A diagnostic complex for monitoring the position, propagation direction, and angular distribution dispersion of a particle beam planned for application in the Boron Neutron Capture Therapy facility is described in this paper. For the beam position and direction, the precision is, respectively, 0.1 mm and 1 mrad at 10 mA CW H- beam with energy of about 35 keV and a diameter of the order of 10 mm. The energy spread and angular divergence were measured within the accuracy of about 100 eV and 3 mrad, respectively. The acceptable precision of about 1 mm for the beam position is obtained at a relatively short exposure to 10 ms. To increase the radiation intensity of the beam, the addition of various gases was studied. The addition of gas decreases the beam width and increases the negative ions stripping.