Accelerating recovery

UK microwave specialists have successfully tested a key component of a new breed of ‘mini particle accelerator’.

The waveguide technology has been designed specifically for a 20MeV electron accelerator, which will be built as part of the CONFORM project at the Daresbury Laboratory in Cheshire.

The particle accelerator, called EMMA, will test the principle of, among other things, Hadron Therapy. The team believes this could be a less harmful method of treating cancer patients compared with traditional radiotherapy.

The waveguide system, developed by Hertfordshire-based Q-par Angus, will distribute microwave energy to specific points around the accelerator ring.

Alex Donnison, a physicist at Q-par Angus, explained that energy from these high-frequency microwaves will be used to energise particles in the accelerator.

The microwaves will be distributed to specific points in the ring through a Q-par Angus developed waveguide-distribution system.

‘Waveguide is basically plumbing,’ he said. ‘It is rectangular sections of open metal and because of the high frequencies it is much more efficient to transfer microwaves in pipes.’

The particles (electrons) will originate from ALICE, another Daresbury Laboratory accelerator.

Donnison said the main challenge for Q-par Angus’s microwave engineer, Simon Davis, was designing the system to fit into the accelerator’s small size. ‘We’re not talking about CERN,’ he said. ‘It fits in a room. It is about 7.59m across.’

Donnison said the small size meant it would be more difficult to keep all the microwaves at various positions around the ring in phase.

‘The waveforms must match otherwise they can cancel each other and you lose power,’ he added. ‘You have to get them all in phase and match all their amplitudes so the whole thing is balanced.’

Donnison said Davis designed phase shifters capable of making adjustments and ensuring all the microwaves are in phase around the ring.

After testing the principle of Hadron Therapy, the CONFORM group hopes to design a proton accelerator called PAMELA for medical uses such as cancer treatment.

Donnison explained Hadron Therapy is expected to be less harmful to patients than current oncology treatments that use X-rays to destroy cancerous cells.

‘With current methods you damage good tissue in patients, largely because the energy deposition profile of X-rays in the body is quite broad,’ he said. ‘So researchers have been looking at alternative forms of therapy using particles such as protons rather than X-rays, because you get a much narrower energy deposition profile. You get less good-tissue damage.’

Q-par Angus has completed testing its system, which will soon be transferred and reassembled at the Daresbury Laboratory. Donnison said the accelerator will be switched on late this year or in early 2010. When it does turn on, he said, the Daresbury facility will study possible applications for the accelerator technology.

Julian Robbins, business development manager for Q-par Angus, said: ‘It could be used in applications ranging from zoology to archaeology. The healthcare side is one of the things people concentrate on but the fields are as diverse as energy and environment, materials research, healthcare and fundamental physics.’

Siobhan Wagner