Non-destructive beam profile measuring system observing fluorescence generated by circulating beam

The KEK-PS has two sets of non-destructive beam profile monitors (NDPM) in the booster and three sets in the main ring for horizontal and vertical plane, which observe those ions produced by circulating protons hitting the residual gas. The measured beam sizes are always larger than those obtained by the BEAM SCOPE method. It results from the space charge of the circulating proton beam. In order to eliminate this demerit, the idea of using a luminescence generated by the beam colliding with the residual gas has occurred. This idea, however, is only an idea without measuring or using test equipment to observe the beam at the beam transport line by a CCD camera. It is very hard to observe the time variation of the beam profile (size) in a synchrotron because of the poor S/N ratio. We inserted an optical shielding in the booster synchrotron ring (proton: 40-500 MeV) with a slit facing the beam. An optical fiber guide is fixed at the end of the slit, led out of the vacuum and connected to a photo-multiplier. A vertical beam profile is obtained by moving the slit vertically without being effected by the electric potential of the circulating beam. The most important factor concerning this method is how to eliminate noise caused by secondary particles generated due to beam loss