Petrography of a "cryptic" mixed magma system – the Mount Waldo granite, coastal Maine

The Mount Waldo granite (MWG), dated at 371 ± 2 Ma, is typical of the younger Devonian intrusions of the coastal Maine magmatic province. It is a coarse-grained, seriate to porphyritic, biotite ± hornblende, titanite-bearing granite with abundant intermediate to felsic magmatic enclaves and less abundant mafic schlieren. The MWG contains feldspars of various textures and composition, including abundant plagioclase-mantled K-feldspar (rapakivi texture), boxy and spongy cellular plagioclase, and plagioclase that show An spikes and/or central cores of higher Ca content. In addition, the magmatic enclaves also preserve textural evidence for mixing and hybridization. Specifically, abundant mafic clots, acicular apatite, inherited megacrysts of all the feldspar varieties common in the host granite, and titanite-plagioclase intergrowths are all observed. Although very little mafic material is observed in the MWG at its present level of erosion, abundant textural evidence suggests that mixing occurred at depth in this intrusion. The thermal, chemical, and physical gradients initiated by the injection of mafic material produced not only the array of mixing textures observed in the MWG but also the large-scale convection needed to distribute these features throughout the pluton including its highest levels. RÉSUMÉ Le granite du mont Waldo (GMW), situé à 371±2 Ma, est caractéristique des intrusions récentes du Dévonien de la province magmatique côtière du Maine. Il s'agit d'un granite titanitifère à gros grain, sérié à porphyrique de biotite ± hornblende comportant une abondance d'enclaves magmatiques intermédiaires à felsiques et une abondance moindre de schlierens mafiques. Le GMW renferme des feldspaths de textures et de compositions diverses, notamment une abondance de feldspath potassique recouvert de plagioclase (texture de rapakiwi), de plagioclase alvéolaire massif et spongieux, et de plagioclase présentant des pics d'An ou des noyaux centraux à teneur supérieure en Ca. De plus, les enclaves magmatiques préservent également une preuve texturale de mélange et d'hybridation. On peut, plus précisément observer la totalité de ces traits : une abondance de grumeaux mafiques, de l'apatite aciculaire, des mégacristaux provenant de tous les types de feldspaths courants dans le granite hôte et des enchevêtrements de titanite-plagioclase. Même si l'on observe très peu de matières mafiques dans le GMW à son niveau actuel d'érosion, d'abondants indices texturaux permettent de supposer que le mixage est survenu en profondeur dans cette intrusion. Les gradients thermiques, chimiques et physiques obtenus par l'injection de matières mafiques a non seulement produit l'éventail de textures de mélange observé dans le GMW, mais également la convection à grande échelle nécessaire à la distribution de ces caractéristiques dans l'ensemble du pluton ainsi qu'à ses niveaux les plus élevés. [Traduit par la rédaction

Carboniferous metamorphism on the north (upper) side of the Sebago Batholith

Guidebook for field trips in southwestern Maine: New England Intercollegiate Geological Conference, 78th annual meeting, Bates College, Lewiston, Maine, October 17, 18, and 19, 1986: Trip C-

Bulk micromegas detectors for large TPC applications

A large volume TPC will be used in the near future in a variety of experiments including T2K. The bulk Micromegas detector for this TPC is built using a novel production technique particularly suited for compact and robust low mass detectors. The capability to pave a large surface with a simple mounting solution and small dead space between modules is of particular interest for these applications. We have built several large bulk Micromegas detectors (27 x 26 cm2) and we have tested them in the former HARP field cage setup with a magnetic field. Cosmic ray data have been acquired in a variety of experimental conditions. Good detector performances and space point resolution have been achieved

Scintillator ageing of the T2K near detectors from 2010 to 2021

The T2K experiment widely uses plastic scintillator as a target for neutrino interactions and an active medium for the measurement of charged particles produced in neutrino interactions at its near detector complex. Over 10 years of operation the measured light yield recorded by the scintillator based subsystems has been observed to degrade by 0.9–2.2% per year. Extrapolation of the degradation rate through to 2040 indicates the recorded light yield should remain above the lower threshold used by the current reconstruction algorithms for all subsystems. This will allow the near detectors to continue contributing to important physics measurements during the T2K-II and Hyper-Kamiokande eras. Additionally, work to disentangle the degradation of the plastic scintillator and wavelength shifting fibres shows that the reduction in light yield can be attributed to the ageing of the plastic scintillator. The long component of the attenuation length of the wavelength shifting fibres was observed to degrade by 1.3–5.4% per year, while the short component of the attenuation length did not show any conclusive degradation

Combination of searches for heavy spin-1 resonances using 139 fb−1 of proton-proton collision data at √s = 13 TeV with the ATLAS detector

A combination of searches for new heavy spin-1 resonances decaying into diferent pairings of W, Z, or Higgs bosons, as well as directly into leptons or quarks, is presented. The data sample used corresponds to 139 fb−1 of proton-proton collisions at √s = 13 TeV collected during 2015–2018 with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting quark pairs (qq, bb, tt¯, and tb) or third-generation leptons (τν and τ τ ) are included in this kind of combination for the frst time. A simplifed model predicting a spin-1 heavy vector-boson triplet is used. Cross-section limits are set at the 95% confdence level and are compared with predictions for the benchmark model. These limits are also expressed in terms of constraints on couplings of the heavy vector-boson triplet to quarks, leptons, and the Higgs boson. The complementarity of the various analyses increases the sensitivity to new physics, and the resulting constraints are stronger than those from any individual analysis considered. The data exclude a heavy vector-boson triplet with mass below 5.8 TeV in a weakly coupled scenario, below 4.4 TeV in a strongly coupled scenario, and up to 1.5 TeV in the case of production via vector-boson fusion

Measurement of vector boson production cross sections and their ratios using pp collisions at √s = 13.6 TeV with the ATLAS detector

Abstract available from publisher's website

Search for the Zγ decay mode of new high-mass resonances in pp collisions at √s = 13 TeV with the ATLAS detector

This letter presents a search for narrow, high-mass resonances in the Zγ final state with the Z boson decaying into a pair of electrons or muons. The √s = 13 TeV pp collision data were recorded by the ATLAS detector at the CERN Large Hadron Collider and have an integrated luminosity of 140 fb−1. The data are found to be in agreement with the Standard Model background expectation. Upper limits are set on the resonance production cross section times the decay branching ratio into Zγ. For spin-0 resonances produced via gluon–gluon fusion, the observed limits at 95% confidence level vary between 65.5 fb and 0.6 fb, while for spin-2 resonances produced via gluon–gluon fusion (or quark–antiquark initial states) limits vary between 77.4 (76.1) fb and 0.6 (0.5) fb, for the mass range from 220 GeV to 3400 GeV

The ATLAS trigger system for LHC Run 3 and trigger performance in 2022

The ATLAS trigger system is a crucial component of the ATLAS experiment at the LHC. It is responsible for selecting events in line with the ATLAS physics programme. This paper presents an overview of the changes to the trigger and data acquisition system during the second long shutdown of the LHC, and shows the performance of the trigger system and its components in the proton-proton collisions during the 2022 commissioning period as well as its expected performance in proton-proton and heavy-ion collisions for the remainder of the third LHC data-taking period (2022–2025)

Search for a new heavy scalar particle decaying into a Higgs boson and a new scalar singlet in final states with one or two light leptons and a pair of τ-leptons with the ATLAS detector

A search for a new heavy scalar particle X decaying into a Standard Model (SM) Higgs boson and a new singlet scalar particle S is presented. The search uses a proton-proton (pp) collision data sample with an integrated luminosity of 140 fb−1 recorded at a centre-of-mass energy of s√ = 13 TeV with the ATLAS detector at the Large Hadron Collider. The most sensitive mass parameter space is explored in X mass ranging from 500 to 1500 GeV, with the corresponding S mass in the range 200–500 GeV. The search selects events with two hadronically decaying τ-lepton candidates from H → τ+τ− decays and one or two light leptons (ℓ = e, μ) from S → VV (V = W, Z) decays while the remaining V boson decays hadronically or to neutrinos. A multivariate discriminant based on event kinematics is used to separate the signal from the background. No excess is observed beyond the expected SM background and 95% confidence level upper limits between 72 fb and 542 fb are derived on the cross-section σ(pp → X → SH) assuming the same SM-Higgs boson-like decay branching ratios for the S → VV decay. Upper limits on the visible cross-sections σ(pp → X → SH → WWττ) and σ(pp → X → SH → ZZττ) are also set in the ranges 3–26 fb and 6–33 fb, respectively