Photon splitting

In experiment with the LKr calorimeter prototype and the scattered electrons tagging system of the KEDR, photon splitting was observed for the first time.

Diagram of photon splitting.

Photon splitting, event selection criteria:

No charged particles detected.
No signal in scintillating target, collimators end veto counter installed before the LKr calorimeter.
Energy measured in LKr calorimeter = energy of tagged photon.
Two photons are reconstructed in calorimeter strip structure.

Example of a photon splitting event.

Referencies:

1. Sh.Zh.Akhmadaliev et al., "First observation of photon splitting in a strong coulomb field. Current status of the experiment". Photon'97 Incorporating the XIth International Workshop on Gamma-Gamma Collisions, Egmond aan Zee, Netherlands, p.246.
2. A.L.Maslennikov. "Photon physics in Novosibirsk", Workshop on photon interactions and the photon structure. Lund 1998, p.347-365.
3.H.Zh.Akhmadaliev et.al., "Experimental investigation of high-energy photon spliting in atomic fields". Phys.Rev.Lett. Vol.89, Numb.6, p.061802, 2002. [PostScript].

17.09.2002