Beam Extraction and Transport

This chapter gives an introduction to low-energy beam transport systems, and discusses the typically used magnetostatic elements (solenoid, dipoles and quadrupoles) and electrostatic elements (einzel lens, dipoles and quadrupoles). The ion beam emittance, beam space-charge effects and the physics of ion source extraction are introduced. Typical computer codes for analysing and designing ion optical systems are mentioned, and the trajectory tracking method most often used for extraction simulations is described in more detail.Comment: presented at the CERN Accelerator School CAS 2012: Ion Sources, Senec, 29 May - 8 June 201

Determiner removal in Balinese nonpivot agents

Patient‐voice clauses within the symmetric voice system of Balinese disallow any extraction from the external‐argument position, while definite external arguments are blocked from occurring altogether. The former fact is traditionally taken as evidence for syntactic ergativity in Austronesian. The latter fact has recently been argued to provide evidence for postsyntactic case licensing via adjacency with the verb. In this article, we offer a simple alternative explanation for the in‐situ properties of patient‐voice agents in Balinese—one that does not make reference to case. We argue that patient‐voice heads come with a feature that triggers removal of the external argument's DP shell, resulting in the loss of a determiner and a category‐D feature that would otherwise enable extraction.German Research Foundation (funding for graduate program Interaction of Grammatical Building Blocks and for Reinhart Koselleck project MU1444/14‐1) http://dx.doi.org/10.13039/501100001659Hans Böckler Foundation (Maria Weber Grant) http://dx.doi.org/10.13039/501100007440Peer Reviewe

Concept for a Future Super Proton-Proton Collider

Following the discovery of the Higgs boson at LHC, new large colliders are being studied by the international high-energy community to explore Higgs physics in detail and new physics beyond the Standard Model. In China, a two-stage circular collider project CEPC-SPPC is proposed, with the first stage CEPC (Circular Electron Positron Collier, a so-called Higgs factory) focused on Higgs physics, and the second stage SPPC (Super Proton-Proton Collider) focused on new physics beyond the Standard Model. This paper discusses this second stage.Comment: 34 pages, 8 figures, 5 table

A Chemical and Morphological Study of Cassava Peel: A Potential Waste as Coagulant Aid

This study investigates the chemical and morphological characteristics of cassava peel (CP) biomass as a potential coagulant aid for turbidity, heavy metals and microbial removal. FE-SEM micrograph shown the surface of the CP samples was covered with smooth and globular in shaped of bound starch granules. FTIR spectra demonstrated that carboxyl and hydroxyl groups were present in abundance. Whereas analysis by XRF spectrometry indicated the CP samples contain Fe2O3 and Al2O3 which might contribute to its coagulation ability. The features of CP obtained from this study promotes the feasibility of CP to be further developed and studied to produce effective coagulant aid as sustainable alternative to reduce the usage of chemical coagulants

Geochemical characteristics of aluminum and magnesium secondary mineral phases in uranium mill tailings

The Athabasca Basin in northern Saskatchewan, Canada is a major source of uranium (U) and an important economic driver for the province and country. The Athabasca Basin U deposits contain elevated concentrations of As, Se, Mo, Ni, and 226Ra (elements of concern; EOCs). The Key Lake U mill uses a stepwise Ca(OH)2 neutralization process (pH 4.0, 6.5, 9.5, and 10.5) to precipitate EOCs from raffinate (acidic, metal-rich wastewater) prior to releasing the effluent to the environment. The neutralization process precipitates a complex mixture of secondary minerals concentrated with EOCs that are deposited to an in-pit tailings management facility (TMF) at pH ≈ 10.1. Extensive studies show adsorption to ferrihydrite is a primary control on aqueous EOC concentrations. Recent studies suggest poorly characterized Al and Mg precipitates could also influence EOC concentrations. The objectives of this thesis were to characterize the Al and Mg secondary mineralogy in the Key Lake neutralization process and quantify controls exerted by these minerals on EOC concentrations. Additionally, a review of all geochemical literature pertaining to in-pit TMFs in the Athabasca Basin was conducted to synthesize the collective science. Laboratory and mill samples were used for the study. The Al and Mg secondary minerals identified were amorphous AlOHSO4 (a hydrobasaluminite-like phase, existing below neutral pH), amorphous Al(OH)3, MgAl-hydrotalcite, and Al-substituted ferrihydrite. In the absence of ferrihydrite, Al and Mg mineral phases sequestered As, Se, Mo, and Ni. Batch adsorption experiments showed MgAl-hydrotalcite adsorbs As, Se, and Mo to the same order of magnitude as ferrihydrite. Arsenic and Ni XAS experiments showed Al and Mg minerals sequester As and Ni in concert with ferrihydrite. Arsenic(V) formed bidentate-binuclear complexes on the surface of ferrihydrite and amorphous Al(OH)3. Hydrotalcite adsorbed As(V) on the mineral surface and/or within the mineral interlayer through bidentate complexation. Nickel was adsorbed to amorphous Al(OH)3 through edge-sharing bidentate-mononuclear complexes and precipitated as a Ni-Al layered double hydroxide at pH 10.5. These results demonstrate that mineralogically complex tailings rich in Fe, Al, and Mg exert multiple mechanisms of controls on EOC solubility and further the understanding of the long-term fate of EOCs in tailings

Science Requirements and Conceptual Design for a Polarized Medium Energy Electron-Ion Collider at Jefferson Lab

This report presents a brief summary of the science opportunities and program of a polarized medium energy electron-ion collider at Jefferson Lab and a comprehensive description of the conceptual design of such a collider based on the CEBAF electron accelerator facility.Comment: 160 pages, ~93 figures This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177, DE-AC02-06CH11357, DE-AC05-060R23177, and DESC0005823. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purpose

Highly charged ion interactions with ultrathin dielectric films

The excitations occurring at a solid surface due to slow highly charged ion (HCI) impacts are interesting from the perspective of fundamental processes in atomic collisions and materials science. This thesis focuses on two questions: 1) How much HCI potential energy deposition is required to form permanent surface modifications?, 2) How does the presence of a thin dielectric surface film change the classical over-the-barrier picture for neutralization above a clean metal? I describe a measurement of craters in thin dielectric films formed by XeQ+ (26 ≤ Q ≤ 44) projectiles. Tunnel junction devices with ion-irradiated barriers were used to amplify the effect of charge-dependent cratering through the exponential dependence of tunneling conductance on barrier thickness. Electrical conductance of a crater σc(Q) increased by four orders of magnitude (7.9 x 10 -4 μS to 6.1 μS) as Q increased, corresponding to crater depths ranging from 2 Å to 11 Å. According to a heated spike model, the energy required to produce the craters spans from 8 keV to 25 keV over the investigated charge states. Considering energy from pre-equilibrium nuclear and electronic stopping as well as neutralization, we find that at least (27 ± 2) % of available projectile neutralization energy is deposited into the thin film during impact. Additionally, an extension of the classical over-barrier model for HCI neutralization above dielectric covered metal surfaces is presented. The model is used to obtain the critical distance for the onset of neutralization above C60/Au(111), Al2O3/ Co, and LiF/Au(111) targets. The model predicts that for thin films with low electrical permittivity and positive electron affinity, the onset of neutralization can begin with the electrons in the metal, and at further ion-surface distances than for clean metals. The model describes three distinct over-the-barrier regimes of \u27vacuum limited\u27 capture from the metal, \u27thin film\u27 limited capture from the metal, and capture from the insulator. These regimes are detailed in terms of charge state, target material parameters and film thickness

Physical properties of nanostructures induced by irradiation in diamond

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in ful llment of the requirements for the degree of Doctor of Philosophy in Physics. Johannesburg, 10 August 2017.We investigate the interaction of slow highly charged ions (SHCIs) with insulating type-Ib diamond (111) surfaces. Bismuth and Xenon SHCI beams produced using an Electron Beam Ion Trap (EBIT) and an Electron Cyclotron Resonance source (ECR) respectively, are accelerated onto type Ib diamond (111) surfaces with impact velocities up to 0.4 Bohr. SHCIs with charge states corresponding to potential energies between 4.5 keV and 110 keV are produced for this purpose. Atomic Force Microscopy analysis (AFM) of the diamond surfaces following SHCI impact reveals surface morphological modi cations characterized as nanoscale craters (nano-craters). To interpret the results from Tapping Mode AFM analysis of the irradiated diamond surfaces we discuss the interplay between kinetic and potential energy in nanocrater formation using empirical data together with Stopping and Range of Ions in Matter (SRIM) Monte Carlo Simulations. In the case of irradiation induced magnetic e ects in diamond, we investigate the magnetic properties of ultra-pure type-IIa diamond following irradiation with proton beams of 1-2 MeV energy. SQUID magnetometry of proton irradiated non-annealed diamond indicates formation of Curie type paramagnetism according to the Curie law. Raman and Photoluminescence spectroscopy measurements show that the primary structural features created by proton irradiation are the centers: GR1, ND1, TR12 and 3H. The Stopping and Range of Ions in Matter (SRIM) Monte Carlo simulations together with ii iii SQUID observations show a strong correlation between vacancy production, proton uence and the paramagnetic factor. At an average surface vacancy spacing of 1-1.6 nm and bulk (peak) vacancy spacing of 0.3-0.5 nm Curie paramagnetism is induced by formation of ND1 centres with an e ective magnetic moment eff (0.1-0.2) B. Post annealing SQUID analysis of proton irradiated diamond shows formation temperature independent magnetism with magnetic moment 6-7 emu superimposed to Curie-type paramagnetism. The response of ultra-pure type-IIa single crystal CVD diamond following 2.2 MeV proton micro-irradiation is further investigated using Atomic Force, Magnetic Force and Electrostatic Force Microscopy (AFM, MFM and EFM) under ambient conditions. Analysis of the phase shift signals using probe polarization dependent magnetization measurements and comparison of the MFM and EFM signals at zero electrical bias, show that measured force gradients originate from a radiation induced magnetic response in the micro-irradiated regions in diamond.LG201