PEPPo: Using a Polarized Electron Beam to Produce Polarized Positrons

An experiment demonstrating a new method for producing polarized positrons has been performed at the CEBAF accelerator at Jefferson Laboratory. The PEPPo (Polarized Electrons for Polarized Positrons) concept relies on the production of polarized e+/e− pairs originating from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a 1.0 mm tungsten pair-production target. This paper describes preliminary results of measurements using an 8.2 MeV/c electron beam with polarization 84% to generate positrons in the range of 3.1 to 6.2 MeV/c with polarization as high as ∼80%

Production of Magnetized Electron Beam from a DC High Voltage Photogun

Bunched-beam electron cooling is a key feature of all proposed designs of the future electron-ion collider, and a requirement for achieving the highest promised collision luminosity. At the Jefferson Lab Electron Ion Collider (JLEIC), fast cooling of ion beams will be accomplished via so-called \u27magnetized cooling\u27 implemented using a recirculator ring that employs an energy recovery linac. In this contribution, we describe the production of magnetized electron beam using a compact 300 kV DC high voltage photogun with an inverted insulator geometry, and using alkali-antimonide photocathodes. Beam magnetization was assessed using a modest diagnostic beamline that includes YAG view screens used to measure the rotation of the electron beamlet passing through a narrow upstream aperture. Magnetization results are presented for different gun bias voltages and for different laser spot sizes at the photocathode, using 532 nm lasers with DC and RF time structure. Photocathode lifetime was measured at currents up to 4.5 mA, with and without beam magnetization

The Continuous Electron Beam Accelerator Facility at 12 GeV

This review paper describes the energy-upgraded Continuous Electron Beam Accelerator Facility (CEBAF) accelerator. This superconducting linac has achieved 12 GeV beam energy by adding 11 new high-performance cryomodules containing 88 superconducting cavities that have operated cw at an average accelerating gradient of 20 MV/m. After reviewing the attributes and performance of the previous 6 GeV CEBAF accelerator, we discuss the upgraded CEBAF accelerator system in detail with particular attention paid to the new beam acceleration systems. In addition to doubling the acceleration in each linac, the upgrade included improving the beam recirculation magnets, adding more helium cooling capacity to allow the newly installed modules to run cold, adding a new experimental hall, and improving numerous other accelerator components. We review several of the techniques deployed to operate and analyze the accelerator performance and document system operating experience and performance. In the final portion of the document, we present much of the current planning regarding projects to improve accelerator performance and enhance operating margins, and our plans for ensuring CEBAF operates reliably into the future. For the benefit of potential users of CEBAF, the performance and quality measures for the beam delivered to each of the experimental halls are summarized in the Appendix

Manufacturing process for high aspect ratio metallic micro parts made by electroplating on partially conductive templates

Extended Abstract In supporting structural integrity of a miniature component, or for providing electric conduction of a through-silicon via (TSV) in three-dimensional integrated circuits (3D-IC), micro-or nano-hole filling with metallic material becomes increasing important in various micro-electrical mechanical systems (MEMSs) In this study, an anodic aluminum oxide (AAO) template containing numerous high aspect ratio nano-sized holes (an average diameter of 130 nm and an aspect-ratio about 20) was used as the cathode. The hydrophobicity/hydrophilicity of the AAO template was adjusted before Cu electrodeposition. Electrodeposition of Cu was carried out in an emulsified sc-CO2 bath containing cupric sulfate aqueous solution as the precursor. Cu deposition into the nano-holes was performed at an apparent constant current density of 2 A/dm 2 for 5 minutes. After electrodeposition, the cross section morphology and chemical composition of the AAO cathode was examined by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) with the aid of a focused-ion-beam (FIB). The experimental results showed that electrodeposition employing sc-CO2 bath to fill Cu into nano-sized holes was successful and superior to that of conventional process carried out at ambient pressure, in terms of uniformity and deposition rate. The high solubility of hydrogen gas in sc-CO2 fluid is the key factor. Moreover, the advantage of sc-CO2 electrodeposition is more pronounced for the AAO cathode exhibiting hydrophobic nature with respect to aqueous bath. References [1] Z

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p<0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p<0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding

Analysis of the relationship between sex and prescriptions for guideline-recommended therapy in peripheral arterial disease, in relation to 1-year all-cause mortality : a primary care cohort study

Objectives To explore population patterns of sex-based incidence and prevalence of peripheral arterial disease (PAD), guideline-directed best medical therapy prescriptions and its relationship with all-cause mortality at 1 year. Design A retrospective cohort study. Setting Anonymised electronic primary care from 787 practices in the UK, or approximately 6.2% of the UK population. Participants All registered patients over 40 with a documented diagnosis of peripheral arterial disease. Outcome measure Population incidence and prevalence of PAD by sex. Patterns of guideline-directed therapy, and correlation with all-cause mortality at 1 year (defined as death due to any outcome) in patients with and without an existing diagnosis of cardiovascular disease. Covariates included Charlson comorbidity, sex, age, body mass index, Townsend score of deprivation, smoking status, diabetes, hypertension, statin and antiplatelet prescription. Results Sequential cross-sectional studies from 2010 to 2017 found annual PAD prevalence (12.7–14.3 vs 25.6 per 1000 in men) and incidence were lower in women (11.6–12.4 vs 22.7–26.8 per 10 000 person years in men). Cox proportional hazards models created for PAD patients with and without cardiovascular disease over one full year analysed 25 121 men and 13 480 women, finding that following adjustment for age, women were still less likely to be on a statin (OR 0.69; 95% CI 0.66 to 0.72; p<0.001) or antiplatelet (OR: 0.87; 95% CI 0.83 to 0.90; p<0.001). Once fully adjusted for guideline recommended medical therapy, all-cause mortality was similar between women and men (adjusted HR (aHR) 0.95, 95% CI 0.87 to 1.03, p=0.198 for all patients, aHR 1.01, 95% CI 0.88 to 1.16, p=0.860 for those with cardiovascular disease). Conclusions Women with a new diagnosis of PAD were not prescribed guideline-directed therapy at the same rate as men. However once adjusted for factors including age, all-cause mortality in men and women was similar

Structuring properties of irrigation systems: Understanding relations between humans and hydraulics through modeling

Irrigation systems were clearly important in ancient times in supplying crops with water. This requires physical distribution facilities and socio-political arrangements to coordinate between actors. Resulting systems are highly diverse, and are being studied extensively within archeology and history. Whether initiated by a central authority or emerging from small-scale initiatives, irrigation systems are shaped through activities of individuals, households, and small groups into patterns and landscapes. This article discusses how hydraulic modeling techniques are powerful methodologies to study such irrigation development. Modeling daily interactions by agents and water fluxes will build better understanding of irrigation systems as anthropogenic landscapes. Three case studies will be used to illustrate this argument. A current irrigation system in Arequipa, Peru, shows that one can relate irrigation infrastructure and social action. A second case from Peru on a pre-Colombian irrigation system suggests that one can link irrigation system, water flows, and settlement. In the third case in the Jordan Valley, this possible link between irrigation and settlement is further studied.Water ManagementCivil Engineering and Geoscience