Innerhalb der handschriftlichen Überlieferung, die aus dem Mittelalter auf uns gekommen ist, gehören Palimpseste zu den Zeugnissen, die schon immer in besonderer Weise das Interesse auf sich gezogen und Phantasien beflügelt haben.

The focus of this thesis is to improve upon the existing neutron cross section data for rhenium (Re) in the energy range 0.01 eV to 1 keV. Neutron transmission and capture yield measurements were performed using natural rhenium samples at the Rensselaer Polytechnic Institute Gaerttner Linear Accelerator Center. Measurements were performed using the time of flight method, in which neutron energies are differentiated using the elapsed times between neutron emission from a pulsed neutron source and the subsequent detector interactions. Transmission measurements were performed using ⁶Li glass scintillation detectors. Capture measurements were performed utilizing a 16-segment NaI(Tl) multiplicity detector. Most measurements were performed at a flight path length of 25 meters, with one set of experiments (thermal transmission) performed at 15 meters. The experiments used several metallic, elemental rhenium samples of various thicknesses, ranging from 1 mil to 100 mils. (1 mil = 0.001 inch = 0.0254 mm) Following the reduction of the experimental data, SAMMY was used to perform the data analysis. SAMMY is a shape-fitting Bayesian analysis code that determines resonance parameters by fitting neutron time of flight data using the Reich-Moore approximation of R-matrix theory. The combined transmission and capture yield data analysis determined resonance parameters for rhenium resonances in the energy range of 0.01 eV to 1 keV. The updated rhenium resonance parameters are compared to previously published parameters and ENDF/B-VII.1. / text

Since 2004, table-top laser-plasma accelerators (LPAs) driven by ˜30fs terwatt laser pulses have produced colimated, nearly mono-energetic eletron bunches with energy up to 1 GeV in laboratories around the world. Large-scale computer simulations show that LPAs can scale to higher energy while retaining high beam quality, but will require laser pulses of higher energy and longer duration than current LPAs. The group of Prof. Mike Downer, in collaboration with the Texas Petawatt (TPW) laser team headed by Prof. Todd Ditmire, is setting up an experiment that uses the TPW laser (1.1 PW, 150 fs) to drive the world’s first multi-GeV LPA. This thesis provides a general overview of the TPW-LPA project, including several diagnostic systems for the beam, plasma and laser pulse. Special attention is given to three of the diagnostic systems: (1)A transverse interferometry diagnostic of the plasma density profile created by the TPW laser pulse; (2)A Thomson scattering diagnostic of the self-guided path of the TPW laser pulse through the plasma; (3)An optical transition radiation diagnostic of the accelerated electron bunch exiting the plasma. In each case, basic principles, theoretical background, calculation and simulation results, and preliminary experimental results will be presented. / text

Incident ions, from a Van de Graaff accelerator, in the MeV energy range, deposit their energy into the near surface of a sample. This, in turn, causes atomic, molecular, cluster and fragment ion species to be desorbed and ionized, while simultaneously emitting characteristic elemental X-rays. The multielemental X-rays provide qualitative elemental information, which may be deconvoluted and fit to a theoretical X-ray spectrum, generated by a quantitative analysis program, GUPIX, while the atomic, molecular, cluster, and fragment ion species are identified using a quadrupole mass spectrometer. This methodology directly links elemental determinations with chemical speciation.The development of this particle desorption ionization particle induced X-ray emission mass spectrometer, the PDI-PIXE-MS (or PIXE-MS) instrument, which has the ability to collect both qualitative multielemental X-rays and mass spectral data is described. This multiplexed instrument has been designed to use millimeter-sized MeV particle beams as a desorption ionization (PDI) and X-ray emission (PIXE) source. Two general methods have been employed, one simultaneous and the other sequential. Both methods make use of a novel X-ray/ion source developed for use with the quadrupole mass spectrometer used in these experiments. The first method uses a MeV heavy ion particle beam, typically oxygen, to desorb and ionize the sample, while simultaneously producing characteristic multielemental X-rays. The resulting molecular, cluster, and fragment ions are collected by the mass spectrometer, and the X-rays are collected using a Si-PIN photodiode detector in conjunction with a multichannel analyzer (MCA). Heavy ions of N+, O+, O+2, Ar+, and Kr+ have been investigated, although heavy ion X-ray and mass spectra have focused on the use of oxygen particle beams. The second method is performed by first collecting the X-ray data with a MeV ion beam of He+ ions, then desorbing and ionizing the sample species with a MeV particle beam of heavy ions, producing good ion yields, for mass spectral data collection. The potential development of a scanning microprobe instrument, that would provide micron-scale, imaged, multielemental, and molecular and fragment ion chemical information is being investigated through the development of this prototype PIXE-MS instrument.

No description available.

This project was done in the context of FNAL Experiment E781 (the charm baryon study), which took data during the 1996-97 "fixed-target" run, using the SELEX detector, and a 650-GeV sigma hyperon beam derived from a production target exposed to the 1-TeV ultra-high energy proton beam out of the FNAL TEVATRON accelerator.We used the SSH encrypted TELNET to penetrate the BSU firewall to gain access to the FNAL E781 computer system.We did SELEX VDC alignments of runs 5577, and 7413, via telnet to the E781 computer system, using E78 I's SOAP analysis package then broadcasted the results to E781 collaborators.Also, we installed REDHAT-6.2's distribution of the LINUX OS, and then studied, downloaded and investigated (installing/compiling/testing) the E781 SOAP analysis package on several local BSU PC's. We analyzed and displayed these local tests results with the PAW graphics software (itself downloaded from the CERN laboratory). / Department of Physics and Astronomy

Eine der wichtigsten nuklearen Prozesse stellt der Neutroneneinfang dar. In der kosmischen Nukleosynthese (s-Prozess) schwerer Elemente werden Kerne mit Massenzahlen größer als die von Eisen (A = 56) produziert, welche durch Kernfusion nicht produziert werden können. Dabei fängt ein Kern ein Neutron ein, wird durch die frei werdende Bindungsenergie angeregt und kann sich anschließend unter Aussenden von Photonen (Gamma-Quanten) wieder abregen. Aus der Abregung über Gammastrahlung können Rückschlüsse auf die Struktur des aktivierten Nuklids gezogen werden. Im Rahmen dieser Arbeit werden die ausgesendeten Photonen des angeregten Elements 78Se, welches durch Neutroneneinfang an 77Se am Reaktor des Instituts Laue-Langevin in Grenoble, Frankreich produziert wurde, näher untersucht. Dazu mussten zunächst Effi zienzkalibrierung und Addback-Korrekturen vorgenommen werden. Im Anschluss konnten mit Hilfe des EXILL-Multidetektoraufbaus Koinzidenzbeziehungen mehrerer aufeinander folgender Photonen untersucht und in einem Niveauschema zusammengefasst werden. Mit Hilfe der Winkelverteilung konnten diversen Zuständen Spins zugeordnet werden. Des Weiteren wurden die Ergebnisse einer Simulation von Gammakaskaden (DEX) und eines Photonenstreuungsexperiments am Elektronenbeschleuniger ELBE des HZDR mit den in Grenoble aufgenommenen experimentellen Daten verglichen.

名古屋大学年代測定総合研究センターシンポジウム報告

As the further development of single-core architectures faces seemingly insurmountable physical and technological limitations, computer designers have turned their attention to alternative approaches. One such promising alternative is the use of several smaller cores working in unison as a programmable hardware accelerator. It is clear that the vast – and, as yet, largely untapped – potential of hardware accelerators is coming to the forefront of computer architecture. There are many challenges that must be addressed for the programmable hardware accelerator to be realized in practice. In this thesis, load-balancing, on-chip communication, and an execution model are studied. Imbalanced distribution of workloads across the processing elements constitutes wasteful use of resources, which results in degrading the performance of the system. In this thesis, a hardware-based load-balancing technique is proposed, which is demonstrated to be more scalable than state-of-the-art loadbalancing techniques. To facilitate efficient communication among ever increasing number of cores, a scalable communication network is imperative. Packet switching networks-on-chip (NoC) is considered as a viable candidate for scalable communication fabric. The size of flit, which is a unit of flow control in NoC, is one of important design parameters that determine latency, throughput and cost of NoC routers. How to determine an optimal flit size is studied in this thesis and a novel router architecture is proposed, which overcomes a problem related with the flit size. This thesis also includes a new execution model and its supporting architecture. An event-driven model that is an extension of hardware description language is employed as an execution model. The dynamic scheduling and module-level prefetching for supporting the event-driven execution model are evaluated.

The aim of this thesis is to analyse the cryogenic process for cooling superconducting radio frequency accelerator test cavities in the LEP accelerator at CERN. A liquefaction cryoplant is analysed, including the production of liquid helium at 4.5 K, the systems for distribution and regulation of liquid helium, and the radio frequency field used for accelerating particles. After discussing regulation problems and modifications planned for a new cavity installation in 1992, different techniques for specifying the control programs for the new installation are evaluated. Various diagramming techniques, standards and methodologies, and Computer Aided Software Engineering-tools, are compared as to their practical usefulness in this kind of process control. Finally, in accordance with anticipated requirements, possible ways of making high and low level control program specifications are suggested.