Macro-PIXE

PIXE instruments are normally divided into two groups, those instruments suitable for macro-PIXE with a beam with cross-section of several mm, and those suitable for micro-PIXE with a beam spot of 1 tm cross-section. The obvious requirement for both PIXE facilities is the availability of an ion accelerator capable of producing beams of a few megaelectronvolts. In the early days of PIXE, parasitic use of accelerators purchased for research in nuclear physics was common. The majority of these... 

Figure 3 (A) Schematic view of a PIXE chamber. Key 1, diaphragms to collimate the beam 2, carousel for the samples 3, lifting mechanism to position the sample in front of the beam 4, sample holders 5, X-ray detector 6, wheel with different absorbers to filter out low-energy X-rays 7, y-detector 8, protractor to position a surface barrier detector. (B) Photograph of a typical PIXE environment with a pelletron accelerator and micro- and macro-PIXE beam lines. (Reprinted with permission from Vis RD, Kramer JLAM, van Langevelde F, and Mars L (1993) The upgraded Amsterdam nuclear microprobe. Physics Review B Nuclear Instrument Methods BTI 41-44 Elsevier.)...

Pa. Fligh vacuum conditions are not crucial for macro-PIXE, but are very much so in micro-PIXE, where beam defocusing by gas molecules must be avoided. 

As is the case for macro-PIXE, micro-PIXE may also be carried out under nonvacuum conditions. Because of scattering of the beam by the gas, however, nonvacuum micro-PIXE is only feasible for moderately small beam sizes (20-100 pm). After collimation and/or focusing, the beam is passed to the nonvacuum region through a pinhole or an exit foil. If the spatial resolution requirements are not too... 

Besides micro-PIXE, macro-PIXE has also been extensively used in art and archaeology, and found to provide very useful information. Actually, the distinction between micro- and macro-PIXE is difficult to make in this field of application, as a lot of work is carried out with (external) probes with beam... 

Data Analysis. For both the macro- and micro-PIXE systems an on line display of the X-ray and RBS spectra is provided by an LSI 11/23, while detailed analysis of the RBS and PIXE spectra are performed using the programs RUMP (1L) and MENUGF (UL) The latter analyzes the 1024... 

Macro- and micro-PIXE find applications in different types of analytical work. 

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