The full-length prototype of the KLOE drift chamber Andryakov, A.; Avanzini, C.; Bacci, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
1998, Volume:
404, Issue:
2
Journal Article
Peer reviewed
The main goal of the KLOE experiment is the study of CP violation in the K mesons system, with an accuracy of 10
−4 in the measurement of
Re(
ε′
ε
)
. This task imposes strong constraints on the ...design and operation of the drift chamber, which must reconstruct the charged decays of low momentum K
L's and K
S's with high efficiency and high resolution. A full-length prototype of the chamber has been built and tested on a 50 GeV/
c beam. The analysis of the large sample of data has allowed a detailed study of the time to distance relations as a function of the track parameters and of the peculiar geometry of the drift cell. The detector performance, in terms of efficiency, spatial resolutions and
dE
dχ
resolution, is illustrated and discussed.
We have measured the radiative decays
φ→
ηγ,
φ→
η′
γ selecting
π
+
π
−
γγγ final state in a sample of ∼5×10
7
φ-mesons produced at the Frascati
φ-factory DA
ΦNE. We obtain
Γ(
φ→
η′
γ)/
Γ(
φ→
...ηγ)=(4.70±0.47±0.31)×10
−3. From this result we derive new accurate values for the branching ratio BR(
φ→
η′
γ)=(6.10±0.61±0.43)×10
−5 and the mixing angle of pseudoscalar mesons in the flavour basis
ϕ
P
=(41.8
+1.9
−1.6)°.
Event data from proton-proton collisions at the LHC will be selected by the ATLAS experiment by a three level trigger system, which reduces the initial bunch crossing rate of 40 MHz at its first two ...trigger levels (LVL1+LVL2) to ~3 kHz. At this rate the Event-Builder collects the data from all Read-Out system PCs (ROSs) and provides fully assembled events to the the Event-Filter (EF), which is the third level trigger, to achieve a further rate reduction to ~200 Hz for permanent storage. The Event-Builder is based on a farm of 0 (100) PCs, interconnected via Gigabit Ethernet to 0 (150) ROSs. These PCs run Linux and multi-threaded software applications implemented in C++. All the ROSs and one third of the Event-Builder PCs are already installed and commissioned. Performance measurements have been exercised on this initial system, which show promising results that the required final data rates and bandwidth for the ATLAS event builder are in reach.
We have studied the ϕ→a0(980)γ process with the KLOE detector at the Frascati ϕ-factory DAΦNE by detecting the ϕ→ηπ0γ decays in the final states with η→γγ and η→π+π−π0. We have measured the branching ...ratios for both final states: Br(ϕ→ηπ0γ)=(7.01±0.10±0.20)×10−5 and (7.12±0.13±0.22)×10−5, respectively. We have also extracted the a0(980) mass and its couplings to ηπ0, K+K−, and to the ϕ meson from the fit of the ηπ0 invariant mass distributions using different phenomenological models.
A fully instrumented slice of the ATLAS central detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the response of the central calorimeters to ...pions with energies in the range between 3 and 9
GeV is presented. The linearity and the resolution of the combined calorimetry (electromagnetic and hadronic calorimeters) was measured and compared to the prediction of a detector simulation program using the toolkit Geant 4.
The ϕ-meson leptonic widths, Γee and Γμμ, are obtained, respectively, from the e+e− forward–backward asymmetry and the μ+μ− cross section around the ϕ-mass energy. We find Γee=1.32±0.05±0.03 keV and ...ΓeeΓμμ=1.320±0.018±0.017 keV. These results, compatible with Γee=Γμμ, provide a precise test of lepton universality. Combining the two results gives Γℓℓ(ϕ)=1.320±0.023 keV.
We have searched for the decay ϕ→K0K¯0γ, by detecting KS pairs plus a photon and with the KS-mesons decaying to π+π−, in a sample of about 1.5×109ϕ-decays collected by the KLOE experiment at DAΦNE. ...The reaction proceeds through the intermediate states f0(980)γ, a0(980)γ. We find five events with 3.2 events expected from background processes. We obtain the upper limit: BR(ϕ→K0K¯0γ)<1.9×10−8 at 90% CL.
The ATLAS level-1 muon trigger will be crucial for the online selection of events with high transverse momentum muons and for its correct association to the bunch-crossing corresponding to the ...detected events. This system uses dedicated coarse granularity and fast detectors capable of providing measurements in two orthogonal projections. The resistive plate chambers (RPCs) are used in the barrel region (|/spl eta/| < 1). The associated trigger electronics is based on a custom chip, the coincidence matrix, that performs space coincidences within programmable roads and time gates. The system is highly redundant and communicates with the ATLAS level-1 trigger processor with the MUCTPI interface. The trigger electronics provides also the readout of the RPCs. Preliminary results achieved with a full trigger tower with production detectors in the H8 test beam at CERN will be shown, in particular preliminary results on the integration of the barrel muon trigger electronics with the MUCTPI interface and with the ATLAS DAQ system will be discussed.
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