What is the advantage of long baseline neutrino accelerators, with respect to short baseline ones ?
Let me clarify : with long baseline, there is important MSW effect from travelling earth. There is also the spread of the focusing of the neutrinos with long distance. All these drive to uncertainties. There is also the cost of big logistic to have two detectors at >100 km distance, for people in a same Community (money for transport for people of the collaboration, etc.)
Why with short Baseline, all these problem don't exist.
Since the important parameter for exploring neutrino phase space is L/E, why just increase the requested energy of the neutrino, from the selection at the production site. In this way, we have a reasonable distance. (The only drawback that I see in the increase of energy is that the separation of pi/kaons (that produce the neutrinos) will be worst, so that there will be a bit more contamination from antineutrino in the neutrino source.)
In addition, it seems, from : Why does the Neutrino cross-section increase with energy? that with increased Energy, we would have increased cross-section.
So what is the advantage of having long baseline experiments accelerators for neutrinos ?