Optical Imaging of Charged Particle Tracks in a Gas

• Published in: Radiation protection dosimetry 1994-04, Vol.52 (1-4), p.323-328
• Main Authors: Hunter, S.R., Gibson, W.A., Hurst, G.S., Turner, J.E., Hamm, R.N., Wright, H.A.
• Format: Article
• Language: English
• ISSN: 0144-8420; 1742-3406
• DOI: 10.1093/oxfordjournals.rpd.a082208

The development of a new detector designed to optically image the track of a charged particle in a gas is outlined. In the detector, a pulsed high voltage (up to (30-40 kV), high frequency (f = 27.126 MHz) RF field is temporarily applied (pulse duration (1-3 µs) across a pair of electrodes, immediately following, or alternatively, just prior to the passage of a charged particle through the chamber. The pulsed RF field excites the subexcitation electrons left along the particle's path leading to excitation and ionisation of the surrounding gas and the emission of light. The track is then imaged by a fast intensified digital camera (shutter speed (0.1-5 µs). The image is recorded in a two-dimensional pixel array (512 x 512 pixels) within the camera, and transferred to a computer for later analysis. The detector has been operated over the total gas pressure range 2.5-100 kPa (20-750 Torr) using a gas mixture of 2-10% N2 in Ar. Images of both a and ß tracks obtained with this detector are discussed to demonstrate the usefulness of the present technique in charged particle track analysis for dosimetry and microdosimetry applications.