We present an approach of improving the LGD
clustering scheme by using the Point Spread Function (PSF).
As the first approximation, the shower shape of isolated photons in the LGD,
generated by the Gradphi, is analysed using a single Gaussian as a PSF.
We found that the shower energy distribution over the LGD blocks is
strongly peaked around the shower center. As a result, the shower radial width
weakly depends on energy. Fitted shower energies are systematically
lower than generated photon energies by
.
This confirms that the shower shape is not a single Gaussian.
In addition, it is found important to integrate a PSF function over the block
area, instead of just sampling a function at the center of the block.
The difference between these two cases can be significant when the PSF
radial width is smaller than the size of the LGD block. The next step in this
approach is to probe the PSF on real data.
