A new experiment for the HERA collider expression of interest

We first review the physics topics which we consider to be the highlights of the proposed program. The increased sensitivity to the correct understanding of radiation in strong interactions is made clear in these sections. We then describe some first ideas on what the optimized detector for this physics would look like. We note that the physics described in the following sections cannot be carried out with HERA-II. This second phase of HERA running is focused on high Q"2 physics, which requires high luminosities. These are achieved by placing combined dipole/quadrupole magnets very near the H1 and ZEUS interaction points, thus limiting access to the small-x, low Q"2 physics which would be a central element in the proposed program. Also, many of the topics one would like to study require a different type of detector than the current H1 and ZEUS detectors. We close with a brief discussion of a possible time scale for the construction of a new detector and what we would consider to be a viable running plan. (orig.)Available from TIB Hannover: RR 2916(03-62) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman