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Developement and Construction - HESR

The HESR (High Energy Storage Ring) is one of the IKP's contributions to FAIR (Facility for Antiproton and Ion Research). As the name suggests the HESR is a storage ring designed for antiprotons and ions in a momentum range from 1.5 to 15 GeV/c (energy range 0.83 to 14.1 GeV. From the injection energy of 3 GeV particles can be either accelerated or decelarated within this range as experimentally required. The ring is designed as a racetrack with a circumference of 575m.

The beam of 1010 particles is held on track by 44 main bending magnets in the two symmetric arcs. The bending dipole's field of between 0.17 and 1.7 T causes a deflection of the beam by 8.2° in each 4.2m long magnet. In addition to these 44 magnets there are 84 quadrupoles in 25 families to provide focusing power to keep the tune near 7.61. Chromaticity correction is achieved with 52 sextupole magnets in 16 families.

In Jülich the IKP-4 is responsible to manage design, acquisition and assembly of all components for HESR. In addition to the magnetic components mentioned above IKP-4 is heading the development of a new concept for stochastic cooling that was specifically designed for the HESR. The pickups and kickers are currently being tested in COSY to provide valuable insight into performance and operation useful to make further improvements to the system in the future. Furthermore, IKP-4 has conceptualized and monitored the design of new power supplies for the HESR to satisfy the extensive requirements set for stability and accuracy by the requested beam parameters. New designs for Beam Position Monitors (BPMs) are currently being developed to provide more accurate measurements of beam behaviour in the HESR once in operation. Additionally, the RF acceleration system was recently redesigned to accommodate changes to the FAIR project. It was previously planned to have an accumulator ring (RESR) to inject into the HESR at an kinetic energy of 3 GeV. Since the RESR has been postponed HESR needs to provide accumulation as well. In order to achieve this the RF system has been redesigned with air cooling and multi-harmonic cavities using high permeability cores. The feasibility of this concept as well as of the injection scheme has recently been demonstrated.

In order to build a machine that is capable of providing beam consistent with the very ambitious specifications set by the planned experiments PANDA and SPARC the scientists and engineers at IKP are constantly pushing the boundaries of what is technically possible and feasible within the given budget constraints. New concepts are systematically developed to achieve even better performance, often under collaboration with industry partners and other research institutes around the world. Concepts are discussed repeatedly with experts in the field at different conferences gaining valuable feedback to make further adjustments and redefine the state of the art in all relevant fields.

Once a design has been adopted and approved manufacturing needs to be planned and supervised. Overall, the IKP takes responsibility for spendings in the order of 64 million Euros. As soon as contracts with industry partners are made IKP-4 staff closely collaborates with staff at the manufacturing companies to ensure quality standards and specifications are met. Every single readily manufactured component is first delivered to Jülich, where it is closely examined and tested. For the magnets this includes a 3D field measurement to ensure the required field homogeneity is maintained at all points. Each power supply is stress tested using a real magnet as test load to detect any unacceptable manufacturing deviations.

All components that pass the tests are ready for preassembly. Groups of components are preassembled in Jülich and then shipped to an intermediate storage close to the GSI campus in Darmstadt to await final assembly on location at the GSI. Assembly is currently scheduled to begin in 2021 with commissioning planned to start no earlier than 2022. By 2019 the IKP will have designed, acquired, tested nearly all HESR components. By May 2017 50% of the dipole magnets have been preassembled and delivered to FAIR.