The time projection chamber for heavy-ion collisions: Trends and perspectives

The very large charged-particle multiplicities expected in a high-energy nucleon-nucleon collision, together with the wide range of energy loss by ionization, makes the conception of a tracking detector extremely challenging. One device, the time projection chamber, widely used in particle-physics experimentation, seems very promising in this context. In the present paper, after a brief summary of the operating principles and of the performances achieved in the existing detectors, I will discuss in more detail the expected performances in a high-multiplicity environment, as well as the recognized problems arising from the large charge densities detected. Some alternative devices that might overcome the recognized limitations of the standard design will also be described.