Direct photons are of great interest for the research program of the CBM experiment. The first objective of the proposal is to evaluate the sensitivity of the CBM calorimeter system to the direct photon signal as a function of pT for each of the state-of-the-art analysis methods (background subtraction, correlations and low-mass e+e- pairs) and to derive an optimized setup. Existing microscopical transport codes like UrQMD, HSD, and RQMD generate only decay photons but do not include direct photon production processes. To obtain a suitable event generator for this study, we plan to incorporate, in collaboration with theoreticians, direct photon production from meson scattering processes (pi rho --> pi gamma, pi pi --> rho gamma, etc) into the HSD code. The second objective is the design and prototyping of a calorimeter handling the large track densities in heavy-ion collisions. The large hit density in the most central region leads to a large probability that photon, electron and hadron showers overlap. Therefore, the photon and electron detection and identification becomes a real challenge in heavy-ion collisions in contrast with pp interactions. The solution of this problem is two-fold. From the hardware side, we need to develop a calorimeter module with a small Moliere radius. From the software side, we will investigate algorithms for unfolding overlapping showers in the calorimeter, to search for the most significant parameters for particle identification. The technological challenge is to improve the technology for the construction of thin scintillator tiles with uniform light collection. After this study we shall have a set of new results: analysis of direct photon production in heavy-ion collisions in the SIS300 energy range in the framework of a microscopical transport model, algorithms for simulation, reconstruction and particle identification in the CBM calorimeter at high-multiplicity environments, the sensitivity of the CBM calorimeter for the direct photon signals, the calorimeter module prototype with small Moliere radius necessary for operating at large occupancy. These will be performed in the framework of the CBMROOT package using a set of generators and transport codes GEANT3/GEANT4, electron and pion beams and test facilities at IHEP and ITEP. The results will be presented in the CBM technical proposal at the end of 2007. This project is an important contribution for the experimental research program in the future heavy-ion physics program at FAIR.