Nuclear activation as a current detector for proton beams produced by a high intensity laser

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• Francesca Fiorini, University of Birmingham
• Friday 06 November 2009, 16:00-16:45
• Physics West 106.

If you have a question about this talk, please contact Dan Kirby.

Preceded by tea, coffee and biscuits in the Poynting coffee lounge at 3.30pm

The Laser Induced Beams of Radiation and their Applications, LIBRA , is a Consortium which aims to develop a new type of ion source by shining a powerful laser beam onto a small target of metal, plastic or liquid. The laser’s energy causes intense high energy ionising radiation to be ejected from the surface of the target and the type of radiation emitted depends on the dimensions and composition of the target. The potential applications of this technique range from cancer treatments to critical fault diagnosis and three dimensional chemical and structural analysis.

The very short pulsed nature (of the order of few fs) of the high intensity laser source creates a similarly pulsed ion beam with very large instantaneous dose rate. This generates a challenge for the dosimetry techniques commonly used. In fact, the usual ways of detection may fail either due to saturation problems (films), recombination effects (gas), or insufficient capability to react to very short irradiation (scintillators). The purpose of this work is to use nuclear activation of a metal target as a detector for the current of the created proton/ion beams. It is known that the nuclear activity is directly proportional to the fluence-rate of the irradiating beam, and the measurable activation can be observed even if the irradiation is really short.

A study of this technique has been conducted using the proton beam at 29.2 MeV produced by the Birmingham Cyclotron, and several different targets (Cd, Ti, Cu) with large proton interaction cross sections and relatively short lifetime daughter nuclei.

The gamma emission spectra, measured with a HpGe detector, are used to measure the activity of the targets irradiated. This activity is then linearly dependent on the ion beam current.

This talk is part of the Molecular and Medical Physics Seminar Series series.

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• Molecular and Medical Physics Seminar Series
• Physics West 106
• What's on in Physics?

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