Maximum number for photon generation

Introduction

In order to speed up simulation processing, we put a hard limit for photon number to simulate for a DOM. This is valid and efficient because we will not have infinitely large pulse due to PMT saturation anyway. However, the hard-wired number has to be enough large, which will be cancelled by the PMT saturation effect afterwards.

Procedure

The current hard-wired limit number is 500k photons. I changed this value to 1 M photons, and compared the results with default one. The script I used for the generation is here.

Results

Event-wise total Npe Vs energy

The current default limit (500 k) The statistics is ~50k.

higher maximum number 1 M The statistics is 10k. The distribution is quite similar to default limit.

other parameters

DOM number distribution black: 500k, red: 1M They are almost identical.	channel-wise atwd npe distributions black: 500k, red: 1M They are almost identical.	channel-wise fadc npe distributions black: 500k, red: 1M They are almost identical.
channel-wise atwd peak amplitude distributions black: 500k, red: 1M They are almost identical.	channel-wise fadc peak amplitude distributions black: 500k, red: 1M They are almost identical.

Summary

• The current maximum photon number for a DOM of 500 k is fine.