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A. Cabrera

Publications and source records attributed to A. Cabrera.

46 records · Page 3Linked to original sources
arXiv2013

The Waveform Digitiser of the Double Chooz Experiment: Performance and Quantisation Effects on PhotoMultiplier Tube Signals

We present the waveform digitiser used in the Double Chooz experiment. We describe the hardware and the custom-built firmware specifically developed for the experiment. The performance of the device is tested with regards to digitising low light level signals from photomultiplier tubes and measuring pulse charge. This highlights the role of quantisation effects and leads to some general recommendations on the design and use of waveform digitisers.

physics.ins-det↗
arXiv2012

First Test of Lorentz Violation with a Reactor-based Antineutrino Experiment

We present a search for Lorentz violation with 8249 candidate electron antineutrino events taken by the Double Chooz experiment in 227.9 live days of running. This analysis, featuring a search for a sidereal time dependence of the events, is the first test of Lorentz invariance using a reactor-based antineutrino source. No sidereal variation is present in the data and the disappearance results are consistent with sidereal time independent oscillations. Under the Standard-Model Extension (SME), we set the first limits on fourteen Lorentz violating coefficients associated with transitions between electron and tau flavor, and set two competitive limits associated with transitions between electron and muon flavor.

hep-ex↗
arXiv2012

The Trigger and Timing System of the Double Chooz Experiment

Modern precision neutrino experiments like Double Chooz require a highly efficient trigger system in order to reduce systematic uncertainties. The trigger and timing system of the Double Chooz experiment was designed according to this goal. The Double Chooz trigger system is driven by the basic idea of triggering on multiple thresholds according to the total visible energy and additionally triggering on the number of active photomultiplier tubes (PMTs) in the detector. To do so, the trigger system continuously monitors the analogue signals from all PMTs in the detector. The amplitudes of these PMT-signals are summed for groups of certain PMTs (group signals) and for all PMTs (sum signal), respectively. The group signals are discriminated by two thresholds for each input channel and four thresholds for the sum signal. The resulting signals are processed by the trigger logic unit which is implemented in a FPGA. In addition to the proper trigger, the trigger system provides a common clock signal for all subsequent data acquisition systems to guarantee a synchronous readout of the Double Chooz detectors. The present design of the system provides a high flexibility for the applied logic and settings, making it useful for experiments other than Double Chooz. The Double Chooz trigger and timing system was installed and commissioned in 2011. This article describes the hardware of the trigger and timing system. Furthermore the setup, implemented trigger logic and performance of the trigger and timing system for the Double Chooz experiment is presented.

physics.ins-det↗
arXiv2012

Direct Measurement of Backgrounds using Reactor-Off Data in Double Chooz

Double Chooz is unique among modern reactor-based neutrino experiments studying $\bar ν_e$ disappearance in that data can be collected with all reactors off. In this paper, we present data from 7.53 days of reactor-off running. Applying the same selection criteria as used in the Double Chooz reactor-on oscillation analysis, a measured background rate of 1.0$\pm$0.4 events/day is obtained. The background model for accidentals, cosmogenic $β$-$n$-emitting isotopes, fast neutrons from cosmic muons, and stopped-$μ$ decays used in the oscillation analysis is demonstrated to be correct within the uncertainties. Kinematic distributions of the events, which are dominantly cosmic-ray-produced correlated-background events, are provided. The background rates are scaled to the shielding depths of two other reactor-based oscillation experiments, Daya Bay and RENO.

hep-ex↗
arXiv2012

Reactor electron antineutrino disappearance in the Double Chooz experiment

The Double Chooz experiment has observed 8,249 candidate electron antineutrino events in 227.93 live days with 33.71 GW-ton-years (reactor power x detector mass x livetime) exposure using a 10.3 cubic meter fiducial volume detector located at 1050 m from the reactor cores of the Chooz nuclear power plant in France. The expectation in case of theta13 = 0 is 8,937 events. The deficit is interpreted as evidence of electron antineutrino disappearance. From a rate plus spectral shape analysis we find sin^2 2θ13 = 0.109 \pm 0.030(stat) \pm 0.025(syst). The data exclude the no-oscillation hypothesis at 99.8% CL (2.9σ).

hep-ex↗
arXiv2012

Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment

The Double Chooz Experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. A ratio of 0.944 $\pm$ 0.016 (stat) $\pm$ 0.040 (syst) observed to predicted events was obtained in 101 days of running at the Chooz Nuclear Power Plant in France, with two 4.25 GW$_{th}$ reactors. The results were obtained from a single 10 m$^3$ fiducial volume detector located 1050 m from the two reactor cores. The reactor antineutrino flux prediction used the Bugey4 measurement as an anchor point. The deficit can be interpreted as an indication of a non-zero value of the still unmeasured neutrino mixing parameter \sang. Analyzing both the rate of the prompt positrons and their energy spectrum we find \sang = 0.086 $\pm$ 0.041 (stat) $\pm$ 0.030 (syst), or, at 90% CL, 0.015 $<$ \sang $\ <$ 0.16.

hep-ex↗
arXiv2011

Comparisons of the MINOS Near and Far Detector Readout Systems at a Test Beam

MINOS is a long baseline neutrino oscillation experiment that uses two detectors separated by 734 km. The readout systems used for the two detectors are different and have to be independently calibrated. To verify and make a direct comparison of the calibrated response of the two readout systems, test beam data were acquired using a smaller calibration detector. This detector was simultaneously instrumented with both readout systems and exposed to the CERN PS T7 test beam. Differences in the calibrated response of the two systems are shown to arise from differences in response non-linearity, photomultiplier crosstalk, and threshold effects at the few percent level. These differences are reproduced by the Monte Carlo (MC) simulation to better than 1% and a scheme that corrects for these differences by calibrating the MC to match the data in each detector separately is presented. The overall difference in calorimetric response between the two readout systems is shown to be consistent with zero to a precision of 1.3% in data and 0.3% in MC with no significant energy dependence.

physics.ins-det↗
arXiv2008

Poisson-Lie T-Duality and non trivial monodromies

We describe a general framework for studying duality between different phase spaces which share the same symmetry group $\mathrm{H}$. Solutions corresponding to collective dynamics become dual in the sense that they are generated by the same curve in $\mathrm{H}$. Explicit examples of phase spaces which are dual with respect to a common non trivial coadjoint orbit $\mathcal{O}_{c,0}(\mathbfα,1) \subset\mathfrak{h}^{\ast}$ are constructed on the cotangent bundles of the factors of a double Lie group $\mathrm{H}=\mathrm{N}\Join\mathrm{N}^{\ast}$. In the case $\mathrm{H}=LD$, the loop group of a Drinfeld double Lie group $D$, a hamiltonian description of Poisson-Lie T-duality for non trivial monodromies and its relation with non trivial coadjoint orbits is obtained.

math-ph↗
arXiv2005

Hamiltonian Loop Group Actions and T-Duality for group manifolds

We carry out a Hamiltonian analysis of Poisson-Lie T-duality based on the loop geometry of the underlying phases spaces of the dual sigma and WZW models. Duality is fully characterized by the existence of equivariant momentum maps on the phase spaces such that the reduced phase space of the WZW model and a pure central extension coadjoint orbit work as a bridge linking both the sigma models. These momentum maps are associated to Hamiltonian actions of the loop group of the Drinfeld double on both spaces and the duality transformations are explicitly constructed in terms of these actions. Compatible dynamics arise in a general collective form and the resulting Hamiltonian description encodes all known aspects of this duality and its generalizations.

hep-th↗