The design of straw tube detector modules developed for the PANDA Forward Tracker is presented. One module consists of 32 straws with 10 mm diameter, arranged in two staggered layers, and has a very ...low material budget of only 8.8ċ10−4X0. The overpressure of the working gas mixture of 1 bar makes the module self-supporting and enables the use of lightweight and compact support frames. Detection planes in the Forward Tracker consist of modules mounted closely, without gaps, next to each other on a support frame. A module can be mounted and dismounted from the frame without the need to remove the neighboring modules, enabling fast repairs. Technical details of the detector design and the assembly procedure of the straw tubes and the straw modules as well as results of performed tests of the modules are given.
The design of the Forward Tracker for the Forward Spectrometer of the PANDA experiment is described. The tracker consists of 6 tracking stations, each comprising 4 planar double layers of straw tube ...detectors, and has a total material budget of only 2% X0. The straws are made self-supporting by a 1 bar over-pressure of the working gas mixture (Ar/CO2). This allows to use lightweight and compact rectangular support frames for the double layers and to split the frames into pairs of C-shaped half-frames for an easier installation on the beam line.
The identification of charged particles based on energy losses in straw tube detectors has been simulated. The response of a new front-end chip developed for the PANDA straw tube tracker was ...implemented in the simulations and corrections for track distance to sense wire were included. Separation power for p−K, p−π and K−π pairs obtained using the time-over-threshold technique was compared with the one based on the measurement of collected charge.
We present the results of the absolute gas gain measurement of a straw drift-tube filled with a binary gaseous mixture Ar-CO sub(2)(90-10) at 2 bar absolute pressure. The measurement has been ...performed using an intense 1.3 GBq super(137)Cs-source producing the primary ionization current. The results, as a function of the high voltage and gas parameters, were fitted and parameterized with a Diethorn's formula.
Performance of the LHCb muon system Alves, AA Jr; Anderlini, L; Anelli, M ...
Journal of instrumentation,
02/2013, Letnik:
7, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The performance of the LHCb Muon system and its stability across the full 2010 data taking with LHC running at square root s = 7 TeV energy is studied. The optimization of the detector setting and ...the time calibration performed with the first collisions delivered by LHC is described. Particle rates, measured for the wide range of luminosities and beam operation conditions experienced during the run, are compared with the values expected from simulation. The space and time alignment of the detectors, chamber efficiency, time resolution and cluster size are evaluated. The detector performance is found to be as expected from specifications or better. Notably the overall efficiency is well above the design requirements.
A precision measurement of the ratio RK of the rates of kaon leptonic decays K±→e±ν and K±→μ±ν with the full data sample collected by the NA62 experiment at CERN in 2007–2008 is reported. The result, ...obtained by analysing ∼150000 reconstructed K±→e±ν candidates with 11% background contamination, is RK=(2.488±0.010)×10−5, in agreement with the Standard Model expectation.
The J/ψ meson has negative G parity so that, in the limit of isospin conservation, its decay into π+π− should be purely electromagnetic. However, the measured branching fraction B(J/ψ→π+π−) exceeds ...by more than 4.5 standard deviations the expectation computed according to BABAR data on the e+e−→π+π− cross section. The possibility that the two-gluon plus one-photon decay mechanism is not suppressed by G-parity conservation is discussed, even by considering other multipion decay channels. As also obtained by phenomenological computation, such a decay mechanism could be responsible for the observed discrepancy. Finally, we notice that the BESIII experiment, having the potential to perform an accurate measurement of the e+e−→π+π− cross section in the J/ψ mass energy region, can definitely prove or disprove this strong G-parity-violating mechanism by confirming or confuting the BABAR data.
A cylindrical GEM detector with analog readout is under development for the upgrade of the Inner Tracker of the BESIII experiment at IHEP (Beijing). The new detector will match the requirements for ...momentum resolution (σpt/pt~0.5% at 1GeV) and radial resolution (σxy~120μm) of the existing drift chamber and will improve significantly the spatial resolution along the beam direction (σz~150μm) with very small material budget (less than 1.5% of X0). With respect to the state of the art the following innovations will be deployed: a lighter mechanical structure based on Rohacell, a new XV anode readout plane with jagged strip layout to reduce the parasitic capacitance, and the use of the analogue readout inside a high intensity magnetic field to have good spatial resolution without increasing the number of channels.
The beam and detector, used for the NA48 experiment, devoted to the measurement of
Re
(
ε
′
/
ε
)
, and for the NA48/1 experiment on rare
K
S
and neutral hyperon decays, are described.
A sample of 7253 K±→π±e+e−(γ) decay candidates with 1.0% background contamination has been collected by the NA48/2 experiment at the CERN SPS, which allowed a precise measurement of the decay ...properties. The branching ratio in the full kinematic range was measured to be BR=(3.11±0.12)×10−7, where the uncertainty includes also the model dependence. The shape of the form factor W(z), where z=(Mee/MK)2, was parameterized according to several models, and, in particular, the slope δ of the linear form factor W(z)=W0(1+δz) was determined to be δ=2.32±0.18. A possible CP violating asymmetry of K+ and K− decay widths was investigated, and a conservative upper limit of 2.1×10−2 at 90% CL was established.
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