Three dimensional photograph of single electron tracks through a scintillator

The reconstruction of particle trajectories makes it possible to distinguish between different types of charged particles. In high-energy physics, where trajectories are rather long, large size trackers must be used to achieve sufficient position resolution. However, in low-background experiments tracks are rather short and three dimensional trajectories could only be resolved in time-projection chambers so far. For detectors of large volume and therefore large drift distances, which are inevitable for low-background experiments, this technique is limited by diffusion of charge carriers. In this work we present a "proof-of-principle" experiment for a new method for the three dimensional tracking of charged particles by scintillation light: We used a setup consisting of a scintillator, mirrors, lenses and a novel imaging device (the hybrid photo detector) in order to image two projections of electron tracks through the scintillator. We took data at the T-24 beam-line at DESY with relativistic electrons with a kinetic energy of 5 GeV and from this data successfully reconstructed their three dimensional propagetion path in the scintillator. With our setup we achieved a position resolution of about 28 mum in the best case.Comment: 9 pages, 13 figures, 1 tabl

Personal Dosimetry in Pulsed Photon Fields with the Dosepix Detector

First investigations regarding dosimetric properties of the hybrid, pixelated, photon-counting Dosepix detector in a pulsed photon field (RQR8) for the personal dose equivalent $H\mathrm{_p(10)}$ are presented. The influence quantities such as pulse duration and dose rate were varied, and their responses were compared to the legal limits provided in PTB-A 23.2. The variation of pulse duration at a nearly constant dose rate of 3.7$\,$Sv/h shows a flat response around 1.0 from 3.6$\,$s down to 2$\,$ms. A response close to 1.0 is achieved for dose rates from 0.07$\,$mSv/h to 35$\,$Sv/h for both pixel sizes. Above this dose rate, the large pixels (220$\,\mathrm{\mu}$m edge length) are below the lower limit. The small pixels (55$\,\mathrm{\mu}$m edge length) stay within limits up to 704$\,$Sv/h. The count rate linearity is compared to previous results, confirming the saturating count rate for high dose rates.Comment: 6 pages, 3 figures. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Atlas Vulnerability and Resilience

International audienc

Favoritism by the governing elite

In this paper, we study the extent to which ministers engage in regional favoritism. We are the first to provide a comprehensive analysis of a larger set of the governing elite, not just focusing on the primary leader. We hand-collect birthplaces of this governing elite globally. Combining this information with extended night-time luminosity and novel population data over the period from 1992 to 2016, we utilize a staggered difference-in-differences estimator and find that birthplaces of ministers globally emit on average roughly 7% more nightlight. We do not find evidence that this is driven by, or induces migration to their home regions. The size of our data set lets us investigate heterogeneities along a number of dimensions: political power, ministerial portfolio, and the institutional setting

Regional redistribution of mineral resource wealth in Africa

We study the economic implications of mineral resource activity for non-mining regions at the grid-level across the African continent. We find that capital cities benefit from mineral resource activity anywhere in the country. Leaders’ birth regions also benefit, but only in autocratic regimes. Generic non-mining regions, on the other hand, are worse off. These results suggest that regional redistribution of resource rents in Africa is primarily undertaken to the benefit of capital cities and leaders’ birth regions. In contrast, non-mining regions do not appear to be sufficiently compensated for the negative spillovers they may face due to mining activity elsewhere in the country

Regional favoritism and human capital accumulation in Africa

We study the long-run implications of regional and ethnic favoritism in Africa. Combining geocoded individual-level survey data from the Demographic and Health Survey (DHS) with data on national leaders’ birthplaces across 41 African countries, we explore the educational attainment of adults who were exposed to favoritism at various points during their life. We find that generic male respondents exposed to regional favoritism during their adolescence have higher educational attainment later in life. This higher human capital accumulated by men leads to more stable employment. For generic women, we observe no beneficial effects of regional favoritism. However, those women who belong to the same ethnic group as their national leader witness an increase in their educational attainment. These results indicate that regular inhabitants rather than only a narrow elite benefit from regional favoritism

Personal Dosimetry in Continuous Photon Radiation Fields With the Dosepix Detector

First measurements characterizing dosimetric properties of a dosimetry system designed for the purpose of active personal dosimetry for photons with mean energies from 12.4 to 1250 keV according to Physikalisch-Technische Bundesanstalt (PTB) requirements are presented. The system consists of three Dosepix detectors, which is a hybrid, pixelated, photon-counting X-ray detector. The energy and angular dependence of the normalized response and the coefficients of variation of the personal dose equivalents Hp(10) and Hp(0.07) are determined on an International Organization for Standardization (ISO) water slab phantom in continuous reference photon radiation fields according to ISO 4037-1 and ISO 4037-3. The energy response is presented for the narrow spectra N-15 to N-300 and the radiation qualities S-Cs and S-Co for angles of incidence of 0◦, 30◦, and ±60◦. The highest deviation of the response from the reference response is found at N-60, −60◦ with 1.179 ± 0.007 (standard deviation) for Hp(10). The energy range of use for Hp(10) is expected to extend from 12.4 to 1250 keV. For the personal dose equivalent Hp(0.07), the normalized response at ±60◦ is below the lower limit for N-15, N-20, and N-25. It results in an energy range of use from 24.6 to 1250 keV. The coefficient of variation increases with increasing photon energy and stays below 1% for all measurements