Patent ID: 7285783

Claim:
A multi-anode type photomultiplier tube comprising: a faceplate made from glass and having a first surface and a second surface opposite to each other; a hollow side tube made from glass, the side tube extending along a tube axis that is substantially perpendicular to the faceplate, the side tube including: a tube main body having a substantially quadrangular prismatic hollow shape, the tube main body extending along the tube axis by a first length, the tube main body having a first size of cross section substantially perpendicular to the tube axis, the cross section having four first corners, each first corner being curved with a first radius of curvature; a tube head having a substantially quadrangular prismatic hollow shape, the tube head extending along the tube axis by a second length, the tube head having a second size of cross section substantially perpendicular to the tube axis, the cross section having four second corners, each second corner being curved with a second radius of curvature, the second length being shorter than the first length, the second size being larger than the first size, the second radius of curvature being smaller than the first radius of curvature, the tube head being connected to the first surface of the faceplate; and a funnel-shaped connection neck connecting the tube head to the tube main body coaxially along the tube axis; a photocathode that is provided on the first surface of the faceplate at its area inside the tube head and that emits photoelectrons in response to incidence of light on the faceplate from the second surface; a plurality of electron multiplying portions provided inside the tube main body in one-to-one correspondence with a plurality of regions on the photocathode; and a plurality of anode electrodes provided inside the tube main body in one-to-one correspondence with the plurality of electron multiplying portions.