Temporal geochemical variations in lavas from Kīlauea's Pu‘u ‘Ō‘ō eruption (1983–2010): Cyclic variations from melting of source heterogeneities

[1] Geochemical time series analysis of lavas from Kīlauea's ongoing Pu‘u ‘Ō‘ō eruption chronicle mantle and crustal processes during a single, prolonged (1983 to present) magmatic event, which has shown nearly two-fold variation in lava effusion rates. Here we present an update of our ongoing monitoring of the geochemical variations of Pu‘u ‘Ō‘ō lavas for the entire eruption through 2010. Oxygen isotope measurements on Pu‘u ‘Ō‘ō lavas show a remarkable range (δ^(18)O values of 4.6–5.6‰), which are interpreted to reflect moderate levels of oxygen isotope exchange with or crustal contamination by hydrothermally altered Kīlauea lavas, probably in the shallow reservoir under the Pu‘u ‘Ō‘ō vent. This process has not measurably affected ratios of radiogenic isotope or incompatible trace elements, which are thought to vary due to mantle-derived changes in the composition of the parental magma delivered to the volcano. High-precision Pb and Sr isotopic measurements were performed on lavas erupted at ∼6 month intervals since 1983 to provide insights about melting dynamics and the compositional structure of the Hawaiian plume. The new results show systematic variations of Pb and Sr isotope ratios that continued the long-term compositional trend for Kīlauea until ∼1990. Afterward, Pb isotope ratios show two cycles with ∼10 year periods, whereas the Sr isotope ratios continued to increase until ∼2003 and then shifted toward slightly less radiogenic values. The short-term periodicity of Pb isotope ratios may reflect melt extraction from mantle with a fine-scale pattern of repeating source heterogeneities or strands, which are about 1–3 km in diameter. Over the last 30 years, Pu‘u ‘Ō‘ō lavas show 15% and 25% of the known isotopic variation for Kīlauea and Mauna Kea, respectively. This observation illustrates that the dominant time scale of mantle-derived compositional variation for Hawaiian lavas is years to decades

Beam Performance with the LHC Injectors Upgrade

The LHC Injectors Upgrade (LIU) project was put in place between 2010 and 2021 to increase the intensity and brightness in the LHC injectors to match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring reliable operation of the injectors complex up to the end of the HL-LHC era (ca. 2040). During the 2019-2020 CERN accelerators shutdown, extensive hardware modifications were implemented in the entire LHC proton and ion injection chains, involving the new Linac4, the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) and the ion PS injectors, i.e. the Linac3 and the Low Energy Ion Ring (LEIR). Since 2021, beams have been recommissioned throughout the injectors’ chain and the beam parameters are being gradually ramped up to meet the LIU specifications using new beam dynamics solutions adapted to the upgraded accelerators. This paper focuses on the proton beams and describes the current state of the art