The status and development of the UNK project

The project of the IHEP Accelerating and Storage Complex (UNK) envisages the possibility of accelerating protons up to 3 TeV with the beam extracted onto the fixed target and of the collision mode at 6 TeV in the c.m.s. The 1st stage of the UNK incorporating the 3 TeV machine with the system extracting the beam onto the fixed target is presently under construction. The UNK is placed in the null 5.1 m underground ring tunnel having a circumference of 20.77 km. The presently existing 70 GeV proton synchrotron, whose intensity is planned to be upgrades up to 5x103 ppp, will be the injector into the UNK. The 1st stage of the UNK, UNK-1, i.e., the 400 GeV conventional machine, is the booster for the 2nd, superconducting stage, UNK-2, but it can also run as a storage ring. Another superconducting ring, UNK-3, is intended for 3x3 TeV proton-proton collisions. The orbits of the 1st and 2nd stages actually coincide, whereas those of UNK-2 and UNK-3 interchange periodically going from the inner wall of the tunnel to the outer one or vice versa to intersect in 4 points of Matched Straight Sections (MSS) 2, 3, 5, 6, where the detectors for colliding beams may be placed. In addition to these MSS's (2, 3, 5, 6), for the experimental setups, each 490 m long, the project also envisages another two 800-m technological sections, MSS1 and MSS4. MSS1 will house the injection, loss localization and beam abort systems as well as the accelerating stations for all the stages. MSS4 is intended for the systems of extraction and beam transfer from UNK-1 into UNK-2 and UNK-3. A part of the MSS6 space is to be occupied by the reverse beam injection from U-70 into UNK-1 in the pp-colliding beam mode