Hi Guo Ning, What I will say is just a suggestion, I am not sure at all. I think that between hits and singles the Adder, Readout and Blurring modules of the digitizer are applied. So if your hits have scattered many times in your crystal, I think the position, energy and time stamp mentioned are for the last one. And so for your singles, there is a sort of average applied by these modules that change the position, energy and time stamp. From the last column of your ascii hits file, you can see what is the last volume where a scatter interaction has occurred. So maybe you could see 'crystal' for some. And those which have not scattered in the crystal are maybe affected by the blurring effects (spatial, energy), if you have fixed some in your digitizer. Am I clear ?? :-) Hope it helps, Simon <div>2007/12/13, 벋퀼 <<a href="mailto:guoning0225@gmail.com">guoning0225@gmail.com</a>>:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Dear Gate users: Here is question about the ASCII output . I want to make clear that what is the relationship between the position,energy deposited and the time stamp information presenting separately to the Hits file and Singles file.That is to say how does the information of these aspects come from in the digitizer mode chain,especially from the hits to singles. As my observation, compared with the same event ID ,the value of position,energy deposited and the time stamp in the Hits file (gateHits.dat) are different from that in Singles file(gateSingles.dat). But there must to be some kind of algorithmic connection between them, since they are come from the same event .I wonder what is it ,may be a method such as weighted average or some others . Can anyone tell me the intrinsic relationship of this, thanks for your attention.                   Guo  Ning _______________________________________________ Gate-users mailing list <a href="mailto:Gate-users@lists.healthgrid.org">Gate-users@lists.healthgrid.org</a> <a href="http://lists.healthgrid.org/mailman/listinfo/gate-users">http://lists.healthgrid.org/mailman/listinfo/gate-users</a> </blockquote> </div>