Triple-focussing electron spectrum selector for in-beam conversion electron spectroscopy

A novel recombinator and injector has been designed for the trace element accelerator mass spectrometer (TEAMS) at the Naval Research Laboratory. It will allow parallel analysis of a broad range of impurities in electronic, biological, and geological materials. The recombinator consists of a tunable Pretzel magnet that serves as a notch mass filter [1]. The mass filter has near-amu mass resolution over the range of 1–200 amu for 40 keV ions. Masks positioned along the Pretzel's symmetry axis block intense matrix-related beams, (e.g. Si, SiO, Si 3 , etc.) while passing beams of interest into the accelerator. The primary and secondary columns of a Physical Electronics model 6300 quadrupole secondary ion mass spectrometer (SIMS) form the key components of the ion source for the injector. This commercially proven instrument facilitates depth profiling, imaging, and the analysis of both conducting and insulating substrates at pressures as low as 10 −10 Torr.

1-200 amu tunable pretzel magnet notch-mass-filter and injector for trace element accelerator mass spectrometry

A wide band electron spectrum analyzer

This paper describes the design and construction of a microwave separator for high energy particle beams, following the original ideas of Panofsky and Wenzel. We used a TM012 rectangular cavity with a Q of 15 000 and a maximum power dissipation of 1.3 Mw (megawatts). With this we could deflect electrons of 150 Mev/c momentum through ¾ in. at the final focus of our analyzing magnet. The available aperture is so small that the technique is not immediately useful, but we anticipate that it may become so at higher energies, when other methods of beam separation become unfeasible.

Microwave Separator for High Energy Particle Beams

The principle of Fermat (or of Maupertuis) contains implicitly the entirety of geometrical optics. It is used in the present paper to find the trajectories of charged particles passing through magnetic systems possessing a plane of radial symmetry. A general formula is given for the calculation of the aberrations at image points. The method is illustrated in its application to certain systems of special interest in which specific second order aberrations cancel. The method outlined herein is believed to possess the advantage of relative simplicity and directness when compared to more general formulations.

https://www.csnsm.in2p3.fr/IMG/pdf/fermat_applied_magn_mat.pdf

Application of Fermat's Principle to Magnetic Spectrometers

A double focusing zero dispersion magnetic spectrometer has been constructed having the following properties: The spectrometer consists of two magnets, each n≅0.25, 110° deflection, 30-in. radius of curvature, bending the particles in the same sense. For the central momentum p0, the useful solid angle Ω0 is ∼0.0055 sr with a possibility of improvement to 0.01 sr. The momentum acceptance Δp is in excess of ±4% with a useful solid angle Ω of ∼0.0015 sr at the 4% points. For a point source and for the solid angles and momentum acceptances given, over 90% of the trajectories terminate within a circle of 2-in. diameter at the focal plane.

W. K. H. Panofsky

Papers

Double Focusing Zero Dispersion Magnetic Spectrometer