Following new Trigger and Data AcQuisition (TDAQ) buffering and rate requirements as well as the high radiation doses and the pileup conditions of the High-Luminosity LHC, the ATLAS Liquid Argon ...Calorimeter electronics will be upgraded to readout the 182,500 calorimeter cells at 40MHz with 16 bit dynamic range. The triangular calorimeter signals are amplified and shaped by the analogue electronics over a dynamic range of 16 bits, with low noise and excellent linearity. Developments of low-power preamplifiers and shapers to meet these requirements are ongoing in CMOS 130nm. In order to digitize the analogue signals on two gains after shaping, radiation-hard, low-power 40MHz 14-bit ADCs are developed using a SAR architecture in 65nm CMOS. Characterization of the first prototypes of the Front-End components show good promise to fulfill all the requirements. The signals will be sent at 40MHz to the off-detector electronics, that will make use of FPGAs connected through high-speed links to perform energy and time reconstruction through the application of digital filtering and appropriate corrections. Reduced data are sent with low latency to the first level trigger, while the full data are buffered until the reception of trigger accept signals. The data-processing, control and timing functions will be realized by dedicated boards connected through ATCA crates. Results of tests of the first prototypes of Front-End components will be presented, along with design studies on the performance of the off-detector readout system.
Abstract
The Phase-I trigger readout electronics upgrade of the ATLAS
Liquid Argon calorimeters enhances the
physics reach of the experiment during the upcoming operation at
increasing Large Hadron ...Collider luminosities.
The new system, installed during the second Large Hadron Collider Long Shutdown,
increases the trigger readout granularity by up to a factor of ten
as well as its precision and range.
Consequently, the background rejection at trigger level is improved
through enhanced filtering algorithms utilizing the additional information
for topological discrimination of electromagnetic and hadronic shower shapes.
This paper presents the final designs of the new electronic elements,
their custom electronic devices, the procedures
used to validate their proper functioning, and the performance achieved
during the commissioning of this system.
We present results from an analysis of B0 to rho+rho- decays using 383.6 million BB-bar pairs collected by the BaBar detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. The measurements of ...the B0 to rho+rho- branching fraction, longitudinal polarization fraction f_L, and the CP-violating parameters S_{long} and C_{long} are: B(B0-> rho+rho-) = (25.5 +/- 2.1 (stat) +3.6/-3.9 (syst))*10^-6 f_L = 0.992 +/- 0.024 (stat) +0.026/-0.013 (syst) S_{long} = -0.17 +/- 0.20 (stat) +0.05/-0.06 (syst) C_{long} = 0.01 +/- 0.15 (stat) +/- 0.06 (syst) We determine the unitarity triangle angle alpha, using an isospin analysis of B to rhorho decays. One of the two solutions, alpha = 73.1, 117.0 degrees at 68% CL is compatible with standard model-based fits of existing data. Constraints on the unitarity triangle are also evaluated using an SU(3) symmetry based approach.
We perform an amplitude analysis of B{sup {+-}} {yields} {var_phi}(1020)K*(892){sup {+-}} decay with a sample of about 384 million B{bar B} pairs recorded with the BABAR detector. Overall, twelve ...parameters are measured, including the fractions of longitudinal f{sub L} and parity-odd transverse f{sub {perpendicular}} amplitudes, branching fraction, strong phases, and six parameters sensitive to CP-violation. We use the dependence on the K{pi} invariant mass of the interference between the J{sup P} = 1{sup -} and 0{sup +} K{pi} components to resolve the discrete ambiguity in the determination of the strong and weak phases. Our measurements of f{sub L} = 0.49 {+-} 0.05 {+-} 0.03, f{sub {perpendicular}} = 0.21 {+-} 0.05 {+-} 0.02, and the strong phases point to the presence of a substantial helicity-plus amplitude from a presently unknown source.
Search for the Rare Decay B → π l + l Aubert, B.; Karyotakis, Y.; Lees, J. P. ...
Physical review letters,
07/2007, Letnik:
99, Številka:
5
Journal Article
Recenzirano
Odprti dostop
We have performed a search for the flavor-changing neutral-current decays B → π ℓ + ℓ − , where ℓ + ℓ − is either e + e − or μ + μ − , using a sample of 230 × 10 6 Υ ( 4 S ) → B ¯¯¯ B decays ...collected with the BABAR detector. We observe no evidence of a signal and measure the upper limit on the isospin-averaged branching fraction to be B ( B → π ℓ + ℓ − ) < 9.1 × 10 − 8 at 90% confidence level. We also search for the lepton-flavor-violating decays B → π e ± μ ∓ and measure an upper limit on the isospin-averaged branching fraction of B ( B → π e ± μ ∓ ) < 9.2 × 10 − 8 at 90% confidence level.
Excitonic energy transport in wide-band inorganic scintillators Ratner, M; Ratner, A; Hryn’ova, T
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2002, Letnik:
486, Številka:
1
Journal Article
Recenzirano
The known experimental data on the energy transport in alkali-halide scintillators and rare gas crystals with a similar electronic structure can be explained only by taking into account the ...vibrational levels of a two-site self-trapped exciton (excimer quasi-molecule). In a crystal, these vibrational levels turn to narrow excitonic subbands with a very large effective mass which provides a possibility for a two-site exciton to be localized in shallow potential wells produced by impurity centers and lattice defects. A very high rate of the excitonic energy transfer, observed for alkali-halide at a low temperature, is explained by a coherent directional motion of two-site excitons with a velocity close to the sound velocity in the crystal. These two mechanisms, in their combination, provide an efficient energy transfer from the host crystal to a weak impurity or radiation defects by self-trapped two-site excitons formed after thermal relaxation of photoproduced electronic excitations.
We present results of a search for the decays $B^0 \to \ell^+\ell^-\gamma$ ($\ell=e$, $\mu$). The search is performed using $320\times 10^{6}$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ ...resonance with the BABAR detector at the PEP-II $B$ Factory at SLAC. We find no significant signal and set the following branching fraction upper limits at the 90% confidence level: $\mathcal{B}(B^0\to e^+e^-\gamma)<1.2\times 10^{-7}$ and $\mathcal{B}(B^0\to \mu^+\mu^-\gamma)<1.5\times 10^{-7}$.
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