A facility with a horizontal beam for the radiobiological experiments was designed and constructed at the Heavy Ion Laboratory in Warsaw. The heavy ion beams from the U200-P Warsaw Cyclotrone are transported in a horizontal vacuum tube with conventional beam tuning components including a fast mechanical beam shutter which can be activated by the irradiation control system. After entrance collimation the beam is spread out passively by thin scattering foils (Au with thickness 50 – 20 mg/cm )
placed 2 m before the biological target. Multiscattering processes around 0o lead into good homogeneity of the radiation over an area of at least 1 cm . A homogeneity of the radiation field better than ±3% has been achieved over the diameter of the irradiated biological targets of 50 mm using controlled x-y step motor. The on-line beam dosimetry is assured by two silicon
detectors mounted at the 15o and 20o inside the scattering chamber. Simultaneously, the experimental output of the facility was proved by the appropriate Monte-Carlo multiscattering simulations. First irradiations of biological samples of the V79 cells
have shown the functionality of the setup.