Timing RPCs in FOPI Schüttauf, A.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2004, Volume:
533, Issue:
1-2
Journal Article
Peer reviewed
The status of our development of strip anode MRPCs in the framework of the FOPI-ToF upgrade project is reviewed. For the counter readout we have developed a fast FEE (front-end-electronics) offering ...a high gain (α∼200) at high bandwidth (δf∼1000MHz) and a new TAC-digitization system with an internal resolution of σt⩽15ps. In order to optimize the signal shape variations, strip/pitch configurations and number of gaps have been investigated.
.
The production of K
+
, K
-
and
(1020) mesons is studied in Al+Al collisions at a beam energy of 1.9A GeV which is close to or below the production threshold in NN reactions. Inverse slopes, ...anisotropy parameters, and total emission yields of K
±
mesons are obtained. A comparison of the ratio of kinetic energy distributions of K
-
and K
+
mesons to the HSD transport model calculations suggests that the inclusion of the in-medium modifications of kaon properties is necessary to reproduce the ratio. The inverse slope and total yield of
mesons are deduced. The contribution to K
-
production from
meson decays is found to be
%. The results are in line with the previous K
±
and
data obtained for different colliding systems at similar incident beam energies.
We present measurements of the excitation function of elliptic flow at midrapidity in Au+Au collisions at beam energies from 0.09 to 1.49 GeV per nucleon. For the integral flow, we discuss the ...interplay between collective expansion and spectator shadowing for three centrality classes. A complete excitation function of transverse momentum dependence of elliptic flow is presented for the first time in this energy range, revealing a rapid change with incident energy below 0.4 AGeV, followed by an almost perfect scaling at the higher energies. The equation of state of compressed nuclear matter is addressed through comparisons to microscopic transport model calculations.
In-Beam Diamond Start Detectors Ciobanu, M.; Berdermann, E.; Herrmann, N. ...
IEEE transactions on nuclear science,
2011-Aug., 2011-08-00, 20110801, Volume:
58, Issue:
4
Journal Article
Peer reviewed
This paper describes operation principles and the in-beam performance of Start Detector (SD) assemblies consisting of Diamond Detectors (DDs) grown by Chemical Vapour Deposition (CVD) and Front End ...Electronics (FEE) which have been designed for and used in various nuclear physics experiments at GSI Helmholtz Center for Heavy Ion Research in Darmstadt. In parallel to the FEE design we have performed extensive calculations to model the dependence of the signal-to-noise ratio (S/N) and the time resolution σ t on various quantities such as the collected charge Q col , the detector capacitance C D , the temperature T, and finally the noise contribution and bandwidth of the amplifier. In combination with the new FEEs (including an application-specific integrated circuit, ASIC) we have tested both polycrystalline and single-crystal diamonds of various sizes and thicknesses with relativisticion beams ranging from protons to heaviest ions. For heavy ions all setups deliver time resolutions σ t <; 60 ps. In case of protons the small primary detector signals require single crystals as material and more elaborated designs like segmentation of the detector area and the increase of the amplifier input impedance. The best time resolution obtained for relativistic pro tons was σ t = 117 ps.
We present a complete systematics (excitation functions and system-size dependences) of global stopping and side flow for heavy ion reactions in the energy range between 0.09A and 1.93A GeV. For the ...heaviest system, Au+Au, we observe a plateau of maximal stopping extending from about 0.2A to 0.8A GeV with a fast drop on both sides. The degree of stopping, which is shown to remain significantly below the expectations of a full stopping scenario, is found to be highly correlated to the amount of side flow.
A forward TPC for STAR Schüttauf, A
Nuclear physics. A,
12/1999, Volume:
661, Issue:
1
Journal Article
Peer reviewed
Two
F
orward
T
ime
P
rojection
C
hambers (FTPC) provide charge and momentum information in the pseudorapidity range between 2.5 < |η| < 4.0. A radial TPC scheme is used, where ionisation electrons ...drift in an electric field perpendicular to the axial solenoidal magnetic field. Curved proportional wire chambers with pad readout record the track information via 19200 electronic channels. We report on measurements with various gas mixtures in a prototype chamber with and without magnetic field. The design and construction of a curved readout chamber is described. Based on the prototype measurements and the final layout of the detector the expected performance in measuring accuracy and two-track-separation is given.
We present an overview of the scientific challenges and achievements during the development of thin film silicon based single and multijunction solar cells with hot-wire chemical vapor deposition ...(HWCVD) of the active silicon layers. The highlights discussed include the development of Ag/ZnO coatings with a proper roughness and morphology for optimal light trapping in single and multijunction thin film silicon solar cells, studies of the structural defects created by a rough substrate surface and their influence on the performance of nc-Si:H n–i–p single junction solar cells, and studies of the phase change during the growth of nc-Si:H by HWCVD and the use of a ‘reverse’ H2 profiling technique to achieve nc-Si:H single junction n–i–p cells with high performance. Thus far, the best AM1.5 efficiency reached for n–i–p cells on stainless-steel with HWCVD i-layers is 8.6% for single junction nc-Si:H solar cells and 10.9% for triple junction solar cells. The opportunities for further improvement of cell efficiency are also discussed. We conclude that the uniqueness of HWCVD and of the i-layers deposited with this technique require some adjustments in the strategy for optimization of single or multijunction solar cells, such as using a reverse H2 profiling technique for the deposition of nc-Si:H i-layers. However, the output performance of solar cells with HWCVD deposited i-layers is close to those with i-layers deposited by other techniques. The difference between the best nc-Si:H n–i–p cells obtained so far in our lab and the reported best n–i–p cells with PECVD i-layers can be mainly attributed to the differences in the rough substrates and to the use of rather thin i-layers.
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