Electron multiplier tube with axial magnetic field
AssigneeA.N.V.A.R.
InventorsKei-ichi Kuroda, Daniel Sillou, Fujio Takeutchi
Life of this patent
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Abstract
Electron multiplier tube, comprising along the principal axis an electron-emitting surface, several dynode stages with distributed structure, capable of reflux secondary electron emission, and an electron-receiving surface, as well as means producing an electron-accelerating electric field generally oriented along the principal axis, from the electron-emitting surface to the electron-receiving surface. With it is associated coil means producing a magnetic field generally oriented along the principal axis of the tube. Particular example is a photomultiplier with high spatial resolution.
Claims14
In an electron multiplier apparatus, comprising
- (1) a vacuum enclosure,
- (2) a plurality of dynode stages, each capable of secondary electron emission when hit by charged particles, each dynode stage having a distributed structure,
- (3) electron-receiving means,
- (4) means for producing an electron accelerating electric field generally oriented along a principal axis passing through said plurality of dynode stages, towards said electron-receiving means,
- (5) means for producing a magnetic field generally oriented along said principal axis,
- the improvement comprising,
- (a) said dynode stages each comprising at least two levels of distributed dynode elements,
- (b) said dynode levels being spaced apart along said principal axis, the dynode elements of each dynode level being shifted between themselves within each dynode stage to thereby define a substantially impervious wall against substantially rectilineal motions of electrons moving parallel to said principal axis,
- (c) the dynode elements in each level having a dimension transverse to said principal axis being selected in relationship with the magnetic field such that the average radius of curvature of secondary electrons emitted therefrom is at least equal to said transverse dimension of the dynode elements,
- (d) the dynode levels being so spaced along said principal axis that substantially no secondary electron emitted from the first dynode level in any given dynode stage will strike the second dynode level in the same dynode stage, while substantially all these said secondary electrons strike a dynode level of the next dynode stage.
Dependencies are inferred from the claim text.