[en] An important aspect of the cooler operation is the collector efficiency. The low loss current improves the vacuum condition, the radiation condition and makes the easy design of the power supply system. This article deals with the reuse of collector at the electrostatic bending in the toroidal section. It's possible to compensate the centrifugal force for the secondary electrons by the electric field because the effect of both forces is independent from the direction of the electron longitudinal velocity. As result the secondary electrons may return into the collector after reflection from the gun. Nonzero loss current is defined mainly by the energy spectrum of the secondary electrons. The review of the experimental data for the different cooler is described in this article. The range of the electron energy is 2-300 keV. Some physical model is proposed for the experiment explanations

[en] Description of equipment developed at BINP SB RAS for precision solenoid magnetic field measurement is presented in the paper. Transversal field components are measured by small compass-based sensor during its motion along the field line. The sensor sensitivity is a few tenth parts of mG and is limited in this range by external noise sources only. Scope of the device application is illustrated by results obtained at BINP during tests of cooling solenoids for electron coolers built at the Institute recently

[en] The subject of the report is the problem of the technical feasibility of fast electron cooling in the energy range between 0.8 and 14.5 GeV. It is very useful for one of the major objectives of the GSI and COSY future plans. For the realization of the cooler device BINP team proposes the design that is like the conventional and elaborated for the low energy cooling (up to 300 keV). The main features of this design are the accelerating tube immersed in the magnetic field along the whole length and the strong magnetic field in the cooling section. The physics of electron cooling is based on the idea of the fast magnetized cooling. The cooling force at strong magnet field was measured at many experiments and can be surely estimated. The magnetized cooling rate enables to obtain the required beam parameters, eliminate the beam heating due to intrabeam scattering, fluctuations of ionization energy losses and multiple scattering in the internal target