Emittance-preserving acceleration of high-quality positron beams using warm plasma filaments

Preserving the quality of positron beams in plasma-based accelerators, where wakefields are generated in electron filaments, is challenging. These wakefields are characterized by transversely non-linear focusing fields and non-uniform accelerating fields. However, a nonzero plasma temperature linearizes the transverse wakefield within the central region of the electron filament. In this study, we employ 3D particle-in-cell simulations with mesh refinement to demonstrate that beams with emittances on the order of tens of nanometers are contained within the linearized region of the transverse wakefield. This enables emittance preservation to one percent, while positron beams with the same charge and micrometer emittances, which sample the non-linear part of the transverse wakefield, experience a relative emittance growth of ten percent. Additionally, we observe a significant reduction in the growth rate of the slice energy spread for the tens of nanometers emittance beams in comparison to the micrometer emittance beams. The utilization of warm plasmas in conjunction with low-emittance beams opens up new avenues for enhancing the beam quality across various plasma-based positron acceleration approaches.Comment: To be submitted as a proceedings for the 6th European Advanced Accelerator Concepts worksho

From Compact Plasma Particle Sources to Advanced Accelerators with Modeling at Exascale

Developing complex, reliable advanced accelerators requires a coordinated, extensible, and comprehensive approach in modeling, from source to the end of beam lifetime. We present highlights in Exascale Computing to scale accelerator modeling software to the requirements set for contemporary science drivers. In particular, we present the first laser-plasma modeling on an exaflop supercomputer using the US DOE Exascale Computing Project WarpX. Leveraging developments for Exascale, the new DOE SCIDAC-5 Consortium for Advanced Modeling of Particle Accelerators (CAMPA) will advance numerical algorithms and accelerate community modeling codes in a cohesive manner: from beam source, over energy boost, transport, injection, storage, to application or interaction. Such start-to-end modeling will enable the exploration of hybrid accelerators, with conventional and advanced elements, as the next step for advanced accelerator modeling. Following open community standards, we seed an open ecosystem of codes that can be readily combined with each other and machine learning frameworks. These will cover ultrafast to ultraprecise modeling for future hybrid accelerator design, even enabling virtual test stands and twins of accelerators that can be used in operations.Comment: 4 pages, 3 figures, submitted to the 20th Advanced Accelerator Concepts Workshop (AAC22

Experimental procedure for the characterization of radiation damage in macromolecular crystals

A novel automatic procedure to determine the sensitivity of macromolecular crystals to radiation damage is presented. The information extracted from this procedure can be directly used for optimal planning of data collection or/and beamline calibration

Controlled density-downramp injection in a beam-driven plasma wakefield accelerator

This paper describes the utilization of beam-driven plasma wakefield acceleration to implement a high-quality plasma cathode via density-downramp injection in a short injector stage at the FLASHForward facility at DESY. Electron beams with charge of up to 105 pC and energy spread of a few percent were accelerated by a tunable effective accelerating field of up to 2.7 GV/m. The plasma cathode was operated drift-free with very high injection efficiency. Sources of jitter, the emittance and divergence of the resulting beam were investigated and modeled, as were strategies for performance improvements that would further increase the wide-ranging applications for a plasma cathode with the demonstrated operational stabilityComment: 11 pages, 9 figure

Searching for a Stochastic Background of Gravitational Waves with LIGO

The Laser Interferometer Gravitational-wave Observatory (LIGO) has performed the fourth science run, S4, with significantly improved interferometer sensitivities with respect to previous runs. Using data acquired during this science run, we place a limit on the amplitude of a stochastic background of gravitational waves. For a frequency independent spectrum, the new limit is $\Omega_{\rm GW} < 6.5 \times 10^{-5}$. This is currently the most sensitive result in the frequency range 51-150 Hz, with a factor of 13 improvement over the previous LIGO result. We discuss complementarity of the new result with other constraints on a stochastic background of gravitational waves, and we investigate implications of the new result for different models of this background.Comment: 37 pages, 16 figure

Upper limit map of a background of gravitational waves

We searched for an anisotropic background of gravitational waves using data from the LIGO S4 science run and a method that is optimized for point sources. This is appropriate if, for example, the gravitational wave background is dominated by a small number of distinct astrophysical sources. No signal was seen. Upper limit maps were produced assuming two different power laws for the source strain power spectrum. For an f^-3 power law and using the 50 Hz to 1.8 kHz band the upper limits on the source strain power spectrum vary between 1.2e-48 Hz^-1 (100 Hz/f)^3 and 1.2e-47 Hz^-1 (100 Hz /f)^3, depending on the position in the sky. Similarly, in the case of constant strain power spectrum, the upper limits vary between 8.5e-49 Hz^-1 and 6.1e-48 Hz^-1. As a side product a limit on an isotropic background of gravitational waves was also obtained. All limits are at the 90% confidence level. Finally, as an application, we focused on the direction of Sco-X1, the closest low-mass X-ray binary. We compare the upper limit on strain amplitude obtained by this method to expectations based on the X-ray luminosity of Sco-X1.Comment: 11 pages, 9 figures, 2 table

Upper limit map of a background of gravitational waves

We searched for an anisotropic background of gravitational waves using data from the LIGO S4 science run and a method that is optimized for point sources. This is appropriate if, for example, the gravitational wave background is dominated by a small number of distinct astrophysical sources. No signal was seen. Upper limit maps were produced assuming two different power laws for the source strain power spectrum. For an f^-3 power law and using the 50 Hz to 1.8 kHz band the upper limits on the source strain power spectrum vary between 1.2e-48 Hz^-1 (100 Hz/f)^3 and 1.2e-47 Hz^-1 (100 Hz /f)^3, depending on the position in the sky. Similarly, in the case of constant strain power spectrum, the upper limits vary between 8.5e-49 Hz^-1 and 6.1e-48 Hz^-1. As a side product a limit on an isotropic background of gravitational waves was also obtained. All limits are at the 90% confidence level. Finally, as an application, we focused on the direction of Sco-X1, the closest low-mass X-ray binary. We compare the upper limit on strain amplitude obtained by this method to expectations based on the X-ray luminosity of Sco-X1.Comment: 11 pages, 9 figures, 2 table

A guide to the crystallographic analysis of icosahedral viruses

Determining the structure of an icosahedral virus crystal by X-ray diffraction follows very much the same course as conventional protein crystallography. The major differences arise from the relatively large sizes of the particles, which significantly affect the data collection process, data processing and management, and later, the refinement of a model. Most of the other differences are due to the high 5 3 2 point group symmetry of icosahedral viruses. This alters dramatically the means by which initial phases are obtained by molecular substitution, extended to higher resolution by electron density averaging and density modification, and the refinement of the structure in the light of high non-crystallographic symmetry. In this review, we attempt to lead the investigator through the various steps involved in solving the structure of a virus crystal. These steps include the purification of viruses, their crystallization, the recording of X-ray diffraction data, and its reduction to structure amplitudes. It further addresses the problems attending phase determination and ultimately the refinement of a model. Finally, we describe the unique properties of virus crystals and the factors that influence their physical and diffraction properties

Haematological alterations in a population affected by intestinal helminths and ectoparasites in Northeast Brazil

GesamtdissertationEs ist seit längerem bekannt, dass Eosinophilie und Anämie in tropischen Gebieten häufig vorkommende Blutbildveränderungen sind, allerdings gibt es nur wenige Daten von populationsbasierten Studien. Unsere Studie untersuchte die Zusammenhänge von Parasitenbefall und Blutbildveränderungen von 874 Studienteilnehmern aller Altersgruppen eines Dorfes im ländlichen Nordosten Brasiliens, wo intestinale Helminthen und Ektoparasiten endemisch vor¬kom¬men. Von den Studienteilnehmern waren 70,1% mit intestinaler Helminthiasis und 45,3% mit Ektoparasitosen infiziert. Im Einzelnen wurden folgende Prävalenzen gefunden: A. lumbricoides (55,3%), A. duodenale (36,1%), T. trichiura (33,9%), T. penetrans (32,5%), P. h. capitis (14%), S. scabiei (9%), kutane Larva migrans (1,9%). Eosinophilen Granulozyten variierten von 40 Zellen/μl bis zu 13.800 Zellen/μl (Median: 900 Zellen/μl) und der Hämoglobingehalt von 4,8/g bis 16,8/g (Median: 12,5/g). Eine Leukozytose wurde bei 13%, eine Eosinophilie bei 74,8%, eine Hypereosinophilie bei 44,2% und eine ¬Anämie bei 34,1% Personen gefunden. Eosinophilie korrelierte stärker mit dem Vorkommen von intestinalen Helminthen als mit dem von Ektoparasiten und am stärksten bei Koinfektionen. Kinder und Jugendliche wiesen die höchsten Zahlen an eosinophilen Granulozyten auf, was auf die altersbedingte immunologische Entwicklung zum einen und die erhöhte Parasitenexposition zum anderen zurückzuführen ist. Für das Vorkommen von Anämien konnte ein Zusammenhang mit Parasitenbefall nicht be¬stätigt werden. Die sich aus dieser Studie ergebenen hohen Prävalenzen von intestinalen Helminthen und damit assoziierte Blutbildveränderungen machen regelmäßige flächendeckende Entwurmungsbehandlungen mit breit wirkenden Antihelminthika zu einer sinnvollen Maßnahme. Dabei müssten auch solche Strategien entwickelt werden, die alle Altersgruppen einbeziehen und das Risiko der Reinfektionen minimieren.It has long been known that blood eosinophilia and anemia are common in the tropical environment, but data derived from population-based studies are scarce. Our study examined the relation of parasite infection and haematological alterations of 874 study participants in a rural village of Northern Brasil where both intestinal helminthiases and parasitic skin diseases are common. From the individuals 70,1% were infected with intestinal helminths and 45,3% with ectoparasites. In the single case the following prevalence has been found: A. lumbricoides (55,3%), A. duodenale (36,1%), T. trichiura (33,9%), T. penetrans (32,5%), P. h. capitis (14%), S. scabiei (9%), cutaneous larva migrans (1,9%). Eosinophil counts ranged between 40 cells/μl and 13.800 cells/μl (median: 900 cells/μl) and the level of hemoglobin between 4,8/g and 16,8/g (median: 12,5/g). Leucocytosis was detected in 13% of the individuals, eosinophilia in 74,8%, hypereosinophilia in 44,2% and anemia in 34,1%. Eosinophilia correlates stronger with the appearance of intestinal helminths as with ectoparasites and especially strong in cases of co- infection. Children and adolescents had the highest number of eosinophil counts which is an age-related immune development on the one hand and an increased parasite exposure on the other hand. Anemia could not be confirmed in relation with parasite infections. The high prevalence of helminthiasis found in this study and the associated haematological alterations makes a regular, area-wide mass treatment with anthelminthic drugs to a reasonnable measure. There should be developed some strategies that include all age-group and minimize the risk of a reinfection