Application of Bent Crystals at IHEP 70-GeV Accelerator to Enhance the Efficiency of its Usage

Bent crystal was extracting 70-GeV protons with average intensity 4x10$^{11}$ (as measured in external beamline) per spill of ~1.6 s duration, in parallel to the simultaneous work of two internal targets in the accelerator ring. An additional crystal, placed in the external beamline, was deflecting a small part of the extracted beam with intensity ~10$^7$ protons toward another physics experiment. Crystal-extracted beam had a typical size of 4 mm by 4 mm fwhm at the end of the external beamline. Measurements for the extraction efficiency and other characteristics at the simultaneous work of four experimental set-ups are presented. With crystal working in the above-said regime during one month, no degradation of channeling was observed. The studies of extraction efficiency have been continued with new crystals.