Multi bunch GMMA Ray generation experiment at ATF

We construct a new detector to monitor $\gamma$ yields in bunch by bunch basis for the Laser Compton experiment at the KEK ATF which is capable to separate $\gamma$ rays in 5.6ns-spacing multi-bunch operation of the KEK ATF. In this article we report a result of measurement of multi bunch $\gamma$ ray detection for the first time at the KEK ATF.