Energy deposition interactions, relative

In relative terms, the distance between energy deposition interactions (and penetrating power) is very large for X-rays and gamma rays (hence their utility for visualization within opaque objects), and moderate for electrons. For more... 

The interaction of an ultrahigh-intensity laser with a dense plasma is of wide interest, as these lasers open up new horizons for research, such as fs X-ray radiation probing [1,2], energetic particle acceleration [3], and inertial confinement fusion [4,5]. A new spectroscopic method that provides the kind of time- and space-resolved information required to obtain a more quantitative understanding of energy deposition than that provided by particle measurements has been under development [5-8]. Because of the relatively low temperatures that can be accessed with current lasers, conventional K-shell line spectroscopy using near-fully ionized plasma is not suitable. 

As high-energy electrons pass through an aqueous colloidal suspension of particles, energy is lost via electronic interactions in both the liquid and solid phases in a ratio determined by their relative electron densities and concentration. Thus, as the percentage of solid material increases, so does the fraction of energy deposited in the solid phase. It is common to conduct radiolytic experiments at constant volume (to ensure constant geometry relative to the radiation source). Thus, the dose absorbed in the sample increases with the increase of total density of the sample. This is shown in Fig. 2 as the upper solid curve. 

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