The ion beam analysis system at LBNL is a user facility at the Materials Sciences Division under the management of Dr. Kin Man Yu (https://sites.google.com/a/lbl.gov/emat-solar/people/kin-man-yu). It is a complete instrument for rapid thin film analysis utilizing an energetic ion beam. The facility is based on a model 5SDH pelletron tandem accelerator manufactured by National Electrostatics Corporation (NEC). Energetic alpha beam up to 5 MeV can be generated by the pelletron with terminal voltage of 1.7MV.
This instrument has the flexibility of variable beam energy from 0.6-5.1 MeV. Variable beam energy allows optimization of the beam energy with respect to energy loss, the overall system resolution, and to the specific resonant reaction needed for the analysis. Higher energy also allows the investigation of low Z elements (C, N, O) in higher Z samples.
The main part of the system is a NEC model 5SDH Pelletron tandem accelerator. The accelerator produces a stable terminal voltage of up to 1.7 MV using a single metal pellet chain. A negative ion beam from an injector at one end of the tandem is accelerated to the terminal where it is stripped in a gas canal to positive charge states which are then further accelerated to the other end of the tandem. The high energy beam is analyzed by bending 15° in a switching magnet which insures high beam purity in the target chamber.
The negative ions are produced in an injector which uses an RF source to produce positive ions which then pass through an alkali vapor to produce negative ions. The source parameters are controlled via manually operated control rods. The negative ions are analyzed and focused into the tandem accelerator.
This accelerator includes electron suppression tube and x-ray shielding to insure that radiation levels are less than 2.0 mr/hr (0.02mSv/hr) everywhere at the tank wall and to less than 0.25 mr/hr (0.0025 mSv/hr) at 1 meter from the tank wall for ion beams guaranteed.
The material analysis end station
The target chamber is evacuated by a Turbo pump and sample loading can be done through a target load lock in the lid of the chamber for rapid sample changing. The chamber is equipped with a particle detector for Rutherford backscattering spectrometry and a Si(Li) for particle induced x-ray emission measurement. A Gamma ray detector (NaI(Tl)) is optional for gamma ray detector for nuclear reaction analysis. The control console provides computer-controlled data acquisition and sample manipulation. The chamber is vacuum sealed and has a view port for a target alignment video camera. The chamber is electrically isolated and can be used as a Faraday cup to monitor beam current.
Ion Beam Analysis: General description and applications
MeV ion beam analytical techniques:
Applications of ion beam analysis:
Strengths of Ion Beam Analysis