Optimization of crystal extraction experiment

Using a computer model for the crystal extraction, we investigate the bent-crystal parameters optimal for the extraction experiment. The optimal crystal curvature is found to be near 1 GeV/cm (for pv/R), i.e. a factor of 2–3 higher than for the crystal application in beam lines. An influence of the accelerator optics on extraction is discussed. A possibility of using the high-Z crystals for extraction is considered. The simulations for the ongoing experiments at the CERN-SPS and the Fermilab Tevatron, and for the proposed extraction at LHC, are presented. ∗E-mail: [email protected] 1 Optimization of single-pass channeling Optimization of channeling in a single pass is well understood[1]. Two effects cause the particle dechanneling in a bent crystal: the bending dechanneling due to centrifugal force, and the scattering. For a given bending angle ΘB, a larger crystal length L means smaller curvature 1/R=ΘB/L and hence smaller bending dechanneling. However, the L increase means larger loss for scattering (characterized by the 1/e-dechanneling length LD). There is an optimal L, when losses from bending and scattering are roughly equal. In a harmonic approximation for the interplanar potential, the bent-crystal transmission can be estimated as F (ΘB, ρ) = AS (1− ρ) 2 exp (