Development of imaging counters using an lens scintillator array

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(1) We have designed the basic shape of a scintillator for the lens scintillator array, using an optics simulation program. The shape in result is based on a cylindrical of 10mm in diameter and has a "neck" to collimate the light path in it. One side of the cylinder is ground as a convex lens, so that we get an effectively parallel light flux, outside.(2) We produced two types of the lens scintillator whose neck diameters are 2mm and 3mm, respectively. We find that that of 2mm has much better focusing of light in an experiment with irradiating an ultraviolet light.(3) We searched for a site where we set the detector for an operation test in the vicinity of the collision point of the KEKB accelerator. We find two candidate places, where we have a photon flux and an electron flux, respectively. The both are emitted by a radiative Bhabha process from electron-position collisions.(4) We produced lens scintillator using BGO crystal. We could produce one with the neck diameter 3mm of this type, in spite of an expected fragility of the crystal.(5) We have set the lens scintillators, a mirror, and a flat-panel-type photomultiplier in a dark box which can be used for a beam test, and have measured the spatial distribution of the emitted light using an ultraviolet light.(6)A test module of the lens scintillator array counter, in which five lens scintillators were set, was placed in the collision region of the KEKB accelerator. We observed a change of spatial distribution pattern of radiation on the counter, according to operation of the accelerator.