1. Status of Electronics Simulation and Energy Resoluton Estimation
Xiao Fang
JUNO Meeting
July 28, 2014

2. Outline Motivation Electronics simulation Energy resolution estimation
Use Daya Bay electronics simulation in JUNO
Implement NHit trigger
A simple background mixing algorithm
Energy resolution estimation
PMT gain fluctuation
PMT dark noise
Electronics noise
After-pulse

3. Motivation
In DYB, the electronics is one of major sources of energy non-
linearity, 6~8%.
In JUNO, we will heavily rely on detector simulation to achieve
the physics results, so it is essential to correctly model
electronics response in simulation.
Electronics simulation is also necessary in current R&D stage to
develop reconstruction algorithm and study detector
performance.
In the first step, we temporarily use DYB electronics simulation
for JUNO with some modifications, like removing shaper, using
FADC, etc.

4. Flow chart of electronics simulation
From Soeren
The following effects have been considered in electronics simulation:
1. PMT gain Quantum efficiency Pre-pulse After-pulse
5. Dark noise time offset time spread Overshoot Ringing Nonlinearity Saturation
Sampling rate: 1GHz

5. PMT pulse from electronics simulation

6. If the number of pulse in one time slice exceed the threshold, we will open a 1us readout window based on trigger time.

7. Hongxin Wang is implementing a more realistic and powerful background mixing algorithm, stay tuned.

8. A more detailed data model will be designed and shared by data and MC.
A simple data model used in electronics simulation
class ElecFeeCrate{
public：
map<int,ElecFeeChannel> m_channelData; // For each PMT we use a class ElecFeeChannel to save amplitude information and time information.
long double m_TimeStamp; // Each event has a TimeStamp,that is the beginning time of the simulation : m_simTimeEarliest.
vector <int> m_triggerTime; // The simple trigger time for each event. }
class ElecFeeChannel{
public:
vector<double> m_adc; // Amplitude information for one PMT
vector<int> m_tdc; // Time information for one PMT
A more detailed data model will be designed and shared by data and MC.

9. Energy resolution estimation
The goal: To estimate the effects on energy resolution from different sources in electronics.
Generate 1MeV gamma at detector center, to get number of hits (p.e.) on each PMT ~ Ni(number of p.e. on i-th PMT).
Add gain fluctuation, Ni = Gaussian(Ni, σgain)
2. Add electronics noise, Ni = Ni + Gaussian(0, ENCs)
Add dark noise, Ni = Ni + Poisson(Ndarknoise)
Add after-pulse based on its probability

10. Energy resolution VS gain fluctuation
The gain fluctuation in DYB is about 0.48.
If we assume that MCP-PMT has the similar gain fluctuation with that used in DYB, then the energy resolution will be worse than no fluctuation ~10%.

11. Energy resolution VS after-pulse
For DYB PMTs, the after-pulse probability is quite low (within 300ns readout window), if it is also true for MCP-PMT, the impact on energy resolution is negligible.

12. Energy resolution VS electronics noise/dark rate
: 0Hz
: 20Hz
: 5kHz
: 50Hz
: 10Hz
Energy resolution becomes better with higher dark rate, because the
high dark rate shifts the energy peak to higher region.
Energy resolution is slightly worse with higher electronics noise/channel.

13. Dark noise can affect the energy non-linearity
: 0Hz
: 20Hz
: 5kHz
: 50Hz
: 10Hz
We see the big effect on energy non-linearity from dark noise.
The correction of dark noise should be applied.

14. Energy resolution VS dark rate
: with dark noise correction
: without dark noise correction
We should keep dark rate as low as possible.
We should keep dark rate as stable as possible.

15. Summary Electronics simulation Energy resolution estimation
ElecSim package is developed within offline software framework, known as SNiPER.
It has been tested and released and can work properly.
A simple NHit trigger and background mixing have been implemented.
Please contact for more details and how to use it.
Will update ElecSim based on real JUNO electronics.
Energy resolution estimation
Gain fluctuation, dark noise, electronics noise and after-pulse have been considered in energy resolution estimation.
Preliminary results shows that energy non-linearity heavily depends on dark noise.

16. Thank You!