M N. Kinnane

The correction of systematic image deformations inherent to two-dimensional proportional counters

Two-dimensional backgammon configuration and multiwire gas proportional counters have been in use for decades in the field of x-ray physics for high-precision or high-flux experiments. Systematics inherent to this type of detector lead to image distortions that are often overlooked or extremely difficult to quantify. They are usually seen as intrinsic to the detector performance, leading to loss of resolution, linearity and signal-to-noise ratio. This work presents the signature, cause and resolution of several key distortions. The physics of the breakdown between the anode and cathode, false event position reconstruction due to the electronic detector response, and the effect of asymmetric field lines between the anode and cathode are developed. The position resolution of these types of detectors is demonstrated to be comparable to a charge-coupled device when used in the same experimental configuration.

Development of backgammon-type multiwire proportional counters for the detection of x rays

A multiwire proportional counter (MWPC) based on a backgammon-type design has been developed for the detection of x-ray photons in two dimensions over the energy range of 4–6keV. The MWPC was designed for operation in an experimental spectroscopy application requiring single photon counting over a wide range of count rates, high photon detection efficiency and resolution, and a highly linear response function across the detector face. A model based on attenuation of the incident x-ray beam by the various components of the detector is presented and highlights key areas for efficiency optimization. The design, construction, testing procedure, and performance of the backgammon MWPC are presented and all objectives are met including a particularly impressive differential nonlinearity.

Characterization of the titanium Kβ spectral profile

Transition metals have K? and K? characteristic radiation possessing complex asymmetric spectral profiles. Instrumental broadening normally encountered in x-ray experiments shifts features of profiles used for calibration, such as peak energy, by many times the quoted accuracies. We measure and characterize the titanium K? spectral profile. The peak energy of the titanium K? spectral profile is found to be 4931.966 ? 0.022?eV prior to instrumental broadening. This 4.5?ppm result decreases the uncertainty over the past literature by a factor of 2.6 and is 2.4 standard deviations from the previous standard. The spectrum is analysed and the resolution-free lineshape is extracted and listed for use in other experiments. We also incorporate improvement in analysis applied to earlier results for V K?.