US 3,955,084 A · Electro-optical detector for use in a wide mass range mass spectrometer

Abstract

An electro-optical detector is disclosed for use in a wide mass range mass spectrometer (MS), in the latter the focal plane is at or very near the exit end of the magnetic analyzer, so that a strong magnetic field of the order of 1000G or more is present at the focal plane location. The novel detector includes a microchannel electron multiplier array (MCA) which is positioned at the focal plane to convert ion beams which are focused by the MS at the focal plane into corresponding electron beams which are then accelerated to form visual images on a conductive phosphored surface. These visual images are then converted into images on the target of a vidicon camera or the like for electronic processing. Due to the strong magnetic field at the focal plane, in one embodiment of the invention, the MCA with front and back parallel ends is placed so that its front end forms an angle of not less than several degrees, preferably on the order of 10.degree.-20.degree., with respect to the focal plane, with the center line of the front end preferably located in the focal plane. In another embodiment the MCA is wedge-shaped, with its back end at an angle of about 10.degree.-20.degree. with respect to the front end. In this embodiment the MCA is placed so that its front end is located at the focal plane.

Claims38

Dependent claims

An electro-optical detector for use with a mass spectrometer of the type focusing ion beams at a focal plane at substantially the exit end of a magnetic analyzer at which a magnetic field is present, the detector comprising:

a microchannel electron multiplier array, defining a plurality of parallel hollow channels each with an inlet end and an outlet end, all of said inlet ends being in a first plane defining a front end of said array and the outlet ends being in a second plane defining a back end of said array, said array being located at said focal plane so that the front end faces said magnetic analyzer and at least said back end is at an angle with respect to said focal plane, whereby ions in said ion beams enter channels in said array through the inlet ends thereof, producing secondary electrons therein, said secondary electrons exiting said channels through said back end forming electron beams;
and
circuit means including electron-sensitive means spaced apart from the array back end and parallel thereto for intercepting each of said electron beams to form an image thereon and means for processing the images formed on said electron-sensitive means.

An electro-optical detector for use in a device in which separate beams of charged particles are focusable at different locations along a longitudinal axis in a focal plane which is in a magnetic field which is substantially in a direction perpendicular to said longitudinal axis, the detector comprising:

a microchannel electron multiplier array, defining a plurality of parallel hollow channels each with an inlet end and an outlet end, all of said inlet ends being in a first plane defining a front end of said array and all the outlet ends being in a second plane defining a back end of said array, said array being positioned with its front end toward said separate beams with the array length parallel to said longitudinal axis, whereby the particles of different beams enter different groups of channels to generate secondary electrons, which exit the channels through said back end and forming separate electron beams, the array being positioned whereby at least its back end is at an angle with respect to said focal plane with at least the inlet ends of channels along a center line of said front end extending along the array length, being in said focal plane;
and
circuit means including electron-sensitive means which are parallel to said back end and spaced apart therefrom for intercepting said electron beams which form images thereon and means for processing said images, each image corresponding to a different charged particles' beam.

Dependencies are inferred from the claim text.

Electro-optical detector for use in a wide mass range mass spectrometer

Life of this patent

Electro-optical detector for use in a wide mass range mass spectrometer

Life of this patent

Abstract

Claims38