Diamond Annual Review 2025-26

Positive Pulse Inverted Negative Pulse Time (ns) Voltage (kV) 0 1 2 3 4 5 6 7 8 9 10 -2 0 2 4 6 8 10 12 14 16 18 20 A total of 217.4 days (5,217 hours) were scheduled for user mode operation, including five beamline start-up days. Most scheduled operation was in standard multibunch mode (900-bunch train) with total current of 300mA. However, 37 days were scheduled for hybrid mode, using a 686‑bunch train, incorporating a high‑charge 3nC bunch positioned in the centre of the dark gap. The annual operating statistics are shown in Figure 1. The overall Mean Time Between Failures (MTBF) Machine operation 2025/26 was our 19th year of operation and carried out in normal operatingmode: running six days per week, from09:00Wednesday to 09:00 Tuesday, interspersed with machine development days. Machine was disappointing at 77.9 hours, but still above the target minimum of 72 hours. User uptime was more disappointing at 94.4%, representing a significant reduction compared with recent years. This decrease was primarily due to approximately one week of lost user time following a major water leak affecting a main Control and Instrumentation Area and causing significant damage. Excluding this single event the uptime would have been 97.1%, consistent with previous years. MTBF (h) 0 2016/17 2017/18 2018/19 2019/20 2020/21 2021/22 2022/23 2023/24 2024/25 2025/26 20 40 60 80 100 120 140 92 94 93 95 96 97 98 99 100 Uptime (%) Figure 1: MTBF and uptime for the last 10 years The kick-and-cancel injection scheme One of themain goals of the Diamond-II upgrade is the ability to inject fresh electrons into the storage ringwithout affecting the user experiments. This is to be achieved by adopting a novel ‘kick-and-cancel’ injection scheme. In this, fast stripline kickers are used to deflect a single stored bunch in the filling pattern, causing it to oscillate at large amplitudes. This is followed by a second kick a few turns later, placing it back on axis. The arrival of the fresh electron bunch from the booster is timed to arrive with the second kick, reducing its oscillation amplitude and allowing it to be captured into the storage ringwith good efficiency. Two new 120 kW solid-state 500 MHz amplifiers installed on a new platform in readiness for Diamond-II. Figure 2: Estimated voltage pulse at the stripline kicker showing close to 3ns full width –Positive pulse – Inverted negative pulse Radiofrequency developments The new SLED system installed in the Linac has been in routine operation throughout the year, allowing operation with a single klystron rather than with two as before, at the same power level. This has proved to be a stable and robust mode of operation, providing greater efficiency and resilience. Significant progress has also been made last year in preparing the RF systems for Diamond-II. Two new 120 kW solid-state amplifiers have been installed on a new RF platform and passed their Site Acceptance Tests. There will eventually be three similar platforms hosting six amplifiers, with two further amplifiers located elsewhere. Overall, for the Diamond-II storage ring there will be eight normal conducting cavities powered by eight amplifiers, to provide redundancy and removing the reliance on superconducting cavities and obsolete IOT amplifiers. 31 32 Annual review 2025/26 Machine