guassian pulse width in cadence

https://www.edaboard.com/attachment....&stc=1

i have generated above 5th order guassian pulse.But i am unable to measure pulse widtn by looking toward guassian pulse. they say it is 0.5n sec but how to measure it in cadence. i tried -3db measurement but it does not work. please see

Use cross function and set threshold at half height