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The Born cross sections and effective form factors for process đ+âąđââÎââąÂŻÎ+ are measured at eight center-of-mass energies between 2.644 and 3.080 GeV, using a total integrated luminosity of 363.9ââpbâ1 đ+âąđâ collision data collected with the BESIII detector at BEPCII. After performing a fit to the Born cross section of đ+âąđââÎââąÂŻÎ+, no significant threshold effect is observed.
A single wavelength heterodyne interferometer has been set up to investigate the free electron density integrated axially along the line of sight (line density) in a theta-pinch plasma to determine its applicability as a plasma target for ion beam stripping. The maximal line density reached in this experiment was (3.57 ± 0.28) Ă 1018 cmâ2 at 80 Pa and 20 kV. The findings demonstrate the pulsed character of the line density and its increase by raising the load voltage and the working gas pressure. Additionally, the results were compared with spectroscopic free electron density estimations, which were carried out by HÎČ -line broadening and peak separation. The time behavior of the line density indicates that its peak value is delayed by about 10 ÎŒs compared to the spectroscopic results. This effect is due to the formation of an extended, magnetically compressed plasma column in the vicinity of the current maximum, although the highest volumetric free electron density is reached near the current zero crossing. Since the line density is an essential parameter in describing the stripping capabilities of the plasma target, the interferometric diagnostic is superior to a spectroscopic diagnostic, because it directly provides integrated values along the line of sight. Furthermore, the measurements of the line density in this experiment partially show nonphysical negative values, which is due to gaseous effects and residual shot vibrations.
The polarization of Î and ÎÂŻ hyperons along the beam direction has been measured relative to the second and third harmonic event planes in isobar Ru+Ru and Zr+Zr collisions at âsNN = 200 GeV. This is the first experimental evidence of the hyperon polarization by the triangular flow originating from the initial density fluctuations. The amplitudes of the sine modulation for the second and third harmonic results are comparable in magnitude, increase from central to peripheral collisions, and show a mild pT dependence. The azimuthal angle dependence of the polarization follows the vorticity pattern expected due to elliptic and triangular anisotropic flow, and qualitatively disagree with most hydrodynamic model calculations based on thermal vorticity and shear induced contributions. The model results based on one of existing implementations of the shear contribution lead to a correct azimuthal angle dependence, but predict centrality and pT dependence that still disagree with experimental measurements. Thus, our results provide stringent constraints on the thermal vorticity and shear-induced contributions to hyperon polarization. Comparison to previous measurements at RHIC and the LHC for the second-order harmonic results shows little dependence on the collision system size and collision energy.
Based on the positive results of the 0.63 m unmodulated 325 MHz Ladder-RFQ prototype from 2013 to 2016 [1, 2], a modulated 3.3m Ladder-RFQ (s. Fig. 1) has been designed and built for the acceleration of up to 100 mA protons from 95 keV to 3.0 MeV at the FAIR p-Linac [3, 4]. In this paper, we will show the results of manufacturing as well as low level RF measurements of the Ladder-RFQ including flatness and frequency tuning.
We investigate the role of the Pauli Exclusion Principle (PEP) for light nuclei, at the examples of 12C and 16O. We show that ignoring the PEP does lead not only to a too dense spectrum at low energy but also to a wrong grouping into bands. Using a geometrical mapping, a triangular structure for 12C and a tetrahedral structure in 16O in the ground state is obtained by using the indistinguishably of the α-particles.
Presolar grain isotopic ratios as constraints to nuclear physics inputs for s-process calculations
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The isotopic abundances in presolar SiC grains of AGB origin provide important and precise constraints to those star nucleosynthesis models. By comparing the values of the s-element abundances resulting from calculations with the ones measured in these dust grains, it turns out that new measurements of weak-interaction rates in ionized plasmas, as well as of neutron-capture cross sections, are needed, especially in the region near the neutron magic numbers 50 and 82.
Results on proton and Î flow, calculated with the UrQMD model that incorporates different realistic density dependent equations of state, are presented. It is shown that the proton and hyperon flow shows sensitivity to the equation of state and especially to the appearance of a phase transition at densities below 4n0. Even though qualitatively hyperons and protons exhibit the same beam energy dependence of the flow, the quantitative results are different. In this context it is suggested that the hyperon measurements can be used to study the density dependence of the hyperon interaction in high density QCD matter.
We study equilibrium as well as out-of-equilibrium properties of the strongly interacting QGP medium under extreme conditions of high temperature T and high baryon densities or baryon chemical potentials ÎŒB within a kinetic approach. We present the thermodynamic and transport properties of the QGP close to equilibrium in the framework of effective models with Nf=3 active quark flavours such as the Polyakov extended Nambu-Jona Lasinio (PNJL) and dynamical quasiparticle model with the CEP (DQPM-CP). Considering the transport coefficients and the EoS of the QGP phase, we compare our results with various results from the literature. Furthermore, out-of equilibrium properties of the QGP medium and in particular, the effect of a ÎŒB- dependence of thermodynamic and transport properties of the QGP are studied within the Parton-Hadron-String-Dynamics (PHSD) transport approach, which covers the full evolution of the system during HICs. We find that bulk observables and flow coefficients for strange hadrons as well as for antiprotons are more sensitive to the properties of the QGP, in particular to the ÎŒB - dependence of the QGP interactions.
We introduce a novel technique that utilizes a physics-driven deep learning method to reconstruct the dense matter equation of state from neutron star observables, particularly the masses and radii. The proposed framework involves two neural networks: one to optimize the EoS using Automatic Differentiation in the unsupervised learning scheme; and a pre-trained network to solve the TolmanâOppenheimerâVolkoff (TOV) equations. The gradient-based optimization process incorporates a Bayesian picture into the proposed framework. The reconstructed EoS is proven to be consistent with the results from conventional methods. Furthermore, the resulting tidal deformation is in agreement with the limits obtained from the gravitational wave event, GW170817.
The appearance of strangeness in the form of hyperons within the inner core of neutron stars is expected to affect its detectable properties, such as its global structure or gravitational wave emission. This work explores the parameter space of hyperonic stars within the framework of the Relativistic Mean Field model allowed by the present uncertainties in the state-of-the-art nuclear and hypernuclear experimental data. We impose multi-physics constraints at different density regimes to restrict the parameter space: Chiral effective field theory, heavy-ion collision data, and multi-messenger astrophysical observations of neutron stars. We investigate possible correlations between empirical nuclear and hypernuclear parameters, particularly the symmetry energy and its slope, with observable properties of neutron stars. We do not find a correlation for the hyperon parameters and the astrophysical data. However, the inclusion of hyperons generates a tension between the astrophysical and heavy-ion data constraining considerably the available parameter space.
This thesis aims to investigate the properties of hadronic matter by analyzing fluctuations of conserved charges. A transport model (SMASH) is used for these studies to achieve this. The first part of this thesis focuses on examining transport coefficients, specifically the diffusion coefficients of conserved charges and the shear viscosity. The second part investigates equal-time correlations of particle numbers in the form of cumulants. The last chapter studies different aspects of the isobar collision systems Ru and Zr.
As a first step, the hadronic medium and interactions between its constituents are introduced, and simultaneously, their impact on transport coefficients is investigated. The methodology is verified by comparing the results of SMASH with Chapman-Enskog calculations, followed by examining 3-to-1 multi-particle reactions, revealing their influence on shear viscosity and electrical diffusion. The analysis of the full hadron gas considers angle-dependent cross-sections and additional elastic cross-sections via the AQM description, showing significant impacts on transport coefficients. The dependency on the number of degrees of freedom is explored, with noticeable effects on diffusion coefficients but a smaller influence on the shear viscosity. At non-zero baryon chemical potential, the diffusion coefficients are strongly influenced, while the shear viscosity remains unaffected. Overall, the study underscores the importance of individual cross-sections and the modeling of interactions on transport coefficients.
The following chapter explores fluctuations of conserved charges, crucial for understanding phase transitions in heavy-ion collision from the quark-gluon plasma to the hadronic phase. Using SMASH, the impact of global charge conservation on particle number cumulants in subvolumes of boxes simulating infinite matter is studied. Comparisons with simpler systems highlights the influence of hadronic interactions on cumulants, especially via charge annihilation processes and the results from SMASH shows agreement with analytical calculations. Calculations at finite baryon chemical potential reveals a transition from a Poisson to Skellam distribution within the net proton cumulants. It is shown that an unfolding procedure to obtain the net baryon fluctuations from the net proton ones deviates from the actual net baryon result, particularly in larger volumes. Finally, net proton correlations at vanishing baryon chemical potential align with ALICE measurements and the net proton cumulants are unaffected by deuteron formation.
In the next step, the goal is to investigate critical fluctuations in the hadronic medium. Therefore, the hadronic system is initialized with critical equilibrium fluctuations by coupling the hadron resonance gas with the 3D Ising model. The single-particle probability distributions are derived from the principle of maximum entropy. Evolving these distributions in SMASH, their development in an expanding sphere adjusted to experimental conditions can be analyzed. It reveals resonance decay and formations as the primary source that affects the particle cumulants. Because of isospin randomization processes, critical fluctuations are better preserved in net nucleon numbers. However, for the strongest coupling investigated in this work, correlations of the critical field are still present in the final state of the evolution in the net proton fluctuations. Examining cumulant dependence on rapidity windows shows a non-monotonic trend.
In the third part, collisions involving the isobars Ru and Zr are studied at a center-of-mass energy of 200 GeV. Initially, SMASH is used to study the initial conditions to hydrodynamical simulations, emphasizing the importance of the nuclear structure of isobars on the geometry of the collision area. It is found that the deformation parameters notably influence the initial state. Correlations between nucleon-nucleon pairs on eccentricity fluctuations yield no significant effect. Subsequently, the hydrodynamic model vHLLE evolves the previously explored initial conditions and for the transition between the hydrodynamic and kinetic descriptions, the Cooper-Frye formula is used. Usage of the canonical ensemble ensures the exact conservation of the conserved charges B, Q, and S. The neutron skin effect, which changes the charge distribution within Ru nuclei, is additionally considered. Fluctuations are assessed, revealing suppression in large rapidity windows due to global charge conservation. The hadronic phase modifies fluctuations of net pions, net kaons, and net protons via annihilation processes, yet fluctuations remain unaffected by the neutron skin effect.
Human feline leukemia virus subgroup C receptor-related proteins 1 and 2 (FLVCR1 and 2) are members of the major facilitator superfamily1. Their dysfunction is linked to several clinical disorders, including PCARP, HSAN, and Fowler syndrome2â7. Earlier studies concluded that FLVCR1 may function as a putative heme exporter8â12, while FLVCR2 was suggested to act as a heme importer13, yet conclusive biochemical and detailed molecular evidence remained elusive for the function of both transporters14â17. Here, we show that FLVCR1 and FLVCR2 facilitate the transport of choline and ethanolamine across human plasma membranes, utilizing a concentration-driven substrate translocation process. Through structural and computational analyses, we have identified distinct conformational states of FLVCRs and unraveled the coordination chemistry underlying their substrate interactions. Within the binding pocket of both transporters, we identify fully conserved tryptophan and tyrosine residues holding a central role in the formation of cation-Ï interactions, essential for choline and ethanolamine selectivity. Our findings not only clarify the mechanisms of choline and ethanolamine transport by FLVCR1 and FLVCR2, enhancing our comprehension of disease-associated mutations that interfere with these vital processes, but also shed light on the conformational dynamics of these MFS-type proteins during the transport cycle.
We investigate the possible formation of a Bose-Einstein condensed phase of pions in the early Universe at nonvanishing values of lepton flavor asymmetries. A hadron resonance gas model with pion interactions, based on first-principle lattice QCD simulations at nonzero isospin density, is used to evaluate cosmic trajectories at various values of electron, muon, and tau lepton asymmetries that satisfy the available constraints on the total lepton asymmetry. The cosmic trajectory can pass through the pion condensed phase if the combined electron and muon asymmetry is sufficiently large: |le+lÎŒ|âł0.1, with little sensitivity to the difference leâlÎŒ between the individual flavor asymmetries. Future constraints on the values of the individual lepton flavor asymmetries will thus be able to either confirm or rule out the condensation of pions during the cosmic QCD epoch. We demonstrate that the pion condensed phase leaves an imprint both on the spectrum of primordial gravitational waves and on the mass distribution of primordial black holes at the QCD scale, e.g., the black hole binary of recent LIGO event GW190521 can be formed in that phase.
A considerable effort has been dedicated recently to the construction of generic equations of state (EOSs) for matter in neutron stars. The advantage of these approaches is that they can provide model-independent information on the interior structure and global properties of neutron stars. Making use of more than 106 generic EOSs, we asses the validity of quasi-universal relations of neutron star properties for a broad range of rotation rates, from slow-rotation up to the mass-shedding limit. In this way, we are able to determine with unprecedented accuracy the quasi-universal maximum-mass ratio between rotating and nonrotating stars and reveal the existence of a new relation for the surface oblateness, i.e., the ratio between the polar and equatorial proper radii. We discuss the impact that our findings have on the imminent detection of new binary neutron-star mergers and how they can be used to set new and more stringent limits on the maximum mass of nonrotating neutron stars, as well as to improve the modelling of the X-ray emission from the surface of rotating stars.
We have investigated the systematic differences introduced when performing a Bayesian-inference analysis of the equation of state of neutron stars employing either variable- or constant-likelihood functions. The former have the advantage that it retains the full information on the distributions of the measurements, making an exhaustive usage of the data. The latter, on the other hand, have the advantage of a much simpler implementation and reduced computational costs. In both approaches, the EOSs have identical priors and have been built using the sound-speed parameterization method so as to satisfy the constraints from X-ray and gravitationalwaves observations, as well as those from Chiral Effective Theory and perturbative QCD. In all cases, the two approaches lead to very similar results and the 90%-confidence levels are essentially overlapping. Some differences do appear, but in regions where the probability density is extremely small and are mostly due to the sharp cutoff set on the binary tidal deformability ÎË â€ 720 employed in the constant-likelihood analysis. Our analysis has also produced two additional results. First, a clear inverse correlation between the normalized central number density of a maximally massive star, nc,TOV/ns, and the radius of a maximally massive star, RTOV. Second, and most importantly, it has confirmed the relation between the chirp mass Mchirp and the binary tidal deformability ÎË. The importance of this result is that it relates a quantity that is measured very accurately, Mchirp, with a quantity that contains important information on the micro-physics, ÎË. Hence, once Mchirp is measured in future detections, our relation has the potential of setting tight constraints on ÎË.
We carry out an in-depth analysis of the prompt-collapse behaviour of binary neutron star (BNS) mergers. To this end, we perform more than 80 general relativistic BNS merger simulations using a family of realistic Equations of State (EOS) with different stiffness, which feature a first order deconfinement phase transition between hadronic and quark matter. From these simulations we infer the critical binary mass Mcrit that separates the prompt from the non-prompt collapse regime. We show that the critical mass increases with the stiffness of the EOS and obeys a tight quasi-universal relation, Mcrit/MTOV â 1.41 ± 0.06, which links it to the maximum mass MTOV of static neutron stars, and therefore provides a straightforward estimate for the total binary mass beyond which prompt collapse becomes inevitable. In addition, we introduce a novel gauge independent definition for a one-parameter family of threshold masses in terms of curvature invariants of the Riemann tensor which characterizes the development toward a more rapid collapse with increasing binary mass. Using these diagnostics, we find that the amount of matter remaining outside the black hole sharply drops in supercritical mass mergers compared to subcritical ones and is further reduced in mergers where the black hole collapse is induced by the formation of a quark matter core. This implies that Mcrit, particularly for merger remnants featuring quark matter cores, imposes a strict upper limit on the emission of any detectable electromagnetic counterpart in BNS mergers.
Die kĂŒnstliche elektrische Stimulation bietet oftmals die einzige Möglichkeit, nicht vorhandene bzw. verloren gegangene motorische sowie sensorische AktivitĂ€ten in gewissem Umfang wieder herzustellen. Im Falle von tauben Patienten wird zur Erlangung von Hörempfindungen die elektrische Stimulation des peripheren auditorischen Systems mit Hilfe von Cochlea- oder Hirnstammimplantaten standardmĂ€Ăig eingesetzt. Es ist dabei notwendig, natĂŒrliche neuronale Entladungsmuster durch die elektrisch evozierten Entladungsmuster nachzubilden. Bei einkanaligen Systemen kann nur die Zeitstruktur des Signals dargeboten werden. Mehrkanalige Systeme bieten hier noch zusĂ€tzlich die Möglichkeit auch örtlich selektiv bestimmte Nervenfasergruppen zu stimulieren und damit die Ortsstruktur in den Entladungsmustern zu reprĂ€sentieren. So hat es sich gezeigt, dass die SprachverstĂ€ndlichkeit durch Verwendung von Mehrkanal-Elektroden verbessert werden kann. Grundvoraussetzung hierfĂŒr ist die Optimierung der Kanalseparation durch Kleinst-Vielkanalelektroden und der Wahl einer optimalen Codierstrategie des Signals.
Die Codierstrategie ist abhĂ€ngig von dem jeweiligen spezifischen Einsatzbereich. So gaben z.B. schon Clopton und Spelman (1995) zu bedenken, dass die als selektiv berechnete tripolare (S3) Konfiguration nur fĂŒr einen bestimmten Stimulationsstrombereich gĂŒltig ist. Hinzu kommt es bei simultaner Verwendung benachbarter KanĂ€le zu schmerzhaften Lautheitssummationen. Ursache hierfĂŒr sind einerseits die Ăberlagerung der durch die Elektroden stimulierten neuronalen Bereiche und andererseits die Wechselwirkungen von Strömen benachbarter ElektrodenkanĂ€le. Diese Effekte fĂŒhren nicht nur zu einer Verringerung der rĂ€umlichen Stimulationsauflösung, sondern auch zu einer EinschrĂ€nkung der exakten Abbildung der Zeitstruktur innerhalb der einzelnen StimulationskanĂ€le.
Die Techniken und Grundlagen der elektrischen Stimulation von neuronalem Gewebe mit Kleinst-Vielkanalelektroden sind bisher kaum untersucht worden. Ziel dieser Arbeit war es, ein mathematisches Modell zu implementieren und QualitÀtsparameter zu definieren, mit deren Hilfe die Verteilung des elektrischen Feldes und die daraus resultierende neuronale Erregung beschrieben und optimiert werden kann. Zur Verifizierung des Modells sollten Methoden und Techniken entwickelt werden, die eine hochauflösende Abtastung der elektrischen Felder und Messung der neuronalen Daten innerhalb eines Messsystems ermöglichen.
Bei der neuronalen Stimulation mit Kleinst-Vielkanalelektroden ergibt sich eine Reihe von Problemen grundsĂ€tzlicher Art. So werden bei elektrodenferner Stimulation gröĂere Stimulationsströme benötigt als bei elektrodennaher Stimulation, wobei fĂŒr den Strombedarf die Stimulationskonfiguration eine entscheidende Rolle spielt: Der S1 Stimulationsmodus benötigt weniger Strom zur Erreichung groĂer Stimulationstiefen als der S2 Stimulationsmodus. Der gröĂte Strom wird mit zunehmendem Elektrodenabstand gleichermaĂen von dem S3 und S7 Stimulationsmodus benötigt. Gleichzeitig verfĂŒgen Kleinst-Vielkanalelektroden bauartbedingt aber nur ĂŒber kleine ElektrodenkontaktoberflĂ€chen und lassen daher auf Grund der kritischen FeldstĂ€rke nur geringe Stimulationsströme zu.
Ein weiteres Problem besteht bei diesen Kleinst-Elektrodendimensionen in der konkreten Lage der Neurone an denen eine neuronale Erregung evoziert wird. Die Dimension der Kleinst-Vielkanalelektroden liegt bei einem Elektrodenkanalkontaktdurchmesser von 70 ”m bereits in der GröĂenordnung der zu stimulierenden Neurone mit einem Durchmesser von 10 bis 15 ”m. Dies macht sich bei den Messungen besonders dann deutlich bemerkbar, wenn nicht der Stimulationsstrom die GröĂe des ĂŒberschwelligen Bereichs modelliert, sondern wenn der Elektrodenkanalabstand durch die Wahl der entsprechenden ElektrodenkanĂ€le verĂ€ndert wird. Hier weisen zwar die meisten neuronalen Antworten noch in die sich aus dem Modell ergebende Richtung, jedoch kommt es zu einer höheren Streuung der Ergebnisse als bei Messungen mit der Folienelektrode, die eine KontaktflĂ€che von 170 ”m besitzt.
Es gibt also eine Reihe von begrenzenden Faktoren bei der optimalen Dimensionierung der Stimulationselektrode, die sowohl abhÀngig von der physiologischen Topologie ist als auch von den eingesetzten Stimulationskonfigurationen. Es ist also zur Stimulation die Wahl der optimalen Codierstrategie und die richtige Dimensionierung der Stimulationselektrode sowie der ElektrodenkanalabstÀnde von entscheidender Bedeutung.
Die neuronalen Messungen wurden erstmalig fĂŒr diese Fragestellung am Hirnschnitt durchgefĂŒhrt, da sie, im Gegensatz zu in-vivo Versuchen, eine exakte Positionierung der Elektroden auf dem Hirnschnitt unter Sichtkontrolle durch das Mikroskop erlauben. Es wurden aus den neuronalen Messungen die Amplituden und Latenzen der exzitatorischen postsynaptischen Potenziale (EPSP) sowie der Feldpotenziale ausgewertet.
Der Versuchsaufbau macht es möglich, die Potenzialfelder mit genau den Konfigurationen abzutasten, mit denen auch die neuronalen Messungen des Hirnschnittes durchgefĂŒhrt wurden. Das implementierte Programm zur Berechnung der Feldverteilung besitzt zum Messprogramm ein Interface, so dass es möglich ist, die Einstellungen des Experimentes, wie Stimulationskonfigurationen, Abtastraster des Feldes und die Koordinaten des Messraums, in der Modellrechnung zu verwenden. Somit ist ein direktes Vergleichen zwischen Messung und Berechnung möglich. In nachfolgenden Arbeiten können die vorliegenden Ergebnisse als Grundlage fĂŒr in-vivo Versuche eingesetzt werden.
Zur DurchfĂŒhrung der Messungen wurden sehr kleine Elektroden aus eigener Herstellung verwendet und es wurden uns freundlicherweise neu entwickelte Folienelektroden des Fraunhofer Instituts St. Ingbert zur VerfĂŒgung gestellt. Die GröĂe der verwendeten Kleinst-Vielkanalelektroden aus eigener Herstellung lag um ca. eine Zehnerpotenz unter den aktuell eingesetzten Elektrodentypen und ist speziell fĂŒr den direkten Kontakt zwischen Elektrode und Gewebe konzipiert. Dies entspricht dem typischen Einsatzbereich von Hirnstammimplantaten. Dies ist auch notwendig, um eine maximale rĂ€umliche Separation der erzeugten Felder zu ermöglichen. AuĂerdem erlaubte das Elektrodendesign auf Grund der hohen Anzahl der ElektrodenkanĂ€le und durch variieren der Konfigurationen die Feldrichtung zu bestimmen, ohne die Elektrode neu auf den Hirnschnitt aufsetzen zu mĂŒssen.
Der in dieser Arbeit implementierte Algorithmus zur Berechnung der Feldverteilungen und die eingefĂŒhrten QualitĂ€tsparameter erlauben, die unterschiedlichen Stimulationskonfigurationen miteinander zu vergleichen und zu optimieren. Die Ergebnisse aus diesen Modellrechnungen wurden sowohl mit den Messungen der elektrischen Felder als auch mit den Ergebnissen aus den neuronalen Antworten verglichen.
Der im Rahmen dieser Arbeit erstellte Versuchsaufbau bestand aus einer ĂŒber mehrere Mikromanipulatoren getriebene mikrometergenaue Positioniereinrichtung. Es konnten sowohl die Stimulationselektrode als auch die Elektrode zur Aufzeichnung der neuronalen Daten gesteuert werden. Die Steuerung des gesamten Setup, d.h. die Positionierung, die Aufzeichnung der neuronalen Daten und die Generierung der Stimulationsmuster wurde ĂŒber den zentralen Messrechner durch ein hierfĂŒr entwickeltes Computerprogramm gesteuert. Die Versuche wurden ĂŒber ein inverses Mikroskop durch eine CCD-Kamera aufgezeichnet.
Der entscheidende Vorteil des in dieser Arbeit gewĂ€hlten Modellansatzes besteht in der grundsĂ€tzlichen Beschreibung der Feldverteilung bei vielkanaliger Stimulation, so dass diese auch auf andere Elektrodenformen bzw. Konfigurationen und Dimensionen ĂŒbertragbar ist. Es lassen sich so den verschiedenen Konfigurationen nach bestimmten QualitĂ€tskriterien bewerten und an die jeweilige Zielrichtung der Stimulation anpassen. Die berechneten Felder konnten erfolgreich in der Messeinrichtung generiert und nachgemessen werden. AuĂerdem ist es gelungen, differenzierte neuronale AktivitĂ€ten auszuwerten, welche die Aussagen des Modells abstĂŒtzen.
Komplex I enthĂ€lt ein Flavinmononukleotid sowie mindestens acht Eisen- Schwefel Zentren als redoxaktive Cofaktoren. Da ein wesentlicher Teil des mitochondrialen Genoms fĂŒr Untereinheiten von Komplex I codiert, betrifft eine Vielzahl von mitochondrialen Erkrankungen diesen Enzymkomplex.
Komplex I wurde bisher aus Mitochondrien, Chloroplasten und Bakterien isoliert. Die Minimalform von Komplex I wird in Bakterien gefunden, wo er aus 14 (bzw 13 im Falle einer Genfusion) Untereinheiten besteht und eine Masse von etwa 550 kDa aufweist. Generell werden sieben hydrophile und sieben hydrophobe Untereinheiten mit ĂŒber 50 vorhergesagten Transmembranhelices gefunden. Im Komplex I aus Eukaryoten wurde eine grössere Anzahl zusĂ€tzlicher, akzessorischer Untereinheiten nachgewiesen. Hier werden die sieben hydrophoben Untereinheiten vom mitochondrialen Genom codiert, wĂ€hrend alle anderen Untereinheiten kerncodiert sind und in das Mitochondrium importiert werden mĂŒssen.
Die obligat aerobe Hefe Yarrowia lipolytica wurde als Modellsystem zur Untersuchung von eukaryotischem Komplex I etabliert. Die bisher am besten untersuchte Hefe Saccharomyces cerevisiae enthĂ€lt keinen Komplex I. Hier wird die Oxidation von NADH durch eine andere Klasse von sogenannten alternativen NADH Dehydrogenasen durchgefĂŒhrt. Auch Y. lipolytica enthĂ€lt ein solches alternatives Enzym, das allerdings mit seiner Substratbindungsstelle zur Aussenseite der inneren Mitochondrienmembran orientiert ist. Durch molekularbiologische Manipulation konnte eine interne Version dieses Enzymes exprimiert werden, wodurch es möglich ist, letale Defekte in Komplex I Deletionsmutanten zu kompensieren. Mittlerweile wurden alle Voraussetzungen geschaffen, um kerncodierte Untereinheiten von Komplex I aus Y. lipolytica gezielt genetisch zu verĂ€ndern. Die Proteinreinigung wird durch die Verwendung einer auf einem His-tag basierenden AffinitĂ€tsreinigung erheblich erleichtert...
We use holography to study the dynamics of a strongly-coupled gauge theory in four-dimensional de Sitter space with Hubble rate H. The gauge theory is non-conformal with a characteristic mass scale M. We solve Einsteinâs equations numerically and determine the time evolution of homogeneous gauge theory states. If their initial energy density is high compared with H4 then the early-time evolution is well described by viscous hydrodynamics with a non-zero bulk viscosity. At late times the dynamics is always far from equilibrium. The asymptotic late-time state preserves the full de Sitter symmetry group and its dual geometry is a domain-wall in AdS5. The approach to this state is characterised by an emergent relation of the form P = w â° that is different from the equilibrium equation of state in flat space. The constant w does not depend on the initial conditions but only on H/M and is negative if the ratio H/M is close to unity. The event and the apparent horizons of the late-time solution do not coincide with one another, reflecting its non-equilibrium nature. In between them lies an âentanglement horizonâ that cannot be penetrated by extremal surfaces anchored at the boundary, which we use to compute the entanglement entropy of boundary regions. If the entangling region equals the observable universe then the extremal surface coincides with a bulk cosmological horizon that just touches the event horizon, while for larger regions the extremal surface probes behind the event horizon.
We use the quantum null energy condition in strongly coupled two-dimensional field theories (QNEC2) as diagnostic tool to study a variety of phase structures, including crossover, second and first order phase transitions. We find a universal QNEC2 constraint for first order phase transitions with kinked entanglement entropy and discuss in general the relation between the QNEC2-inequality and monotonicity of the Casini-Huerta c-function. We then focus on a specific example, the holographic dual of which is modelled by three-dimensional Einstein gravity plus a massive scalar field with one free parameter in the self-interaction potential. We study translation invariant stationary states dual to domain walls and black branes. Depending on the value of the free parameter we find crossover, second and first order phase transitions between such states, and the c-function either flows to zero or to a finite value in the infrared. We present evidence that evaluating QNEC2 for ground state solutions allows to predict the existence of phase transitions at finite temperature.
Determining the sound speed cs in compact stars is an important open question with numerous implications on the behavior of matter at large densities and hence on gravitational-wave emission from neutron stars. To this scope, we construct more than 107 equations of state (EOSs) with continuous sound speed and build more than 108 nonrotating stellar models consistent not only with nuclear theory and perturbative QCD, but also with astronomical observations. In this way, we find that EOSs with subconformal sound speeds, i.e., with cs 1 3 2 < within the stars, are possible in principle but very unlikely in practice, being only 0.03% of our sample. Hence, it is natural to expect that cs 1 3 2 > somewhere in the stellar interior. Using our large sample, we obtain estimates at 95% credibility of neutron-star radii for representative stars with 1.4 and 2.0 solar masses, R1.4 12.42 km 0.99 0.52 = - + , R2.0 12.12 km 1.23 1.11 = - + , and for the binary tidal deformability of the GW170817 event, 1.186 485 211 225 L = - Ë + . Interestingly, our lower bounds on the radii are in very good agreement with the prediction derived from very different arguments, namely, the threshold mass. Finally, we provide simple analytic expressions to determine the minimum and maximum values of LË as a function of the chirp mass.
Using more than a million randomly generated equations of state that satisfy theoretical and observational constraints, we construct a novel, scale-independent description of the sound speed in neutron stars, where the latter is expressed in a unit cube spanning the normalized radius, r/R, and the mass normalized to the maximum one, M/MTOV. From this generic representation, a number of interesting and surprising results can be deduced. In particular, we find that light (heavy) stars have stiff (soft) cores and soft (stiff) outer layers, or that the maximum of the sound speed is located at the center of light stars but moves to the outer layers for stars with M/MTOV âł 0.7, reaching a constant value of cs = 1 2 2 as M â MTOV. We also show that the sound speed decreases below the conformal limit cs = 1 3 2 at the center of stars with M = MTOV. Finally, we construct an analytic expression that accurately describes the radial dependence of the sound speed as a function of the neutron-star mass, thus providing an estimate of the maximum sound speed expected in a neutron star.
We have investigated the systematic differences introduced when performing a Bayesian-inference analysis of the equation of state (EOS) of neutron stars employing either variable- or constant-likelihood functions. The former has the advantage of retaining the full information on the distributions of the measurements, making exhaustive usage of the data. The latter, on the other hand, has the advantage of a much simpler implementation and reduced computational costs. In both approaches, the EOSs have identical priors and have been built using the sound speed parameterization method so as to satisfy the constraints from X-ray and gravitational waves observations, as well as those from chiral effective theory and perturbative quantum chromodynamics. In all cases, the two approaches lead to very similar results and the 90% confidence levels essentially overlap. Some differences do appear, but in regions where the probability density is extremely small and are mostly due to the sharp cutoff on the binary tidal deformability LË ï 720 set in the constant-likelihood approach. Our analysis has also produced two additional results. First, an inverse correlation between the normalized central number density, nc,TOV/ns, and the radius of a maximally massive star, RTOV. Second, and most importantly, it has confirmed the relation between the chirp mass and the binary tidal deformability. The importance of this result is that it relates ïchirp, which is measured very accurately, and LË , which contains important information on the EOS. Hence, when ïchirp is measured in future detections, our relation can be used to set tight constraints on LË .
A considerable effort has been dedicated recently to the construction of generic equations of state (EOSs) for matter in neutron stars. The advantage of these approaches is that they can provide model-independent information on the interior structure and global properties of neutron stars. Making use of more than 106 generic EOSs, we assess the validity of quasi-universal relations of neutron-star properties for a broad range of rotation rates, from slow rotation up to the mass-shedding limit. In this way, we are able to determine with unprecedented accuracy the quasi-universal maximum-mass ratio between rotating and nonrotating stars and reveal the existence of a new relation for the surface oblateness, i.e., the ratio between the polar and equatorial proper radii. We discuss the impact that our findings have on the imminent detection of new binary neutron-star mergers and how they can be used to set new and more stringent limits on the maximum mass of nonrotating neutron stars, as well as to improve the modeling of the X-ray emission from the surface of rotating stars.
The spectral properties of the post-merger gravitational-wave signal from a binary of neutron stars encodes a variety of information about the features of the system and of the equation of state describing matter around and above nuclear saturation density. Characterising the properties of such a signal is an âoldâ problem, which first emerged when a number of frequencies were shown to be related to the properties of the binary through âquasi-universalâ relations. Here we take a new look at this old problem by computing the properties of the signal in terms of the Weyl scalar Ï4. In this way, and using a database of more than 100 simulations, we provide the first evidence for a new instantaneous frequency, f Ï4 0, associated with the instant of quasi timesymmetry in the postmerger dynamics, and which also follows a quasi-universal relation. We also derive a new quasi-universal relation for the merger frequency f h mer, which provides a description of the data that is four times more accurate than previous expressions while requiring fewer fitting coefficients. Finally, consistently with the findings of numerous studies before ours, and using an enlarged ensamble of binary systems we point out that the â = 2, m = 1 gravitational-wave mode could become comparable with the traditional â = 2, m = 2 mode on sufficiently long timescales, with strain amplitudes in a ratio |h 21|/|h 22| ⌠0.1 â 1 under generic orientations of the binary, which could be measured by present detectors for signals with large signal-to-noise ratio or by third-generation detectors for generic signals should no collapse occur.
The amplification of magnetic fields plays an important role in explaining numerous astrophysical phenomena associated with binary neutron star mergers, such as mass ejection and the powering of short gamma-ray bursts. Magnetic fields in isolated neutron stars are often assumed to be confined to a small region near the stellar surface, while they are normally taken to fill the whole star in numerical modeling of mergers. By performing high-resolution, global, and high-order general-relativistic magnetohydrodynamic simulations, we investigate the impact of a purely crustal magnetic field and contrast it with the standard configuration consisting of a dipolar magnetic field with the same magnetic energy but filling the whole star. While the crust configurations are very effective in generating strong magnetic fields during the KelvinâHelmholtz-instability stage, they fail to achieve the same level of magnetic-field amplification of the full-star configurations. This is due to the lack of magnetized material in the neutron-star interiors to be used for further turbulent amplification and to the surface losses of highly magnetized matter in the crust configurations. Hence, the final magnetic energies in the two configurations differ by more than 1 order of magnitude. We briefly discuss the impact of these results on astrophysical observables and how they can be employed to deduce the magnetic topology in merging binaries.
The spectral properties of the post-merger gravitational-wave signal from a binary of neutron stars encodes a variety of information about the features of the system and of the equation of state describing matter around and above nuclear saturation density. Characterizing the properties of such a signal is an âoldâ problem, which first emerged when a number of frequencies were shown to be related to the properties of the binary through âquasiuniversalâ relations. Here we take a new look at this old problem by computing the properties of the signal in terms of the Weyl scalar Ï4. In this way, and using a database of more than 100 simulations, we provide the first evidence for a new instantaneous frequency, y f0 4, associated with the instant of quasi-time-symmetry in the dynamics, and which also follows a quasi-universal relation. We also derive a new quasi-universal relation for the merger frequency f h mer, which provides a description of the data that is 4 times more accurate than previous expressions while requiring fewer fitting coefficients. Finally, consistent with the findings of numerous studies before ours, and using an enlarged ensemble of binary systems, we point out that the â = 2, m = 1 gravitational-wave mode could become comparable with the traditional â = 2, m = 2 mode on sufficiently long timescales, with strain amplitudes in a ratio |h21|/|h22| ⌠0.1â1 under generic orientations of the binary, which could be measured by present detectors for signals with a large signal-to-noise ratio or by third-generation detectors for generic signals should no collapse occur.
One-photon and multi-photon absorption, spontaneous and stimulated photon emission, resonance Raman scattering and electron transfer are important molecular processes that commonly involve combined vibrational-electronic (vibronic) transitions. The corresponding vibronic transition profiles in the energy domain are usually determined by Franck-Condon factors (FCFs), the squared norm of overlap integrals between vibrational wavefunctions of different electronic states. FC profiles are typically highly congested for large molecular systems and the spectra usually become not well-resolvable at elevated temperatures. The (theoretical) analyses of such spectra are even more difficult when vibrational mode mixing (Duschinsky) effects are significant, because contributions from different modes are in general not separable, even within the harmonic approximation. A few decades ago Doktorov, Malkin and Man'ko [1979 J. Mol. Spectrosc. 77, 178] developed a coherent state-based generating function approach and exploited the dynamical symmetry of vibrational Hamiltonians for the Duschinsky relation to describe FC transitions at zero Kelvin. Recently, the present authors extended the method to incorporate thermal, single vibronic level, non-Condon and multi-photon effects in energy, time and probability density domains for the efficient calculation and interpretation of vibronic spectra. Herein, recent developments and corresponding generating functions are presented for single vibronic levels related to fluorescence, resonance Raman scattering and anharmonic transition.
The article investigates the results obtained from numerical simulations and experimental tests concerning the propagation of guided waves in corroded steel plates. Developing innovative methodologies for assessing corrosion-induced degradation is crucial for accurately diagnosing offshore and ship structures exposed to harsh environmental conditions. The main aim of the research is to analyze how surface irregularities affect wave propagation characteristics. An investigation was conducted for antisymmetric fundamental mode A0. Specifically, the study examines the asymmetrical wavefronts generated by nonuniform thickness in damaged specimens. Initially, numerical analysis explores the impact of thickness variation on wave field symmetry. Corroded plates with varying levels of degradation are modeled using the random fields approach, with degradation levels ranging from 0 % to 60 %. Subsequently, the research investigates how the standard deviation of thickness distribution (from 5 % to 20 % of the initial thickness) and excitation frequency (from 50 to 150 kHz) influence recorded signals and the shape of reconstructed wavefronts. Each scenario compares wavefront symmetry levels estimated using rotational and bilateral symmetry degrees as indicative parameters. The numerical simulations are complemented by experimental tests conducted on plates with three different degradation levels. The results demonstrate the efficacy of the proposed wave field analysis approach for assessing structural integrity, as evidenced by the agreement between numerical predictions and experimental observations.
Dielectrons are unique observables in ultra-relativistic heavy-ion collisions. Thanks to their penetrating nature, they carry information from all stages of the collision and can provide knowledge about pre-equilibirium dynamics, QGP temperature and transport coefficients, and chiral symmetry restoration. On the other hand, experimental challenges are enormous because production cross sections are small and the signal of interest is eclipsed by a huge combinatorial and physics background from light- and heavy-flavour hadron decays. In this talk the status of dielectron measurements with ALICE is shown and the perspectives with the recently installed and planned ALICE detector upgrades are discussed.
The equation of state (EoS) of matter at extremely high temperatures and densities is currently not fully understood, and remains a major challenge in the field of nuclear physics. Neutron stars harbor such extreme conditions and therefore serve as celestial laboratories for constraining the dense matter EoS. In this thesis, we present a novel algorithm that utilizes the idea of Bayesian analysis and the computational efficiency of neural networks to reconstruct the dense matter equation of state from mass-radius observations of neutron stars. We show that the results are compatible with those from earlier works based on conventional methods, and are in agreement with the limits on tidal deformabilities obtained from the gravitational wave event, GW170817. We also observe that the resulting squared speed of sound from the reconstructed EoS features a peak, indicating a likely convergence to the conformal limit at asymptotic densities, as expected from quantum chromodynamics. The novel algorithm can also be applied across various fields faced with computational challenges in solving inverse problems. We further examine the efficiency of deep learning methods for analyzing gravitational waves from compact binary coalescences in this thesis. In particular, we develop a deep learning classifier to segregate simulated gravitational wave data into three classes: signals from binary black hole mergers, signals from binary neutron star mergers, or white noise without any signals. A second deep learning algorithm allows for the regression of chirp mass and combined tidal deformability from simulated binary neutron star mergers. An accurate estimation of these parameters is crucial to constrain the underlying EoS. Lastly, we explore the effects of finite temperatures on the binary neutron star merger remnant from GW170817. Isentropic EoSs are used to infer the frequencies of the rigidly rotating remnant and are noted to be significantly lower compared to previous estimates from zero temperature EoSs. Overall, this thesis presents novel deep learning methods to constrain the neutron star EoS, which will prove useful in future, as more observational data is expected in the upcoming years.
Im Rahmen dieser Doktorarbeit werden drei Schwerpunkte behandelt: 1) Die hocheffektive Beschleunigung von Elektronen und Protonen durch die Wechselwirkung von relativistischen Laserpulsen mit SchĂ€umen. 2) Die Erzeugung und Messung hochintensiver Betatronstrahlung von direkt laserbeschleunigten (DLA-) Elektronen. 3) Die Anwendung von DLA-Elektronen fĂŒr den biologischen FLASH-Effekt mit einer rekordbrechenden Dosisrate.
Die direkte Laserbeschleunigung von Elektronen wurde durch die Wechselwirkung eines sub-ps-Laserpulses mit einer IntensitĂ€t von ~ 10^19 W/cm^2 mit einem Plasma nahe kritischer Elektronendichte (NCD) untersucht. Ein sub-mm langes NCD-Plasma wurde durch Erhitzen eines Schaums mit einer niedrigen Dichte mit einem ns-Puls von 10^13-10^14 W/cm^2 erzeugt. Die Experimente wurden an der PHELIX-Anlage (Petawatt Hoch- Energie Laser fĂŒr Schwerionenexperimente) in den Jahren 2019 â 2023 durchgefĂŒhrt. WĂ€hrend der Suche nach optimalen Bedingungen fĂŒr die Beschleunigung von Elektronen und Protonen wurden die Parameter des ns-Pulses variiert und verschiedene Targets verwendet. Es wurde gezeigt, dass das Plasma im Schaum gute Voraussetzungen fĂŒr die Erzeugung gerichteter, ultrarelativistischer DLA-Elektronen mit Energien von bis zu 100 MeV bietet. Die Elektronen weisen eine Boltzmann-Ă€hnliche Energieverteilung mit einer Temperatur von 10-20 MeV auf.
Optimale Bedingungen fĂŒr eine effektive Beschleunigung von DLA-Elektronen wurden bei der Kombination eines CHO-Schaums mit einer Dichte von 2 mg/cm3 und einer Dicke von 300-500 ”m mit einer Metallfolie erreicht. Die Gesamtladung der detektierten Elektronen mit Energien ĂŒber 1,5 MeV erreichte 0,5-1 ”C mit der Umwandlungseffizienz der Laserenergie von ~ 20-30%.
AuĂerdem wird die Beschleunigung von Protonen durch DLA-Elektronen anders verursacht als bei typischer Target Normal Sheath Acceleration (TNSA). FĂŒr die Untersuchung der lokalen Protonenenergieverteilung wurden Magnetspektrometer unter verschiedenen Winkeln zur Laserachse verwendet. DafĂŒr wurde eine Filtermethode entwickelt, welche es ermöglicht, Spektren von Protonen mit Energien von bis zu 100 MeV zu rekonstruieren. Es wurde gezeigt, dass am PHELIX durch die Kombination von einem ~ 300-400 ”m dicken CHO-Schaum mit einer Dichte von 2 mg/cm^3 und einer 10 ”m dicken Au-Folie bei einer IntensitĂ€t des sub-ps-Pulses von ~ 10^19 W/cm^2 und unter Verwendung eines optimierten ns-Vorpulses eine optimale Protonenbeschleunigung erreicht wurde. Es wurde ein TNSA-Ă€hnliches Regime mit einer maximalen Cut-off-Energie von 34±0,5 MeV beobachtet. Im Vergleich dazu wurde bei der typischen TNSA unter Verwendung einer 10 ”m dicken Au-Folie als Target und derselben LaserintensitĂ€t eine maximale Cut-off-Energie von 24±0,5 MeV gemessen. DarĂŒber hinaus beobachteten wir einen sehr schwachen Abfall der Protonenanzahl in AbhĂ€ngigkeit von der Protonenenergie (anders als bei der typischen TNSA) und eine sehr regelmĂ€Ăige Protonenstrahlverteilung in einem breiten Winkelbereich bis zu hohen Energien. Dies könnte zur Verbesserung der QualitĂ€t der Protonenradiographie von Plasmafeldern genutzt werden.
Beim DLA-Prozess (im NCD-Plasma) entsteht Betatronstrahlung durch die Oszillationen von Elektronen in quasi-statischen elektrischen und magnetischen Feldern des Plasmakanals. Um diese Strahlung zu untersuchen, wurde ein neues modifiziertes Magnetspektrometer (X-MS) konstruiert. Das X-MS ermöglicht die 1D-Auflösung mehrerer Quellen. Dank dieser Spezifikation war es möglich, Betatronstrahlung von Bremsstrahlung der ponderomotorischen Elektronen im Metallhalter zu trennen und zu messen.
Im Experiment mit einem CHO-Schaum mit einer Dichte von 2 mg/cm^3 und einer Dicke von ~ 800 ”m als Target wurde die von den optimierten DLA-Elektronen erzeugte Betatronstrahlung gemessen. Bei einer Peak-IntensitĂ€t des dreieckigen ns-Pulses von ~ 3·10^13 W/cm^2 und des sub-ps-Pulses von ~ 10^19 W/cm^2, welcher 4±0,5 ns gegenĂŒber dem ns-Puls verzögert war, betrug der Halbwinkel im FWHM-Bereich des Elektronenstrahls 17±2°. Unter diesen Bedingungen war die Betatronstrahlung mit einem Halbwinkel im FWHM-Bereich von 11±2° fĂŒr die Photonen mit Energien ĂŒber 10 keV ebenfalls gerichtet. Die Photonenanzahl mit Energien ĂŒber 10 keV wurde auf etwa 3Î10^10 / 3Î10^11 (gerichtete Photonen / Photonen im Halbraum entlang der Laserstrahlrichtung) abgeschĂ€tzt. Die maximale Photonenanzahl pro Raumwinkel betrug ~2·10^11 photons/sr. Die Brillanz der registrierten Betatronstrahlung erreichte ~ 2·10^20 photons/s/mm^2/mrad^2/(0.1% BW) bei 10 keV.
Die Verwendung eines Hochstromstrahls aus DLA-Elektronen fĂŒr die FLASH-Strahlentherapie ermöglicht das Erreichen einer Dosis von bis zu 50-70 Gy wĂ€hrend eines sub-ps-Laserpulses. Im Jahr 2021, wĂ€hrend der P213-Strahlzeit am PHELIX wurde der Sauerstoffkonzentrationsabfall bei der Bestrahlung von Medien (Wasser und andere biologische Medien) mit DLA-Elektronen in AbhĂ€ngigkeit von der Dosis untersucht. Die Strahlendosis wurde hierbei indirekt gemessen. HierfĂŒr wurde eine Rekonstruktionsmethode entwickelt, die es ermöglicht, die Dosis innerhalb des âWasser-Containersâ auf Basis von Messungen auĂerhalb des Containers mit einem untersuchten Medium zu ermitteln. Es wurde eine gute Ăbereinstimmung zwischen dem Experiment und einer Monte-Carlo-Simulation fĂŒr Wasser gezeigt. Die registrierte Dosisrate erreichte einen Rekordwert von ~ 70 TGy/s.
The strong force is one of the four fundamental interactions, and the theory of it is called Quantum Chromodynamics (QCD). A many-body system of strongly interacting particles (QCD matter) can exist in different phases depending on temperature (T) and baryonic chemical potential (”B). The phases and transitions between them can be visualized as ”BâT phase diagram. Extraction of the properties of the QCD matter, such as compressibility, viscosity and various susceptibilities, and its Equation of State (EoS) is an important aspect of the QCD matter study. In the region of near-zero baryonic chemical potential and low temperatures the QCD matter degrees of freedom are hadrons, in which quarks and gluons are confined, while at higher temperatures partonic (quarks and gluons) degrees of freedom dominate. This partonic (deconfined) state is called quark-gluon plasma (QGP) and is intensively studied at CERN and BNL. According to lattice QCD calculations at ”B=0 the transition to QGP is smooth (cross-over) and takes place at Tâ156 MeV. The region of the QCD phase diagram, where matter is compressed to densities of a few times normal nuclear density (”B of several hundreds MeV), is not accessible for the current lattice QCD calculations, and is a subject of intensive research. Some phenomenological models predict a first order phase transition between hadronic and partonic phases in the region of TâČ100 MeV and ”Bâł500 MeV. Search for signs of a possible phase transition and a critical point or clarifying whether the smooth cross-over is continuing in this region are the main goals of the near future explorations of the QCD phase diagram.
In the laboratory a scan of the QCD phase diagram can be performed via heavy-ion collisions. The region of the QCD phase diagram at Tâł150 MeV and ”Bâ0 is accessible in collisions at LHC energies (âsNN of several TeV), while the region of TâČ100 MeV and ”Bâł500 MeV can be studied with collisions at âsNN of a few GeV. The QCD matter created in the overlap region of colliding nuclei (fireball) is rapidly expanding during the collision evolution. In the fireball there are strong temperature and pressure gradients, extreme electromagnetic fields and an exchange of angular momentum and spin between the system constituents. These effects result in various collective phenomena. Pressure gradients and the scattering of particles, together with the initial spatial anisotropy of the density distribution in the fireball, form an anisotropic flow - a momentum (azimuthal) anisotropy in the emission of produced particles. The correlation of particle spin with the angular momentum of colliding nuclei leads to a global polarization of particles. A strong initial magnetic field in the fireball results in a charge dependence and particle-antiparticle difference of flow and polarization.
Anisotropic flow is quantified by the coefficients vâ from a Fourier decomposition of the azimuthal angle distribution of emitted particles relative to the reaction plane spanned by beam axis and impact parameter direction. The first harmonic coefficient vâ quantifies the directed flow - preferential particle emission either along or opposite to the impact parameter direction. The vâ is driven by pressure gradients in the fireball and thus probes the compressibility of the QCD matter. The change of the sign of vâ at âsNN of several GeV is attributed to a softening of the EoS during the expansion, and thus can be an evidence of the first order phase transition. The global polarization coefficient PH is an average value of the hyperonâs spin projection on the direction of the angular momentum of the colliding system. It probes the dynamics of the QCD matter, such as vorticity, and can shed light on the mechanism of orbital momentum transfer into the spin of produced particles.
In collisions at âsNN of several GeV, which probe the region of the QCD phase diagram at TâČ100 MeV and ”Bâł500 MeV, hadron production is dominated by u and d quarks. Hadrons with strange quarks are produced near the threshold, what makes their yields and dynamics sensitive to the density of the fireball. Thus measurement of flow and polarization, in particular of (multi-)strange particles, provides experimental constraints on the EoS, that allows to extract transport coefficients of the QCD matter from comparison of data with theoretical model calculations of heavy-ion collisions.
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The production of Kâ(892)± meson resonance is measured at midrapidity (|y|<0.5) in Pb-Pb collisions at sNNââââ=5.02 TeV using the ALICE detector at the LHC. The resonance is reconstructed via its hadronic decay channel Kâ(892)±âK0Sϱ. The transverse momentum distributions are obtained for various centrality intervals in the pT range of 0.4-16 GeV/c. The reported measurements of integrated yields, mean transverse momenta, and particle yield ratios are consistent with previous ALICE measurements for Kâ(892)0. The pT-integrated yield ratio 2Kâ(892)±/(K++Kâ) in central Pb-Pb collisions shows a significant suppression (9.3Ï) relative to pp collisions. Thermal model calculations overpredict the particle yield ratio. Although both simulations consider the hadronic phase, only HRG-PCE accurately represents the measurements, whereas MUSIC+SMASH tends to overpredict them. These observations, along with the kinetic freeze-out temperatures extracted from the yields of light-flavored hadrons using the HRG-PCE model, indicate a finite hadronic phase lifetime, which increases towards central collisions. The pT-differential yield ratios 2Kâ(892)±/(K++Kâ) and 2Kâ(892)±/(Ï++Ïâ) are suppressed by up to a factor of five at pT<2 GeV/c in central Pb-Pb collisions compared to pp collisions at sâ= 5.02 TeV. Both particle ratios and are qualitatively consistent with expectations for rescattering effects in the hadronic phase. The nuclear modification factor shows a smooth evolution with centrality and is below unity at pT>8 GeV/c, consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium.
The production of Kâ(892)± meson resonance is measured at midrapidity (|y|<0.5) in Pb-Pb collisions at sNNââââ=5.02 TeV using the ALICE detector at the LHC. The resonance is reconstructed via its hadronic decay channel Kâ(892)±âK0Sϱ. The transverse momentum distributions are obtained for various centrality intervals in the pT range of 0.4-16 GeV/c. The reported measurements of integrated yields, mean transverse momenta, and particle yield ratios are consistent with previous ALICE measurements for Kâ(892)0. The pT-integrated yield ratio 2Kâ(892)±/(K++Kâ) in central Pb-Pb collisions shows a significant suppression (9.3Ï) relative to pp collisions. Thermal model calculations overpredict the particle yield ratio. Although both simulations consider the hadronic phase, only HRG-PCE accurately represents the measurements, whereas MUSIC+SMASH tends to overpredict them. These observations, along with the kinetic freeze-out temperatures extracted from the yields of light-flavored hadrons using the HRG-PCE model, indicate a finite hadronic phase lifetime, which increases towards central collisions. The pT-differential yield ratios 2Kâ(892)±/(K++Kâ) and 2Kâ(892)±/(Ï++Ïâ) are suppressed by up to a factor of five at pT<2 GeV/c in central Pb-Pb collisions compared to pp collisions at sâ= 5.02 TeV. Both particle ratios and are qualitatively consistent with expectations for rescattering effects in the hadronic phase. The nuclear modification factor shows a smooth evolution with centrality and is below unity at pT>8 GeV/c, consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium.
The production of Kâ(892)± meson resonance is measured at midrapidity (|y|<0.5) in PbâPb collisions at âsNN=5.02 TeV using the ALICE detector at the CERN Large Hadron Collider. The resonance is reconstructed via its hadronic decay channel Kâ(892)±âK0Sϱ. The transverse momentum distributions are obtained for various centrality intervals in the pT range of 0.4â16 GeV/c . Measurements of integrated yields, mean transverse momenta, and particle yield ratios are reported and found to be consistent with previous ALICE measurements for Kâ(892)0 within uncertainties. The pT-integrated yield ratio 2Kâ(892)±/(K++Kâ) in central PbâPb collisions shows a significant suppression at a level of 9.3Ï relative to pp collisions. Thermal model calculations result in an overprediction of the particle yield ratio. Although both hadron resonance gas in partial chemical equilibrium (HRG-PCE) and music + smash simulations consider the hadronic phase, only HRG-PCE accurately represents the measurements, whereas music + smash simulations tend to overpredict the particle yield ratio. These observations, along with the kinetic freeze-out temperatures extracted from the yields measured for light-flavored hadrons using the HRG-PCE model, indicate a finite hadronic phase lifetime, which decreases with increasing collision centrality percentile. The pT-differential yield ratios 2Kâ(892)±/(K++Kâ) and 2Kâ(892)±/(Ï++Ïâ) are presented and compared with measurements in pp collisions at âs=5.02 TeV. Both pa rticle ratios are found to be suppressed by up to a factor of five at pT<2.0 GeV/c in central PbâPb collisions and are qualitatively consistent with expectations for rescattering effects in the hadronic phase. The nuclear modification factor (RAA) shows a smooth evolution with centrality and is found to be below unity at pT>8 GeV/c, consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium.
A new, more precise measurement of the Î hyperon lifetime is performed using a large data sample of PbâPb collisions at âsNN p ÂŒ 5.02 TeV with ALICE. The Î and ÎÂŻ hyperons are reconstructed at midrapidity using their two-body weak decay channel Î â p ĂŸ Ïâ and ÎÂŻ â pÂŻ ĂŸ ÏĂŸ. The measured value of the Î lifetime is ÏÎ ÂŒ Âœ261.07 0.37Ă°stat:Ă 0.72Ă°syst:Ă ps. The relative difference between the lifetime of Î and ÎÂŻ , which represents an important test of CPT invariance in the strangeness sector, is also measured. The obtained value Ă°ÏÎ â ÏÎÂŻĂ=ÏÎ ÂŒ 0.0013 0.0028Ă°stat:Ă 0.0021Ă°syst:Ă is consistent with zero within the uncertainties. Both measurements of the Î hyperon lifetime and of the relative difference between ÏÎ and ÏÎÂŻ are in agreement with the corresponding world averages of the Particle Data Group and about a factor of three more precise.
The production of prompt +c baryons has been measured at midrapidity in the transverse momentum interval 0 < pT < 1 GeV/c for the first time, in pp and pâPb collisions at a center-of-mass energy per nucleon-nucleon collision âsNN = 5.02 TeV. The measurement was performed in the decay channel +c â pK0S by applying new decay reconstruction techniques using a Kalman-Filter vertexing algorithm and adopting a machine-learning approach for the candidate selection. The pT -integrated +c production cross sections in both collision systems were determined and used along with the measured yields in PbâPb collisions to compute the pT -integrated nuclear modification factors RpPb and RAA of +c baryons, which are compared to model calculations that consider nuclear modification of the parton distribution functions. The +c /D0 baryon-to-meson yield ratio is reported for pp and pâPb collisions. Comparisons with models that include modified hadronization processes are presented, and the implications of the results on the understanding of charm hadronization in hadronic collisions are discussed. A significant (3.7Ï) modification of the mean transverse momentum of + c baryons is seen in pâPb collisions with respect to pp collisions, while the pT -integrated +c /D0 yield ratio was found to be consistent between the two collision systems within the uncertainties.
Long- and short-range correlations for pairs of charged particles are studied via two-particle angular correlations in pp collisions at sâ=13 TeV and pâPb collisions at sNNââââ=5.02 TeV. The correlation functions are measured as a function of relative azimuthal angle ÎÏ and pseudorapidity separation Îη for pairs of primary charged particles within the pseudorapidity interval |η|<0.9 and the transverse-momentum interval 1<pT<4 GeV/c. Flow coefficients are extracted for the long-range correlations (1.6<|Îη|<1.8) in various high-multiplicity event classes using the low-multiplicity template fit method. The method is used to subtract the enhanced yield of away-side jet fragments in high-multiplicity events. These results show decreasing flow signals toward lower multiplicity events. Furthermore, the flow coefficients for events with hard probes, such as jets or leading particles, do not exhibit any significant changes compared to those obtained from high-multiplicity events without any specific event selection criteria. The results are compared with hydrodynamic-model calculations, and it is found that a better understanding of the initial conditions is necessary to describe the results, particularly for low-multiplicity events.
The inclusive production of the charm-strange baryon âŠ0c is measured for the first time via its semileptonic decay into âŠâe+Îœe at midrapidity (|y| < 0.8) in protonâproton (pp) collisions at the centre-of-mass energy âs = 13 TeV with the ALICE detector at the LHC. The transverse momentum (pT) differential cross section multiplied by the branching ratio is presented in the interval 2 < pT < 12 GeV/c. The branching-fraction ratio BR(âŠ0c â âŠâe+Îœe)/BR(âŠ0c â âŠâÏ+) is measured to be 1.12 ± 0.22 (stat.) ± 0.27 (syst.). Comparisons with other experimental measurements, as well as with theoretical calculations, are presented.
The inclusive production of the charm-strange baryon âŠ0c is measured for the first time via its semileptonic decay into âŠâe+Îœe at midrapidity (|y| < 0.8) in protonâproton (pp) collisions at the centre-of-mass energy âs = 13 TeV with the ALICE detector at the LHC. The transverse momentum (pT) differential cross section multiplied by the branching ratio is presented in the interval 2 < pT < 12 GeV/c. The branching-fraction ratio BR(âŠ0c â âŠâe+Îœe)/BR(âŠ0c â âŠâÏ+) is measured to be 1.12 ± 0.22 (stat.) ± 0.27 (syst.). Comparisons with other experimental measurements, as well as with theoretical calculations, are presented.
The measurement of the production of deuterons, tritons and 3He and their antiparticles in Pb-Pb collisions at âsNN = 5.02 TeV is presented in this article. The measurements are carried out at midrapidity (y|< 0.5) as a function of collision centrality using the ALICE detector. The pT-integrated yields, the coalescence parameters and the ratios to protons and antiprotons are reported and compared with nucleosynthesis models. The comparison of these results in different collision systems at different center-of-mass collision energies reveals a suppression of nucleus production in small systems. In the Statistical Hadronisation Model framework, this can be explained by a small correlation volume where the baryon number is conserved, as already shown in previous fluctuation analyses. However, a different size of the correlation volume is required to describe the proton yields in the same data sets. The coalescence model can describe this suppression by the fact that the wave functions of the nuclei are large and the fireball size starts to become comparable and even much smaller than the actual nucleus at low multiplicities.
The knowledge of the material budget with a high precision is fundamental for measurements of direct photon production using the photon conversion method due to its direct impact on the total systematic uncertainty. Moreover, it influences many aspects of the charged-particle reconstruction performance. In this article, two procedures to determine data-driven corrections to the material-budget description in ALICE simulation software are developed. One is based on the precise knowledge of the gas composition in the Time Projection Chamber. The other is based on the robustness of the ratio between the produced number of photons and charged particles, to a large extent due to the approximate isospin symmetry in the number of produced neutral and charged pions. Both methods are applied to ALICE data allowing for a reduction of the overall material budget systematic uncertainty from 4.5% down to 2.5%. Using these methods, a locally correct material budget is also achieved. The two proposed methods are generic and can be applied to any experiment in a similar fashion.
The knowledge of the material budget with a high precision is fundamental for measurements of direct photon production using the photon conversion method due to its direct impact on the total systematic uncertainty. Moreover, it influences many aspects of the charged-particle reconstruction performance. In this article, two procedures to determine data-driven corrections to the material-budget description in ALICE simulation software are developed. One is based on the precise knowledge of the gas composition in the Time Projection Chamber. The other is based on the robustness of the ratio between the produced number of photons and charged particles, to a large extent due to the approximate isospin symmetry in the number of produced neutral and charged pions. Both methods are applied to ALICE data allowing for a reduction of the overall material budget systematic uncertainty from 4.5% down to 2.5%. Using these methods, a locally correct material budget is also achieved. The two proposed methods are generic and can be applied to any experiment in a similar fashion.
Long- and short-range correlations for pairs of charged particles are studied via two-particle angular correlations in pp collisions at âsNN = 13 TeV and pâPb collisions at âs = 5.02 TeV. The correlation functions are measured as a function of relative azimuthal angle âÏ and pseudorapidity separation âη for pairs of primary charged particles within the pseudorapidity interval |η| < 0.9 and the transverse-momentum interval 1 < pT < 4 GeV/c. Flow coefficients are extracted for the long-range correlations (1.6 < |âη| < 1.8) in various high-multiplicity event classes using the low-multiplicity template fit method. The method is used to subtract the enhanced yield of away-side jet fragments in high-multiplicity events. These results show decreasing flow signals toward lower multiplicity events. Furthermore, the flow coefficients for events with hard probes, such as jets or leading particles, do not exhibit any significant changes compared to those obtained from high-multiplicity events without any specific event selection criteria. The results are compared with hydrodynamic-model calculations, and it is found that a better understanding of the initial conditions is necessary to describe the results, particularly for low-multiplicity events.
The total charm-quark production cross section per unit of rapidity dÏ(cc)/dy, and the fragmentation fractions of charm quarks to different charm-hadron species f(c â hc), are measured for the first time in pâPb collisions at âsNN = 5.02 TeV at midrapidity (â0.96 < y < 0.04 in the centre-ofmass frame) using data collected by ALICE at the CERN LHC. The results are obtained based on all the available measurements of prompt production of ground-state charm-hadron species: D0, D+,D+s, and J/Ï mesons, and Î+cand Î0cbaryons. The resulting cross section is dÏ(cc)/dy = 219.6±6.3 (stat.)+10.5â11.8(syst.)+7.6â2.9(extr.)±5.4 (BR)±4.6 (lumi.)±19.5 (rapidity shape) +15.0 (âŠ0c) mb, which is consistent with a binary scaling of pQCD calculations from pp ollisions. The measured fragmentation fractions are compatible with those measured in pp collisions at âs = 5.02 and 13 TeV, showing an increase in the relative production rates of charm baryons with respect to charm mesons in pp and pâPb collisions compared with e+e â and eâp collisions. The pT-integrated nuclear modification factor of charm quarks, RpPb(cc) = 0.91±0.04 (stat.) +0.08 â0.09 (syst.) +0.04 â0.03 (extr.)±0.03 (lumi.), is found to be consistent with unity and with theoretical predictions including nuclear modifications of the parton distribution functions.
This work aims to differentiate strangeness produced from hard processes (jet-like) and softer processes (underlying event) by measuring the angular correlation between a high-momentum trigger hadron (h) acting as a jet-proxy and a produced strange hadron (Ï(1020) meson). Measuring hâÏ correlations at midrapidity in pâPb collisions at âsNN = 5.02 TeV as a function of event multiplicity provides insight into the microscopic origin of strangeness enhancement in small collision systems. The jet-like and the underlying-event-like strangeness production are investigated as a function of event multiplicity. They are also compared between a lower and higher momentum region. The evolution of the per-trigger yields within the near-side (aligned with the trigger hadron) and away-side (in the opposite direction of the trigger hadron) jet is studied separately, allowing for the characterization of two distinct jet-like production regimes. Furthermore, the hâÏ correlations within the underlying event give access to a production regime dominated by soft production processes, which can be compared directly to the in-jet production. Comparisons between hâÏ and dihadron correlations show that the observed strangeness enhancement is largely driven by the underlying event, where the Ï/h ratio is significantly larger than within the jet regions. As multiplicity increases, the fraction of the total Ï(1020) yield coming from jets decreases compared to the underlying event production, leading to high-multiplicity events being dominated by the increased strangeness production from the underlying event
Human feline leukaemia virus subgroup C receptor-related proteins 1 and 2 (FLVCR1 and FLVCR2) are members of the major facilitator superfamily1. Their dysfunction is linked to several clinical disorders, including PCARP, HSAN and Fowler syndrome2,3,4,5,6,7. Earlier studies concluded that FLVCR1 may function as a haem exporter8,9,10,11,12, whereas FLVCR2 was suggested to act as a haem importer13, yet conclusive biochemical and detailed molecular evidence remained elusive for the function of both transporters14,15,16. Here, we show that FLVCR1 and FLVCR2 facilitate the transport of choline and ethanolamine across the plasma membrane, using a concentration-driven substrate translocation process. Through structural and computational analyses, we have identified distinct conformational states of FLVCRs and unravelled the coordination chemistry underlying their substrate interactions. Fully conserved tryptophan and tyrosine residues form the binding pocket of both transporters and confer selectivity for choline and ethanolamine through cationâÏ interactions. Our findings clarify the mechanisms of choline and ethanolamine transport by FLVCR1 and FLVCR2, enhance our comprehension of disease-associated mutations that interfere with these vital processes and shed light on the conformational dynamics of these major facilitator superfamily proteins during the transport cycle.
Das Heidelberger Ionenstrahl-Therapiezentrum (HIT) stellt Protonen-, Helium- und Kohlenstoff-Ionenstrahlen unterschiedlicher Energie und IntensitĂ€t fĂŒr die Krebsbehandlung und Sauerstoff-Ionenstrahlen fĂŒr Experimente zur VerfĂŒgung. Der hierfĂŒr verwendete Beschleuniger ist darĂŒber hinaus in der Lage auch IonenstrahlintensitĂ€ten unterhalb der fĂŒr Therapien verwendeten bereitzustellen. Allerdings ist das derzeit installierte Strahldiagnosesystems nicht in der Lage, das Strahlprofil bei solchen geringen IntensitĂ€ten (< 10^5 Ionen/s) zu messen. Dabei existieren mögliche medizinische Anwendung fĂŒr diese niederintensiven Ionen-strahlen, wie beispielsweise eine neuartige und potentiell klinisch vorteilhafte Bildgebung: die Ionenradiographie. Eine essentielle Voraussetzung fĂŒr diese und andere Anwendungen ist ein System zur Ăberwachung von Ionenstrahlen niedriger IntensitĂ€t. Ein solches System wurde im Rahmen dieser Arbeit konzipiert, realisiert, getestet und optimiert.
Das Funktionsprinzip basiert auf szintillierenden Fasern, insbesondere solchen mit erhöhter StrahlungshĂ€rte fĂŒr die Möglichkeit einer dauerhaften Platzierung im Therapiestrahl. Ein diese Fasern durchlaufendes Ion regt den darin enthaltenen Szintillator durch StoĂprozesse kurzzeitig an. Die dabei deponierte Energie wird anschlieĂend in Form von Photonen wieder emittiert. Silizium-Photomultiplier sind an den Enden der Fasern montiert und wandeln die Photonensignale in verstĂ€rkte elektrische Impulse um. Diese Impulse werden von einer neuartigen und dedizierten Ausleseelektronik aufgezeichnet und verarbeitet. Ein Prototypaufbau, bestehend aus den genannten Teilen, wurde im Strahl getestet und kann das transversale Strahlprofil erfolgreich im IntensitĂ€tsbereich von 10^7 Ionen/s bis hinunter zu 10^2 Ionen/s aufzeichnen. DarĂŒber hinaus konnte, durch die erfolgreiche Ankunftszeitmessung von einzelnen Ionen bis zu IntensitĂ€ten von 5*10^4 Ionen/s, ein Machbarkeitsnachweis fĂŒr die Messung der Spur von einzelnen Teilchen erbracht werden.