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The quality of slowly, typically several seconds, extracted beams from the GSI synchrotron SIS18 is characterized with respect to the temporal beam stability, the so-called spillμstructure on the 100 µs scale. A pilot experiment was performed utilizing transverse emittance exchange to reduce the beam size in the extraction plane, and the improvement of spillμstructure was found. Important beam instrumentation comprises an Ionization Profile Monitor for beam profile measurement inside the synchrotron and a plastic scintillator at the external transfer line for ion counting with up to several 10⁶ particles per second and 20 µs time slices. The performant data acquisition systems, including a scaler and a fast Time-to-Digital Converter (TDC), allow for determining the spill quality. The application of the TDC in the measurement and related MAD-X simulations are discussed., Proceedings of the 11th International Beam Instrumentation Conference, IBIC2022, Kraków, Poland

OpenCMW is an open-source modular event-driven micro- and middle-ware library for equipment- and beam-based monitoring as well as feedback control systems for the FAIR Accelerator Facility. Based on modern C++20 and Java concepts, it provides common communication protocols, interfaces to data visualisation and processing tools that aid engineers and physicists at FAIR in writing functional high-level monitoring and (semi-)automated feedback applications. The focus is put on minimising the required boiler-plate code, programming expertise, common error sources, and significantly lowering the entry-threshold that is required with the framework. OpenCMW takes care of most of the communication, data-serialisation, data-aggregation, settings management, Role-Based-Access-Control (RBAC), and other tedious but necessary control system integrations while still being open to expert-level modifications, extensions or improvements., Proceedings of the 18th International Conference on Accelerator and Large Experimental Physics Control Systems, ICALEPCS2021, Shanghai, China

With the recent developments on improving spill quality at GSI/FAIR, appropriate measurement devices have come into focus again. In contrast to commonly used scaler-based approaches where events at a certain sample frequency are counted, we present a measurement concept resolving single event detector timestamps in the sub-ns regime leveraging a well established off-the-shelf TDC VMEbus module. This allows for high resolution time structure information with respect to the ring RF as well as valuation of inter-particle separation distributions. This yields insightful information for specific experiments at GSI whose efficiencies are heavily limited by pile-ups and detector dead times. We will present the concept of the measurement setup and exemplary data taken in recent campaigns in context of spill microstructure improvements for slow extraction., Proceedings of the 10th International Beam Instrumentation Conference, IBIC2021, Pohang, Rep. of Korea

The accurate graphical representation of accelerator- or beam-based parameters is crucial for commissioning and operation in any modern accelerator. Charts are one of the most visible but at the same time often underappreciated accelerator control system components even though these are crucial for easing and improving a quick intuitive understanding of complex or large quantities of data, which in turn is used to efficiently control, troubleshoot or improve the accelerator performance. While the Java SDK and other third-party libraries provide some charting components, we found that these lack either functionality, performance, or are based on outdated complex APIs. Based on earlier GSI and CERN designs and careful analysis of missing functionalities, performance bottlenecks, and long-term maintenance risks for the necessary workarounds, we decided that it was worth to re-engineer a new scientific charting library that preserves the functionality of established other libraries while addressing the performance bottlenecks and APIs issues. The new library offers a wide variety of plot types common in the scientific community, a flexible plugin system to extend the functionality towards chart interactors as well as online parameter measurements commonly found in oscilloscopes. Tailored towards high performance, it achieves real-time update rates up to 25 Hz for data sets with a few 10k up to 5 million data points. The new API shields the complexity from and eases the library’s use by normal users, while still being modular and having explicitly open interfaces that allow more-inclined developers to modify, add or extend missing functionalities. This contribution provides a performance and functionality comparison with other existing Java-based charting libraries., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

We present the beam instrumentation of CRYRING@ESR, a low-energy experiment facility at the GSI Helmholtz-Centre for heavy ion research. The 1.44 Tm synchrotron and storage ring, formerly hosted at the Manne Siegbahn laboratory in Stockholm, Sweden, was modified in its configuration and installed behind the existing ESR, the experimental storage ring. As the first machine within the ongoing FAIR project, the facility for antiproton and ion research, it is built on the future timing system and frameworks for data supply and acquisition. Throughout the past year CRYRING was commissioned including its electron cooler with hydrogen beams from the local linear accelerator. Storage, acceleration and cooling have been demonstrated. The contribution provides an overview of the beam instrumentation. The design of the detector systems and their current performance are presented. Emphasis is given to beam position monitors, detectors for intensity measurements, and the ionization profile monitors., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

In preparation of FAIR, several well-established beam instrumentation systems of the GSI heavy-ion synchrotron SIS18 and its connected high-energy beam transfer lines (HEBT) have to be modernized. In this contribution, the data acquisition upgrade of particle detectors such as ion chambers and plastic scintillators is described. This covers the replacement of an outdated custom-built readout- and control hardware by modern FMC (FPGA mezzanine card) based I/O hardware, new multi-channel high voltage power supplies and a new data acquisition system (DAQ) for the VME based scalers. The latter will replace the old Kylix-based ABLASS software by LASSIE (Large Analog Signal and Scaling Information Environment) to fit into the new FAIR control system concept. LASSIE is based on FESA (Front End Software Architecture). FESA was originally developed by CERN and enhanced by GSI-specific modifications. Furthermore, the new particle detector DAQ will be able to take full advantage of the new FAIR timing system which is based on the White Rabbit protocol., Proceedings of the 15th Int. Conf. on Accelerator and Large Experimental Physics Control Systems, ICALEPCS2015, Melbourne, Australia

At FAIR the re-assembly of the well known CRYRING accelerator, formerly hosted by Manne Siegbahn Laboratory (MSL) Stockholm, is currently in progress. This compact low energy heavy ion synchrotron and experimental storage ring will be a testing platform for all control system (CS) concepts decided on for FAIR. The CRYRING CS will be based on the system originally developed by CERN which combines the JAVA based application level LSA (LHC Software Architecture) , the data acquisition level FESA (Front-End Software Architecture) and the White Rabbit based timing system. All parts have been enhanced with GSI specific functionality. In preparation for the commissioning of CRYRING later in 2015 all required beam instrumentation (BI) equipment including the software is now under development. The data acquisition (DAQ) concepts for the various instruments is presented, with emphasis on the seamless integration into the overall CS. For standard BI systems, such as digital imaging, profile and intensity measurement, VME and IndustryPC based DAQ systems are used. For beam position monitoring a new hardware strategy which combines the microTCA and FMC (FPGA mezzanine card) form factors is under evaluation., Proceedings of the 15th Int. Conf. on Accelerator and Large Experimental Physics Control Systems, ICALEPCS2015, Melbourne, Australia

GSI Scientific Report 2014 - GSI Report 2015-1

Accelerator facilities require access to many beam parameters during operation. The field of beam instrumentation serves this crucial role in commissioning, setup and optimisation of the facility. An important information is contained in the phase-space distribution of the accelerated particles. In case of GSI (Helmholtzzentrum für Schwerionenforschung) those are ions from protons to uranium. If established methods to access certain beam parameters do not exist, new approaches have to emerge. This is the case for the presented measurement setup which has been designed and realised by Forck et al. to support commissioning of the GSI high-current injector. It is aiming at an experimental method to access the longitudinal phase-space distribution at low energies of 1.4 AMeV. Established methods for higher energies and based on the measurement of the electric field distribution are not feasible at non-relativistic velocities. The presented method is based on a time-of-flight (TOF) measurement between two particle detectors. A modification allows, alternatively, the direct measurement of the kinetic energy using a mono-crystalline (MC) diamond detector. Currently, besides others, the focus of the optimisation of the injector is put on the longitudinal phase-space distribution. It allows for a systematic optimisation of the matching into the accelerator cavities and, thus, an improved transmission as well as lower emittance values. The new accelerator facility FAIR (Facility for Antiproton and Ion Research), a large-scale upgrade at GSI, requires an improved beam quality at the existing injector. In this work the experimental setup is investigated for its feasibility to measure the longitudinal phase-space distribution. To this end, the phase and momentum of the single ions along the beam axis have to be determined with high precision. Finally, the longitudinal phase-space distribution is identified with the measured ensemble. The setup is presented in detail, introducing necessary concepts such as the phase space and emittance and is followed by a discussion of the data acquisition and data analysis. An important part of the latter is the introduction of a robust estimator for the covariance matrix of the measured distribution which is directly connected to the RMS emittance. However, the classical estimator is very sensitive to outliers in the measured data. The usual approach of subjective selection of cut regions is thereby avoided. The TOF setup has been tested with low and high current beams where a general sensitivity to the longitudinal phase-space distribution was confirmed. Furthermore, the gas pressure at the stripper section and the setup of the high-current slits, required for beam attenuation, have an impact on the measured distributions. Scattering of ions at the slits leads to a larger energy spread, larger bunch length and, consequently, emittance. Independent of the configuration, deviations from the expected values of the energy spread ∆E/⟨E⟩ ≈ 1 % and the Twiss parameter α ≈ 4 have been measured. The energy spreads were larger than the theory values by a factor of 1.5-1.6. However, a direct measurement of the bunch structure, while using sensible high-current slit settings, proved valuable. Low-current measurements with the MC diamond detector featured a gain loss of 5 % pulse height and 2 % pulse integral after irradiation with ≈ 3×10^4 argon ions. Although this effect is corrected in the data analysis, the energy spread is significantly larger than expected, like in the TOF measurements. Similarly, the values for α were below 0.5. Prominent trails in the measured distribution showed a broad energy spectrum and could be quantitatively attributed to interaction with the collimator apertures. As the measurements hint an insufficient energy resolution, this effect has been investigated in a Gaussian model space. The discrepancies between expected and measured values ∆E/⟨E⟩, α and emittance could be resolved by assuming a system response of 1.3 %. In the scope of this model space and knowledge of the TOF resolution an approximation to the real longitudinal phase-space parameter by back transformation of the covariance matrix was suggested. Furthermore, the Gaussian model space allowed to deduce an analytic formula for the required energy resolution. This showed a high dependency of the resolution on the Twiss parameter α which scales with 1/α. For instance, to target a precision of the emittance within 10 % requires a TOF resolution of better than 30 ps. This motivated a survey on the possible systematic contributions. The dominating contribution was found to be the inhomogeneity of the foils. The tantalum foil alone contributes an energy broadening of σE/⟨E⟩ ≈ 1 % and is of the same size of the expected energy spread of beam. Including all systematic sources quantitatively supports the considerations made in the Gaussian model space. While the experimental setup is not yet able to measure the full longitudinal phase-space distribution, it is capable of providing valuable information about the bunch structure. Several campaigns have been successfully supported with bunch-structure measurements.