Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Illuminating Light

Neutral meson production and direct photon correlations from small to large collision systems at the LH

Light neutral meson production in the era of precision physics at the LHC

The production of light neutral mesons in different collision systems is interesting for a variety ofreasons: In nucleus-nucleus (AA) collisions the measurements provide important information onthe energy loss of partons traversing the Quark-Gluon Plasma (QGP) which is formed in heavyion collisions at the LHC. In proton–proton (pp) collisions, neutral mesons allow us to test withhigh precision the predictions of perturbative QCD and other model calculations, and also serveas a reference for pA and AA collisions. In pA collisions, cold nuclear matter effects are studied.In the ALICE experiment, which is dedicated to the study of the QGP, neutral mesons can bedetected via their decay to two photons. The latter can be reconstructed using the two calorimetersEMCal and PHOS or via conversions in the detector material.Combining state-of-the-art reconstruction techniques with the large data sample delivered by theLHC in Run 2 gives us the opportunity to enhance the precision of our measurements. In theseproceedings, an overview of neutral meson production in pp, p–Pb and Pb–Pb collisions at LHCenergies, as measured with the ALICE detector is presented

Light neutral meson production in heavy ion collisions with ALICE in the era of precision physics at the LHC

The production of light neutral mesons in AA collisions probes the physics of the Quark-Gluon Plasma (QGP), which is formed in heavy-ion collisions at the LHC. More specifically, the centrality dependent neutral meson spectra in AA collisions compared to its spectra in minimum-bias pp collisions, scaled with the number of hard collisions, provides information on the energy loss of partons traversing the QGP. The measurement allows to test with high precision the predictions of theoretical model calculations. In addition, the decay of the π0 and η mesons are the dominant back- grounds for all direct photon measurements. Therefore, pushing the limits of the precision of neutral meson production is key to learning about the temperature and space-time evolution of the QGP. In the ALICE experiment neutral mesons can be detected via their decay into two photons. The latter can be reconstructed using the two calorimeters EMCal and PHOS or via conversions in the detector material. The excellent momentum resolution of the conversion photons down to very low pT and the high reconstruction efficiency and triggering capability of calorimeters at high pT, allow us to measure the pT dependent invariant yield of light neutral mesons over a wide kinematic range. Combining state-of-the-art reconstruction techniques with the high statistics delivered by the LHC in Run 2 gives us the opportunity to enhance the precision of our measurements. In these proceedings, new ALICE run 2 preliminary results for neutral meson production in pp and Pb–Pb collisions at LHC energies are presented

Illuminating Light: Neutral meson production and direct photon correlations from small to large collision systems at the LHC

In an ultra relativistic collision between two heavy nuclei the temperature of the matter in the overlap region gets so large that a phase transition occurs between normal hadronic matter and a deconfined strongly coupled medium that we call the quark gluon plasma. In my thesis, this state of matter is studied using data from the ALICE detector at the LHC, using photons as the main experimental probe. My work pushed the photon reconstruction capabilities of the detector to its limits, measuring neutral mesons and direct photons with increased momentum range and precision. This allows us to learn more about particle production mechanisms even in the non-perturbative regime across all system sizes. Furthermore, there is a hint of a direct photon puzzle at the LHC

Illuminating Light: Neutral meson production and direct photon correlations from small to large collision systems at the LHC

In an ultra relativistic collision between two heavy nuclei the temperature of the matter in the overlap region gets so large that a phase transition occurs between normal hadronic matter and a deconfined strongly coupled medium that we call the quark gluon plasma. In my thesis, this state of matter is studied using data from the ALICE detector at the LHC, using photons as the main experimental probe. My work pushed the photon reconstruction capabilities of the detector to its limits, measuring neutral mesons and direct photons with increased momentum range and precision. This allows us to learn more about particle production mechanisms even in the non-perturbative regime across all system sizes. Furthermore, there is a hint of a direct photon puzzle at the LHC

Isotopic insights into livestock production in Roman Italy: diet, seasonality, and mobility on an imperial estate

Agriculture is the most important intersection between farming communities and the natural world, with major implications for land exploitation and labour organisation. In Italy, at the heart of the Roman Empire, understanding of agriculture remains heavily dependent on ancient sources, which are unable to provide a regional or diachronic view of practices across the socio-economic spectrum. In order to gain insight into agricultural economies in Roman Italy and their social and environmental implications, this article reconstructs agro-pastoral strategies at an imperial estate in southern Italy through a multi-isotope investigation of livestock bone collagen and tooth enamel. Analysis of carbon, nitrogen, oxygen and strontium isotopes (δ13C, δ15N, δ18O, 86Sr/87Sr) are combined to evaluate animal management and mobility at Vagnari vicus and the villa of San Felice in the Basentello Valley. Results reveal taxon-specific herding strategies with the potential for significant inputs from legume forage/fodder and/or natural environments. Caprine herding did not appear to include long-distance transhumance. This analysis moves past previous text-based generalisations to provide a new and nuanced perspective on animal production in rural southern Italy and its economic and environmental implications