O. Fateev

Energy loss of pions and electrons of 1– in drift chambers operated with Xe,CO2(15%)

Abstract We present measurements of the energy loss of pions and electrons in drift chambers (DC) operated with a Xe,CO 2 (15%) mixture. The measurements are carried out for particle momenta from 1 to 6 GeV /c using prototype DC for the ALICE transition radiation detectors. Microscopic calculations are performed using input parameters calculated with GEANT3. These calculations reproduce well the measured average and most probable values for pions, but a higher Fermi plateau is required in order to reproduce our electron data. The widths of the measured distributions are smaller for data compared to the calculations. The electron/pion identification performance using the energy loss is also presented.

Pulse height measurements and electron attachment in drift chambers operated with Xe, CO2 mixtures

We present pulse height measurements in drift chambers operated with Xe,CO2 gas mixtures. We investigate the attachment of primary electrons on oxygen and SF6 contaminants in the detection gas. The measurements are compared with simulations of properties of drifting electrons. We present two methods to check the gas quality: gas chromatography and 55 Fe pulse height measurements using monitor detectors.

Development of low-mass drift chambers for the HADES spectrometer

Abstract The High Acceptance Di-Electron Spectrometer (HADES) is a detector arrangement combined with a superconducting toroid for lepton pair spectroscopy presently built up at GSI (Darmstadt). HADES is designed to cope with the high-multiplicity environment of heavy ion collisions at 1xa0AGeV and intensities of up to 10 8 beam particles per second and central event rates of 10 5 s −1 . The detector has a geometrical acceptance of almost 50% for e + e − pairs and a mass resolution of 0.8% for ρ and ω mesons. Four low-mass drift chamber systems, two before and two behind the magnet, serve for charged particle track reconstruction. Design aspects of the drift chambers and first results from beam tests are presented.

Transition Radiation Spectra of Electrons from 1 to 10 GeV/c in Regular and Irregular Radiators

Abstract We present measurements of the spectral distribution of transition radiation generated by electrons of momentum 1–10xa0GeV/c in different radiator types. We investigate periodic foil radiators and irregular foam and fiber materials. The transition radiation photons are detected by prototypes of the drift chambers to be used in the Transition Radiation Detector (TRD) of the ALICE experiment at CERN, which are filled with a Xe, CO2 (15%) mixture. The measurements are compared to simulations in order to enhance the quantitative understanding of transition radiation production, in particular the momentum dependence of the transition radiation yield.

Position reconstruction in drift chambers operated with Xe, CO2 (15%)

Abstract We present measurements of position and angular resolution of drift chambers operated with a Xe, CO 2 (15%) mixture. The results are compared to Monte Carlo simulations and important systematic effects—in particular the dispersive nature of the absorption of transition radiation and non-linearities—are discussed. The measurements were carried out with prototype drift chambers of the ALICE Transition Radiation Detector, but our findings can be generalized to other drift chambers with similar geometry, where the electron drift is perpendicular to the wire planes.

Space charge in drift chambers operated with the Xe,CO2(15%) mixture

Using prototype modules of the ALICE Transition Radiation Detector (TRD) we investigate space-charge effects and the dependence of the pion rejection performance on the incident angle of the ionizing particle. The average pulse height distributions in the drift chambers operated with the Xe; CO2ð15%Þ mixture provide quantitative information on the gas gain reduction due to space charge accumulating during the drift of the primary ionization. Our results demonstrate that the pion rejection performance of a TRD is better for tracks which are not at normal incidence to the anode wires. We present detailed simulations of detector signals, which reproduce the measurements and lend strong support to our interpretation of the measurements in terms of space-charge effects. r 2004 Elsevier B.V. All rights reserved. PACS: 29.40.Cs

Test results of the parallax-free X-ray area detector SD-1000 in the diffractometer CARD-7

Abstract A parallax-free X-ray area detector with a spherical Be-window has been tested in a diffractometer. The detector provides a DQE of ∼80% (8–17 keV), a parallax-free solid angle of 50°, and accuracies of 1% for the intensity and of 0.025° for the angle.

Time-Projection Chamber for the MPD NICA project

The Time-Projection Chamber (TPC) is the main device for tracking and identification of charged particles in the MPD experiment at the NICA collider. The article presents the design consideration of this detector for registration of central Au-Au collisions at energies up to 11 Gev/c and NICA event rate of 5 kHz. The status of the TPC construction and features of its main parts (field cage, read-out chambers, front end electronics, gas and cooling systems, laser-calibration) are described.

Parallax-free X-ray area detector with high spatial resolution

The new parallax-free X-ray 2D detector (SD-1000) with the pixel array of 1024 × 1024 has been designed and tested. This detector is the basic element of the X-ray diffractometer which is constructed for the investigation of biological macromolecules, viruses, liquid crystals and powders. The first test results are presented.

TPC status for MPD experiment of NICA project

In a frame of the JINR scientific program on study of hot and dense baryonic matter a new accelerator complex Ion Collider fAcility (NICA) based on the Nuclotron-M is under realization. It will operate at luminosity up to 1027 cm−2s−1 for Au79+ ions. Two interaction points are foreseen at NICA for two detectors which will operate simultaneously. One of these detectors, the Multi-Purpose Detector (MPD), is optimized for investigations of heavy-ion collisions. The Time-Projection Chamber (TPC) is the main tracking detector of the MPD central barrel. It is a well-known detector for 3-dimensional tracking and particle identification for high multiplicity events. The conceptual layout of MPD and detailed description of the design and main working parameters of TPC, the readout system based on MWPC and readout electronics as well as the TPC subsystems and tooling for assembling and integration TPC into MPD are presented.