The high-acceptance dielectron spectrometer HADES Agakichiev, G.; Alvarez-Pol, H.; Balanda, A. ...
The European physical journal. A, Hadrons and nuclei,
08/2009, Letnik:
41, Številka:
2
Journal Article
Recenzirano
Odprti dostop
HADES is a versatile magnetic spectrometer aimed at studying dielectron production in pion, proton and heavy-ion-induced collisions. Its main features include a ring imaging gas Cherenkov detector ...for electron-hadron discrimination, a tracking system consisting of a set of 6 superconducting coils producing a toroidal field and drift chambers and a multiplicity and electron trigger array for additional electron-hadron discrimination and event characterization. A two-stage trigger system enhances events containing electrons. The physics program is focused on the investigation of hadron properties in nuclei and in the hot and dense hadronic matter. The detector system is characterized by an 85% azimuthal coverage over a polar angle interval from 18
°
to 85
°
, a single electron efficiency of 50% and a vector meson mass resolution of 2.5%. Identification of pions, kaons and protons is achieved combining time-of-flight and energy loss measurements over a large momentum range ( 0.1 <
p
< 1.0 GeV/
c
. This paper describes the main features and the performance of the detector system.
The cross sections of forward emission of one, two and three neutrons by 158A GeV 115In nuclei in collisions with Al, Cu, Sn and Pb targets are reported. The measurements were performed in the ...framework of the ALICE–LUMI experiment at the SPS facility at CERN. Various corrections accounting for the absorption of beam nuclei and produced neutrons in target material and surrounding air were introduced. The corrected cross section data are compared with the predictions of the RELDIS model for electromagnetic fragmentation of 115In in ultraperipheral collisions, as well as with the results of the abrasion–ablation model for neutron emission in hadronic interactions. The measured neutron emission cross sections well agree with the RELDIS results, with the exception of In–Al collisions where the measured cross sections are larger compared to RELDIS. This is attributed to a relatively large contribution of hadronic fragmentation of In on Al target with respect to electromagnetic fragmentation, in contrast to similar measurements performed earlier with 30A GeV 208Pb colliding with Al.
We present performance studies of a full-length prototype for the CASTOR quartz-tungsten sampling calorimeter, installed in the very forward region of the CMS experiment at the LHC. The response ...linearity and energy resolution, the uniformity, as well as the showers’ spatial properties in the prototype have been studied with electrons, pions and muons of various energies. A special study was also carried out for testing the light-output with a 90-degree cut of the quartz plates of the calorimeter. The data were taken during the CASTOR test beam at CERN/SPS in 2007.
Usage of electrodes made of glass with low bulk resistivity seems to be a promising way to adapt the Resistive Plate Chambers (RPC) to the high-rate environment of the upcoming CBM experiment. A ...pilot four-gap RPC sample with electrodes made of phosphate glass, which has bulk resistivity in the order of 1010Ωcm, has been studied with MIP beam for TOF applications. The tests have yielded satisfactory results: the efficiency remains above 95% and the time resolution stays within 120ps up to the particle rate of 18kHz/cm2. The increase in rate from 2.25 to 18kHz/cm2 leads to an increase of estimated tails fraction in the time spectrum from 1.5% to 4%.
The application of micro-pixel Avalanche photodiodes (MAPD) for the readout of hadron calorimeters is discussed. A prototype calorimeter was constructed consisting of individual lead/scintillator ...sandwich modules with a sampling satisfying the compensating condition. The light from each scintillator tile is captured and transported with WLS fibers embedded in the scintillator and extended to the rear end of the module. A set of 6 WLS fibers from neighboring tiles is grouped in one bundle and viewed by a 3×3
mm
2 avalanche micro-pixel photodiode. The design provides a longitudinal segmentation of the module into 10 sections with independent MAPD readout. Use of MAPDs with pixel density 10
4/mm
2 ensures good linearity of calorimeter response over a wide dynamical range. The performance of the calorimeter prototype in beam tests is reported.
The construction and performance of a modular hadron calorimeter prototype is described. The prototype consists of 9 individual lead/scintillator sandwich modules with the sampling satisfying the ...compensating condition. The light from the individual scintillator tiles is captured and transported with the WLS-fibers embedded in the scintillator and extended along the lateral side to the rear end of the module. Set of 6 WLS-fibers from the neighboring tiles is grouped in one bundle and viewed by a 3×3
mm
2 avalanche micro-pixel photodiode. The construction ensures a longitudinal segmentation of the module in 10 independent sections. The results of beam tests of the calorimeter prototype are presented. The energy resolution
σ
/
E
≈
53
%
/
E
(
GeV
)
was obtained.
Four-gap resistive plate chamber (RPC) prototypes with silicate glass electrodes (bulk resistivity ∼10
8–10
9
Ω
cm) were studied for suitability in time-of-flight (TOF) applications at high rates. ...These studies were performed using a continuous electron beam of 34
MeV at the FZ Dresden–Rossendorf electron linac ELBE. Time resolutions of about 100
ps and efficiencies larger than 95% were obtained for flux densities up to 20
kHz/cm
2.
The HADES-at-FAIR project Lapidus, K.; Agakishiev, G.; Balanda, A. ...
Physics of atomic nuclei,
05/2012, Letnik:
75, Številka:
5
Journal Article
Recenzirano
Odprti dostop
After the completion of the experimental program at SIS18 the HADES setup will migrate to FAIR, where it will deliver high-quality data for heavy-ion collisions in an unexplored energy range of up to ...8
A
GeV. In this contribution, we briefly present the physics case, relevant detector characteristics and discuss the recently completed upgrade of HADES.
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