Topicality of this work is caused by the fact that modern detectors aren't effective in searching electrons and positrons with energies higher than 1 TeV and therefore, such particles remain practically uninvestigated. The investigation of high- energy electrons and positrons will allow to define local sources of cosmic rays and processes of cosmic ray propagation in the interstellar space. It is necessary to note a great interest of scientific community to the problem of increase of a positrons fraction in total flux of electrons and positrons at high energies obtained in "PAMELA" experiment [2]and later confirmed by Fermi-LAT[6] and AMS02 [3] (fig.1). The development of a new detector can help to investigate the origin of the positron excess at high energy. Introduction Methods 1. O. F. Prilutskii. The possibility of registering primary cosmic electrons by means of synchrotron radiation in the geomagnetic field. JETP, 1972.V. ZhETFPis. Red. 16, No. 8, O. Adriani et al.[ PAMELA collaboration] An anomalous positron abundance in cosmic rays with energies 1.5–100 GeV. Nature 2009V. Vol April M Aguilar,.D. Aisa, A. Alvino et al. [ AMS02 collaboration] Electron and Positron Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station Physical Review Letters, Volume 113, Issue 12, id JI. Musser et al. Limits on the Multi-TeVCosmic Ray Electron Flux from CREST,PoS,Proc. 34th ICRC, 2015, V. S. Berezinskii, S. V. Bulanov, V. A. Dogiel, V. L. Ginzburg (Ed.), V. S. Ptuskin: Astrophysics of Cosmic Rays. North-Holland, Amsterdam, M. Ackermann, et al., (Fermi LAT Collaboration) Measurement of Separate Cosmic-Ray Electron and Positron Spectra with the Fermi Large Area Telescope Phys. Rev. Lett. 108 (2012) To identify electron and positron the registration of signals is required for at least two emitted photons and the particle itself. Background can be created mainly by upward secondary gammas from interaction inside the instrument or accidental coincidences. Its rate was estimated from paper [4]. Acknowledgments We would like to thank Dr. A. Berdnikova for providing us test data of CdTe detectors References Procedure. Conclusion Calculations have shown a possibility of creation of the orbital detector, for registration of positrons and electrons with energy higher than 3 TeV, based on their synchrotron radiation in the magnetic field of the Earth. Purpose To estimate parameters and possibilities of the orbital detector for registration of high energy electrons and positrons based on their synchrotron radiation in magnetic field of the Earth. To determine the position of a particle, recorded by the detector on the boundary of the magnetosphere, its antiparticle (positron for electron) was started up from the surface of the detector calculating its trajectory to a height of several tens of thousands kilometers. The second part of the program reproduced trajectory of the particle in opposite direction from boundary of the magnetosphere to the detector. At the same time emission of photons is simulated and their trajectories are also calculated. Finally the checking was carried out that the synchrotron photons are within the sensitive surface of the detector. Results. In 1972 in the work [1]was suggested studying cosmic rays with the help of the detector which would detect electrons and positrons by using their synchrotron photons they emit, moving along the trajectories, curved by magnetic field of the Earth. The quantitative estimation of parameters of such kind of detector is made in the project Topicality The table shows the results of the estimation of the average number of photons that will fall on the detector size of 1m 2. Obviously that than more photons will be registered on the detector than identification of electrons and positrons will be better and the accuracy of the energy measurement will be higher. Also spatial resolution was evaluated of the detector which needed to reduce the count of background events. In the presence of random 5 noise pulses on 1m 2 for each event [4] and at spatial detector resolution of about 10 mm this background does not exceed 5%, which is an acceptable value for the expected number of events (about one hundred per year). fig.7 Picture of CdTe detector with Au electrodes used for the tests in MEPHI laboratory (photo authors) The instrument consists of two layers of X-ray strip detectors (d1,d2) and two layers of fast scintillator detectors (C1, C2) to provide trigger. To discriminate cosmic ray protons tungsten layer will be used between C1 and C2. Only events with trigger signal C2>> C1 will be considered. All electrons will interact in tungsten layer W producing electromagnetic shower and providing trigger condition. fig.5 physical scheme of the detector. fig.3 Model of event detection. fig.9 Energy resolution vs voltage About CdTe x-ray detector The detector is widely used in various fields (space research, e.q. in the Swift mission, medical devices, etc). According to data providing us by the MEPHI electronics laboratory rather the good characteristics of the detector can be achieved using even standard laboratory equipment. Figure 9 shows energy resolution as function of voltage and figure 8 shows obtained energy spectrum of Cs source at 350 V. Gamma line 600 keV is clearly visible on the figure. Finally CdTe detector allows to register gamma-rays from about 1keV with good energy resolution. Using strips is possible to achieve a high spatial resolution of the instrument. Results fig. 1 The electron energy spectrum obtained in modern experiments. Ref. in [2,3] fig.6 Average calculated photon energy vs. altitude of emission point for different electron energies. Detector threshold is shown by dashed line. Altitude of International Space Station (ISS) is about 400 km fig.8 Energy distribution for the source fig. 10 Size of detector as function of electron (positron) energy fig.2 The positron fraction shows a rapid decrease from 1 to 8 GeV followed by an anomaly increase [3]. fig.4 event topology the average energy of the photons l-average path length of the radiation IGRF2010 model ( a.gov) of magnetic field was used in the analysiswww.ngdc.noa a.gov