A thesis presented in fulfillment of the requirements for the degree of: Master of Science in Physics, University of the Witwatersrand, Johannesburg, 2017 / Tile Online software is a set of Trigger and Data Acquisition (TDAQ) required for the operation of Tile. It is built on top of ATLAS TDAQ software following AT LAS management tools and policies. The TDAQ software has been migrated from CMT to CMake, and from SVN to Git, in favor of modern software development tools and procedures. Since Tile Online software follows ATLAS TDAQ, there was a need of reorganization, simplification and clean-up of Tile Online software packages. Tile Online software packages have been migrated and reorganized to the newest ATLAS TDAQ release and the outcome is now used at Point-1 with success. The diagnostic and verification system (DVS) is part of the ATLAS TDAQ online software packages used for configuring and executing tests for TDAQ com ponents, and for advising recovery actions to the TDAQ operator/user. A wrapper way to start complex Tile DVS tests that required two separate programs to run on separate computers has been implemented and tests can now be run from a graphical user interface with detailed presentation of the results by non-experts. The upgrade of the Large Hadron Collider (LHC) to the High-Luminosity LHC will provide significant opportunities to explore new physics beyond the Standard Model. This however presents significant challenges to the detector and the TDAQ systems. The Tile Calorimeter will undergo upgrades whereby the current readout electronics will be completely redesigned and replaced in phase-II to cope with the increased luminosity imposed by the HL-LHC. / XL2018

No description available.

A Moak type radio frequency ion source, capable of producing a pulsed beam of deuterons has been built for use with a Cockcroft-Walton accelerator. Pulsed deuterons striking a deuteron target produce neutrons in bursts thus allowing dynamic measurements of moderator and reactor core properties. Beam pulsing is accomplished by means of an einzel lens and an alternating potential applied to a pair of deflection plates. Proteins have been used exclusively in adjusting the source for optimum results since the radiation background due to the protons is much less than that due to deuterons. In actual experiments, however, when using deuterons, no modifications need to be made in the source. Beam currents have been measured at the source and at a target located at the end of the accelerator tube. Maximum currents measured are 150 microamperes and 60 microamperes respectively. Details of construction, maximum operating conditions, and oscillogram sof purse shapes are included in this report. / M.S.

A generating voltmeter capable of measuring one, two, or found million volts has been designed and constructed for use with the Virginia Polytechnical Institute electrostatic accelerator. The voltmeter is a grounded shutter type, the rectified output of which is measured by a vacuum tube voltmeter. The voltmeter was calibrated by known nuclear resonances of fluoride. The calibration showed the meter to be accurate to within five percent at half scale deflation on the one million volts range the less than plus or minus three percent on the two million volts range. / Master of Science

A magnetic analyzer capable of bending the four million electron volt bean of the Virginia Polytechnic Institute electrostatic accelerator has been constructed. The magnet is the circumferential yoke, double-focusing type. Tests show its field to be uniform within one percent along its 16-inch radius, its magnetization curve to agree with the design requirements, and its cooling system to be more than adequate. A motor-generator set and a motor amplydine have been obtained for the magnet power supply, delivery now awaited. A voltage feedback system has been designed for field stabilization, and the considerations in supplying nuclear magnetic resonance equipment to field stabilization have been examined. / Master of Science

Matrix and tensor accelerators play indispensable roles in the field of artificial intelligence (AI). Although most of the matrix accelerators, such as graphic processing units (GPUs) and tensor processing units (TPUs), are still electronics based, the energy efficiency and scalability limits of electronic accelerators have presented an opportunity for photonics to perform matrix and tensor acceleration. This dissertation explores silicon photonics as an enabling and cost-effective platform for developing photonic systems, in particular, photonic tensor accelerators. The thesis presents a detailed design procedure for active and passive components, forming a comprehensive Process Design Kit (PDK) in a foundry-compatible silicon photonic platform. The PDK library includes passive waveguide building blocks as well as active components such as micro ring modulators with an EO bandwidth of more than 20GHz and Ge-on-Si photodetectors with >25GHz bandwidth. Having our own PDK ensures consistency in the layout and fabrication of silicon photonic integrated circuits (PIC) across different foundries. We designed and fabricated multidimensional photonic tensor accelerators, each of which consists of many waveguides, splitters/couplers, coherent modulators, and balanced detectors, and successfully demonstrated PIC-based matrix-vector multiplications.

A helicon plasma source is a device that can efficiently ionize a gas to create high density, low temperature plasma. There is growing interest in utilizing a helicon plasma source in propulsive applications, but it is not yet known if the helicon plasma source is able to function as both an ion source and ion accelerator, or whether an additional ion acceleration stage is required. In order to evaluate the capability of the helicon source to accelerate ions, the acceleration and ionization processes must be decoupled and examined individually. To accomplish this, a case study of two helicon thruster configurations is conducted. The first is an electrodeless design that consists of the helicon plasma source alone, and the second is a helicon ion engine that combines the helicon plasma source with electrostatic grids used in ion engines. The gridded configuration separates the ionization and ion acceleration mechanisms and allows for individual evaluation not only of ion acceleration, but also of the components of total power expenditure and the ion production cost. In this study, both thruster configurations are fabricated and experimentally characterized. The metrics used to evaluate ion acceleration are ion energy, ion beam current, and the plume divergence half-angle, as these capture the magnitude of ion acceleration and the bulk trajectory of the accelerated ions. The electrode-less thruster is further studied by measuring the plasma potential, ion number density, and electron temperature inside the discharge chamber and in the plume up to 60 cm downstream and 45 cm radially outward. The two configurations are tested across several operating parameter ranges: 343-600 W RF power, 50-450 G magnetic field strength, 1.0-4.5 mg/s argon flow rate, and the gridded configuration is tested over a 100-600 V discharge voltage range. Both configurations have thrust and efficiency below that of contemporary thrusters of similar power, but are distinct in terms of ion acceleration capability. The gridded configuration produces a 65-120 mA ion beam with energies in the hundreds of volts that is relatively collimated. The operating conditions also demonstrate clear control over the performance metrics. In contrast, the electrodeless configuration generally produces a beam current less than 20 mA at energies between 20-40 V in a very divergent plume. The ion energy is set by the change in plasma potential from inside the device to the plume. The divergence ion trajectories are caused by regions of high plasma potential that create radial electric fields.. Furthermore, the operating conditions have limited control of the resulting performance metrics. The estimated ion production cost of the helicon ranged between 132-212 eV/ion for argon, the lower bound of which is comparable to the 157 eV/ion in contemporary DC discharges. The primary power expenditures are due to ion loss to the walls and high electron temperature leading to energy loss at the plasma sheaths. The conclusion from this work is that the helicon plasma source is unsuitable as a single-stage thruster system. However, it is an efficient ion source and, if paired with an additional ion acceleration stage, can be integrated into an effective propulsion system.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (M.S.); Submitted to Tel Aviv Univ. (IL); 1 Dec 2003. / Published through the Information Bridge: DOE Scientific and Technical Information. "JLAB-PHY-03-219" "DOE/ER/40150-2651" Ran Shneor. 12/01/2003. Report is also available in paper and microfiche from NTIS.

The development of charged particle accelerators is today reaching far beyond the realm of fundamental particle physics research. Many non-trivial social and political problems may find part of their solution lies in accelerator physics. For example, with fossil fuels becoming ever more controversial and expensive to obtain, the use of Accelerator Driven Sub-critical Reactors (ADSR) powered by rapid cycling, high current proton accelerators and thorium fuel could become part of the energy solution. Through the simplicity of the Bragg peak, cancer therapy could be enhanced through the use of high repetition rate, variable energy proton accelerators small enough to use in treatment centres. The growing problem of long lived nuclear waste storage could become a moot point through the use of high current, high power proton accelerators coupled with neutron spallation. These rapidly growing areas of study are fuelled by the development of the Fixed-Field Alternating-Gradient (FFAG) accelerator, and more recently the non-scaling FFAG. The FFAG has the ability to accelerate high current, low quality bunches of particles in very short time scales due to the fixed-field nature of its magnets. This rapid acceleration can be of the order 500 nanoseconds to 1 microsecond meaning a fast cycling rate of the machine is possible. This allows the realistic development of the ADSR, proton therapy machine and even the muon accelerator. The Electron Model with Many Applications (EMMA) accelerator is the world's first linear non-scaling FFAG and is an electron proof-of-principle accelerator based at Daresbury Laboratory, UK. EMMA can accelerate over its energy range of 10 - 20 MeV in approximately 5 - 10 machine revolutions (~275 - 500 nanoseconds) using fixed-frequency novel acceleration techniques. The accelerator contains fixed-field, constant gradient quadrupole magnets which provide all the bending and focussing to the particles. Due to the linear non-scaling nature of EMMA, many transverse integer tune values are crossed which typically cause resonant effects resulting in bunch degradation and loss. It was proposed and demonstrated that rapid crossing (in 5 - 10 turns) of integer tune values in EMMA did not result in transverse amplitude growth and particle loss. If the wider societal goals of the non-scaling FFAG are to be realised, protons and other heavy ions must be accelerated. Current technological limitations dictate that longer acceleration times of the order 1000's of turns would be necessary in proton machines of similar design to EMMA. Hence slower integer tune crossing was studied using acceleration in a synchrotron bucket in EMMA. It was found experimentally that below the nominal EMMA operating acceleration rate of 2.0 MV per turn, instabilities begin to manifest. This was indicated in the growth of closed orbit distortion (COD) and through simulation it was found that betatron amplitude growth coupled with COD resulted in eventual loss of particles to the physical aperture when crossing integer tunes. Through simulation, the amplitude growth of particles crossing integer tunes in the EMMA non-scaling FFAG was found to agree with a theory of resonance crossing proposed by R. Baartman. This theory shows that amplitude growth is proportional to $1/\sqrt(Q')$ where $Q'$ is the tune crossing rate of the particles. This means that the slower the acceleration, the slower an integer tune is crossed and hence more amplitude is gained. It was also shown that strength of the magnetic errors driving the resonant conditions was proportional to the amplitude growth.