Effects of proton beam energy

Effect of Proton Beam Energy on the Sensitivity and Contrast of Select Si-Containing Resists... 

Figure 4. The effect of proton beam energy on the sensitivity (QH) of the MOTSS copolymer resists.

It is clear that even radiations of lowest LET value, most penetrating, must deposits concentrations of energy in narrow zones on the molecular level. From experiments on aqueous solutions and later on solids, one can assume, that ca 80% of energy is deposited in single ionizations. That proportion turns into increase of participation of multi-ionization spurs with the increase of the LET value of the applied radiation. Effects of proton beam of comparatively low energy of 10 MeV are already easy to recognize. 

Straggling effects become more dominant further into the sample. They are most pronounced with proton beams, because the ratio of energy straggling to energy loss decreases with increasing ion mass. For protons, these effects may be quite substantial for example, depth resolutions in excess of 1000 A are typical for 1-MeV protons a few pm into a material. 

MeV required in proton-therapy for an effective treatment of deep seated tumors [26]. Fuchs and co-authors have proposed a scaling law [27], allowing the necessary laser parameters to produce proton beams of interest for such applications to be estimated. In their work, best suited to hundreds of fs/some ps duration laser pulses, they use the self-similar fluid model proposed by Mora [28] giving the following estimate for the maximum FWD proton energy ... 

Over the years, Jens Oddershede has written extensively on various aspects of energy deposition by swift ions in material targets. In many cases, he has been concerned with the orientational effects of target molecules with respect to the projectile beam direction, and has explained these differences in the context of the relevant oscillator strength distribution of the target [1-8]. It is in the spirit of Jens work that we carried out this study of the orientational aspects of the energy deposition by swift protons in water, and we report them now in celebration of his the-third-times-twentieth birthday. 

Radiolysis experiments using heavy ion beams (protons and heavier atomic nuclei stripped of all electrons) occupy an important role, despite the relatively small number of investigators in this area. Because heavy ions have much higher LET values, the pattern of energy deposition, or track structure, is much denser than with "lighter" radiations. The variation of yields of radiolytic products as a function of LET, and the effects of variable... 

The maximum energies available in conventional cyclotrons of the constant frequaicy type are about 25 MeV for protons and deuterons, and 50 MeV for a-particles. The shape of the electrostatic field at the gap between the dees as well as the design of the magnetic held to produce a slight non-uniformity at the outer edges of the dees produce a focusing effect on the beam particles. The ion currents are usually 0.5 mA for the internal beam, and about a factor 10 less for an external beam. 

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