The purpose of GRAINE (Gamma-Ray Astro-Imager with Nuclear Emulsion) project is precise observation of cosmic gamma-ray by using a balloon-borne emulsion detector. All phenomena occured in flight are reccorded in emulsion and it is interesting to study not only gamma-ray events but also hadron interaction events incuded by primary cosmic rays. Especially study of charmed particle production in primary cosmic rays interactions at high altitude is major interest of this article, since this information is important to validate prompt neutrino ( atmospheric neutrino ) flux as most of them are decay products of charmed particles. By using automated emulsion readout system HTS ( Hyper Track Selector ), it is possible to readout all tracks recorded in emulsion and analyze all hadron interactions to search for charmed particle decays.
This article describes a preliminary results of a test experiment using CERN accelertor beam. A method to estimate energy of primary cosmic rays by an automated analysis is checked in this test.