3D-characterisation of HPGe detectors

Related material

Talk at Swedish Nuclear Physics meeting 2018

A. Såmark-Roth et al., Compex: a cubic germanium detector. Eur. Phys. J. A 56, 141 (2020).

The upgraded Lundium Chamber features new High Purity Germanium (HPGe) detectors for γ-ray detection. These are denoted Compex, and they are novel in the sense that they differ from the standard cylindrical coaxial HPGe detectors.  The importance of the spectroscopic performance of the Compex detectors in the low-statistics superheavy experiments, cannot be stressed enough. In order to confidently discover new physics and propose new nuclear structure properties it is of utmost importance to know the characteristics of the detectors, especially if it is a new type of detector. In this regard it is hence essential to characterise the Compex set-up in detail. The characterisation can be achieved through an x-y-z scanning.

The lab in Lund now hosts a scanning system for HPGe detectors. The basic principle of the scanner was presented here. It is soon in its final shape. Just recently a raster scan was completed for an in-house cylindrical HPGe detector. The result of this scan is presented in the following figure, Figure 1. The circular shape is reproduced well, such as the core electrode contact (the green region in the center).

Raster scan of an in-house coaxial HPGe detector. Each (x, y) pixel represents a measured coordinate. The colour indicate the number of photons that were detected for each coordinate, going from purple to red with increasing counts.
Figure 1. Raster scan of an in-house coaxial HPGe detector. Each (x, y) pixel represents a measured coordinate. The colour indicate the number of photons that were detected for each coordinate, going from purple (few counts) to red (many counts).