Two Compton polarimeter constructions for modern standard γ-spectroscopy

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 357; no. 2; pp. 458 - 466
• Main Authors: von der Werth, A., Becker, F., Eberth, J., Freund, S., Hermkens, U., Mylaeus, T., Skoda, S., Thomas, H.G., Teichert, W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 21-04-1995
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/0168-9002(95)00025-9

Two types of Compton polarimeters for γ-linear polarization measurements are presented. The first one consists of standard Ge-detectors and unites an easy handling and high grade of universality with high polarization sensitivity in the γ-ray energy range 180–2500 keV. In this device, a low efficiency Ge-crystal scatterer is used with a special diameter-to-length ratio which optimizes the probability for Compton scattering. In addition, the background in the summed energy spectra is significantly reduced by requiring coincident γ-ray energies to obey the Compton scattering formula. The second device fits the need of accessory units which can be used with the new generation of multi-detector arrays. It is based on a segmented planar Ge-crystal surrounded by an anti-Compton shield and possesses a high coincidence efficiency in the 50–1000 keV range. For both spectrometers we performed calibration measurements to obtain the sensitivity
Q and the coincidence efficiency
ε
c. From these values we deduced the “figure of merit”
F =
Q
2
ε
c which gives a kind of quality description for polarimeters.