Research Group Joachim Enders
Technical Nuclear Physics

R&D at the GSI Helmholtz Research Center for Heavy-ion Research and at the future Facility for Antiproton and Ion Research (FAIR)

At the GSI Helmholtz Research Center for Heavy-ion Research in Darmstadt-Wixhausen the future Facility for Antiproton and Ion Research is currently being built that includes a powerful accelerator system enabling research in hadron physics, nuclear physics, and atomic physics. The NuSTAR collaboration uses the intense heavy-ion beams to produce and subsequently investigate short-lived atomic nuclei. Central work-horse for the production of short-lived nuclei will be the superconducting fragment separator (Super-FRS). The existing fragment separator FRS at GSI will be used for tests and preparatory experiments (“FAIR Phase 0”) until FAIR gets completed. Nuclear physics topics to be addressed by our group include, among other things, the single-particle structure of radioactive nuclides, the limits of nuclear stability, and fission of unstable nuclei.

Figure: Schematic representation of accelerator controls at GSI and FAIR using the LHC Software Architecture LSA.

To facilitate such experiments one needs not only state-of-the-art hardware, detector systems, experimental setups, supplies, cryogenics, and vacuum technology, but also a functioning and reliable control system providing a unified environment for operating beam transport at GSI and FAIR. Another aspect is that GSI/FAIR is supposed to be able to operate several experiments at the same time.

To this end, the framework LSA (LHC Software Architecture), which has originally been developed by CERN, is implemented for use at the GSI Helmholtz Research Center and FAIR. Among the challenges are data-base design, application development, or machine modeling of systems like the SIS18 accelerator or the FSI. The new controls are aimed at intuitive operability while allowing individual settings to experts. Until the start of FAIR Phase-0 the new system needs to be operable to warrant a smooth operation of experiments. To this end, regular dry runs are carried out before beam time commences. This allows the control system to be tests under realistic conditions without beam to identify possible faults or missing system functionality.

The figure shows the structural design of the new controls that will be particularly for operating the (Super-)FRS, where the passage of swift ions through matter needs to be included in the setup. The control system features a client-server architecture that allows various applications to communicate with the LSA server. The central LSA Core connects applications with a data base of stored values and device lists and with the devices.

Figure: Working Range of IC, SEETRAM, diamand detectors and plastic scintillators in dependency of beam rate and ion charge. Taken from: Lecture Notes on Beam Instrumentation and Diagnostics, Peter Forck, GSI, Darmstadt.

The Intensity of the future synchrotron SIS100 is expected to be about 100 times higher compared to the current synchrotron SIS18. Intensities of up to 3*1011 238U/spill at energies of 1.5 GeV/nucl. are expected to be achieved in the target area of the Super-FRS. These high intensities and energies are a big challenge to detectors and front-end electronics, due to the high radiation levels in the target area. For monitoring and particle identification, we work with collaboration partners on suitable detector systems. To monitor the beam intensity in the target area and behind the pre-separator – intensities up to 109 ions are still expected at this position – a 3 staged particle detection system (PDC) is in development.

This combination will consist of a diamand detector, suited for low intensities, an Ionisation Chamber (IC), for medium intensities, and a Secondary Electron Transmission Monitor (SEETRAM) for high intensities. At each position, a PDC will be placed, a combination of the detectors has to be chosen, dedicated to allow a calibration of each detector, starting with the diamond detector as absolute intensity reference. So far multiple test experiments were performed, investigating the radiation hardness and efficiency of the diamond detectors and prototypes of a new IC design, developed for FAIR, and a SEETRAM design, consisting of aluminum foils were tested. All detectors were performing well regarding the future operation along the Super-FRS beam line.

Collaboration partners


  • The BMBF is funding research activities within the international NUSTAR collaboration, which are in direct connection with the FAIR facility, which is constructed at GSI near Darmstadt. This also includes numerous projects at other research facilities, where experimental techniques and technologies are developed, which later will be used at FAIR. Herein, the research groups of TU Darmstadt have leading roles in a number of FAIR relevant projects. For example, preparatory experiments of the R3B and the HISPEC/DESPEC collaborations are presently conducted at the Japanese large research facility RIKEN-RIBF in Tokyo. The conditions here are very similar to those expected at FAIR, where the reach of experimentally accessible atomic nuclei will yet further be expanded.

  • Cooperation Contract between TU Darmstadt and GSI Helmholtz Research Center for Heavy-ion Research.

L. Atar et al., Quasifree (p, 2p) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength, Phys. Rev. Lett. 120, 052501 (2018)

J. P. Hucka et al., Implementation and test of a setting generator for the GSI fragment separator FRS in the LHC Software Architecture LSA, GSI Scientific Report 2016, p. 458 (2017)

S. Schlemme et al., Calibration of an ionization chamber with diamond detector, GSI Scientific Report 2015, p. 369 (2016)