Backstage Science has returned to the Diamond Light Source - an immense synchrotron facility just outside Oxford, UK.
This time the machine was switched off for a month of major upgrades.
Not great for scientists who want to use Diamond's light beams for research - but a golden (and necessary) opportunity for engineers to make improvements.
And also a golden opportunity for me to get inside and see it up close.
When the machine's operating it's far too dangerous to go near the electron beam, which gives off powerful radiation.
And here are some earlier videos from Diamond.