...Explaination of algorithms used and comparison between different algorithms will come soon..

Results with logarithmic method

Experimental data were obtained from run31330 to run31509. only good runs were analyzed. Online analyzer was used with online odb. One can see the data quality from pibeta graph. There are prompts leaking in, which needs further studies.

Simulation data were obtained using Geant. Only pibeta events were generated and gamma-gamma angle was calculated directly from clump 1 and clump 2 data without applying other cuts than requiring g-g angle be larger than 160. The parameters about profile of stopping pions were obtained from Tomography. These parameters are centers of x, y, and z, as well as sigma of x, y and z distribution. The centers of x and y are essentially zero, the offset in z direction is 9.58 mm. The sigma X and sigma Y are around 8.55 mm, while sigma z is 1.7 mm. Both data then normalized to having same area. The result is showed in g-g angle plot

© October 20000. by Weidong Li for PIBETA collaboration.