897 research outputs found
Commissioning of the electron injector for the AWAKE experiment
The advanced wakefield experiment (AWAKE) at CERN is the first proton beam-driven plasma wakefield acceleration experiment. The main goal of AWAKE RUN 1 was to demonstrate seeded self-modulation (SSM) of the proton beam and electron witness beam acceleration in the plasma wakefield. For the AWAKE experiment, a 10-meter-long Rubidium-vapor cell together with a high-power laser for ionization was used to generate the plasma. The plasma wakefield is driven by a 400 GeV/c proton beam extracted from the super proton synchrotron (SPS), which undergoes a seeded self-modulation process in the plasma. The electron witness beam used to probe the wakefields is generated from an S-band RF photo-cathode gun and then accelerated by a booster structure up to energies between 16 and 20 MeV. The first run of the AWAKE experiment revealed that the maximum energy gain after the plasma cell is 2 GeV, and the SSM mechanism of the proton beam was verified. In this paper, we will present the details of the AWAKE electron injector. A comparison of the measured electron beam parameters, such as beam size, energy, and normalized emittance, with the simulation results was performed
su(1,1) Algebraic approach of the Dirac equation with Coulomb-type scalar and vector potentials in D + 1 dimensions
We study the Dirac equation with Coulomb-type vector and scalar potentials in
D + 1 dimensions from an su(1, 1) algebraic approach. The generators of this
algebra are constructed by using the Schr\"odinger factorization. The theory of
unitary representations for the su(1, 1) Lie algebra allows us to obtain the
energy spectrum and the supersymmetric ground state. For the cases where there
exists either scalar or vector potential our results are reduced to those
obtained by analytical techniques
Transition between nuclear and quark-gluon descriptions of hadrons and light nuclei
We provide a perspective on studies aimed at observing the transition between
hadronic and quark-gluonic descriptions of reactions involving light nuclei. We
begin by summarizing the results for relatively simple reactions such as the
pion form factor and the neutral pion transition form factor as well as that
for the nucleon and end with exclusive photoreactions in our simplest nuclei. A
particular focus will be on reactions involving the deuteron. It is noted that
a firm understanding of these issues is essential for unraveling important
structure information from processes such as deeply virtual Compton scattering
as well as deeply virtual meson production. The connection to exotic phenomena
such as color transparency will be discussed. A number of outstanding
challenges will require new experiments at modern facilities on the horizon as
well as further theoretical developments.Comment: 37 pages, 17 figures, submitted to Reports on Progress in Physic
First order phase transition from ferromagnetism to antiferromagnetism in Ce(FeAl)
Taking the pseudobinary C15 Laves phase compound
Ce(FeAl) as a paradigm for studying a ferromagnetic to
antiferromagnetic phase transition, we present interesting thermomagnetic
history effects in magnetotransport as well as magnetisation measurements
across this phase transition. A comparison is made with history effects
observed across the ferromagnetic to antiferromagnetic transition in
RSrMnO crystals.Comment: 11 pages of text and 4 figures; submitted to Physical Review Letter
Research-based flow cytometry assays for pathogenic assessment in the human B-cell biology of gene variants revealed in the diagnosis of inborn errors of immunity: a Bruton’s tyrosine kinase case-study
IntroductionInborn errors of immunity (IEI) are an expanding group of rare diseases whose field has been boosted by next-generation sequencing (NGS), revealing several new entities, accelerating routine diagnoses, expanding the number of atypical presentations and generating uncertainties regarding the pathogenic relevance of several novel variants.MethodsResearch laboratories that diagnose and provide support for IEI require accurate, reproducible and sustainable phenotypic, cellular and molecular functional assays to explore the pathogenic consequences of human leukocyte gene variants and contribute to their assessment. We have implemented a set of advanced flow cytometry-based assays to better dissect human B-cell biology in a translational research laboratory. We illustrate the utility of these techniques for the in-depth characterization of a novel (c.1685G>A, p.R562Q) de novo gene variant predicted as probably pathogenic but with no previous insights into the protein and cellular effects, located in the tyrosine kinase domain of the Bruton’s tyrosine kinase (BTK) gene, in an apparently healthy 14-year-old male patient referred to our clinic for an incidental finding of low immunoglobulin (Ig) M levels with no history of recurrent infections.Results and discussionA phenotypic analysis of bone marrow (BM) revealed a slightly high percentage of pre-B-I subset in BM, with no blockage at this stage, as typically observed in classical X-linked agammaglobulinemia (XLA) patients. The phenotypic analysis in peripheral blood also revealed reduced absolute numbers of B cells, all pre-germinal center maturation stages, together with reduced but detectable numbers of different memory and plasma cell isotypes. The R562Q variant allows Btk expression and normal activation of anti-IgM-induced phosphorylation of Y551 but diminished autophosphorylation at Y223 after anti IgM and CXCL12 stimulation. Lastly, we explored the potential impact of the variant protein for downstream Btk signaling in B cells. Within the canonical nuclear factor kappa B (NF-κB) activation pathway, normal IκBα degradation occurs after CD40L stimulation in patient and control cells. In contrast, disturbed IκBα degradation and reduced calcium ion (Ca2+) influx occurs on anti-IgM stimulation in the patient’s B cells, suggesting an enzymatic impairment of the mutated tyrosine kinase domain
A Framework for Sustainable Design of Algal Biorefineries: Economic Aspects and Life Cycle Analysis
Band-width control in a perovskite-type 3d^1 correlated metal Ca_{1-x}Sr_xVO_3. I. Evolution of the electronic properties and effective mass
Single crystals of the perovskite-type metallic alloy system
CaSrVO were synthesized in order to investigate metallic
properties near the Mott transition. The substitution of a Ca ion for a
Sr ion reduces the band width due to a buckling of the V-O-V bond
angle from for SrVO to for CaVO. Thus,
the value of can be systematically controlled without changing the number
of electrons making CaSrVO: one of the most ideal systems for
studying band-width effects. The Sommerfeld-Wilson's ratio (), the
Kadowaki-Woods ratio (in the same region as heavy Fermion systems), and a large
term in the electric resistivity, even at 300 K, substantiate a large
electron correlation in this system, though the effective mass, obtained by
thermodynamic and magnetic measurements, shows only a systematic but moderate
increase in going from SrVO to CaVO, in contrast to the critical
enhancement expected from the Brinkmann-Rice picture. It is proposed that the
metallic properties observed in this system near the Mott transition can be
explained by considering the effect of a non-local electron correlation.Comment: 14 pages in a Phys. Rev. B camera-ready format with 10 EPS figures
embedded. LaTeX 2.09 source file using "camera.sty" and "prbplug.sty"
provided by N. Shirakawa. For OzTeX (Macintosh), use "ozfig.sty" instead of
"psfig.sty". "ozfig.sty" can be also obtained by e-mail request to N.
Shirakawa: . Submitted to Phys. Rev.
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