In oder to increase the maximum achievable intensity of medium charge state heavy ion beams in SIS18 at GSI for FAIR-operation, the installation of cryoinserts is foreseen. These cryogenic surfaces with high sticking probability provide high pumping speed, where most of the beam-loss induced gas desorption takes place. Such, gas particles get quickly removed, minimizing beam loss by charge exchange from interaction with the residual gas. A prototype cryoinsert was designed, manufactured and tested, showing the clear reduction of artificial gas pulses. Most recently, the prototype was installed into SIS18. There, a reduction of the static pressure extending several meters after cooldown was observed. In 2025 the first beam experiments with medium charged Uranium beams and the cryoinserts took place to observe their influence. The charge exchange could be measured, showing a significant decrease due to the cryoinserts and also a slight influence on the transmission through an acceleration cycle was measurable. In the meantime, a series production of cryoinserts is prepared, including improvements and simplifications of the design.

Superconducting magnets are widely used in the FAIR facility in Darmstadt, Germany. For the main accelerator, the heavy-ion synchrotron SIS100, the iron dominated superconducting magnets are fast ramped, with up to 4 T/s for the dipole magnet. The ion-optical elements of Super-FRS are realized by large aperture superconducting magnets mostly. The large aperture dipole magnet will be installed a cave for Compressed Baryonic Matter (CBM) experiments. These magnets have a coil wound with low temperature superconductor (LTS, namely Niobium-Titanium), are cooled down to 4 K. For SIS100, installation and interconnection of the dipole magnets in the accelerator ring tunnel have been already started. Complex supply chain from the production to the assembled module testing of the quadrupole magnets with corrector magnets and beam instrumentations were reinforced. The first three Super-FRS multiplets at the pre-target area have been installed into the FAIR tunnel and connected to the local cryogenic system. For enabling FAIR's first scientific objective, so called Early Science, a comprehensive review workshop on Super-FRS's superconducting magnets was held. Production of the large aperture dipole magnet for CBM is ongoing at German industry. From the production, acceptance tests of the magnets and magnet modules, to the installation and the commissioning strategy of these magnets will be presented.

Two-plane multiturn injection is planned for SIS18 to enable the delivery of high-intensity heavy-ion beams, which will subsequently be accelerated and extracted toward SIS100 at a repetition rate of 2.7 Hz. To accommodate this new injection scenario, the existing SIS18 injection line must be redesigned to allow simultaneous injection into both the horizontal and vertical planes of the synchrotron. Ion-optical studies have been performed to evaluate the expected performance of the upgraded injection system, and the results are presented in this paper. The simulations demonstrate that the injection efficiency strongly depends on the emittance and transverse beam distribution of the beam delivered from UNILAC. Furthermore, a mismatch between the injected orbit and the equilibrium orbit defined by the transfer line optics leads to additional efficiency degradation. The paper discusses the impact of beam collimation in the transfer line, analyzes the sensitivity of the injection efficiency to various mismatch scenarios, and provides guidance for optimizing the two-plane multiturn injection process for SIS18.

Within the FAIR project, SIS18 is planned to be used as an injector and booster to increase the intensity of ion beams. To achieve higher intensities, a two-plane multi-turn injection scheme for SIS18 is being developed at GSI. The new injection system will allow a substantial increase in the number of accumulated turns with high efficiency, significantly reducing beam losses at the electrostatic septum (ES). This paper presents the conceptual design of the two-plane injection system and the results of studies on the expected properties of the U²⁸⁺ beam delivered from the upgraded UNILAC, including its parameters after collimation in the TK transfer line. Furthermore, the paper discusses the design requirements for the injection line and the anticipated performance of the two-plane injection system in SIS18, taking into account the beam optics of the injection line, collimation effects, and overall injection efficiency.

The accelerator complex for the Facility for Antiproton and Ion Research (FAIR) is currently being built in Darmstadt, Germany. After the arrival of the cold box for the central cryogenic facility (CRYO2) in winter 2023, the installation of the accelerator components in the machine and supply tunnels started early 2024. Meanwhile the installation has moved forward. CRYO2 has been handed over to the commissioning team and the commissioning is in progress. The accelerator installation is ongoing in all parts of the beamlines of the High Energy Beam Transfer Lines (HEBT), the Super Fragment Separator (SFRS) and the Heavy Ion Synchrotron (SIS100). In parallel, the installation plans for the experiments (NUSTAR and CBM) are being developed and installation preparations are taking place. In this paper the status and challenges of the machine installation in those areas are presented and an outlook for the next steps towards realisation of the project phases for Early and First Science is given.

SIS100 is a new and unique heavy ion synchrotron presently under construction at GSI, Darmstadt. It becomes the main accelerator of the international FAIR project and shall provide intense beams of all ions from Protons to Uranium. SIS100 is a fast ramped superconducting synchrotron and comprises lots of new technical features dedicated to the operation with high intensity, low charge state heavy ions. The major aim at designing SIS100 was the stabilization of the so called dynamic vacuum, which is the main challenge for minimizing charge exchange processes and corresponding beam loss at operation with low charge states. A new lattice concept, the so called charge separator lattice, cryogenic ion catchers, a LHe cooled and cryogenic UHV system and fast acceleration were chosen as major features of the overall machine concept. The functionality of this concept has been proven at the existing heavy ion synchrotron SIS18 and the SIS100 stringtest. Although SIS100 is a superconducting synchrotron, in order to serve the broad spectrum of users it shall provide a similar operation flexibility in terms of cycling as room temperature machines. In order to cope with the very different heat loads, dominated by AC loss in the magnet yokes, several technical measures have been implemented to assure a stable magnet cooling. The installation of SIS100 in the underground tunnel has been launched early 2024 and will lead into commissioning with beam in 2028.

SIS18, the main synchrotron of the present GSI accelerator complex, will serve as booster for the FAIR facility. Several major and minor upgrade programs were realized since 2008 to improve SIS18 for this purpose. We will report on new capabilities of the synchrotron for present and future user operation, which were not directly attributed to FAIR injector operation. Namely, a spill feedback system to control macroscopic spill shape and optimize spill microstructure during slow extraction. The operation of SIS18 with the new FAIR control system in conjunction with the RF upgrades allows beam operation without restrictions at lower injection energies. Acceleration of two beams consisting of ions with different mass to charge ratios at different revolution frequencies during acceleration are now possible and were successfully demonstrated in 2025. Possible users are medical research and plasma physics. As outlook we describe future plans for beam shaping before fast extraction for medical research.

How to "cool" intense beams of relativistic heavy ions? This is a very challenging task, especially when established ion beam cooling techniques have profound difficulties under such conditions. At the heavy-ion synchrotron SIS100 of the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, we will apply "bunched beam laser cooling" with a novel 3-beam concept, where laser beams from three complementary laser systems (1x cw and 2x pulsed) will be overlapped in space, time and energy to interact simultaneously with a very broad ion velocity range in order to maximize the cooling efficiency. We will present this project, including the facility and the laser and detector systems, and show new results from our simulations.

At GSI the design of a prototype electron lens to demonstrate space charge compensation in bunched ion beams is being continued. The ultimate goal is to increase the beam intensity for FAIR by compensating for the space charge forces in the synchrotrons operating with high intensity beams by overlapping with a pulsed electron beam in the electron lens. The development of the key components — e-gun and collector — is currently underway with the aim of installing them in the SIS18 e-cooler and demonstrating the concept for the first time. The conceptual design of the RF-modulated electron gun is completed, construction will start in mid 2026 and delivery is scheduled for autumn 2026. In the meantime, a test stand is being designed and will be set up at GSI to commission the e-gun and subsequently the collector. In this contribution, an overview of the ongoing activities regarding the details of the gun design, collector and the test stand set-up will be presented.

In this contribution, we report on the successful simultaneous acceleration of a beam composed of two different ions with unequal mass-to-charge ratio within the same cycle of the heavy ion synchrotron SIS18 at GSI. While acceleration of multiple charge states of a single ion species has been accomplished in linear accelerators, in a synchrotron this has never been done before to the knowledge of the authors. In a proof-of-principle experiment, low intensities of 56Fe25+ and 209Bi68+ were successively injected with horizontal multi-turn injection. Using two RF cavities, each ion species was then independently captured and accelerated in the same magnetic fields at its respective revolution frequency, the bunches of the lighter ion continuously overtaking those of the heavier ion. Such a beam composed of different ions has potential applications in particle therapy, plasma physics, nuclear physics, and materials research. The distinct revolution frequencies make this scheme attractive whenever independent control over the extraction of both ions is desired.