Strangeness Prospects with the CBM Experiment

The CBM experiment will study strongly interacting matter at high net-baryon densities with nuclear collisions up to 45A GeV beam energy at the future FAIR facility. With interaction rates unprecedented in heavy-ion collisions, CBM will give access also to extremely rare probes and thus to the early stage of the collisions, in search for the first-order phase transition from confined to deconfined matter and the QCD critical point. The CBM physics programme will be started with beams delivered by the SIS-100 synchrotron, providing energies from 2 to 11 GeV/nucleon for heavy nuclei, up to 14 GeV/nucleon for light nuclei, and 30 GeV for protons. The highest net baryon densities will be explored with ion beams up to 45 GeV/nucleon energy delivered by SIS-300 in a later stage of the FAIR project

Technical Design Report for the CBM : Muon Chambers (MuCh)

This document describes the technical layout and the performance of the Muon Chamber (MuCh) System of the Compressed Baryonic Matter (CBM) experiment at FAIR. The MuCh system is designed to identify muon pairs which are produced in high-energy heavy-ion collisions in the beam energy range from 4 to 40 AGeV. The measurement of lepton pairs is a central part of the CBM research program, as they are very sensitive diagnostic probes of the conditions inside the fireball. At low invariant masses, dileptons provide information on the in-medium modification of vector mesons which is a promising observable for the restoration of chiral symmetry. At intermediate invariant masses, the dilepton spectrum is dominated by thermal radiation from the fireball reflecting its temperature. At invariant masses around 3 GeV/c2, dileptons are the appropriate tool to study the anomalous charmonium suppression in the deconfined phase. In the CBM experiment both electrons and muons will be measured in order to obtain a consistent and comprehensive picture of the dilepton physics

Novel production method for large double-sided microstrip detectors of the CBM Silicon Tracking System at FAIR

The silicon sensors of the Silicon Tracking System of the Compressed Baryonic Matter experiment at FAIR, GSI are connected to the read-out electronics by low mass flexible microcables due to tight material budget restrictions. The cable length of up to 50 cm and its flexible nature make detector module assembly one of the most critical parts in STS. A novel low mass, low capacitance multilayer copper microcable has been designed and produced to facilitate detector assembly. Furthermore, a novel detector production method based on high-density gold stud bump bonding of silicon die on microcable has been developed. We present the Cu microcable design, capacitance simulations and measurements together with the individual steps performed in the STS detector assembly

Using multiplicity of produced particles for centrality determination in heavy-ion collisions with the CBM experiment

The evolution of matter created in a heavy-ion collision depends on its initial geometry. Experimentally collision geometry is characterized with centrality. Procedure of centrality determination for the Compressed Baryonic Matter (CBM) experiment at FAIR is presented. Relation between parameters of the collision geometry (such as impact parameter magnitude) and centrality classes is extracted using multiplicity of produced charged particles. The latter is connected to the collision geometry parameters using Monte-Carlo Glauber approach

DN interaction from meson exchange

A model of the DN interaction is presented which is developed in close analogy to the meson-exchange KbarN potential of the Juelich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (rho, omega) exchange and higher-order box diagrams involving D*N, D\Delta, and D*\Delta intermediate states. The coupling of DN to the pi-Lambda_c and pi-Sigma_c channels is taken into account. The interaction model generates the Lambda_c(2595) resonance dynamically as a DN quasi-bound state. Results for DN total and differential cross sections are presented and compared with predictions of an interaction model that is based on the leading-order Weinberg-Tomozawa term. Some features of the Lambda_c(2595) resonance are discussed and the role of the near-by pi-Sigma_c threshold is emphasized. Selected predictions of the orginal KbarN model are reported too. Specifically, it is pointed out that the model generates two poles in the partial wave corresponding to the Lambda(1405) resonance.Comment: 14 pages, 8 figure

Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR

Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (mu_B > 500 MeV), effects of chiral symmetry, and the equation-of-state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2022, in the context of the worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal

CBM Progress Report 2019

The report summarises the activties of the CBM Collaboration in the year 2019

mCBM@SIS18

We propose a full-system test-setup for the Compressed Baryonic Matter experiment CBM atSIS18 under the name mCBM@SIS18 (“mini-CBM”, later shortened to “mCBM”), comprisingfinal prototypes or pre-series components of all CBM detector subsystems. The primary aim is tostudy, commission and test the complex interplay of the different detector systems with the freestreamingdata acquisition and the fast online event reconstruction and selection. In particular, itwill allow to test the detector and electronics components developed for the CBM experiment aswell as the corresponding online/offline software packages under realistic experiment conditionsup to top CBM interaction rates of 10MHz.Commissioning and operating mCBM in 2018 and 2019 will prove the proper functioning ofthe detectors as well as the read-out electronics before the final series production starts. Theexperiences gathered during the operation of the complete mCBM campaign will be of highestvalue to minimize the commissioning time for the full CBM experiment at SIS100.With mCBM, the ambitious detector sub-systems, readout and data processing concept of CBMwill be validated on the base of a benchmark observable, namely the Λ production yield inAu+Au and Ni+Ni collisions at top SIS18 energies, which can be compared to publisheddata. The feasibility has been successfully demonstrated by performing Monte-Carlo simulationsincluding GEANT geometries of all mCBM detector subsystems and full detector response