A new spectrometer for Rutherford backscattering spectrometry

A new spectrometer for cyclotron Rutherford backscattering spectrometry (CRBS) is designed, which has a reasonably large solid angle and a high energy resolution compared with those of conventional RBS systems. The system consists of a cryogen-free superconducting magnet that produces a uniform magnetic field, and a two-dimensional position sensitive detector (2D-PSD) that has a small hole for transmittance of incident ions. Both the detector and the specimen are placed in the uniform magnetic field. Probe ions, accelerated by a small accelerator, pass through the hole of the detector and an energy resolving aperture before incident onto the specimen. Since the incident direction is adjusted to be parallel to the magnetic field, the trajectory of the incident beam is not affected by the magnetic field. Ions, backscattered from the specimen, travel along the cyclotron trajectories in the magnetic field, and only ions that satisfy a certain relationship between their energy and scattering angles, pass through the energy resolving aperture. The energy and scattering angle can be determined from the position of the detection in the 2D-PSD. It is shown that this new spectrometer can provide both a large solid angle and a reasonably high energy resolution.