[en] Purpose: Assessment of relative biological effectiveness (RBE) of the proton medical beam at Moscow synchrotron. Methods and Materials: The study was performed at Moscow proton medical facility (Institute for Theoretical and Experimental Physics). Relative biological effectiveness of the synchrotron proton beam was assessed at the entry of the unmodulated 179 MeV beam and in the center of spread out Bragg peak (SOBP), from measurements of the survival of Chinese hamster cells (clone 431). Gamma-radiation of ⁶⁰Co was used as a reference source. Results: According to the linear regression model, mean RBE values at 37% survival level were found to be 1.10 ± 0.04 at the beam entry and 1.14 ± 0.05 in the center of SOBP. Values of RBE obtained using the linear-quadratic model for 10% and 37% survival levels were 1.09 and 1.07, respectively, at the beam entry and 1.07 and 1.08, respectively, in the center of SOBP. Conclusions: The data obtained indicate that (a) the RBE values at the entry of the unmodulated beam and at the center of the SOBP are in close agreement, with an average of about 1.10; (b) protons are radiobiologically somewhat more effective than ⁶⁰Co gamma rays; and, (c) high pulse dose rate of the medical beam does not significantly affect biological effects of the beam

[en] Numerous applications of protons and ions accelerated by laser radiation require charged particle beams of high quality (i.e., such that the ratio of the energy width of the beam to its mean energy is small). In order to produce beams with controlled quality, it is proposed to use two-layer targets in which the first layer consists of heavy multicharged ions and the second layer (thin and narrow in the transverse direction) consists of protons. The possibility of generating a high-quality proton beam in the interaction of ultraintense laser radiation with such a two-layer target is demonstrated by three-dimensional particle-in-cell computer simulations. (author)