Development of an automatic system to characterize Silicon detectors using light ions and fission fragments

Goal

Determine the sensitive area of one or several thin Si-detectors and determine if and in which way this depends on the incoming particle.

Project

At the Department of Applied Nuclear Physics, we conduct several research projects where we study different types of nuclear reactions at international research facilities (for example, GANIL in Caen, France). These nuclear reactions create, among others, light ions and fission products. To register these particles, we use Si detectors. One goal of these studies is to measure reaction cross-sections, i.e., the probabilities of different types of nuclear reactions. The exact size of the sensitive surface of the detector is therefore important to know. This may differ from the nominal value and, for design reasons, would also depend on the particle type.

The active area of the detector can be determined in our lab by using radiation sources and, with the help of radiation shielding, irradiating only a small part of the detector surface. By moving the irradiated part, the entire detector is scanned and the sensitive area can be determined.

As a radiation source, a Cf-252 source is used, which emits both alpha particles and fission products. The latter have a significantly higher mass and the sensitive surface of the detector could therefore differ from that of the relatively light alpha particles. Since the Si detector measures energy of the incoming particles, one can easily distinguish between these different particle types. The measurement takes place in a vacuum chamber located here at Ångström laboratory.

An important part of the project is to build a computer-controlled device that moves the radiation source step by step to irradiate different parts of the detector without having to break a vacuum for each individual measurement.

Thereafter, a series of measurement series will be performed and the collected measurement data will be analyzed to finally determine the detector's response to these different particle types.

Contact

Diego Tarrío

Stephan Pomp