110500799
A fast programmable trigger for pattern recognition
Abstract We have built a fast programmable trigger processor based on a state-of-the-art Field Programmable Gate Array (FPGA) IC for the Palo Verde Neutrino Oscillation Experiment. The trigger processor can accommodate 160 ECL input signals, 8 NIM input signals, 16 ECL output signals and 8 NIM output signals. Our two-level trigger logic is designed asynchronously to maximize speed. We have attained trigger times of 40 ns for level 1 and 100 ns for level 2 with 132 asynchronous inputs. The trigger processor can be upgraded by replacing the FPGA with more advanced versions of the chip as they appear.
122214277
A water Cherenkov calorimeter for long baseline neutrino oscillation experiments
Abstract We propose a water-based large homogeneous calorimeter as the next generation neutrino detector for ν factories and/or conventional ν beams. The Cherenkov light produced in water is sufficient to have good energy resolution, and the pattern recognition is realized by a modular water tank structure. Monte Carlo simulations show that the detector performance is excellent for identifying neutrino CC events while rejecting backgrounds.
56005177
Inclusive J production in Z0 decays
Abstract Inclusive J production in Z0 decays is observed via the leptonic decay mode J → l+l− (l = e,μ). We measure the branching ratio Br(Z0 → J + X) = (4.1 ± 0.7 (stat.) ± 0.3 (sys.)) × 10−3. We have calculated the fraction of the J mesons from b-hadron decay and find a branching ratio of Br(b → J + X)= (1.3±0.2(stat.)±0.2(sys.)) × 10−2. We determine the average fractional energy of bottom hadrons 〈XE > = 0.70±0.03 (stat.)+0.02−0.01 (sys.) using the momentum spectrum of the J mesons. From a study of the angle between the J and the most energetic jet, we set an upper limit on the branching ratio Br ( Z 0 → q q g ∗ ; g ∗ → J + X ) −4 at 90% confidence level.
125677069
TUBE CHAMBERS FOR THE MUON FILTER OF THE L3 DETECTOR
118039047
Physics of tau and charm
The physics of tau and charm started in early 70's after J/$\psi$ and $\tau$ were discovered. Since then several dedicated accelerators and experiments were built with increasing luminosities and studies on light hadron spectroscopy, charmonium, electroweak and QCD were never interupted. New interests and surprises are not rare in this area. With the newly built BEPCII/BESIII, an even brighter future is foreseen.
18893994
The mass production and quality control of RPCs for the Daya Bay experiment
Abstract Resistive plate chambers will be used in the Daya Bay reactor neutrino experiment to help veto backgrounds created by cosmic-ray muons. The mass production of RPCs began in 2008 and by the end of 2009, 1600 RPCs (3500 m 2 ) had been produced and tested. This paper describes the production and quality control procedures, and quality assurance using cosmic-ray testing.
110710115
Readout electronics of the ALICE photon spectrometer
The photon spectrometer (PHOS) in the ALICE experiment at LHC is a PbWO4 crystal based electromagnetic calorimeter, dedicated to measuring photons, π°'s and η's over a broad pT range from about 100 MeV/c to 100 GeV/c with the best possible energy and position resolution. The front-end electronics of the PHOS is thus required to cover a large dynamic range, to achieve a timing resolution better than ~ 2 ns in order to discriminate against 1-2 GeV/c (anti-)neutrons, and to provide high pT trigger to select rare high pT events. In this paper, we present the full PHOS readout system, including the avalanche photo-diode, the low noise charge sensitive preamplifier, the 32 channel front-end electronics card, the trigger region unit and the trigger OR module. Results from PHOS commissioning with beam particles and cosmic rays will also be presented to address the performance of the PHOS readout electronics.
117748445
Measurements of Dihadron Correlations Relative to the Event Plane in Au+Au Collisions at $\sqrt{s_{NN}}=200$ GeV
Dihadron azimuthal correlations containing a high transverse momentum ($\pt$)
trigger particle are sensitive to the properties of the nuclear medium created
at RHIC through the strong interactions occurring between the traversing parton
and the medium, i.e. jet-quenching. Previous measurements revealed a strong
modification to dihadron azimuthal correlations in Au+Au collisions with
respect to \pp\ and \dAu\ collisions. The modification increases with the
collision centrality, suggesting a path-length dependence to the jet-quenching
effect. This paper reports STAR measurements of dihadron azimuthal correlations
in mid-central (20-60\%) Au+Au collisions at $\snn=200$~GeV as a function of
the trigger particle's azimuthal angle relative to the event plane,
$\phis=|\phit-\psiEP|$. The azimuthal correlation is studied as a function of
both the trigger and associated particle $\pt$. The subtractions of the
combinatorial background and anisotropic flow, assuming Zero Yield At Minimum
(\zyam), are described. The away-side correlation is strongly modified, and the
modification varies with $\phis$, which is expected to be related to the
path-length that the away-side parton traverses. The pseudo-rapidity ($\deta$)
dependence of the near-side correlation, sensitive to long range $\deta$
correlations (the ridge), is also investigated. The ridge and jet-like
components of the near-side correlation are studied as a function of $\phis$.
The ridge appears to drop with increasing $\phis$ while the jet-like component
remains approximately constant. ...
120991936
SIMULATION STUDIES OF TRIGGER DECISION CRITERION FOR THE ALICE/PHOS
This paper gives some results about trigger decision criterion of the ALICE PHOton Spectrometer (PHOS) by Monte Carlo simulations, including four parts: (1) an overview of trigger decision criterion of PHOS; (2) the energy reconstruction performance of PHOS; (3) the selection of trigger threshold and the event trigger efficiency distribution; (4) the photon event trigger rate of PHOS in p–p interactions and Pb–Pb collisions.
119242452
Unified dark fluid with constant adiabatic sound speed and cosmic constraints
As is known above 90% of the energy content in Universe is made of unknown dark component. Usually this dark fluid is separated into two parts: dark matter and dark energy. However, it may be a mixture of these two energy components, or just one exotic unknown fluid. This property is dubbed as dark degeneracy. With this motivation, in this paper, a unified dark fluid having constant adiabatic sound speed $c_s^2=\alpha$, which is in the range $[0,1]$, is studied. At first, via the energy conservation equation, its energy density, $\rho_d/\rho_{d0}=(1-B_s)+B_s a^{-3(1+\alpha)}$ where $B_s$ is related to integration constant from energy conservation equation as another model parameter, is presented. Then by using Markov Chain Monte Carlo method with currently available cosmic observational data sets which include type Ia supernova Union 2, baryon acoustic oscillation and WMAP 7-year data of cosmic background radiation, we show that small values of $\alpha$ are favored in this unified dark fluid model. Furthermore, we show that smaller values of $\alpha<10^{-5}$ are required to match matter (baryon) power spectrum from SDSS DR7.
110807481
Development of a high power 1.2 MW CW L-band klystron
The high power CW L-band klystron has been developed as the RF source of the PNC high power CW electron linac (10 MeV, 100 mA). CW power of 1.2 MW at 1.249135 GHz and efficiencies over 65% were the design goals. RF analysis of the windows using high-frequency simulation codes provided information about power loss distribution in the ceramic and optimizing properties of the RF structure. The prototype klystron window was replaced with a long pill-box type beryllia window as a result of the simulation and hardware tests. The klystron has reached CW power of 885 kW with efficiency above 45%. This paper describes key points of the designs and results of the high power RF tests.