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P: Plasmaphysik

P 3: Dense Plasmas

P 3.4: Vortrag

Dienstag, 3. April 2001, 17:15–17:30, 2053

Photoneutron production with table-top TW lasers — •Stefan Düsterer¹, Rolf Behrens², Christian Ziener¹, Heinrich Schwoerer¹, and Roland Sauerbrey¹ — ¹Inst. für Optik und Quantenelektronik, Uni Jena — ²Physikalisch-Technische Bundesanstalt, Braunschweig

We report on the photofission of nuclei with a TW Ti:sapphire laser. For the first time nuclei were split by the use of a table-top laser system.
Extremely hot plasma (T_hot ∼ 500keV) is created when an intensive femtosecond laser pulse (5 × 10¹⁸ W cm⁻²) interacts with a solid high Z target. Electrons are accelerated by the laser within this plasma to energies of several MeV. They emit high energetic bremsstrahlung when they interact with the surrounding matter. X-rays with energies above the fission threshold of 1.67 MeV initiate the photofission of Be resulting in two alpha particles and a neutron: ⁹Be → 2 α + n. The neutrons were detected by another nuclear reaction. Gold nuclei were activated by ¹⁹⁷Au + n → ¹⁹⁸Au. The subsequent γ-decay of the ¹⁹⁸Au was measured and showed that about 100 neutrons were produced per laser shot.
The production of neutrons with a compact table-top laser system enables medical applications. The needs and demands of radiology and their feasibility will be discussed.