discovered_01_2016 - Lasers as Particle Turbos

WWW.HZDR.DE discovered 01.16 TITLE // HZDR physicists are working on novel acceleration methods for radiation therapy. Karl Zeil has donned his white coat, changed his shoes and pulled on a mob cap. The physicist explains the reason for the surgical gear: "We are now going into our laser lab, and that’s a cleanroom. We have to keep it totally free of dust because dust is the arch-enemy of optics!" Zeil then opens the door and enters a space the size of a classroom crammed full of long tables weighed down with apertures, mirrors and lenses. Just a couple of narrow aisles are left for the staff to move around. "This is the high-power laser DRACO, our workhorse," Zeil’s colleague Arie Irman comments. DRACO stands for Dresden Laser Acceleration Source. The device functions in several phases: a Ti:Sapphire laser, hardly bigger than a shoebox, generates ultra-short, relatively weak infrared pulses. They then pass through several amplifier stages during which special optics form, stretch, expand, compress and bundle them. At the end of the process, the pulses have a billion times more power, up to a petawatt, a quadrillion watts – although only for the extremely short span of just 30 femtoseconds, which is significantly less than one quadrillionth of a second. The superlaser serves one single purpose: Zeil and Irman are trying to find the most efficient way of accelerating particles almost up to the speed of light. They both head junior research groups at Helmholtz-Zentrum Dresden-Rossendorf. While Irman’s team concentrates on electron laser acceleration, Zeil and his colleagues are trying to speed up protons and other ions. Their vision is to create an efficient, relatively compact irradiation facility for modern proton tumor therapy. Particle accelerators play a prominent role in today’s research and applications: In our efforts to investigate the elemental building blocks of matter, a vast facility like LHC (Large _TEXT . Frank Grotelüschen LASERS AS PARTICLE TURBOS MAXIMUM: Laser physicist Arie Irman carefully adjusts the amplifier stages on the DRACO laser to optimize the intensity and profile of the beam. Photo: Oliver Killig

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