Abstract: A theta (13) oscillation analysis based on the observed antineutrino rates at the Double Chooz far and near detectors for different reactor power conditions is presented. This approach provides a so far unique simultaneous determination of theta (13) and the total background rates without relying on any assumptions on the specific background contributions. The analysis comprises 865 days of data collected in both detectors with at least one reactor in operation. The oscillation results are enhanced by the use of 24.06 days (12.74 days) of reactor-off data in the far (near) detector. The analysis considers the nu <mml:mo stretchy=“true”><overbar></mml:mover>e interactions up to a visible energy of 8.5 MeV, using the events at higher energies to build a cosmogenic background model considering fast-neutrons interactions and Li-9 decays. The background-model-independent determination of the mixing angle yields sin(2)(2 theta (13)) = 0.094 0.017, being the best-fit total background rates fully consistent with the cosmogenic background model. A second oscillation analysis is also performed constraining the total background rates to the cosmogenic background estimates. While the central value is not significantly modified due to the consistency between the reactor-off data and the background estimates, the addition of the background model reduces the uncertainty on theta (13) to 0.015. Along with the oscillation results, the normalization of the anti-neutrino rate is measured with a precision of 0.86%, reducing the 1.43% uncertainty associated to the expectation.

Abstract: The new silicon microstrip sensors of the End-cap part of the HL-LHC ATLAS Inner Tracker (ITk) present a number of challenges due to their complex design features such as the multiple different sensor shapes, the varying strip pitch, or the built-In stereo angle. In order to investigate these specific problems, the “petalet” prototype was defined as a small End-cap prototype. The sensors for the petalet prototype include several new layout and technological solutions to investigate the issues, they have been tested in detail by the collaboration. The sensor description and detailed test results are presented in this paper. New software tools have been developed for the automatic layout generation of the complex designs. The sensors have been fabricated, characterized and delivered to the institutes in the collaboration for their assembly on petalet prototypes. This paper describes the lessons learnt from the design and tests of the new solutions implemented on these sensors, which are being used for the full petal sensor development. This has resulted in the ITIc strip, community acquiring the necessary expertise to develop the full End-cap structure, the petal.

Abstract: Annihilation of dark matter particles accumulated in the Sun would produce a flux of high-energy neutrinos whose prospects of detection in neutrino telescopes and detectors have been extensively discussed in the literature. However, for annihilations into Standard Model particles, there would also be a flux of neutrinos in the MeV range from the decays at rest of muons and positively charged pions. These low-energy neutrinos have never been considered before and they open the possibility to also constrain dark matter annihilation in the Sun into e(+)e(-), mu(+)mu(-) or light quarks. Here we perform a detailed analysis using the recent Super-Kamiokande data in the few tens of MeV range to set limits on the WIMP-nucleon scattering cross section for different annihilation channels and computing the evaporation rate of WIMPs from the Sun for all values of the scattering cross section in a consistent way.