical axis is Preshower measured energy.
Blue point is electron,and red point is charged paion.
We can separate electron and charged pion in two dimensions by using Preshower.
I tried to study these on sPHENIX frame work.
Result of earlier study
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

5. γ/ π0 Separation Incident particle is π0 [40GeV]
Decay channel π0 -> 2γ
Deposited Energy
PRESHOWER
Size of cell
dφ = , dη = 0.024
(1mm) (25mm)
Separate 2γ
eta
phi
Deposited Energy
CEMC
dφ = , dη = 0.024
2γ are merged
From here, result of γ/pai0 separation of Geant4 simulation.
Incident particle is 40GeV pi0.
The left row shows deposited energy cell by cell in preshower and emcal.
X axis is φ, and Y axis is η, Z axis is deposited energy.
The right row figures view from top.
Size of preshower cell is dφ = and dη =
It is can be separated high pt 2γ from pi0 if this cell size.
On the other hand,
The Size of emcal cell is dφ and dη =
In case of this cell size, 2γ are merged.
But 2γ are decided　each center point on Emcal by using preshower.
Due to decide center point, It is can be measured energy of each γ by some algorithm.
eta
phi
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

6. e/pi Separation vs Sampling Fraction
Incident Particle
e- and π+ 5GeV (×2000)
e/pi separation
preshower Measured Energy
= Energy Deposit in active volume of Preshower vs
Total Measured Energy
= Energy Deposit in active volume of Preshower & CEMCal
Sampling Fraction
= <Evis>/<Evis+Einvis>
・ SF_EMC = 0.035
Calibrate Measured Energy
= Evis×<Evis+Einvis>/ <Evis>
e- _5GeV
π+ _5GeV
e- _5GeV
π+ _5GeV
Calibrate
Next I would like to talk about e/pi separation.
Incident particles are 5 GeV electron and charged pion.
Horizontal axis is Preshower and Emcal measured energy, and Vertical axis is Preshower measured energy.
Charged Pion of MIP scarcely drop energy, Because of preshower is very thin.
In contrast electron drop energy by bremsstrahlung.
So,It is can be separated electron and pion in two dimensions.
I have defined Sampling fraction to calibrate　Emcal measured energy.
Sampling fraction is represented by this equation.
Evis is deposited energy in EMCal, Einvis is deposited energy in absorbar
In case of Emcal, Sampling fraction is
I calibrated Emcal measured energy by sampling fraction and reploted for e/pi separation.
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

7. Efficiency and Rejection
3.7
5.3
0.9
0.36
e- _5GeV
π+ _5GeV
1 dimension cut with EMCal
・ Electron Efficiency -> 0.91
・ Pion Rejection -> 4.1
2 dimension cut
with EMCal + Preshower
・ Electron Efficiency -> 0.78
・ Pion Rejection -> 16.9
Rejection rate is
four times better
I calculated Electron efficiency and Pion rejection by cut two ways.
In case of 1 dimension cut　mean EMCal measured energy cut,
When electron efficiency is 0.91,Pion rejection is 4.
In case of 2 dimension cut mean EMCal and Preshower measured energy,
When electron efficiency is 0.78,Pion rejection is 16.9.
As a results, case2 is four times better than case1.
But This result is worse than expected.
There is cause.
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

8. Efficiency and Rejection
e_5GeV
pi_5GeV
5.5
3.8
0.0035
0.0175
Incident particle
π+ [5GeV]
Deposited energy
of π+
1 dimension cut
・ Electron Efficiency -> 0.91
・ Pion Rejection -> 5.4
2 dimension cut
・ Electron Efficiency -> 0.78
・ Pion Rejection -> 30.1
Deposited energy of
reflected particle
from Hcal
There figures shows deposited energy of charged pion cell by cell Preshower and EMCal.
Deposited energy of charged pion in EMCal with only a point.
Other points are deposited energy of reflected particle from Hcal.
All Reflected particles deposited energy is 10% of total deposited energy.
So, I selected roughly-active area.
In the result, Pion rejection is 2 times better on same condition of electron efficiency.
Because Pion deposited energy is reduced 10% by selecting active area.
This study is on going. So pion rejection may be better by cutting number of shower.
×5.5
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

9. Energy Resolution (Preshower + EMCal)
5 GeV e-
5 GeV π+
Energy resolution
σ/E = 0.1
Energy resolution is not bad
with Preshower + EMCal
The earlier study by Liang Xue
I would like to talk about energy resolution in this slide.
I calculated energy resolution.
In case of Incident particle is 5GeV electron, σ/E is 0.1.
This result is consistent with the earlier study by Liang Xue.
This plot is Energy response with only EMCal.
From this, Energy resolution is not bad by using the preshower.
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

10. Summary I’m able to simulate on sPHENIX frame work.
I make sure that 2γ can be separated by Preshower.
-size of preshower cell is dφ=1mm, dη=25mm.
Pion rejection is 30
by using Preshower + EMCal.
Energy resolution is σ/E = 0.1 in case of 5 GeV
for Preshower + EMCal.
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

11. Back Up
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

12. Back Up
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

13. Back Up
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

14. Back Up
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

15. Energy spectra & linearity & resolution
Reasonable good energy linearity for both geometries.
Better energy resolution (~15%) for EMCal with 30 layers, 20% for 4 slats crossing EMCal.
Liang Xue
06/10/2013

16. Calibration constant Correlation of SF and ED Sampling Fraction
Fit by pol1
Fit Palameter
P0= P1=0.009
Sampling Fraction
Constant Liner Function
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

17. Calibration
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN

18. Calibration of measured Energy
Sampling Fraction
SF = <Evis>/<Evis+Einvis>
SF’ = (Evis)*
e_5GeV
pi_5GeV
Preshower Measured Energy
= [Total Energy Deposit in Preshower] / SF’ vs
Total Measured Energy
= [Total Energy Deposit in Preshower & CEMCal] / SF
2013/7/30
PHENIX Workshop on Physics Prospects with Detector and Accelerator Upgrades at Nishina hall, RIKEN