Detectors for Education

Due to their low-cost production and simple visualization of physical processes, gas-filled detectors are also suitable as example detectors in teaching at university, highschool and events for the general public. In order to cover the different applications and to demonstrate the different principles of operation, we are working on very different detectors including classical detectors like wire chambers, spark chambers or cloud chambers. In this area, the focus is not only on the detectors themselves, but also on the didactic concepts that are used to teach the detection principle and particle physics in general.


CLEOPATRA (CLassroom Experiment On PArticle TRAcking) is a compact particle detector for physics education. The centerpiece of the experiment is is a compact particle detector, a time projection chamer (TPC). It can be used to reconstruct particle tracks in three dimensions and in real time.

The aim of the project is to evaluate the use of gas-filled detectors in teaching and science communication. For this purpose, the setup is continuously improved. In addition, materials for the use of the CLEOPATRA detector in lab courses, in school lessons, at exhibitions or at public events are being developed.

Eine Wissenschaftlerin und ein Wissenschaftler arbeiten hinter einer Glasfassade und mischen Chemikalien mit Großgeräten.
© J. Streun (modified)

Setup of the  CLEOPATRA detector

The CLEOPATRA detector uses a cylindrical gas volume that is 8 cm in diameter and 10 cm long. Printed circuit boards are attached to the end caps of the drift region to form the anode and cathode. Both are equipped with connections for gas and high voltage. On the anode there is also a segmented readout unit (not visible from the outside) consisting of four GridPix chips. In addition, the CLEOPATRA detector can be operated with two scintillators, which act as triggers for the time measurement.

Functional principle of a time projection chamber

time projection chamber consists of a gas volume, also called a drift region. One end cap of the volume is a cathode on high voltage, the other end cap acts as an anode. As a result, an electric field is present within the drift region. When an ionizing particle flies through the gas volume, it ionizes the gas along its trajectory. The electrons released move to the anode due to the electric field, where they induce a signal. A finely segmented readout unit is located at the anode. This can be used to precisely determine the point at which an electron arrives. In this way, the flight path of the detected particle is projected onto the anode and is thus reconstructed in two dimensions. The third spatial coordinate is determined by the time that elapses between the ionization of the medium and the arrival of the electrons at the anode. All in all, a 3-dimensional reconstruction of the track of a particle in the detector is possible by a projection as well as by using the time information. This gives the detector the name time projection chamber.

operation principle of a TPC
© Laura Rodríguez Gómez / Universität Bonn

2. Additional Detectors

Eine Wissenschaftlerin und ein Wissenschaftler arbeiten hinter einer Glasfassade und mischen Chemikalien mit Großgeräten.
spark camber and tip counter as examples for the outreach detectors © Jochen Kaminski

Spark Chamber, Cloud Chamber, Coke Can Detector

Furthermore, we also develop other gas-filled detectors, which are particularly suited for teaching because to their detection principle or their illustrative presentation. These detectors are built and tested by university or highschool student during an internship. For example, we are in the process of building a spark chamber and a larger cloud chamber as demonstration objects at exhibitions and fairs. In contrast, the tip counter and the Coke can detector are designed to build a particle detector with the simplest possible things from everyday life and thus to arouse the curiosity and interest of the general public and especially of highschool students.

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