The dispersion from the production target into the ESR is not matched.
This is not good for momentum acceptance, but we anyway want to cut the acceptance.
Dispersion will oscillate with the tune of ESR. After 3 turns we expect a maximum dispersion. 
The picture shows in red the dispersion curve for dp/p=0.1% and beam envelopes of 10 mm mrad.
So we can use scrapers in north or south arc to cut Brho. It should be done from both sides.
How much? Watch the intensity drop.
Best positions look at plot. Straight section outside for low Brho, arc outside for high Brho.
Could be EEXDS2HA and E02DSH (outside).