GAMKA to be the pride of nuclear research in the South

First experiments with the GAMKA spectrometer @ iThemba LABS

 In 2018, a UWC-led consortium comprising four Universities (Stellenbosch, UniZulu, Wits and UWC) and iThemba LABS was awarded R35 million by the National Research Foundation (NRF) for a new gamma-ray spectrometer. The Gamma Ray Spectrometer for Knowledge in Africa, dubbed GAMKA –  the Khoisan word for ‘The Lion’ – is currently housed at iThemba LABS (Cape Town) after commissioning in May 2021.  After some initial setbacks, GAMKA is running its first experiment in June 2025 and will investigate a wide range of nuclear physics and nuclear astrophysics phenomena involving, among others, chiral symmetry, tilted precession and wobbling motion in nuclei, nuclear dipole polarizability, giant dipole resonances, nuclear collectivity and shapes via the determination of level schemes, branching and mixing ratios, matrix elements or nuclear lifetimes.

Poster designed by Shaun Hendricks (Kuils River, Cape Town).

GAMKA: The Lion of African Physics

Using lasers to align the GAMKA spectrometer with the beam line.

iThemba LABS (the iThemba Laboratory for Accelerator-Based Sciences) is a primary centre of expertise in radiation medicine and nuclear science and technologies in South Africa.  As iThemba LABS’s existing detection equipment was outdated, a consortium of four universities – the Universities of the Western Cape, Witwatersrand,  Stellenbosch and Zululand – and iThemba LABS made a submission to the NRF to acquire new detectors in order to build a new gamma-ray spectrometer. The upgrade includes four clover detectors made of high purity germanium with BGOs for energy resolution and 17 large lanthanum bromide detectors for high-energy efficiency. The GAMKA project comprises: 

a) 4 HPGe clover detectors.
b) 2 BGO (Bismuth Germinate) Compton suppression shields.
c) 15 large volume (89x203mm) LaBr3 detectors.
d) 3 XIA PIXIE 16 digital data acquisition cards (16 bit 250Mz digitization) with a crate.
e) A high voltage system for 6kV at low current (clovers) and for 2kV at high current (BGO and LaBr3).
f) 1 annealing system for clover detectors.
g) Asymmetric array support frames that can accommodate both clover and LaBr3 detectors - Soccerball : NS, Dandelion.
h) Liquid nitrogen generator.

GAMKA in the making! Elena and Kobus Lawrie together with Nikita Bernier and lots of students setting up the GAMKA spectrometer.

“The spectrometer is actually a bunch of detectors that detect gamma rays, high energy photons’ light that is not visible to us, but is to the device. The detectors contain semi-conductor crystals, reasonably large in size, made of high purity germanium and stacked in a clover configuration. The germanium is very fragile and expensive so it has to be housed in a vacuum and cooled with liquid nitrogen at all times.  The other part of the spectrometer is the lanthanum bromide detectors, which are highly efficient and can detect more gamma rays for a given number of events,” says Prof Smarajit Triambak.

Senior nuclear physicist from the Department of Physics and Astronomy at UWC, Robbie Lindsay, points out that the new detector system will be the only one of its size in the Southern hemisphere which can perform experiments at a stable beam facility.

“Not just other universities in the Southern hemisphere will be interested, but also those in the Northern hemisphere, because a lot of the big facilities are moving towards radioactive ion beam experiments so this one, for stable beams, becomes more unique,” says Prof Lindsay.                                                                                                                                                                                                                                                                     

UWC-led GAMKA Project Makes South Africa Potential World Leader in Nuclear Physics Research

Nico Orce presenting GAMKA @ INSTRANS 2024 in Paris, France.

The bidding consortium was led by Prof Nico Orce of UWC’s Department of Physics and Astronomy, who says it was a hard slog to get the submission exactly right. The process started in October 2012, when the iThemba LABS Users voted Nico Orce to lead this project. Although the initial submission to the NRF National Equipment Programme (NEP) was unsuccessful because of the maximum funding for this call was R10 million, the national priority given to the GAMKA spectrometer prompted the NRF to open a new funding call – under the Strategic Research Equipment Programme  (SREP) – for project proposals valued up to R35 million. The input from all partners in the Science Case and the Business Plan describes the potential positive impact of the proposed spectrometer on the fields of nuclear physics and astrophysics.

“The impact is on producing high-impact research on nuclear physics and astrophysics leading to internationally competitive training of our postgraduate students and young scientists as the key to an advanced knowledge-based economy and society. GAMKA opens a new door of dreams for novel research in South Africa,” says Prof Nico Orce.

“When the proposal was defended in front of the NRF panel in 2017, each consortium member committed to putting a certain amount of money into the project for doing GAMKA-related research and for general maintenance. So the commitment is there to keep it going,” adds Prof Orce.

Poster presented by Shaun Hendricks at INTRANS 2024 in Paris, France, showing the different phases towards construction. The dandelion frame is based on Elena Lawrie’s original idea of using the dandelion flower as the supporting structure.

The consortium managed to get GAMKA commissioned in May 2021 working through the COVID-19 pandemic and having regular ZOOM meetings in the evenings after work. 

Many zoom meetings during the evenings of the pandemic.

A UWC-led consortium of universities was awarded R35 million by the National Research Foundation (NRF) for a nuclear spectrometer in 2018. The GAMKA spectrometer was commissioned in May 2021. 

GAMKA in the NRF News (May 2021).

GAMKA is supported by the National Research Foundation of South Africa (Strategic Research Equipment Grant Number: 114668), and by contributions from iThemba LABS, Stellenbosch University, University of the Western Cape, University of the Witwatersrand, and the University of Zululand.

Acknowledgements. Thanks to everyone who was part of this project.

New state-of-the-art detector plates

SKA, MANDELA and GAMKA projects continue to promote science in UWC and SA