Count‐rate, linearity, and performance of new backgammon detector technology

Abstract

The meander wire backgammon technology has high levels of flux and spatial linearity across a wide range of energies. One of the attractive features of these technologies is the stability of response and robustness under long X-ray exposure, compactness, and portability. A key problem historically has been the limited range of count-rate for processing to the optimum resolution. We report dramatic advances in this and other areas appropriate for high-accuracy experiments including tests of quantum electrodynamics, fundamental relativistic atomic physics, X-ray calibration, and crystallography. We illustrate this technology applied to the K 1,2 spectra of titanium, chromium, and copper. The quality of the spectra permits deeper insight into atomic and solid state science and permits accurate measurement of energy and relativistic atomic physics processes, below 1-m accuracy or down to 1 ppm in energy. 218 The University of Melbourne (UM) backgammon detector relies on a sophisticated data acquisition system specifically developed for the detector and its use as part of our Johann-type curved crystal X-ray spectrometer. The design allows single photon counting over a wide range of count rates. [30]

The characteristic radiation of copper K β including radiative Auger processes

“…The beam was diffracted using a monolithic Si(111) channel-cut crystal, attenuated using aluminum foils and then projected onto the detector face. Full details of the experiment, detector and initial processing steps are described in [73].…”

Vignetted photon fields, recharacterisation of V Kα, and reducing X‐ray uncertainties by a factor of two

“…The detector arm length is 1,500(5)mm, source to crystal length is 330(5)mm, and the source width (FWHM) is 5(1)mm. The overall performance, count‐rate, and linearity of the backgammon detector is discussed by Melia et al [ 17 ] Figure 2 provides a schematic and Figure 3 gives a photograph of the diffractometer and source. Key geometric characteristics are given in Table 1.…”

“…There are inevitably certain systematics to shift the apparent position of an X‐ray event, including electromagnetic edge effects and detector wire non‐uniformity. [ 17 ]…”

High accuracy characterisation for the absolute energy of scandium Kα

“…Our backgammon two-dimensional ion chamber x-ray detector was filled with P10 (10% methane in argon) gas at approximately 1060 Torr (slightly above atmospheric pressure). The value of backgammon detectors has been discussed [44][45][46][47][48][49][50]. Our backgammon active area is about 22 mm×22 mm.…”

“…Backgammon detectors have advantages of compactness, price, and portability, together with good spatial resolution and excellent linearity. The capacity to change the gas and gas pressure is a major advantage at lower energies where the absorption coefficient becomes large [50]. Key parameters for the x-ray optical geometry are outlined in table 1.…”