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In this paper, the problem of undesirable photonuclear, electronuclear and neutron capture reactions taking place in the treatment room during emission of the typical high-energy therapeutic beams from two different medical accelerators, i.e. Primus Siemens and Varian Clinac-2300, is presented. The radioisotopes (187)W, (56)Mn, (28)Al, (57)Ni, (38)Cl, (57)Co and (19)Au and the neutron activation of (1)H were identified as a consequence of these reactions. Moreover, the increased photon fluence rate behind the door of the accelerator bunker in the operator console room was observed during emission of the 20 MV X-rays from the Varian Clinac-2300 as well as in the case of the 15 MV X-ray beam from the Primus Siemens. No increased radiation was observed during the 6 MV X-ray beam emission. The performed measurements produced evidences on the presence of neutrons in the operator console room during emission of the 15 MV X-ray beam from the Primus Siemens as well as the 20 MV X-rays and the 22 MeV electrons from the Varian Clinac-2300 accelerator.

Measurements of the analyzing power for the pp-->pp eta reaction have been performed at excess energies of Q=10 and 36 MeV. The determined analyzing power is essentially consistent with zero, implying dominance of the s wave at both excess energies. The angular dependence of the analyzing power, combined with the isospin dependence of the total cross section for the eta meson production in nucleon-nucleon collisions, reveal that the excitation of the nucleon to the S11(1535) resonance is predominantly due to the exchange of the pi meson between the colliding nucleons.

A method involving a Wallac 1414 WinSpectral alpha/beta liquid scintillation counter for determining 222Rn in aqueous samples is described. Samples were collected from 23 springs and 4 taps in health resorts of the Klodzka valley in the Sudety mountains in Poland. Half of the investigated spring water samples were radon enriched with an activity concentration higher than 74 Bq/l. In the tap waters the radon concentration level is very low or below the lower limit of detection. Owing to the statistical nature of radioactive decay the uncertainty of the measurement was determined as the standard deviation of 222Rn activity. The method introduced is fast and simple and does not require a chemical sample preparation procedure.