Unrecognized Backscattering in Low Energy Beta Spectroscopy

We present studies on electron backscattering from the surface of plastic scintillator beta detectors. By using a setup of two detectors coaxial with a strong external magnetic field - one detector serving as primary detector, the other as veto-detector to detect backscattering - we investigate amount and spectrum of unrecognized backscattering, i.e. events where only one detector recorded a trigger signal. The implications are important for low energy particle physics experiments.Comment: 5 pages, 8 figures; v2: published NIM A versio

Development of an electron density probe Final report, 22 Jun. 1964 - 22 Mar. 1965

Electron density probes to perform measurements in flow fields at high altitude

The Efficiency-Equity Tradeoffs in Agricultural Research Priority Setting: The Potential Impacts of Agricultural Research on Economic Surplus and Poverty Reduction in Nigeria

Public agricultural research has come under increasing pressure to redefine its strategic priorities to contribute to poverty alleviation goals. However, the issue of whether the poor benefit more from agricultural research that pursues efficiency or equity objectives remains unresolved, largely due to lack of empirical evidence on the nature and magnitude of the efficiencyequity tradeoffs. This paper estimates the potential impacts of agricultural research on economic surplus and poverty reduction in Nigeria, identifies strategic priorities according to both efficiency and equity criteria, and examines the nature and magnitude of the efficiencyequity tradeoffs. The results show that there are no significant efficiencyequity tradeoffs because the rural poor in Nigeria depend mainly on the production of food staples for both consumption and household income. Although introducing a poverty dimension does not result in a significant shift in strategic priorities, greater benefits to the poor are possible through poverty-based targeting without compromising total benefits. However, efforts made towards the realization of potential benefits to the poor from pursuing either efficiency or equity objectives would be more important than mere targeting of research. Therefore, both agricultural research and support services, including extension, credit, input supply, and infrastructure, should be targeted to the poor to achieve poverty alleviation goals through agricultural research.poverty reduction, economic surplus, research priority setting, Nigeria, Research and Development/Tech Change/Emerging Technologies, I32, I38, O13, O32, Q16,

The influence of the chameleon field potential on transition frequencies of gravitationally bound quantum states of ultra-cold neutrons

We calculate the chameleon field potential for ultracold neutrons, bouncing on top of one or between two neutron mirrors in the gravitational field of the Earth. For the resulting non--linear equations of motion we give approximate analytical solutions and compare them with exact numerical ones for which we propose the analytical fit. The obtained solutions may be used for the quantitative analysis of contributions of a chameleon field to the transition frequencies of quantum states of ultra-cold neutrons bound in the gravitational field of the Earth.Comment: 11 pages, 4 figure

Finding Team Mates who are not prone to Sucker and Free-Rider effects: The Protestant Work Ethic as a Moderator of Motivation Losses in Group Performance

This study examines the contribution of a personality variable in motivation losses in group performance. Differences in the endorsement of the ‘Protestant Work Ethic’ can account for variance in motivation losses in group work. Male student scores on the Mirels- Garrett Protestant Work Ethic Scale and Ho’s Australian Work Ethic Scale as well as different preferences for reward distributions were used as moderator variables. The study tested motivation losses in a situation that was designed to provoke the free-rider effect and in a situation that was designed to provoke the sucker-effect. Results showed that different facets of the Protestant Work Ethic have different effects on behavior in group work situations: Whereas approval of the equity principle moderates the sucker-effect, belief in work as a value moderates the free-rider effect

Neutron Interferometry constrains dark energy chameleon fields

We present phase shift measurements for neutron matter waves in vacuum and in low pressure Helium using a method originally developed for neutron scattering length measurements in neutron interferometry. We search for phase shifts associated with a coupling to scalar fields. We set stringent limits for a scalar chameleon field, a prominent quintessence dark energy candidate. We find that the coupling constant $\beta$ is less than 1.9 $\times10^7$~for $n=1$ at 95\% confidence level, where $n$ is an input parameter of the self--interaction of the chameleon field $\varphi$ inversely proportional to $\varphi^n$.Comment: 7 pages, 4 figure

Micro Laser Melting: Analyses of Current Potentials and Restrictions for the Additive Manufacturing of Micro Structures

Although there is a significant requirement for complex micro parts, current metal processing additive manufacturing techniques are limited in achievable part accuracy and geometric resolution. Due to the recently developed process of Micro Laser Melting (MLM) new potentials in micro manufacturing are realizable. This paper gives an overview of the present potentials of MLM using 316L steel powder. While using powder material with a grain size of ≤ 5 µm this technique enables layer thicknesses from 5 to 7 µm. Due to the use of different exposure strategies and laser modes (pulsed and continuous radiation) high aspect ratios up to 260 could be realized with thin wall structures. Furthermore, the influence of laser mode and exposure sequence on the part density, surface quality and accuracy of lattice structures with a minimum wall thickness lower than 40 µm is analyzed.Mechanical Engineerin