A first generation prototype for the CBM micro vertex detector Deveaux, M.; Amar-Youcef, S.; Fröhlich, I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Volume:
718
Journal Article
Peer reviewed
The Compressed Baryonic Matter (CBM) experiment will be a fixed target heavy ion experiment at the future FAIR facility in Darmstadt, Germany. Its Micro Vertex Detector (MVD) is to identify open ...charm particles in the rich background of 15–35AGeV heavy ion collisions. We show a concept how to match the required combination of high rate capability and excellent secondary vertex resolution and discuss the status of the MVD prototype.
.
We report on the investigation of dielectron production in tagged quasi-free neutron-proton collisions by using a deuteron beam of kinetic energy 1.25GeV/u impinging on a liquid hydrogen target. ...Our measurements with HADES confirm a significant excess of
e
+
e
-
pairs above the
π
0
mass in the exclusive channel
d
p
→
n
p
e
+
e
-
(
p
s
p
e
c
t
)
as compared to the exclusive channel
p
p
e
+
e
-
measured in proton-proton collisions at the same energy. That excess points to different bremsstrahlung production mechanisms. Two models were evaluated for the role of the charged pion exchange between nucleons and double-
Δ
excitation combined with intermediate
ρ
-meson production. Differential cross sections as a function of the
e
+
e
-
invariant mass and of the angles of the virtual photon, proton and electrons provide valuable constraints and encourage further investigations on both experimental and theoretical sides.
CMOS monolithic active pixel sensors (MAPS) have demonstrated excellent performance as tracking detectors for charged particles. They provide an outstanding spatial resolution (a few μm), a detection ...efficiency of ≳99.9%, very low material budget (0.05%X0) and good radiation tolerance (≳1Mrad, ≳1013neq/cm2) (Deveaux et al. 1). This makes them an interesting technology for various applications in heavy ion and particle physics. Their tolerance to bulk damage was recently improved by using high-resistivity (∼1kΩcm) epitaxial layers as sensitive volume (Deveaux et al. 1, Dorokhov et al. 2).
The radiation tolerance of conventional MAPS is known to depend on the pixel pitch. This is as a higher pitch extends the distance, which signal electrons have to travel by thermal diffusion before being collected. Increased diffusion paths turn into a higher probability of loosing signal charge due to recombination. Provided that a similar effect exists in MAPS with high-resistivity epitaxial layer, it could be used to extend their radiation tolerance further. We addressed this question with MIMOSA-18AHR prototypes, which were provided by the IPHC Strasbourg and irradiated with reactor neutrons. We report about the results of this study and provide evidences that MAPS with 10μm pixel pitch tolerate doses of ≳3×1014neq/cm2.
The PLUME (Pixelated Ladder with Ultra-Low Material Embedding) Collaboration is developing ultra-light ladders for the vertex detector for a future linear collider. The double-sided ladder will ...integrate the sensors, readout infrastructure and mechanical supports with the aim of total material budget of 0.3% of radiation length. The requirement of as light as possible construction is driven by physics, in particular by measurements requiring determination of the quark charge sign. The first prototype ladders were prepared and tested in the beam. The alignment issues for the ladders will be tested within the AIDA (Advanced European Infrastructures for Detectors at Accelerators) EU FP7 project.
Radiative transition of an excited baryon to a nucleon with emission of a virtual massive photon converting to dielectron pair (Dalitz decays) provides important information about baryon-photon ...coupling at low
q
2
in timelike region. A prominent enhancement in the respective electromagnetic transition Form Factors (etFF) at
q
2
near vector mesons
ρ/ω
poles has been predicted by various calculations reflecting strong baryon-vector meson couplings. The understanding of these couplings is also of primary importance for the interpretation of the emissivity of QCD matter studied in heavy ion collisions via dilepton emission. Dedicated measurements of baryon Dalitz decays in proton-proton and pion-proton scattering with HADES detector at GSI/FAIR are presented and discussed. The relevance of these studies for the interpretation of results obtained from heavy ion reactions is elucidated on the example of the HADES results.
HADES is a running spectrometer installed at GSI, Germany. PANDA and CBM are planned detector systems for the new FAIR facility at GSI. For these detectors, a general-purpose trigger and readout ...board with on-board DAQ functionality was developed. The original motivation for this project was the implementation of a 128-channel time to digital converter (TDC) with a time resolution of sigma=40 ps based on the HPTDC chip from CERN into a fully fledged data acquisition system. The application of the board is detector independent, includes a 2 Gbit/s optical link and has the option to employ the TDC chips and/or to integrate versatile add-on boards through 16 Gbit/s connectors. The latter one may interface to the front end electronics of other types of detectors. A large FPGA (Xilinx Virtex 4 LX40) and a TigerSharc DSP can be used as on-board resources for trigger and on-line analysis algorithms. Data transfer to mass storage and slow control is done via an ETRAX processor running Linux and a 100 Mbit/s Ethernet interface.
CMOS Monolithic Active Pixel Sensors (MAPS) integrate very small sensing elements with a pitch of
10
–
40
μ
m
together with analog and digital signal processing circuits into a monolithic chip, which ...may be thinned down to a thickness of
∼
50
μ
m
. These features make MAPS an interesting sensor for a broad range of vertex detectors in charged particle tracking (e.g. CBM, STAR, ILC). Intense R&D was performed in the last years in order to improve the radiation tolerance and hence the lifetime of the sensors toward the level required.
One strategy to reach this improvement is reducing the number of metastable, radiation induced defects in the sensor material by thermal annealing. To test the feasibility of this approach, we studied systematically the effect of annealing on neutron and X-ray irradiated MAPS. The results of the studies are presented and the option to recover a strongly irradiated, MAPS based vertex detector by means of thermal treatment is discussed.
We present and discuss recent experimental activities of the HADES collaboration on open and hidden strangeness production close or below the elementary NN threshold. Special emphasis is put on the ...feed-down from φ mesons to antikaons, the presence of the Ξ- excess in cold nuclear matter and the comparison of statistical model rates to elementary p+p data. The implications for the interpretation of heavy-ion data are discussed as well.
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