Messung der B s-Oszillation mit dem semileptonischen Zerfall B 0 s D - s (phi pi -) my + ny my mit dem D0-Detektor

Das Standardmodell (SM) der Teilchenphysik beschreibt sehr präzise die fundamentalen Bausteine und deren Wechselwirkungen (WW). Trotz des Erfolges gibt es noch offene Fragen, die vom SM nicht beantwortet werden können. Ein noch noch nicht abgeschlossener Test besteht aus der Messung der Stärke der schwachen Kopplung zwischen Quarks. Neutrale B- bzw. $bar{B}$-Mesonen können sich innerhalb ihrer Lebensdauer über einen Prozeß der schwachen WW in ihr Antiteilchen transformieren. Durch die Messung der Bs-Oszillation kann die Kopplung Vtd zwischen den Quarksorten Top (t) und Down (d) bestimmt werden. Alle bis Ende 2005 durchgeführten Experimente lieferten lediglich eine untere Grenze für die Oszillationsfrequenz von ms>14,4ps-1. Die vorliegenden Arbeit beschreibt die Messung der Bs-Oszillationsfrequenz ms mit dem semileptonischen Kanal BsD(-)+. Die verwendeten Daten stammen aus Proton-Antiproton-Kollisionen, die im Zeitraum von April 2002 bis März 2006 mit dem DØ-Detektor am Tevatron-Beschleuniger des Fermi National Accelerator Laboratory bei einer Schwerpunktsenergie von $sqrt{s}$=1,96TeV aufgezeichnet wurden. Die verwendeten Datensätze entsprechen einer integrierten Luminosität von 1,3fb-1 (620 millionen Ereignisse). Für diese Oszillationsmessung wurde der Quarkinhalt des Bs-Mesons zur Zeit der Produktion sowie des Zerfalls bestimmt und die Zerfallszeit wurde gemessen. Nach der Rekonstruktion und Selektion der Signalereignisse legt die Ladung des Myons den Quarkinhalt des Bs-Mesons zur Zeit des Zerfalls fest. Zusätzlich wurde der Quarkinhalt des Bs-Mesons zur Zeit der Produktion markiert. b-Quarks werden in $pbar{p}$-Kollisionen paarweise produziert. Die Zerfallsprodukte des zweiten b-Hadrons legen den Quarkinhalt des Bs-Mesons zur Zeit der Produktion fest. Bei einer Sensitivität von msenss=14,5ps-1 wurde eine untere Grenze für die Oszillationsfrequenz ms>15,5ps-1 bestimmt. Die Maximum-Likelihood-Methode lieferte eine Oszillationsfrequenz ms>(20+2,5-3,0(stat+syst)0,8(syst,k))ps-1 bei einem Vertrauensniveau von 90%. Der nicht nachgewiesene Neutrinoimpuls führt zu dem systematischen Fehler (sys,k). Dieses Resultat ergibt zusammen mit der entsprechenden Oszillation des Bd-Mesons eine signifikante Messung der Kopplung Vtd, in Übereinstimmung mit weiteren Experimenten über die schwachen Quarkkopplungen.

Fast and accurate numerical solutions in some problems of particle and radiation transport: synthetic acceleration for the method of short characteristics, Doppler-broadened scattering kernel, remote sensing of the cryosphere

The aim of this work is to present various aspects of numerical simulation of particle and radiation transport for industrial and environmental protection applications, to enable the analysis of complex physical processes in a fast, reliable, and efficient way. In the first part we deal with speed-up of numerical simulation of neutron transport for nuclear reactor core analysis. The convergence properties of the source iteration scheme of the Method of Characteristics applied to be heterogeneous structured geometries has been enhanced by means of Boundary Projection Acceleration, enabling the study of 2D and 3D geometries with transport theory without spatial homogenization. The computational performances have been verified with the C5G7 2D and 3D benchmarks, showing a sensible reduction of iterations and CPU time. The second part is devoted to the study of temperature-dependent elastic scattering of neutrons for heavy isotopes near to the thermal zone. A numerical computation of the Doppler convolution of the elastic scattering kernel based on the gas model is presented, for a general energy dependent cross section and scattering law in the center of mass system. The range of integration has been optimized employing a numerical cutoff, allowing a faster numerical evaluation of the convolution integral. Legendre moments of the transfer kernel are subsequently obtained by direct quadrature and a numerical analysis of the convergence is presented. In the third part we focus our attention to remote sensing applications of radiative transfer employed to investigate the Earth's cryosphere. The photon transport equation is applied to simulate reflectivity of glaciers varying the age of the layer of snow or ice, its thickness, the presence or not other underlying layers, the degree of dust included in the snow, creating a framework able to decipher spectral signals collected by orbiting detectors.

Feasibility studies of the pp pi 0 e + e - electromagnetic channel at PANDA

Among all possible realizations of quark and antiquark assembly, the nucleon (the proton and the neutron) is the most stable of all hadrons and consequently has been the subject of intensive studies. Mass, shape, radius and more complex representations of its internal structure are measured since several decades using different probes. The proton (spin 1/2) is described by the electric GE and magnetic GM form factors which characterise its internal structure. The simplest way to measure the proton form factors consists in measuring the angular distribution of the electron-proton elastic scattering accessing the so-called Space-Like region where q2 < 0. Using the crossed channel antiproton proton <--> e+e-, one accesses another kinematical region, the so-called Time-Like region where q2 > 0. However, due to the antiproton proton <--> e+e- threshold q2th, only the kinematical domain q2 > q2th > 0 is available. To access the unphysical region, one may use the antiproton proton --> pi0 e+ e- reaction where the pi0 takes away a part of the system energy allowing q2 to be varied between q2th and almost 0. This thesis aims to show the feasibility of such measurements with the PANDA detector which will be installed on the new high intensity antiproton ring at the FAIR facility at Darmstadt. To describe the antiproton proton --> pi0 e+ e- reaction, a Lagrangian based approach is developed. The 5-fold differential cross section is determined and related to linear combinations of hadronic tensors. Under the assumption of one nucleon exchange, the hadronic tensors are expressed in terms of the 2 complex proton electromagnetic form factors. An extraction method which provides an access to the proton electromagnetic form factor ratio R = |GE|/|GM| and for the first time in an unpolarized experiment to the cosine of the phase difference is developed. Such measurements have never been performed in the unphysical region up to now. Extended simulations were performed to show how the ratio R and the cosine can be extracted from the positron angular distribution. Furthermore, a model is developed for the antiproton proton --> pi0 pi+ pi- background reaction considered as the most dangerous one. The background to signal cross section ratio was estimated under different cut combinations of the particle identification information from the different detectors and of the kinematic fits. The background contribution can be reduced to the percent level or even less. The corresponding signal efficiency ranges from a few % to 30%. The precision on the determination of the ratio R and of the cosine is determined using the expected counting rates via Monte Carlo method. A part of this thesis is also dedicated to more technical work with the study of the prototype of the electromagnetic calorimeter and the determination of its resolution.

Measurement of the e + e - pi + pi - pi + pi - cross section using initial state radiation at BABAR

One of the most precisely measured quantities in particle physics is the magnetic moment of the muon, which describes its coupling to an external magnetic field. It is expressed in form of the anomalous magnetic moment of the muon a_mu=(g_mu-2)/2 and has been determined experimentally with a precision of 0.5 parts per million. The current direct measurement and the theoretical prediction of the standard model differ by more than 3.5 standard deviations. Concerning theory, the contribution of the QED and weak interaction to a_mu can be calculated with very high precision in a perturbative approach.rnAt low energies, however, perturbation theory cannot be used to determine the hadronic contribution a^had_mu. On the other hand, a^had_mu may be derived via a dispersion relation from the sum of measured cross sections of exclusive hadronic reactions. Decreasing the experimental uncertainty on these hadronic cross sections is of utmost importance for an improved standard model prediction of a_mu.rnrnIn addition to traditional energy scan experiments, the method of Initial State Radiation (ISR) is used to measure hadronic cross sections. This approach allows experiments at colliders running at a fixed centre-of-mass energy to access smaller effective energies by studying events which contain a high-energetic photon emitted from the initial electron or positron. Using the technique of ISR, the energy range from threshold up to 4.5GeV can be accessed at Babar.rnrnThe cross section e+e- -> pi+pi- contributes with approximately 70% to the hadronic part of the anomalous magnetic moment of the muon a_mu^had. This important channel has been measured with a precision of better than 1%. Therefore, the leading contribution to the uncertainty of a_mu^had at present stems from the invariant mass region between 1GeV and 2GeV. In this energy range, the channels e+e- -> pi+pi-pi+pi- and e+e- -> pi+pi-pi0pi0 dominate the inclusive hadronic cross section. The measurement of the process e+e- -> pi+pi-pi+pi- will be presented in this thesis. This channel has been previously measured by Babar based on 25% of the total dataset. The new analysis includes a more detailed study of the background contamination from other ISR and non-radiative background reactions. In addition, sophisticated studies of the track reconstruction as well as the photon efficiency difference between the data and the simulation of the Babar detector are performed. With these auxiliary studies, a reduction of the systematic uncertainty from 5.0% to 2.4% in the peak region was achieved.rnrnThe pi+pi-pi+pi- final state has a rich internal structure. Hints are seen for the intermediate states rho(770)^0 f_2(1270), rho(770)^0 f_0(980), as well as a_1(1260)pi. In addition, the branching ratios BR(jpsi -> pi+pi-pi+pi-) and BR(psitwos -> jpsi pi+pi-) are extracted.rn

Erste Messung der Pi-0-Photoproduktion an transversal polarisierten Protonen nahe der Schwelle

Diese Arbeit befasst sich mit der photoinduzierten Erzeugung neutraler Pionen, sehr nahe an der Schwellenenergie. Dabei werden zwei Ziele verfolgt: Zum einen die Überprüfung von Vorhersagen dieser effektiven Theorien und Modelle, zum anderen werden hier erstmals alle relevanten Partialwellenamplituden modellunabhängig aus gemessenen Observablen bestimmt. Diese Methode soll in Zukunft auch bei höheren Energien im Bereich der Nukleonresonanzen Anwendung finden. rnrnKonkret wird die Durchführung und Analyse eines Experiments vorgestellt, welches am Mainzer Mikrotron (MAMI) in den Jahren 2010 bis 2013 mit zirkular polarisiertem Photonenstrahl stattfand. Der Photonenstrahl wurde an einer Anlage zur Erzeugung energiemarkierter Bremsstrahlung aus dem Elektronenstrahl von MAMI gewonnen. Zum Nachweis der Reaktionsprodukte diente das hermetische 4pi CB/TAPS-Detektorsystem. Erstmalig standen bei derartigen Messungen auch transversal polarisierte Protonen zur Verfügung. Dazu wird Butanol in einer speziellen Apparatur dynamisch polarisiert. Molekularer Wasserstoff lässt sich aufgrund der para-Konfiguration nicht polarisieren. Wegen der Verwendung von Butanol als Targetmaterial, bei dem weniger als 5% aller erzeugten Pionen an polarisierten Protonen produziert wurden, ist die Behandlung des Untergrunds eine zentrale Aufgabe. rnrnEs werden zwei Methoden der Untergrundseparation vorgestellt, wovon die bessere in der Analyse angewendet wurde. Abschließend findet eine ausführliche Bewertung systematischer Fehler statt.rnrnDie erstmalige Verwendung transversal polarisierter Protonen ermöglicht den Zugang zu bisher nicht gemessenen Spin"=Freiheitsgraden. In Kombination mit einem komplementären Vorläufer-Experiment aus dem Jahr 2008 mit linear polarisiertem Photonenstrahl konnten aus den gewonnenen Daten erstmals alle komplexen s- und p-Partialwellenamplituden modellunabhängig bestimmt werden. rnrnDarüber hinaus wurden im Rahmen dieser Arbeit wesentliche Verbesserungen am apparativen Aufbau erzielt. Beispiele sind ein Elektronenstrahl-Polarimeter, ein zellularer CB-Multiplizitätstrigger, sowie signifikante Verbesserungen der Datennahmeelektronik und des Triggersystems, die teilweise in dieser Arbeit vorgestellt werden.

A method for automated generation of radiotherapy treatment plans for lung cancer

La radioterapia è una tecnica molto impiegata per la cura del cancro. Attualmente la somministrazione avviene principalmente attraverso la intensity modulated radiotherapy (IMRT, sovrapposizione di campi ad intensità modulata), un cui sviluppo recente è la volumetric modulated arc therapy (VMAT, irradiazione continua lungo un arco ininterrotto). La generazione di piani richiede esperienza ed abilità: un dosimetrista seleziona cost functions ed obiettivi ed un TPS ottimizza la disposizione dei segmenti ad intensità modulata. Se il medico giudica il risultato non soddisfacente, il processo riparte da capo (trial-and-error). Una alternativa è la generazione automatica di piani. Erasmus-iCycle, software prodotto presso ErasmusMC (Rotterdam, The Netherlands), è un algoritmo di ottimizzazione multicriteriale di piani radioterapici per ottimizzazione di intensità basato su una wish list. L'output consiste di piani Pareto-ottimali ad intensità modulata. La generazione automatica garantisce maggiore coerenza e qualità più elevata con tempi di lavoro ridotti. Nello studio, una procedura di generazione automatica di piani con modalità VMAT è stata sviluppata e valutata per carcinoma polmonare. Una wish list è stata generata attraverso una procedura iterativa su un gruppo ristretto di pazienti con la collaborazione di fisici medici ed oncologi e poi validata su un gruppo più ampio di pazienti. Nella grande maggioranza dei casi, i piani automatici sono stati giudicati dagli oncologi migliori rispetto ai rispettivi piani IMRT clinici generati manualmente. Solo in pochi casi una rapida calibrazione manuale specifica per il paziente si è resa necessaria per soddisfare tutti i requisiti clinici. Per un sottogruppo di pazienti si è mostrato che la qualità dei piani VMAT automatici era equivalente o superiore rispetto ai piani VMAT generati manualmente da un dosimetrista esperto. Complessivamente, si è dimostrata la possibilità di generare piani radioterapici VMAT ad alta qualità automaticamente, con interazione umana minima. L'introduzione clinica della procedura automatica presso ErasmusMC è iniziata (ottobre 2015).

Crystallization, optimization and preliminary X-ray characterization of a metal-dependent PI-PLC from Streptomyces antibioticus

A recombinant metal-dependent phosphatidylinositol-specific phospholipase C (PI-PLC) from Streptomyces antibioticus has been crystallized by the hanging-drop method with and without heavy metals. The native crystals belonged to the orthorhombic space group P222, with unit-cell parameters a = 41.26, b = 51.86, c= 154.78 A. The X-ray diffraction results showed significant differences in the crystal quality of samples soaked with heavy atoms. Additionally, drop pinning, which increases the surface area of the drops, was also used to improve crystal growth and quality. The combination of heavy-metal soaks and drop pinning was found to be critical for producing high-quality crystals that diffracted to 1.23 A resolution.

Australia: new screening method for cold tolerance during the reproducitve stage in rice

Low temperature, particularly during the reproductive stage of the development of rice, limits productivity in the Riverina region of New South Wales (NSW). This study primarily examined genotypic differences in cold damage that are associated with low temperature during reproductive development. Results from experiments in temperature-controlled rooms and the cold water facility were combined with four years of field experiments, which used natural exposure to low temperature to examine the response of over 50 cultivars from diverse origins. Plants were exposed to day/night air temperatures of 27°/13°C in temperature-controlled rooms and to a constant temperature of 19°C in the cold water facility. Low temperature treatments were imposed from panicle initiation (PI) to 50% heading. In field experiments several techniques were used to increase the likelihood of inducing cold damage such as sequential sowing dates (five to eight sowing dates each year), shallow water depths (5cm) and high nitrogen rates (e.g. 300kgN ha-1). Several cultivars were identified that were more cold tolerant than Australia’s commercial cultivars.

A new scheduling method for enhanced quality of experience in LTE systems

In this paper a new approach to the resource allocation and scheduling mechanism that reflects the effect of user's Quality of Experience is presented. The proposed scheduling algorithm is examined in the context of 3GPP Long Term Evolution (LTE) system. Pause Intensity (PI) as an objective and no-reference quality assessment metric is employed to represent user's satisfaction in the scheduler of eNodeB. PI is in fact a measurement of discontinuity in the service. The performance of the scheduling method proposed is compared with two extreme cases: maxCI and Round Robin scheduling schemes which correspond to the efficiency and fairness oriented mechanisms, respectively. Our work reveals that the proposed method is able to perform between fairness and efficiency requirements, in favor of higher satisfaction for the users to the desired level. © VDE VERLAG GMBH.

A search for an exotic meson in the gamma + P decaying to delta++ + pi- + eta reaction

A Partial Waves Analysis (PWA) of γp → Δ ++X → pπ+ π - (η) data taken with the CLAS detector at Jefferson Lab is presented in this work. This reaction is of interest because the Δ++ restricts the isospin of the possible X states, leaving the PWA with a smaller combination of partial waves, making it ideal to look for exotic mesons. It was proposed by Isgur and Paton that photoproduction is a plausible source for the Jpc=1–+ state through flux tube excitation. The π1(1400) is such a state that has been produced with the use of hadron production but it has yet to be seen in photoproduction. A mass independent amplitude analysis of this channel was performed, followed by a mass dependent fit to extract the resonance parameters. The procedure used an event-based maximum likelihood method to maintain all correlations in the kinematics. The intensity and phase motion is mapped out for the contributing signals without requiring assumptions about the underlying processes. The strength of the PWA is in the analysis of the phase motion, which for resonance behavior is well defined. In the data presented, the ηπ– invariant mass spectrum shows contributions from the a0(980) and a2(1320) partial waves. No π1 was observed under a clear a2 signal after the angular distributions of the decay products were analyzed using an amplitude analysis. In addition, this dissertation discusses trends in the data, along with the implemented techniques.

Análise da variabilidade climática sobre a produtividade da soja no município de Bom Jesus (PI)

The climate is still main responsible for the variations soybean productivity (Glycine max (L.) Merrill), exerting a limiting action on these agricultural systems. The bomjesuense cerrado, this culture has proved, over the years, an increase of cultivated areas, however, productivity does not keep the same pace, going through periods of oscillations. Thus, although the crop is added to high technology, culture has great vulnerability to climatic adversities. Thus, the present study aims to analyze possible trends in meteorological variables, which can influence the soybean yield in Bom Jesus. For this purpose, different datasets were used, as follows: i) two periods of daily data (1984-2014 and 1974-2014), both obtained from the National Meteorological Institute (INMET); ii) climate normals from 1961-1990 as defined by INMET; iii) local agricultural production data of soybean-year (1997/1998 to 2012/2013) obtained from the Municipal Agricultural Production (PAM) dataset, which is management by Brazilian Institute of Geography and Statistics (IBGE). The analysis procedures included calculations of climate normals for 1984 to 2014 period and some statistical applications, as follows: i) the Wilcoxon test, used to evaluate differences between climate normals (1961 to 1990 and 1984 to 2014); ii) the Mann-Kendall nonparametric test, in order to analyze the linear trend of agrometeorological variables (rainfall, maximum temperature, minimum temperature and diurnal range of temperature; iii) cluster analysis by Ward method and the Spearman correlation test (rs) to identify the relationship between agrometeorological variable and soybean annual productivity. We adopted a statistical significance level of 5%. The results indicate changes in seasonality of the 1984-2014 climatology with respect to past climatology for all variables analyzed, except for insolation and precipitation. However, the monthly analysis of precipitation indicate negative trend during October and positive trend in December, causing a delay in start of rainy season. If this trend is persistent this result must be considered in futures definitions of the soybean crop sowing date over the region studied. With Mann-Kendall test was possible to identify positive trends with statistical significance in maximum temperature for all month forming part of soybean cycle (from November to April), which in turn tends to cause adverse effects on crop physiology, and consequently impacts on the final yield. Was identified a significant positive correlation between soybean yield and precipitation observed in March, thus precipitation deficit in this month is harmful to the soybean crop development. No statistically significant correlation was identified among maximum temperature, minimum temperature, and DTR with annual soybean productivity due these range of meteorological variables are not limiting factors in the final soybean yield in Bom Jesus (PI). It is expected that this study will contribute to propose planning strategies considering the role of climate variability on soybean crop final yield.

Aplicação do método de Monte Carlo no estudo da padronização de radionuclídeos com esquema de desintegração complexos em sistema de coincidencias 4-pi-beta-gama

Tese (Doutoramento)

Desenvolvimento de um sistema eletronico com registro simultaneo de amplitude e instante de ocorrencias dos pulsos, aplicado ao metodo de coincidencias 4'pi''beta''gama'

Dissertacao (Mestrado)

Tracking changes to a microplankton community in a North Atlantic sea loch using the microplankton index PI(mp).

Microplankton plays a vital part in marine ecosystems and its importance has been recognised by the inclusion of microplankton community composition in regulatory frameworks such as the European Water Framework Directive and the Marine Strategy Framework Directive as an indicator of ecological status. Quantitative techniques are therefore required to assess the environmental status of the microplankton in a water body. Here we demonstrate the use of a method known as the Microplankton Index PI(mp) to evaluate changes in the microplankton community of the West coast Scottish Sea Loch Creran. Microplankton in this fjord has been studied since the 1970’s providing a data set spanning four decades. Our analysis compares an arbitrarily chosen reference period between 1979 and 1981 with a period between 2011 and 2013 and demonstrates that between these two periods community structure has changed considerably with a substantial drop in the numbers of observed diatoms accompanied by a rise in the number of autotrophic/mixotrophic dinoflagellates as well as an increase in the potentially toxin producing genus Pseudo-nitzschia and that these are related to changes in both the intensity and timing of local patterns of precipitation. The PI(mp) is shown to be a useful and robust method to visualise and quantify changes in the underlying structure of the microplankton community and is a powerful addition to the toolbox of techniques needed to determine the health of our seas.