Great question! The biggest difference is luminosity. The proposed collider, eRHIC (electron Relativistic Heavy Ion Collider), will generate 100-1000x more collisions per second than HERA.
Second, eRHIC will generate ion beams as well a proton beams. This is a key distinction as protons and neutrons are modified by being inside a nucleus so their internal quark distributions are modified as well. These differences will shed light on some of the key properties of the strong nuclear force.
Third, the detectors and collider will be designed to probe further down into the low-energy tail of the sea quark distribution than HERA and other previous e-p colliders did. This will include designing the beam and detector to allow for very forward instruments which would measure small deflections due to extremely low-energy particles.
Ah interesting! Thanks for answering. The question came from looking up electron-ion colliders on wikipedia and noticing that one had already been built. So was curious as to what had changed. Thanks again.
Second, eRHIC will generate ion beams as well a proton beams. This is a key distinction as protons and neutrons are modified by being inside a nucleus so their internal quark distributions are modified as well. These differences will shed light on some of the key properties of the strong nuclear force.
Third, the detectors and collider will be designed to probe further down into the low-energy tail of the sea quark distribution than HERA and other previous e-p colliders did. This will include designing the beam and detector to allow for very forward instruments which would measure small deflections due to extremely low-energy particles.