# Resurgence of a Nation's Radiation Science Driven by Its Nuclear Industry Needs
### Accelerator Systems  
The DCF ion beam accelerator facility comprises a pair of electrostatic Pelletron accelerators manufactured by the National Electrostatics Corporation (NEC), a 5 MV tandem 15 SDH-4 and a 2.5 MV single-ended 7.5 SH-2 accelerator with a suite of six dedicated end-stations contained in two independently shielded and interlocked target rooms. The beam lines from the 2.5 MV accelerator meet two of the beam lines from the 5 MV tandem to provide common locations to allow beams from both accelerators to be combined in future dual-beam experiments. To avoid confusion, the text uses beam-line numbers from the 5 MV tandem to refer to the end stations, which each have unique capability. The 5 MV tandem has a choice of two ion sources at its low energy end: a toroidal volume ion source (TORVIS [8]) capable of generating up to 100 \(\upmu\)A of proton current, or 1 \(\upmu\)A of He ion (alpha) current; a second, multi-cathode source of negative ions by cesium sputtering (MC-SNICS) for the production of heavy ion beams [9]. The MC-SNICS source uses a custom cathode wheel from NEC with 20 cathode positions, each taking a 6 mm diameter cathode. This large cathode diameter gives high volumes of cathode material with long lifetimes--over 50 h of continuous beam production at constant current is typical. Having many cathodes installed on the wheel at the same time means that switching to a fresh cathode is very quick, and a selection of different ion species can also be readily available. Due to the tandem design of the 5 MV accelerator, it can deliver protons beams of up to 10 MeV, alpha beams of up to 15 MeV, and heavy ions to a maximum of 35 MeV in energy. The 2.5 MV single-ended accelerator is equipped with a positive RF plasma ion source within its terminal shell. This is primarily a source of high-current proton or He ion (100 \(\upmu\)A each) beams, although other noble gas ion beams have been routinely produced; krypton and xenon ion beams have proved popular for simulating radiation damage within nuclear fuels or fuel surrogates as these ions are common fission products produced during nuclear fuel burn-up. At the high energy end of each accelerator is a dipole switching magnet which can direct the accelerated ion beam into the desired beamline. Whilst each accelerator can only supply an ion beam to a single beamline at a time, having a choice of beamlines allows for a variety of dedicated end-stations to be permanently provided. The layout of the accelerator complex and relation of the various beamlines are depicted in Figure 2.  
Line 1: To cater for the very high levels of prompt radiation (gamma and neutron) generated by high current, high energy proton irradiations (up to 100 \(\upmu\)A at 10 MeV), this beam line is designated for high damage studies using high energy proton beams and so is equipped with an irradiation end-station inside its own hotell. The hotell is a radiation enclosure that complements the concrete shielding of the target room, funded as an EPSRC (Engineering and Physical Sciences Research Council) National Nuclear User Facility (NNUF). A second, attached, shielded enclosure allows for irradiated samples to be demounted remotely. Such samples, following prolonged high-dose, high-energy proton irradiation can be activated to a level that requires either local, shielded storage--provided for in the hotell--or to be safely loaded into a shielded 'croft' pot for transport to an active handling lab for subsequent analysis. Line 2: The only beam line not to have its own dedicated end station. This allows for users with their own experimental vessels to interface them to the DCF ion beam accelerators. The fitting of fast reaction (35 ms response) valves in this beam line allow for more direct coupling to liquid or gas filled enclosures, such as those proposed for in situ corrosion studies, or simulation of radiation chemistry in deep-space ice cores.