It is with deep sadness that we share the news of the loss of our friend and colleague, John Pett, former member and leader of the LHC Power Converter group. He was an important member of the group, contributing with his great experience, knowledge and efforts in innovation.
John was born in December 1942 in Toddington, UK. His early interest in electronics led him to study engineering and to work at PYE Electronics in Cambridge. In 1966, a colleague saw a CERN job advert in the New Scientist and John applied. The recruitment was fast: the interview was in September, and he started work in October.
John began at CERN in the Beam Transfer (BT) group of the Intersecting Storage Rings (ISR). He developed a Digital–Analog Converter (DAC) for the control of all the BT power supplies, enabling the first computer control. He then went on to develop a high-precision 16-bit DAC for the ISR main ring supplies, which was later also deployed in the pulsed beam lines and the Antiproton Accumulator (AA). He also studied the new switch-mode technology and designed the first 6 kW converters for some ISR correctors. Later, he was instrumental in creating a new control system for all ISR power supplies, based on CAMAC control and the first microprocessors.
In 1980, the group’s focus shifted to the LEP project and John led the development of a new control system for the ~900 power converters, based entirely on microprocessors, a real-time operating system, hybrid DACs and Analog–Digital Converters (ADCs) and the 1553 field bus. He was also the divisional representative on CERN committees for training and standardisation of electronic components.
In autumn 1989, John was appointed group leader and managed the merger of the LEP and SPS converter groups and prepared for the forthcoming LHC project. He developed a groundbreaking 22-bit Delta-Sigma ADC over a number of years with unprecedented accuracy and speed. It would go on to be part of, again, an entirely new control system for the LHC converters. John successfully managed this development, based on digital signal processing, multi-microprocessors and the new real-time WorldFIP fieldbus.
In John’s last years at CERN, up to his retirement in 2002, he also made significant design contributions to the current calibration system, which is the basis for the outstanding performance of the LHC power converters. These calibration devices have been widely recognised and some are used in national standards laboratories.
His achievements were presented in several papers to the Institute of Electrical and Electronics Engineers (IEEE) conferences and Transactions journal, thus gaining international recognition outside CERN.
After a few years of struggle with illness, John passed away on 12 December 2024. His contributions to high-precision electronics at CERN were outstanding. He was very persistent in attacking and solving difficult problems and was a good partner in discussions, not afraid to question statements and opinions. He also had a great sense of British humour, and we laughed a lot. John will be remembered as a great professional engineer and a good friend.
His friends and colleagues