Large area transition-edge sensor array for proton and heavy ion PIXE

Department of Physics, University of Jyväskylä, P.O.Box 35, 40014 University of Jyväskylä, Finland

In the field of PIXE the division between the use of the two detector types has for a long time been clear: most commonly Si or Ge based energy dispersive (ED) detectors are used when a broad energy range and large solid angle are needed, and wavelength dispersive (WD) detectors are used to obtain ultimate energy resolution. The limitations of the WD detectors are the narrow energy range and small solid angle. 

Today energy dispersive transition-edge sensors (TES) have matured to the state that they are used in number of applications, thanks to their superior energy resolution and sensitivity. Here we present the Jyväskylä TES-PIXE measurement setup, in which TES detector arrays are used to detect X-rays in proton and heavy ion PIXE. The energy resolution of a TES detector, when used in PIXE, is over an order of magnitude better compared to silicon drift detectors (SDD) and comparable to that of WD detectors. This makes it possible to recognize spectral lines in materials analysis that have previously been impossible to resolve over large energy range (1.0–15 keV), and even obtain chemical information from the analyzed sample. Our 160 sensors with total active area of 15.6 mm2 are cooled to the operation temperature of about 65 mK.

In this paper the design, electronics and data acquisition of the Jyväskylä TES detector array are described. The merits of the TES detector array in the analysis of different materials researchproblems from thin films to cultural heritage objects will be presented. The benefits and shortcomings of the TES detector in comparison to WD and silicon drift detectors will be discussed.

[1] M.R.J. Palosaari et al., Journal of Low Temperature Physics 176 (2014) 285.