Hi all, I am currently working analysising silicon pixel detectors for the LHC at my university. One thing i have to do is to find clusters of signal in a silicon pixel detector. I have directory of macros which handles the data and getting it ready, not important. My goals are to create a macro/ algorithym that finds clusters of data, with this i want to: 1) find number of 1 cluster hits, 2 cluster, 3 cluster etc.... on the sensor 2) this info will be made into a histo (not a problem) 3) histo's of 1 cluster, 2 cluster and 3 or more clusters will be filled with the total relevant signal background: The sensors i used are silicon pixel, they are very small and are designed for charge sharing, this means that pixels are prone to share there charge with surrounding pixels. this allows for a good resolution. The sensor is made up of 2048 pixels sensors with 256 read out channels. therefore each channel is attached to 8 pixels. the pixels aren't next to each other they6 are spread out over the sensor in a specific pattern. pixels connected to channel 1 and 2 arnt next to each other either. i used a 2D array as a model of the sensor layout. were each element can be thought of as a pixel. each element in the array is filled with the relevant channel for that "pixel" vectors havnt been used to simpilfy things since a spacial position isnt required merely a position with refference to the other pixels. The 2D array has the form PIXEL[16][128] where the signal for each channel is _signal[256] any help about how to find the clusters is much apreiated Thx