The Compressed Baryonic Matter Experiment at FAIR: Progress with feasibility studies and detector developments

The Compressed Baryonic Matter (CBM) experiment is being planned at the international research center FAIR, under realization next to the GSI laboratory in Darmstadt, Germany. Its physics programme addresses the QCD phase diagram in the region of highest net baryon densities. Of particular interest are the expected first order phase transition from partonic to hadronic matter, ending in a critical point, and modifications of hadron properties in the dense medium as a signal of chiral symmetry restoration. Laid out as a fixed-target experiment at the heavy-ion synchrotrons SIS-100/300, the detector will record both proton-nucleus and nucleus-nucleus collisions at beam energies between 10 and 45$A$ GeV. Hadronic, leptonic and photonic observables have to be measured with large acceptance. The interaction rates will reach 10 MHz to measure extremely rare probes like charm near threshold. Two versions of the experiment are being studied, optimized for either electron-hadron or muon identification, combined with silicon detector based charged-particle tracking and micro-vertex detection. The CBM physics requires the development of novel detector sytems, trigger and data acquisition concepts as well as innovative real-time reconstruction techniques. Progress with feasibility studies of the CBM experiment and the development of its detector systems are reported.Comment: 4 pages, 3 figures - FINAL - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

Status of the CBM experiment

Abstract. The Compressed Baryonic Matter (CBM) experiment at the Facility for Anti-Proton and Ion Research (FAIR) will explore the phase diagram of strongly interacting matter at highest net baryon densities and moderate temperatures. The CBM physics pro-gram 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 29 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 the next stage of FAIR. Collision rates up to 107 per second are required to produce very rare probes with unprecedented statistics in this energy range. Their signatures are complex. These conditions call for detector systems designed to meet the extreme requirements in terms of rate capability, momentum and spatial resolution, and a novel DAQ and trigger concept which is not limited by latency but by throughput. The article discusses the development status of the CBM sub-systems for charged particle tracking, vertex detection, electron/muon identifi-cation, hadron/time-of-flight measurement, electromagnetic and zero-degree calorimetry, in terms of prototypes and expected physics performance. The concept and develop-ment status of CBM’s central detector, the Silicon Tracking System STS are presented in somewhat more detail.

Development of a CO2CO_2 cooling prototype for the CBM Silicon Tracking System

Traumatic brain injury (TBI) frequently occurs during childhood and adolescence with long-term neuropsychological and behavioral effects. Greater personal awareness of injury is associated with better outcomes. However, personal awareness is often assessed using ratings obtained from family members or significant others. Surprisingly, the accuracy of family-ratings compared with self-ratings has not been well studied in the TBI population. Thus, the purpose of this study was to examine self versus family-ratings of frontal dysfunction and secondly, the association between self/family reported frontal dysfunction and measured executive function outcomes. A total of 60 participants, approximately 10 years post-TBI, comprised 3 groups including; moderate/severe TBI (N=26; mean age 22.9, SD=3.0), mild TBI (N=20; mean age, 21.7, SD=2.7), and control (N=14: mean age, 21.6, SD=3.7). Neuropsychological testing was used to obtain domain scores for executive function and working memory/attention for each participant, and nominated family members and participants with TBI were asked to complete the Frontal Systems Behaviour Scale (FrSBe), consisting of three sub-scales; apathy, disinhibition, and executive dysfunction. Using the FrSBe there was no significant difference between the groups in executive function score, but the moderate/severe and mild groups had significantly lower working memory/attention scores compared with the control group (p<0.05). Repeated measures analysis of variance showed higher self-ratings on all sub-scales compared with family in each group (p<0.05). Scores on executive function and working memory/attention domains correlated with self, but not family reported executive dysfunction. Self-rated executive dysfunction explained 36% of the variance in executive function (p<0.001). While agreement between self-rated and family-rated total FrSBe scores was significant in all groups (p<0.001), our results showed that self-ratings were of higher predictive utility for executive functioning compared with family ratings. Further, at 10 years post-TBI, patients show greater awareness of deficits compared with family who rate consistently closer to the normal functioning range

First mock-up of the CBM STS module based on a new assembly concept

A molecular dynamics model has been developed to investigate the effect of the crystallographic orientation on the material deformation behaviors in nano- indentation/scratching of BCC iron. Two cases with different substrate orientations have been simulated. The orientations along x, y and z direction are [001], [100] and [010] for Case I and [111], [-1-12] and [1-10] for Case II, respectively. Case I and Case II exhibit different deformation patterns in the substrate. During indentation, the pile-up can be observed in Case I, but not in Case II. During scratching the pile-up ahead of the movement of the indenter has been enlarged in Case I, while a chip with the disordered atoms is generated in Case II. It has been found that Case I has both higher hardness and larger coefficient of friction. The ratios of the hardness and the coefficient of friction between cases I and II are nearly 2. The reason is attributed to the different crystallographic orientations used in both cases

Running experience with the DELPHI pixel detector: Reflections on design characteristics and system features

Introduction DELPHI&apos;s pixel detector is the rst application of an active, true two-dimensionally segmented semiconductor tracking detector in a collider experiment. It was built in the framework of detector upgrades, performed by the DELPHI collaboration when preparing its experiment for LEP2, the high energy physics period of LEP. During the LEP1 operation at center-of-mass energies near the Z boson mass, emphasis was put especially on ecient and precise track reconstruction and particle identication in DELPHI&apos;s central detector part [1]. Tracking in the end-caps at polar angles below 25 (\very forward region&quot;) was less ecient, caused by more than one radiation length of support material between the interaction region and the forward tracking chambers and subsequent multiple scattering and showering. DELPHI pixel detector group: CERN, Geneva, Switzerland; CPPM, Universite Aix de Marseille II, Marseille, France; IEK Universit\u7fat Karlsruhe, Karlsruhe, G

Status of the Compressed Baryonic Matter Experiment at FAIR and Its Silicon Tracking System

The Compressed Baryonic Matter (CBM) experiment will carry out systematic research on the properties of nuclear matter under extreme conditions, in particular, at highest net baryon densities. These conditions will be met by colliding beams of heavy ions on targets in the energy range from 2 to 14, eventually 45 GeV/nucleon, as they will be provided with highest intensities by the heavy-ion synchrotron SIS-100, and in a future stage by the SIS-300 machine of the Facility for Antiproton and Ion Research (FAIR) at GSI, Darmstadt, Germany. The paper summarizes the CBM physics case and observables, and updates on the status of the experimental preparations. The development of CBM’s central detector, the Silicon Tracking System for charged particle reconstruction and momentum measurement, is described in more detail. Synergies with the commissioning of the tracker’s components in the stationary target experiment BM@N, under preparation at an extraction beamline of JINR’s Nuclotron, are addressed

Vertex detector upgrade plans for the PHENIX experiment at RHIC

The PHENIX experiment at the Relativistic Heavy Ion Collider has completed its baseline instrumentation for the start of the presently ongoing third physics run. In the next few years, PHENIX will focus on high-statistics measurements in this configuration. It is expected that the collider will reach full luminosity with heavy ion and polarized proton beams by the year 2006. An upgraded collider is intended for the second half of the decade, with a luminosity increase to about 20-40 times the design value of 8 multiplied by 10 **2**6 cm**-**2s**-**1 for Au+Au, and 2 multiplied by 10 **3**2 cm**- **2s**-**1 for polarized proton beams. The collision energies of root s//N//N=200 GeV will increase to root s//N//N=500 GeV for proton beams. The PHENIX collaboration plans to upgrade its experiment to exploit with an enhanced detector new physics then in reach. A silicon vertex detector comprising pixel and novel microstrip sensors in a new vertex spectrometer is the main new sub-system discussed. This paper overviews the physics motivation and the detector concept chosen, and explains the directions of the beginning research and development effort