A South African company based in the Blackheath, Kuilsrivier, area - in collaboration with the University of the Western Cape (UWC) and international institutions - has designed state-of-the-art equipment for the ISOLDE (Isotope Separator On Line Facility) Radioactive Ion Beam Facility at CERN.

Fig. 1. Nico Orce and Shaun Hendricks working on the design of the SPEDE chamber. For that, the whole IDS experimental set up had to be perfectly reproduced to scale.

ISOLDE is one of the facilities at CERN, the European Organization for Nuclear Research located on the Franco-Swiss border. Unlike the massive ATLAS and ALICE collaborations that explore high-energy particle physics using the Large Hadron Collider (LHC), ISOLDE is a more modest yet versatile facility comprising numerous experimental setups. Its research spans a wide range of fields, including low-energy nuclear, atomic, molecular, and solid-state physics, as well as biophysics and astrophysics.

Science at ISOLDE focuses on measuring the properties of exotic nuclei with extremely short lifetimes; many of which can only be produced at ISOLDE (and in stellar explosions!) thanks to the exceptional expertise of CERN’s accelerator teams. The facility is particularly dynamic, with most experiments led by university research groups from around the world. Co-authorship on ISOLDE publications typically requires direct involvement in the specific measurements and physics of a given experiment.

ISOLDE conducts about 50 highly-competitive experiments each year. In November 2024, Prof. Nico Orce’s group from UWC led their own experiments at the ISOLDE Decay Station (IDS), with UWC postgraduate students Ms. Geneva  April and Mr. Manfred  Jaftha analysing the resulting data as part of their research (Experiment IS694).

But that’s a story to be told once the work is complete. Here, we highlight the commissioning of the SPEDE spectrometer at CERN and South Africa’s contribution to this achievement; namely, the design of the SPEDE chamber led by Orce’s group at UWC and Design Engineer Shaun Hendricks from CJ Dustraction Systems, a family-owned company based in Blackheath, Kuilsrivier.

Hendricks provided the final design of the SPEDE chamber, which houses an electron spectrometer for the direct measurement of internal conversion electrons emitted in flight — that is, without the use of magnetic fields to transport the electrons. This breakthrough enables high-precision electron spectroscopy in exotic nuclei, many of which will be studied in this way for the first time.

This was not the first time Hendricks developed complex designs for nuclear experiments.

Expertise came through the collaboration with UWC and iThemba LABS scientists (Kobus and Elena Lawrie) in designing large state-of-the-art equipment for nuclear physics experiments through the GAMKA project. The Gamma Ray Spectrometer for Knowledge in Africa, dubbed GAMKA the Khoisan word for ‘The Lion’ – is a R35-million project led by Prof Orce, commissioned in May 2021 and currently housed at iThemba LABS in Somerset West.

Fig. 2. Design of the SPEDE chamber by Shaun Hendricks submitted to CERN in August 2024 (left) and commissioned in October 2025 (right). The SPEDE spectrometer is at the center of the array.

The SPEDE spectrometer was originally conceived by the Universities of Liverpool and Jyväskylä to enable the simultaneous measurement of electrons and gamma rays at the ISOLDE Decay Station (IDS) and the MINIBALL array at HIE-ISOLDE. Prof Orce, who has led several experiments at both of these facilities, naturally took the initiative to lead the design of the SPEDE chamber.

He said: “The SPEDE spectrometer is the culmination of a project spanning more than a decade and now stands ready to enable pioneering research for the global nuclear physics community. It is ideally suited for investigating shape coexistence and collective structures in exotic nuclei, offering a uniquely versatile detector array.” 

Hendricks’ design of the SPEDE chamber considered many innovations, like holding vacuum through, which was needed to deliver a liquid cooling system at approx -20 C without the chamber freezing over, and all having as thin as possible aluminium walls as well as being mechanically strong. Quite an engineering challenge! The design was delivered to CERN in August 2024, as shown in Figure 2 before and after being manufactured in Madrid by Bruno Olaizola and colleagues. The chamber was successfully commissioned in an experiment similar to those proposed by UWC. These studies focus on achieving the first electron spectroscopy of neutron-rich strontium (Sr) isotopes (UWC’s proposal targets the neutron-deficient side of the Sr isotopes) to explore shape coexistence — the phenomenon arising from the mixing of different nuclear shapes within a nucleus. Electron measurements may continue during CERN’s long shutdown using long-lived samples. 

This project was achieved through close collaboration and regular meetings with scientists and engineers from several institutions worldwide, including James Cubiss (York/Edinburgh/CERN), Zixuan Yue and Josh Wilson (York), Razvan Lica (CERN/IFIN-HH Bucharest), Janne Pakarinen and Joonas Ojala (Jyväskylä), Bruno Olaizola (Madrid), Dave Seddon (Liverpool), Nikita Bernier and Nico Orce (UWC), and Hendricks (CJ Dustraction Systems), among others.

Commenting on the success of the commissioning experiment, which combined the SPEDE spectrometer with 13 clover detectors for angular correlation measurements, James Cubiss (York/Edinburgh/CERN) noted:  “The chamber and parts Shaun designed were great. As expected, the cooling system was a pain to get working, but this was outside of Shaun’s work, so everything he contributed was good. It was a nice little chamber and looks good inside the Ge array!”

We shall be back at CERN for more, but for now, Prof Orce will be presenting his work at CERN twice in early December on Light-Ion Collision at the LHC and ISOLDE Workshops.