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Bach, E. et al, Bernabeu, J., Lacasta, C., Solaz, C., & Soldevila, U. (2024). Analysis of the quality assurance results from the initial part of production of the ATLAS18 ITK strip sensors. Nucl. Instrum. Methods Phys. Res. A, 1064, 169435–8pp.
Abstract: The production of strip sensors for the ATLAS Inner Tracker (ITk) started in 2021. Since then, a Quality Assurance (QA) program has been carried out continuously, by using specific test structures, in parallel to the Quality Control (QC) inspection of the sensors. The QA program consists of monitoring sensor-specific characteristics and the technological process variability, before and after the irradiation with gammas, neutrons, and protons. After two years, half of the full production volume has been reached and we present an analysis of the parameters measured as part of the QA process. The main devices used for QA purposes are miniature strip sensors, monitor diodes, and the ATLAS test chip, which contains several test structures. Such devices are tested by several sites across the collaboration depending on the type of samples (non-irradiated components or irradiated with protons, neutrons, or gammas). The parameters extracted from the tests are then uploaded to a database and analyzed by Python scripts. These parameters are mainly examined through histograms and timeevolution plots to obtain parameter distributions, production trends, and meaningful parameter-to-parameter correlations. The purpose of this analysis is to identify possible deviations in the fabrication or the sensor quality, changes in the behavior of the test equipment at different test sites, or possible variability in the irradiation processes. The conclusions extracted from the QA program have allowed test optimization, establishment of control limits for the parameters, and a better understanding of device properties and fabrication trends. In addition, any abnormal results prompt immediate feedback to a vendor.
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Amarilo, K. M., Ferreira Filho, M. B., Araujo Filho, A. A., & Reis, J. A. A. S. (2024). Gravitational waves effects in a Lorentz-violating scenario. Phys. Lett. B, 855, 138785–7pp.
Abstract: This paper focuses on how the production and polarization of gravitational waves are affected by spontaneous Lorentz symmetry breaking, which is driven by a self-interacting vector field. Specifically, we examine the impact of a smooth quadratic potential and a non-minimal coupling, discussing the constraints and causality features of the linearized Einstein equation. To analyze the polarization states of a plane wave, we consider a fixed vacuum expectation value (VEV) of the vector field. Remarkably, we verify that a space-like background vector field modifies the polarization plane and introduces a longitudinal degree of freedom. In order to investigate the Lorentz violation effect on the quadrupole formula, we use the modified Green function. Finally, we show that the space-like component of the background field leads to a third-order time derivative of the quadrupole moment, and the bounds for the Lorentz-breaking coefficients are estimated as well.
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Belchior, F. M., & Maluf, R. (2024). Duality between the Maxwell-Chern-Simons and self-dual models in very special relativity. Phys. Lett. B, 855, 138794–7pp.
Abstract: This work investigates the classical and quantum duality between the SIM (1)-Maxwell-Chern-Simons (MCS) model and its self -dual counterpart. Initially, we focus on free -field cases to establish equivalence through two distinct approaches: comparing the equations of motion and utilizing the master Lagrangian method. In both instances, the classical correspondence between the self -dual and MCS dual fields undergoes modifications due to very special relativity (VSR). Specifically, the duality is established when the associated VSR-mass parameters are identical, and the dual field is introduced through a non -local VSR correction. Furthermore, we analyze the duality when the self -dual model is minimally coupled to fermions. As a result, we demonstrate that Thirring-like interactions, corrected for non -local VSR contributions, are included in the MCS model. Additionally, we establish the quantum equivalence of the models by performing a functional integration of the fields and comparing the resulting effective Lagrangians.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., Cantero, J., et al. (2024). Measurement of vector boson production cross sections and their ratios using pp collisions at √s=13.6 TeV with the ATLAS detector. Phys. Lett. B, 854, 138725–27pp.
Abstract: Fiducial and total W+ and Z boson cross sections, their ratios and the ratio of top-antitop-quark pair and.. -boson fiducial cross sections are measured in proton-proton collisions at a centre-of-mass energy of root s = 13.6 TeV, corresponding to an integrated luminosity of 29 fb(-1) of data collected in 2022 by the ATLAS experiment at the Large Hadron Collider. The measured fiducial cross-section values for W+ -> l(+) v, W- -> l(-) v- <overline>, and Z -> l(+)l(-) (l =e or mu) boson productions are 4250 +/- 150 pb, 3310 +/- 120 pb, and 744 +/- 20 pb, respectively, where the uncertainty is the total uncertainty, including that arising from the luminosity of about 2.2%. The measurements are in agreement with Standard-Model predictions calculated at next-to-next-to-leading-order in alpha(s) ,next-to-nextto-leading logarithmic accuracy and next-to-leading-order electroweak accuracy.
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Yaneva, A. et al, & Algora, A. (2024). The shape of the Tz =+1 nucleus 94Pd and the role of proton-neutron interactions on the structure of its excited states. Phys. Lett. B, 855, 138805–7pp.
Abstract: Reduced transition probabilities have been extracted between excited, yrast states in the N = Z + 2 nucleus Pd-94. The transitions of interest were observed following decays of the I-pi = 14(+), E-x = 2129-keV isomeric state, which was populated following the projectile fragmentation of a Xe-124 primary beam at the GSI Helmholtzzentrum fur Schwerionenforschung accelerator facility as part of FAIR Phase-0. Experimental information regarding the reduced E2 transition strengths for the decays of the yrast 8(+) and 6(+) states was determined following isomer-delayed E-gamma 1 – E-gamma 2 – Delta T-2,T-1 coincidence method, using the LaBr3(Ce)-based FATIMA fast-timing coincidence gamma-ray array, which allowed direct determination of lifetimes of states in Pd-94 using the Generalized Centroid Difference (GCD) method. The experimental value for the half-life of the yrast 8(+) state of 755(106) ps results in a reduced transition probability of B(E2:8(+)-> 6(+)) = 205(-25)(+34) e(2) fm(4), which enables a precise verification of shell-model calculations for this unique system, lying directly between the N = Z line and the N = 50 neutron shell closure. The determined B(E2) value provides an insight into the purity of (g(9/2))(n) configurations in competition with admixtures from excitations between the (lower) N = 3pf and (higher) N = 4gds orbitals for the first time. The results indicate weak collectivity expected for near-zero quadrupole deformation and an increasing importance of the T = 0 proton-neutron interaction at N = 48.
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