upholder, pileup, deadtime

我的simulation里有下面三个模块：

# ENERGY BLURRING
/gate/digitizer/Singles/insert blurring
/gate/digitizer/Singles/blurring/setResolution 0.0
/gate/digitizer/Singles/blurring/setEnergyOfReference 140. keV

# THRESHOLDER / UPHOLDER (refer to benchmarkSPECT)
/gate/digitizer/Singles/insert thresholder
/gate/digitizer/Singles/thresholder/setThreshold 20. keV
/gate/digitizer/Singles/insert upholder
/gate/digitizer/Singles/upholder/setUphold 190. keV
/gate/digitizer/Singles/thresholder/verbose 0

#PILEUP
/gate/digitizer/Singles/insert pileup
/gate/digitizer/Singles/pileup/setDepth 4
/gate/digitizer/Singles/pileup/setPileup 60 ns

#DEADTIME
/gate/digitizer/Singles/insert deadtime
/gate/digitizer/Singles/deadtime/setDeadTime 1000 ns
/gate/digitizer/Singles/deadtime/setMode nonparalysable
/gate/digitizer/Singles/deadtime/chooseDTVolume rsector

为了看到pileup的效果，source使用了高达10^10Bq的点源，并且把energy resolution设成了0.
运行结果里大部分events的能量都是140keV，少数低于140（由于crystal的compton等效应），更少数是280keV（两个140叠加）。问题是：我既然设置了setUphold
190. keV，为什么这些280keV的例子仍然被记录了？