SIS Accelerator Research Articles

Progress and Status on Civil Construction of the SIS100 Accelerator Building

Progress and Status on Civil Construction of the SIS100 Accelerator Building

Status of the FAIR facility in Darmstadt

The Facility for Antiproton and Ion Research (FAIR) is currently being built in Darmstadt, Germany. The SIS100 accelerator is at the heart of FAIR and will provide proton and heavy-ion beams for a variety of experiments. There are four main research pillars at FAIR specialized in the field of nuclear, hadron and elementary particle physics, atomic and antimatter physics, high density plasma physics, as well as applications in condensed matter physics, biology and the biomedical sciences. In these proceedings I briefly review the main research pillars of FAIR and the status of its realization.

The transition radiation detector in the CBM experiment at FAIR

As the civil works for the SIS100 accelerator have started at FAIR/GSI and the design of the Compressed Baryonic Matter (CBM) experiment and its detector subsystems have progressed to an almost complete level, also the production of most of the detectors and components is starting soon. Commissioning of larger test systems (“FAIR Phase 0”) and last detector characterisations are being conducted. In this paper, the design of the MWPC-based Transition Radiation Detector (TRD) for the very high particle rates of the CBM experiment is shown. We present details of the self-triggered front-end electronics of the TRD and general aspects of the read-out. Furthermore, results on the energy resolution of the TRD and first insights into recent measurements of TRD-MWPCs in the high-rate field of the CERN Gamma Irradiation Facility are presented.

MRPC3b mass production for CBM-TOF and eTOF at STAR

The Compressed Baryonic Matter (CBM) spectrometer aims to study strongly interacting matter under extreme conditions. The key element providing hadron identification at incident energies between 2 and 11AGeV in heavy-ion collisions at the SIS100 accelerator is a Time-of-Flight (TOF) wall covering the polar angular range from 2.5̂–25̂ and full azimuth. CBM is expected to be operational in the year 2024 at the Facility for Anti-proton and Ion Research (FAIR) in Darmstadt, Germany. The existing conceptual design foresees a 120 m2 TOF-wall composed of Multi-gap Resistive Plate Chambers (MRPC) which is subdivided into a high rate region, a middle rate region and a low rate region. The MRPC3b Multistrip-MRPCs, foreseen to be integrated in the low rate region, have to cope with charged particle fluxes up to 1 kHz/cm2 and therefore will be constructed with thin float glass (0.28 mm thickness) as resistive electrode material. In the scope of the FAIR phase 0 program it is planned to install about 36% of the MRPC3b counters in the east endcap region of the STAR experiment at BNL as an upgrade for the Beam Energy Scan campaign (BESII) in 2019/2020.

Towards new front-end electronics for the HADES drift chamber system

Operating HADES at the future FAIR SIS-100 accelerator challenges the rate capability of DAQ and electronics. A new, more robust version of front-end electronics needs to be built for the HADES drift chamber system. Due to the unavailability of the previously used ASD-8 analog read-out ASIC, PASTTREC (PANDA straw tube read-out ASIC) was tested as an ASD-8 replacement in different scenarios including a beam test. PASTTREC falls 20% short of the ASD-8 time precision but performs better w.r.t. signal charge measurements and overall operation stability. The measured time precision as a function of distance to the sense wire was modeled within a 3D GARFIELD simulation of the HADES drift cell.

Charmonium interaction in nuclear matter at FAIR

We have studied the dissociation of J/ψ mesons in low energy proton-nucleus (p + A) collisions in the energy range of the future SIS100 accelerator at Facility for Anti-proton and Ion Research (FAIR). According to the results of our calculations, various scenarios of J/ψ absorption in nuclear matter show very distinct suppression patterns in the kinematic regime to be probed at FAIR. This suggests that the SIS100 energies are particularly suited to shed light on the issue of interaction of J/ψ resonance in nuclear medium.

Optimization of the Radiation Resistant Quadrupole Magnets for the SIS100 Accelerator of the FAIR Project

The SIS100 is a charged particle accelerator developed as a part of the challenging international project Facility for Anti-proton and Ion Research taking place in Darmstadt, Germany. The ion optics of the SIS100 accelerator includes superconducting and normal conducting quadrupole magnets. To fulfill the requirements of the field quality in the magnet aperture, it is necessary to find an optimal pole tip shape as well as an optimal configuration of the coil system. Requirements for radiation resistant magnets installed in the extraction section of the SIS100 accelerator combine high quality of the field distribution, maximum field intensity at the pole tip of more than 1.3 T, and a wide range of the flux density variation. We used a specially developed optimization procedure for designing the magnet cross section. The pole border line is described by a superposition of hyperbolic functions corresponding to different Fourier components of the magnetic field expansion. Strong correlation between amplitudes of the pole shape and field harmonics enables high performance of the optimization algorithms. The developed procedures have been used for designing a quadrupole magnet with especially wide range of the flux density variation. Integral 3-D properties of the developed quadrupoles were ensured by optimization of the magnet end chamfers.

Magnetic Septa for the SIS100 Accelerator at FAIR

The future heavy ion synchrotron SIS100 will have a series of two dc magnetic septa for the injection and three dc septa on the extraction line. The extraction line will allow for two different extraction schemes for vertical fast extraction and initially horizontal slow extraction. The latter requires, among other components, two additional Lambertson-type septa. The design of the magnets had to account not only for creating a high field with a narrow septum width, but also had to find way of providing bakeout jackets while limiting the technicians’ exposure to radiation. Another issue was to minimize the chance of failure, e.g., by limiting the number of soldered joints with contact to the cooling channels and by reducing the current density with help of wedge-shaped conductors. The injection septa are under construction while some design work is still in progress for the extraction septa. We will present some of our solutions and concepts.

Sub-threshold charm production in nuclear collisions

We present the first predictions for sub-threshold open charm and charmonium production in nuclear collisions. The production mechanism is driven by multistep scatterings of nucleons and their resonance states, accumulating sufficient energy for the production of $J/\mathrm{\ensuremath{\Psi}}$, ${\mathrm{\ensuremath{\Lambda}}}_{c}+\overline{D}$, and $D+\overline{D}$. Our results are of particular importance for the CBM experiment at FAIR, as they indicate that already at the SIS100 accelerator one can expect a significant number of charmed hadrons to be produced. This opens new possibilities to explore charm dynamics and the formation of charmed nuclei.

Sub-threshold strangeness and charm production in UrQMD

We present recent results on the sub-threshold production of strange and charmed hadrons in nuclear collisions. In particular we highlight how the excitation and decay of heavy baryonic resonances can be used to describe the production yield of ϕ mesons at the SIS18 accelerator and show how this production mechanism also consistently describes the ϕ nuclear transparency ratio. Including even more massive baryonic resonances in the model we are able to extend our approach and make, for the first time, realistic predictions on the sub-threshold production of J/Ψ and Λc in nuclear collisions at the SIS100 accelerator at FAIR. We find that even at a beam energy of Elab = 6 A GeV, charm physics is feasible at the CBM experiment, which opens up new opportunities to study charmed hadron properties at large baryon densities.

Conception and design of a control and monitoring system for the mirror alignment of the CBM RICH detector

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Anti-proton and Ion Research (FAIR) complex will investigate the phase diagram of strongly interacting matter at high baryon density and moderate temperatures created in A+A collisions. For the SIS100 accelerator, the foreseen beam energy will range up to 11 AGeV for the heaviest nuclei. One of the key detector components required for the CBM physics program is the Ring Imaging CHerenkov (RICH) detector, which is developed for efficient and clean electron identification and pion suppression. An important aspect to guarantee a stable operation of the RICH detector is the alignment of the mirrors. A qualitative alignment control procedure for the mirror system has been implemented in the CBM RICH prototype detector and tested under real conditions at the CERN PS/T9 beamline. Collected data and results of image processing are reviewed and discussed. In parallel a quantitative method using recorded data has also been employed to compute mirror displacements of the RICH mirrors. Results based on simulated events and the limits of the method are presented and discussed as well. If mirror misalignment is detected, it can be subsequently included and rectified by correction routines. A first correction routine is presented and a comparison between misaligned, corrected and ideal geometries is shown.

Development of integrated superconducting quadrupole doublet modules for operation in the SIS100 accelerator

The FAIR project (Facility for Antiproton and Ion Research) evolves and builds an international accelerator- and experimental facility for basic research activities in various fields of modern physics. Within the course of this project, integrated quadrupole doublet modules are in development. The quadrupole doublet modules provide a pair of superconducting main quadrupoles (focusing and defocusing), corrector magnets, cryogenic collimators and beam position monitors as integrated sets of ion-optical elements. Furthermore LHe cooled beam pipes and vacuum cold-warm transitions are used as ultra-high vacuum components for beam transportation. Superconducting bus bars are used for 13 kA current supply of the main quadrupole magnets. All components are integrated as one common cold mass into one cryostat. High temperature super conductor local current leads will be applied for the low current supply of corrector magnets. The quadrupole doublet modules will be operated in the SIS100 heavy ion accelerator, the core component of the FAIR project. A first version of a corrector magnet has already been manufactured at the Joint Institute for Nuclear Research (JINR), Russia, and is now ready for testing. The ion-optical lattice structure of SIS100 requires multiple configurations of named components. Eleven different configurations, organized in four categories, provide the required quadrupole doublet module setups. The high integration level of multiple ion-optical, mechanical and cryogenic functions, based on requirements of operation safety, is leading towards a sophisticated mechanical structure and cooling solution, to satisfy the demanding requirements on position preservation during thermal cycling. The mechanical and cryogenic design solutions will be discussed.

Spinodal density enhancements in nuclear collisions at the CBM experiment

We discuss a novel approach to describe the evolution of a fireball, created in a high-energy nuclear collision, experiencing spinodal instabilities due to the first-order deconfinement phase transition of quantum chromo dynamics (QCD). We show that initial density fluctuations in these collisions are enhanced in the mechanically unstable region of the QCD phase diagram. In our study we find that the most favorable energy range for observing these density enhancements is at the lower end of the SIS100 accelerator at FAIR, currently under construction. Furthermore we discuss how one can distinguish and constrain different types of QCD phase transitions, one of hadron-quark type and one of liquid-gas type, leading to strong differences in the dynamical evolution of the QCD medium.

String Test Preparation for the Superconducting SIS100 Accelerator of FAIR

GSI plans to build a test string in the Series Test Facility (STF) for SIS100 at GSI. The SIS100 cryomagnetic modules and local cryocomponents will be assembled and intensively tested. The purpose of the string test is to confirm technical systems of cryogenic, vacuum, interlock and quench protection, and powering under normal and extreme conditions. Acquirement of knowledge through experiences in test string construction, commissioning, and testing is crucial for the SIS100 construction and operation. We present the planning and preparation status of the string test.

Status of the SC Magnets for the SIS100 Synchrotron and the NICA Project

The upcoming machines, the SIS100 accelerator and the NICA booster and collider are a direct offspring of the successful NUCLOTRON magnet concept. SIS100 is now being realized with the dipoles ordered. NICA is in its R&D stage with the first prototype magnets built. The experience gained in the GSI-JINR collaboration dedicated to improving the magnets during the last decade of R&D led now to the common agreement to realize the magnet production and testing in a cooperation for both projects. We describe the parameters, the optimization and tradeoffs made for these magnets and outline the differences. The status of the different magnets next to first results obtained on model or prototype magnets are given. Special attention is given to the advantages of cooling the superconducting magnets with a forced two-phase Helium flow.

FIRST experiment: Fragmentation of Ions Relevant for Space and Therapy

Nuclear fragmentation processes are relevant in different fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications. The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at SIS accelerator of GSI laboratory in Darmstadt, has been designed for the measurement of different ions fragmentation cross sections at different energies between 100 and 1000 MeV/nucleon. The experiment is performed by an international collaboration made of institutions from Germany, France, Italy and Spain. The experimental apparatus is partly based on an already existing setup made of the ALADIN magnet, the MUSIC IV TPC, the LAND2 neutron detector and the TOFWALL scintillator TOF system, integrated with newly designed detectors in the interaction Region (IR) around the carbon removable target: a scintillator Start Counter, a Beam Monitor drift chamber, a silicon Vertex Detector and a Proton Tagger for detection of light fragments emitted at large angles (KENTROS). The scientific program of the FIRST experiment started on summer 2011 with the study of the 400 MeV/nucleon 12C beam fragmentation on thin (8mm) carbon target.

The FIRST experiment at GSI

The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at the SIS accelerator of GSI laboratory in Darmstadt has been designed for the measurement of ion fragmentation cross-sections at different angles and energies between 100 and 1000MeV/nucleon. Nuclear fragmentation processes are relevant in several fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications.The start of the scientific program of the FIRST experiment was on summer 2011 and was focused on the measurement of 400MeV/nucleon 12C beam fragmentation on thin (8mm) graphite target.The detector is partly based on an already existing setup made of a dipole magnet (ALADiN), a time projection chamber (TP-MUSIC IV), a neutron detector (LAND) and a time of flight scintillator system (TOFWALL). This pre-existing setup has been integrated with newly designed detectors in the Interaction Region, around the carbon target placed in a sample changer. The new detectors are a scintillator Start Counter, a Beam Monitor drift chamber, a silicon Vertex Detector and a Proton Tagger scintillator system optimized for the detection of light fragments emitted at large angles.In this paper we review the experimental setup, then we present the simulation software, the data acquisition system and finally the trigger strategy of the experiment.

Fast Ramped Superferric Prototypes and Conclusions for the Final Design of the SIS 100 Main Magnets

The 100 Tm synchrotron SIS 100 is the core component of the Facility of Antiproton and Ion Research (FAIR). An intensive R&D allowed reducing the AC losses considerably as well as improving the field quality. High priority was also given to the investigation of the mechanical stability of the superconducting coil to guarantee a long term life time of at least 20 years with more than 2middot108 operation cycles and to position the cable windings precisely. Prototype magnets were built last year with the first dipole magnet completed by Babcock Noell GmbH and currently being under preparation for intensive testing. After a brief description of the main R&D results the key features of three full scale dipoles and a quadrupole prototype are given as well as the expected heat load at 4 K for the 3 m long dipoles for the most important operation modes requested for the SIS100 accelerator. During prototyping additional, more intensive operation cycles were requested by beam dynamics and more cooling power by the vacuum requirements. The consequences for the cooling stability of the dipoles were estimated and preliminary tested on a hydraulic equivalent magnet system and will be verified by the upcoming measurements of the full size models. Necessary modifications for the series production are discussed and the actual chosen SIS100 dipole design fulfilling also the additional operation requirements is outlined.

Kaon production at subthreshold energies: what do we learn about the nuclear medium?

The IQMD model is used to compare spectra and elliptic flow of kaons produced at subthreshold energies with data taken at the SIS accelerator at GSI. We find that temperatures of the spectra are dominated by the rescattering of the kaons. The study of elliptic flow observables indicates the influence of rescattering as well as of the optical potential of the kaons with increasing dominance of the optical potential at lower incident energies.

DIELECTRON PRODUCTION IN C + C AND p + p COLLISIONS WITH HADES

The High Acceptance Di-Electron Spectrometer HADES1 has been constructed at the SIS accelerator (GSI Darmstadt) to investigate electron-positron pairs produced in proton, pion and heavy ion induced reactions. The main goal of these studies is to explore properties of hadrons in nuclear matter. The apparatus and the experimental results from C + C at 2.0 AGeV and 1.0 AGeV and p + p at 2.2 GeV compared with Monte-Carlo events from a generator based on known cross-sections and branching ratios are presented.