The relationship between particle freeze-out distributions and HBT radius parameters

The relationship between pion and kaon space-time freeze-out distributions and the HBT radius parameters in high-energy nucleus-nucleus collisions is investigated. We show that the HBT radius parameters in general do not reflect the R.M.S. deviations of the single particle production points. Instead, the HBT radius parameters are most closely related to the curvature of the two-particle space-time relative position distribution at the origin. We support our arguments by studies with a dynamical model (RQMD 2.4).Comment: RevTex, 10 pages including 3 figures. v2: Discussion of the lambda parameter has been added. PRC, in prin

The ARTEMIS simulations: stellar haloes of Milky Way-mass galaxies

We introduce the Assembly of high-ResoluTion Eagle-simulations of MIlky Way-type galaxieS (ARTEMIS) simulations, a new set of 42 zoomed-in, high-resolution (baryon particle mass of ≈2×104M⊙h−1⁠), hydrodynamical simulations of galaxies residing in haloes of Milky Way mass, simulated with the EAGLE galaxy formation code with re-calibrated stellar feedback. In this study, we analyse the structure of stellar haloes, specifically the mass density, surface brightness, metallicity, colour, and age radial profiles, finding generally very good agreement with recent observations of local galaxies. The stellar density profiles are well fitted by broken power laws, with inner slopes of ≈−3, outer slopes of ≈−4, and break radii that are typically ≈20–40 kpc. The break radii generally mark the transition between in situ formation and accretion-driven formation of the halo. The metallicity, colour, and age profiles show mild large-scale gradients, particularly when spherically averaged or viewed along the major axes. Along the minor axes, however, the profiles are nearly flat, in agreement with observations. Overall, the structural properties can be understood by two factors: that in situ stars dominate the inner regions and that they reside in a spatially flattened distribution that is aligned with the disc. Observations targeting both the major and minor axes of galaxies are thus required to obtain a complete picture of stellar haloes

S-shaped magnetic macroparticle filter for cathodic arc deposition

A new magnetic macroparticle filter design consisting of two 90{sup o} filters forming an S-shape is described. Transport properties of this S-filter are investigated using Langmuir and deposition probes. It is shown that filter efficiency is product of the efficiencies of two 90{sup o} filters and the deposition rate is still acceptably high to perform thin film deposition. Films of amorphous hard carbon have been deposited using a 90{sup o} filter and the S-filter, and macroparticle content of the films are compared

Sedimentary ancient DNA from Lake Skartjorna, Svalbard: assessing the resilience of arctic flora to Holocene climate change

Reconstructing past vegetation and species diversity from arctic lake sediments can be challenging because of low pollen and plant macrofossil concentrations. Information may be enhanced by metabarcoding of sedimentary ancient DNA (sedaDNA). We developed a Holocene record from Lake Skartjørna, Svalbard, using sedaDNA, plant macrofossils and sediment properties, and compared it with published records. All but two genera of vascular plants identified as macrofossils in this or a previous study were identified with sedaDNA. Six additional vascular taxa were found, plus two algal and 12 bryophyte taxa, by sedaDNA analysis, which also detected more species per sample than macrofossil analysis. A shift from Salix polaris-dominated vegetation, with Koenigia islandica, Ranunculaceae and the relatively thermophilic species Arabis alpina and Betula, to Dryas octopetala-dominated vegetation ~6600–5500 cal. BP suggests a transition from moist conditions 1–2°C warmer than today to colder/drier conditions. This coincides with a decrease in runoff, inferred from core lithology, and an independent record of declining lacustrine productivity. This mid-Holocene change in terrestrial vegetation is broadly coincident with changes in records from marine sediments off the west coast of Svalbard. Over the Holocene sedaDNA records little floristic change, and it clearly shows species persisted near the lake during time intervals when they are not detected as macrofossils. The flora has shown resilience in the presence of a changing climate, and, if future warming is limited to 2°C or less, we might expect only minor floristic changes in this region. However, the Holocene record provides no analogues for greater warming

Plasma deposited diamond-like carbon films for large neural arrays

To understand how large systems of neurons communicate, we need to develop methods for growing patterned networks of large numbers of neurons. We have found that diamond-like carbon thin films formed by energetic deposition from a filtered vacuum arc carbon plasma can serve as "neuron friendly" substrates for the growth of large neural arrays. Lithographic masks can be used to form patterns of diamond-like carbon, and regions of selective neuronal attachment can form patterned neural arrays. In the work described here, we used glass microscope slides as substrates on which diamond-like carbon was deposited. PC-12 rat neurons were then cultured on the treated substrates and cell growth monitored. Neuron growth showed excellent contrast, with prolific growth on the treated surfaces and very low growth on the untreated surfaces. Here we describe the vacuum arc plasma deposition technique employed, and summarize results demonstrating that the approach can be used to form large patterns of neurons.Щоб зрозуміти, як взаємодіють між собою великі системи нейронів, ми повинні розвивати методи вирощування рельєфних структур великого числа нейронів. Ми установили, що алмазоподібні вуглецеві тонкі плівки, що утворюються в результаті могутнього опромінення фільтрованою вуглецевою плазмою вакуумної дуги, можуть бути використані в ролі «нейроно-дружелюбніх» субстанцій для вирощування великих нейронних структур. Літографічні маски можуть бути використані для вормування алмазоподібної вуглецевої структури , а області селективного нейронного приєднання можуть утворювати систематичні нейронні структури. В експериментах, описаних нижче, як підкладку ми використовували предметні стекла мікроскопа, на які наносилися алмазоподібні вуглецеві покриття. Потім на опромінених підкладках були вирощені щурячі нейрони PC-12 і спостерігався ріст кліток. Спостерігався величезний контраст у рості нейронів, від багатого росту на опромінених поверхнях до слабкого на неопромінених. У даній роботі описана використовувана для опромінення вакуумно-дугова установка й узагальнені результати, що показують, що даний метод може бути використаний для формування великих структур нейронів.Чтобы понять, как взаимодействуют между собой большие системы нейронов, мы должны развивать методы выращивания рельефных структур большого числа нейронов. Мы установили, что алмазоподобные углеродные тонкие пленки, образующиеся в результате мощного облучения фильтрованной углеродной плазмой вакуумной дуги, могут быть использованы в качестве «нейроно-дружелюбных» субстанций для выращивания больших нейронных структур. Литографические маски могут применяться для формирования алмазоподобной углеродной структуры, а области селективного нейронного присоединения могут образовывать систематические нейронные структуры. В экспериментах, описываемых ниже, в качестве подложки мы использовали предметные стекла микроскопа, на которые наносились алмазоподобные углеродные покрытия. Затем на облученных подложках были выращены крысиные нейроны PC-12 и наблюдался рост клеток. Отслежен огромный контраст в росте нейронов, от обильного роста на облученных поверхностях до слабого на необлученных. В данной работе описана используемая для облучения вакуумно- дуговая установка и обобщены результаты, показывающие, что данный метод может быть использован для формирования больших структур нейронов

Transport and acceleration of high current uranium ion beams

Measurements have been made of the transport of beams produced by the high current ion source, MEVVA, and of the injection of these beams into the GSI heavy ion RFQ linac. This configuration has provided initial tests of the MEVVA ion source in an injector environment, and of the RFQ with uranium as the accelerated species. Beam currents of 78 mA of titanium and 19 mA of uranium, at an extraction voltage of 40 kV, have been transported through a 4.7 m long beam transport channel, and up to 40 mA of uranium has been transported through a single-gap accelerating column at a voltage of about 150 kV. A current of up to 5 mA of UT has been measured at the exit detector of the RFQ

Renormalization Group and Decoupling in Curved Space: II. The Standard Model and Beyond

We continue the study of the renormalization group and decoupling of massive fields in curved space, started in the previous article and analyse the higher derivative sector of the vacuum metric-dependent action of the Standard Model. The QCD sector at low-energies is described in terms of the composite effective fields. For fermions and scalars the massless limit shows perfect correspondence with the conformal anomaly, but similar limit in a massive vector case requires an extra compensating scalar. In all three cases the decoupling goes smoothly and monotonic. A particularly interesting case is the renormalization group flow in the theory with broken supersymmetry, where the sign of one of the beta-functions changes on the way from the UV to IR.Comment: 27 pages, 8 figure

Polaron Effective Mass, Band Distortion, and Self-Trapping in the Holstein Molecular Crystal Model

We present polaron effective masses and selected polaron band structures of the Holstein molecular crystal model in 1-D as computed by the Global-Local variational method over a wide range of parameters. These results are augmented and supported by leading orders of both weak- and strong-coupling perturbation theory. The description of the polaron effective mass and polaron band distortion that emerges from this work is comprehensive, spanning weak, intermediate, and strong electron-phonon coupling, and non-adiabatic, weakly adiabatic, and strongly adiabatic regimes. Using the effective mass as the primary criterion, the self-trapping transition is precisely defined and located. Using related band-shape criteria at the Brillouin zone edge, the onset of band narrowing is also precisely defined and located. These two lines divide the polaron parameter space into three regimes of distinct polaron structure, essentially constituting a polaron phase diagram. Though the self-trapping transition is thusly shown to be a broad and smooth phenomenon at finite parameter values, consistency with notion of self-trapping as a critical phenomenon in the adiabatic limit is demonstrated. Generalizations to higher dimensions are considered, and resolutions of apparent conflicts with well-known expectations of adiabatic theory are suggested.Comment: 28 pages, 15 figure

Physics Opportunities with the 12 GeV Upgrade at Jefferson Lab

This white paper summarizes the scientific opportunities for utilization of the upgraded 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab. It is based on the 52 proposals recommended for approval by the Jefferson Lab Program Advisory Committee.The upgraded facility will enable a new experimental program with substantial discovery potential to address important topics in nuclear, hadronic, and electroweak physics.Comment: 64 page