Following text introduces a method to define a clump using iterate methods. the corresponding energy resolutions for positron and photon at 70Mev, 50Mev and 30Mev were calculated and presented using geant-simulate data.

How To Define A Clump

First find out the crystal with maximum energy. Using a predefined ANGLE_RANGE to define a cone centered at this crystal. All crystals within this cone are considered to belong to the same clump.The new center of clump is calculated with following formulars:

in which crystal i is within the cone. Then the cone will be redefined by the ANGLE_RANGE and new center. The calculation will not stop until the new center is the same as the previous one.

Energy Resolutions with Deferent ANGLE_RANGES

The Energy Resolution FWHM is a function of ANGLE_RANGE, the graphs FWHM vs ANGLE_RANGE are presented with different energies of photons and positrons respectively. We use geant simulation code to generate events with or without pedestals apart. In each case, monoenergetic particles are emitted from the center of the target uniformly in all directions. The results of 70 Mev positrons and 70 Mev photons are presented in which red lines denote data without pedestals while black lines denote data with pedestals allowed for.
we also prsent the energy resolution FWHM of photons at 50 Mev, 30 Mev with pedestal and of positrons at 50 Mev, 30 Mev with pedestal.

© composed with care by:weidong li