  Currently a fast vertical 1.08-m long kicker (notcher) located in the
Fermilab Booster Long-5 straight section is used to remove 3 out of 84
circulating bunches after injection to generate an abort gap. With magnetic
field of 72.5 Gauss it removes only 87% of the 3-bunch intensity at 400 MeV,
with 75% loss on pole tips of the focusing Booster magnets, 11% on the Long-6
collimators, and 1% in the rest of the ring. We propose to improve the notching
efficiency and reduce beam loss in the Booster by using two horizontal kickers
in the Long-12 section. The STRUCT calculations show that using such horizontal
notchers, one can remove up to 99% of the 3-bunch intensity at 400-700 MeV,
directing 96% of it to a new beam dump at the Long-13 section. This fully
decouples notching and collimation. The beam dump absorbs most of the impinging
proton energy in its jaws. The latter are encapsulated into an appropriate
radiation shielding that reduces impact on the machine components, personnel
and environment to the tolerable levels. The MARS simulations show that
corresponding prompt and residual radiation levels can be reduced ten times
compared to the current ones.
