Only get the first t1

Particles, Track, Event, Run and Biasing
#1

2021-05-12 14-13-50屏幕截图
As above,it’s a part of my SteppingAction. And this is the result I have taken.

2021-05-12 14-17-31屏幕截图
2021-05-12 14-17-31屏幕截图1024×595 90.3 KB

I only want the first t1, and I don’t care others. But I don’t know how to write my code.

#2

Question has been solved. Thanks.