the flame sensor range is 60 degrees , does that mean a range of cone of 60 degree or just a triangle of 60 degree in one plane?
You must provide a link to the data sheet for 'the flame sensor'.
We have no idea which flame sensor you are referring to.
Which flame sensor? Post a link.
Probably a 60 degree cone.
You should test the sensor, using a match or cigarette lighter flame, and determine the angle yourself.