76 research outputs found
Beam Diagnostic Requirements: an Overview
Beam diagnostics and instrumentation are an essential part of any kind of
accelerator. There is a large variety of parameters to be measured for
observation of particle beams with the precision required to tune, operate, and
improve the machine. In the first part, the basic mechanisms of information
transfer from the beam particles to the detector are described in order to
derive suitable performance characteristics for the beam properties. However,
depending on the type of accelerator, for the same parameter, the working
principle of a monitor may strongly differ, and related to it also the
requirements for accuracy. Therefore, in the second part, selected types of
accelerators are described in order to illustrate specific diagnostics needs
which must be taken into account before designing a related instrument.Comment: 102 pages, contribution to the CAS - CERN Accelerator School: Beam
Instrumentation, 2-15 June 2018, Tuusula, Finlan
Simulation of 2D point spread function dominated beam profile images based on backward transition radiation from the tilted target
Simulation of 2D point spread function dominated beam profile images based on backward transition radiation from the tilted target
Micron-scale vertical beam size measurements based on transition radiation imaging with a Schwarzschild objective
This report presents preliminary results of a measurement of a micron–scale vertical beam size based on imaging of optical transition radiation in the visible region. The visualization of point spread function dominated beam images was carried out using a Schwarzschild objective that provides high magnification and that is free of some of aberrations. According to the preliminary data treatment, a vertical rms beam size of 1.37 +- 0.07 micrometer was measured at the 855MeV beam of the Mainz Microtron MAMI (Germany)
Spatial distribution of PXR generated by 855 MeV electrons. Comparison of simulation results with experimental data
Electron beam profile imaging in the presence of coherent optical radiation effects
High-brightness electron beams with low energy spread at existing and future
x-ray free-electron lasers are affected by various collective beam
self-interactions and microbunching instabilities. The corresponding coherent
optical radiation effects, e.g., coherent optical transition radiation, render
electron beam profile imaging impossible and become a serious issue for all
kinds of electron beam diagnostics using imaging screens. Furthermore, coherent
optical radiation effects can also be related to intrinsically ultrashort
electron bunches or the existence of ultrashort spikes inside the electron
bunches. In this paper, we discuss methods to suppress coherent optical
radiation effects both by electron beam profile imaging in dispersive beamlines
and by using scintillation imaging screens in combination with separation
techniques. The suppression of coherent optical emission in dispersive
beamlines is shown by analytical calculations, numerical simulations, and
measurements. Transverse and longitudinal electron beam profile measurements in
the presence of coherent optical radiation effects in non-dispersive beamlines
are demonstrated by applying a temporal separation technique.Comment: 12 pages, 11 figures, submitted to Phys. Rev. ST Accel. Beam
Genomic and transcriptomic changes complement each other in the pathogenesis of sporadic Burkitt lymphoma
Burkitt lymphoma (BL) is the most common B-cell lymphoma in children. Within the International Cancer Genome Consortium (ICGC), we performed whole genome and transcriptome sequencing of 39 sporadic BL. Here, we unravel interaction of structural, mutational, and transcriptional changes, which contribute to MYC oncogene dysregulation together with the pathognomonic IG-MYC translocation. Moreover, by mapping IGH translocation breakpoints, we provide evidence that the precursor of at least a subset of BL is a B-cell poised to express IGHA. We describe the landscape of mutations, structural variants, and mutational processes, and identified a series of driver genes in the pathogenesis of BL, which can be targeted by various mechanisms, including IG-non MYC translocations, germline and somatic mutations, fusion transcripts, and alternative splicing
The genomic and transcriptional landscape of primary central nervous system lymphoma
Primary lymphomas of the central nervous system (PCNSL) are mainly diffuse large B-cell lymphomas (DLBCLs) confined to the central nervous system (CNS). Molecular drivers of PCNSL have not been fully elucidated. Here, we profile and compare the whole-genome and transcriptome landscape of 51 CNS lymphomas (CNSL) to 39 follicular lymphoma and 36 DLBCL cases outside the CNS. We find recurrent mutations in JAK-STAT, NFkB, and B-cell receptor signaling pathways, including hallmark mutations in MYD88 L265P (67%) and CD79B (63%), and CDKN2A deletions (83%). PCNSLs exhibit significantly more focal deletions of HLA-D (6p21) locus as a potential mechanism of immune evasion. Mutational signatures correlating with DNA replication and mitosis are significantly enriched in PCNSL. TERT gene expression is significantly higher in PCNSL compared to activated B-cell (ABC)-DLBCL. Transcriptome analysis clearly distinguishes PCNSL and systemic DLBCL into distinct molecular subtypes. Epstein-Barr virus (EBV)+ CNSL cases lack recurrent mutational hotspots apart from IG and HLA-DRB loci. We show that PCNSL can be clearly distinguished from DLBCL, having distinct expression profiles, IG expression and translocation patterns, as well as specific combinations of genetic alterations
Beam Diagnostic Requirements: an Overview
Beam diagnostics and instrumentation are an essential part of any kind of accelerator. There is a large variety of parameters to be measured for observation of particle beams with the precision required to tune, operate, and improve the machine. In the first part, the basic mechanisms of information transfer from the beam particles to the detector are described in order to derive suitable performance characteristics for the beam properties. However, depending on the type of accelerator, for the same parameter, the working principle of a monitor may strongly differ, and related to it also the requirements for accuracy. Therefore, in the second part, selected types of accelerators are described in order to illustrate specific diagnostics needs which must be taken into account before designing a related instrument
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