Beam halo crystal extraction from the Tevatron during collider runs

We have shown by the computer simulation how to extract 1-TeV beam halo protons from the Tevatron using a bent crystal. More than 107 protons per second, now lost on scrapers and collimators, can be extracted in a ''passive'' mode, without interference with colliding beam experiments. This would reduce background in the colliding beam detectors. The problem of an existing imperfect layer at a bent crystal surface is solved by means of a thin crystal that is used as a crystal mirror for beam halo particles. The extraction efficiency can be as large as 99%. The availability of an extracted beam will enhance detector R and D studies at Fermilab and give an additional boost to the U.S. participation in the LHC experiments. As a second priority, small fixed target experiments could be carried out. Crystal scrapers-deflectors would also work well for the LHC where background radiation due to a beam halo loss could be reduced by the factor of 100. (orig.)