CMOS monolithic active pixel sensors (MAPS) are proposed as a technology for various vertex detectors in nuclear and particle physics. We discuss the mechanisms of ionizing radiation damage on MAPS ...hosting the dead time free, so-called self bias pixel. Moreover, we introduce radiation hardened sensor designs which allow operating detectors after exposing them to irradiation doses above 1
Mrad.
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.
Triple differential cross sections ital dsup 3sigma/ital dpsup 3 for charged pions produced in symmetric heavy-ion collisions were measured with the KaoS magnetic spectrometer at the heavy-ion ...synchrotron facility SIS at GSI. The correlations between the momentum vectors of charged pions and the reaction plane in sup 197Au+sup 197Au collisions at an incident energy of 1 GeV/nucleon were determined. We observe, for the first time, an azimuthally anisotropic distribution of pions, with enhanced emission perpendicular to the reaction plane. The anisotropy is most pronounced for pions of high transverse momentum in semicentral collisions.
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.
.
Two-proton decay of the unbound
nucleus
16
Ne , produced in one-neutron knockout from a 500 MeV/u
17
Ne beam, has been studied at GSI. The ground state, at a resonance energy 1.388(15) MeV, (
MeV) ...above the
14
O +p+p threshold, and two narrow resonances at
MeV and 7.57(6) MeV have been investigated. A comparison of the energy difference between the first excited 2
+
state and the 0
+
ground state in
16
Ne with its mirror nucleus
16
C reveals a small Thomas-Ehrman shift (TES) of
keV. A trend of the TES for the
T
= 2 quintet is obtained by completing the known data with a prediction for
16
F obtained from an IMME analysis. The decay mechanisms of the observed three resonances were revealed from an analysis of the energy and angular correlations of the
14
O +p+p decay products. The ground state decay can be considered as a genuine three-body (democratic) mode and the excited states decay sequentially via states in the intermediate nucleus
15
F , the 3.22 MeV state predominantly via the
15
F ground-state resonance, while the 7.57 MeV state decays via the 5/2
+
resonance in
15
F at 2.8 MeV above the
14
O +p+p threshold. Further, from an analysis of angular correlations, the spin-parity of the 7.57 MeV state has been determined as
and assigned as the third 2
+
state in
16
Ne based on a comparison with
16
C.
Flow coefficients v_{n} of the orders n=1-6 are measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI for protons, deuterons, and tritons as a function of centrality, transverse ...momentum, and rapidity in Au+Au collisions at sqrts_{NN}=2.4 GeV. Combining the information from the flow coefficients of all orders allows us to construct for the first time, at collision energies of a few GeV, a multidifferential picture of the angular emission pattern of these particles. It reflects the complicated interplay between the effect of the central fireball pressure on the emission of particles and their subsequent interaction with spectator matter. The high precision information on higher order flow coefficients is a major step forward in constraining the equation of state of dense baryonic matter.
Optimisation of low-mass drift chambers for HADES Garabatos, C; Karig, W; Müntz, C ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/1998, Letnik:
412, Številka:
1
Journal Article
Recenzirano
A set of low-mass drift chambers designed for the tracking of di-electrons in the HADES spectrometer is presented. Short radiation length is ensured by using a Helium-based gas mixture and aluminium ...cathode wires, whereas the acceptance is maximised by limiting the width of the side frames of the detectors. The measured performance of these devices, which improves with increasing concentration of quencher gas, is shown and discussed. Position resolutions down to 70
μm have been obtained under stable operation. Long-term gain stability is also reported.
We report on the first observation of the unbound proton-rich nucleus 15 Ne. Its ground state and first excited state were populated in two-neutron knockout reactions from a beam of 500 MeV/u 17 Ne. ...The 15 Ne ground state is found to be unbound by 2.522(66) MeV. The decay proceeds directly to 13 O with simultaneous two-proton emission. No evidence for sequential decay via the energetically allowed 2 − and 1 − states in 14 F is observed. The 15 Ne ground state is shown to have a strong configuration with two protons in the (sd) shell around 13 O with a 63(5)% (1s 1/2 ) 2 component.
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