Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
1,631
result(s) for
"Jones, James K"
Sort by:
Poemhood, our black revival : history, folklore & the Black experience: a young adult poetry anthology
Featuring contributions from an award-winning, bestselling group of Black voices, past and present, this powerful poetry anthology elicits vital conversations about race, belonging, history and faith to highlight Black joy and pain.
Book
Acceleration of relativistic beams using laser-generated terahertz pulses
Particle accelerators driven by laser-generated terahertz (THz) pulses promise unprecedented control over the energy–time phase space of particle bunches compared with conventional radiofrequency technology. Here we demonstrate acceleration of a relativistic electron beam in a THz-driven linear accelerator. Narrowband THz pulses were tuned to the phase-velocity-matched operating frequency of a rectangular dielectric-lined waveguide for extended collinear interaction with 35 MeV, 60 pC electron bunches, imparting multicycle energy modulation to chirped (6 ps) bunches and injection phase-dependent energy gain (up to 10 keV) to subcycle (2 ps) bunches. These proof-of-principle results establish a route to whole-bunch linear acceleration of subpicosecond particle beams, directly applicable to scaled-up and multistaged concepts capable of preserving beam quality, thus marking a key milestone for future THz-driven acceleration of relativistic beams.Relativistic 35 MeV electron bunches with charges of 60 pC are accelerated in a terahertz-wave-driven dielectric waveguide. When the terahertz pulse energy is 0.8 μJ, an accelerating gradient of 2 MeV m−1 and energy gain of 10 keV are achieved.
Journal Article
Recirculating linac free-electron laser driver
This paper describes the design of a recirculating linac as a driver for the suite of seeded free-electron lasers (FELs) proposed in the UK New Light Source (NLS) project. The choice of superconducting technology for NLS is required in order to deliver bunches at high repetition rates up to 1 MHz. This raises the question of whether a shorter linac in recirculating mode can deliver the beam quality required for seeded FELs. To design such a facility, careful layout choices and optimizations must be made to ensure emittance growth is minimized. Effects leading to emittance dilution include chromatic transport terms, incoherent and coherent synchrotron radiation. The design outlined here is based on a modular philosophy to separate beam injection and extraction from a three stage compression scheme. The design uses many novel design concepts and optimizations to deliver the necessary high peak currents while preserving beam quality for seeded FELs. Start-to-end simulations including the FELs show that the necessary pulse coherence and output power can be provided from the beam thus generated.
Journal Article
Dynamics of particles in non scaling fixed field alternating gradient accelerators
Non scaling Fixed-Field Alternating Gradient (FFAG) accelerators have an unprecedented potential for muon acceleration, as well as for medical purposes based on carbon and proton hadron therapy. They also represent a possible active element for an Accelerator Driven Subcritical Reactor (ADSR). Starting from first principle the Hamiltonian formalism for the description of the dynamics of particles in non-scaling FFAG machines has been developed. The stationary reference (closed) orbit has been found within the Hamiltonian framework. The dependence of the path length on the energy deviation has been described in terms of higher order dispersion functions. The latter have been used subsequently to specify the longitudinal part of the Hamiltonian. It has been shown that higher order phase slip coefficients should be taken into account to adequately describe the acceleration in non-scaling FFAG accelerators. A complete theory of the fast (serpentine) acceleration in non-scaling FFAGs has been developed.
Journal Article
Controlling external injection in laser-plasma accelerators with terahertz frequency bunch manipulation
Laser-plasma wakefield acceleration (LWFA) offers ultrahigh accelerating gradients in compact setups, but the complex non-linear nature of the process makes it challenging to generate high-quality beams. Injection of electron bunches from an external source into a plasma accelerator provides a promising route to improved performance; however, electron bunches from conventional radio-frequency (RF)-based injectors suffer from non-linear compression and laser-beam asynchrony, leading to energy jitter and emittance growth. We present a fundamental concept of terahertz-controlled electron bunches for external injection into LWFA. This terahertz-frequency approach provides temporal locking between the electron beam and the drive laser, and enables the compression of high-quality beams to sub-10-fs durations before injection into the LWFA. Numerical simulations demonstrate that GeV-scale acceleration with excellent beam quality and stability -- energy jitter and energy spread around 0.2% -- can be achieved using this method. This concept opens new opportunities for stable, multi-stage laser-driven accelerators and supports the development of next-generation applications such as free-electron lasers (FELs).
Paper
Dynamics of Particles in Non Scaling Fixed Field Alternating Gradient Accelerators
Non scaling Fixed-Field Alternating Gradient (FFAG) accelerators have an unprecedented potential for muon acceleration, as well as for medical purposes based on carbon and proton hadron therapy. They also represent a possible active element for an Accelerator Driven Subcriticai Reactor (ADSR). Starting from first principle the Hamiltonian formalism for the description of the dynamics of particles in non-scaling FFAG machines has been developed. The stationary reference (closed) orbit has been found within the Hamiltonian framework. The dependence of the path length on the energy deviation has been described in terms of higher order dispersion functions. The latter have been used subsequently to specify the longitudinal part of the Hamiltonian. It has been shown that higher order phase slip coefficients should be taken into account to adequately describe the acceleration in non-scaling FFAG accelerators. A complete theory of the fast (serpentine) acceleration in non-scaling FFAGs has been developed. An example of the theory is presented for the parameters of the Electron Machine with Many Applications (EMMA), a prototype electron non-scaling FFAG to be hosted at Daresbury Laboratory. [PUBLICATION ABSTRACT]
Journal Article
Terahertz control of relativistic electron beams for femtosecond bunching and laser-synchronized temporal locking
Femtosecond relativistic electron bunches and micro-bunch trains synchronised with femtosecond precision to external laser sources are widely sought for next-generation accelerator and photonic technologies, from extreme UV and X-ray light sources for materials science, to ultrafast electron diffraction and future high-energy physics colliders. While few-femtosecond bunches have been demonstrated, achieving the control, stability and femtosecond-level laser synchronisation remains critically out of reach. Here we demonstrate a concept for laser-driven compression of high-energy (35.5 MeV) electron bunches with temporal synchronisation to a high-power (few-TW) laser system. Laser-generated multi-cycle terahertz (THz) pulses drive periodic electron energy modulation, enabling subsequent magnetic compression capable of generating tuneable picosecond-spaced bunch trains with 30 pC total charge and 50 A peak currents, or to compress a single bunch by a factor of 27 down to 15 fs duration. The THz-driven compression simultaneously drives temporal-locking of the bunch to the THz drive laser, providing a route to femtosecond-level synchronisation, overcoming the timing jitter inherent to radio-frequency accelerators and high-power laser systems. This THz technique offers compact and flexible bunch control with unprecedented temporal synchronisation, opening a pathway to unlock new capabilities for free electron lasers, ultrafast electron diffraction and novel plasma accelerators.
Paper
An analysis of the relationship between student performance on high -stakes testing programs (Missouri Assessment Program and American College Test) in Missouri high schools: Implications to school leaders
The purpose of this study is to determine the relationship that exists between student performance on the Missouri Assessment Program (MAP) and the American College Test (ACT). It will be determined if a correlation exists between student achievement levels on the MAP and the ACT. Correlation will be determined using the scores from three of the four core areas of the MAP of Missouri high school students and their corresponding ACT scores. The academic reputation of Missouri school districts are often based on achievement levels on these two high-stakes tests. The reputation of school administrators parallels the reputation of the district. Accountability of meeting lofty achievement goals on high-stakes tests is of specific importance to school superintendents and principals. Four different correlation coefficients were determined as a result of the research. The first identified the relationship between the overall assessment tools. This correlation coefficient resulted from the relationship of the composite ACT score of individual Missouri high school students with the mean of their communication arts, mathematics, and science MAP scores. The final three identified the relationship between the sub-tests of the two assessment tools. Quantitative data was collected from 20 mid-sized school districts throughout Missouri. Approximately 1,000 students are represented by numerical data for conclusion in the study. The Pearson Correlation Coefficient (r) was utilized to measure the direction and degree of relationship between individual student ACT achievement and MAP achievement in Missouri public schools. The four hypotheses were tested using the Pearson Correlation Coefficient (r). The correlation coefficient measures the degree of linear relationship between two variables. The research revealed that a positive correlation exists between individual student achievement on the MAP and the ACT. The strengths of the correlation varied on the specific disciplines addressed by each assessment. The correlations ranged from +.84 to +.66 as determined by the Pearson Correlation Coefficient (r). School administrators now have reason to believe that efforts in teaching and learning are having similar results on the two assessments when considering the achievement of individual students.
Dissertation
