A new analysis chamber with a rotating target holder for total-sample PIXE analysis of aerosol deposits collected in Berner impactors

Abstract

We describe an external PIXE analysis chamber provided with means for determining the total amount of aerosol material sampled in Berner impactors. The deposits are concentrated in equally spaced small spots along a circle with a diameter of 50 mm. To pass the whole distribution of material through the probing proton beam, the thin backing film is mounted on a rotatable target holder. Driven by a motor, the holder is rotating at a speed of typically 1/min. Depending on the total duration of the analysis, the sample is rotated 3–10 times through the beam. For high sample throughput the analysis chamber is coupled to a helium-backfilled transfer box in which six holders can be stored, at the same pressure as in the analysis chamber. Loading of the transfer box, with a minimum loss of helium, is accomplished by activating load locks on either side of the box. The first experience gained with aerosol samples as well as with dedicated reference standards is discussed with particular reference to the uniformity of aerosol deposits.