CHARACTERIZATION OF A NEW MULTIANODE PMT FOR OPTICAL-FIBER READOUT ATLOW-LEVEL LIGHT-INTENSITY

We have characterized the new Hamamatsu R5900-L16 multianode photomult iplier with regard to its suitability for charge division position-sen sitive readout with just two analog channels for each 16-anode PMT. Be cause of the low capacitance of the anode structure of the PMT, we obt ain an output pulse width of less than 20 ns in response to narrow LED input pulses. We were able to obtain position-sensitive readout of li ght pulses corresponding to a single photoelectron with a spatial widt h of less than 1 mm FWHM for a collimated light source and of about 2 mm FWHM for a single fiber. Combined with the good single photoelectro n peak for the R5900-L16, this provides excellent performance at very low-level light intensity. We discuss application of this device to th e precise determination of gamma-ray interaction position within thin crystal scintillators.