The Appropriateness of the Poolability Assumption for Multiproduct Technologies: Evidence from the English Water and Sewerage Utilities

The empirical literature on the cost structure of multiproduct firms (e.g., public utilities providing in combination gas, water, and electricity) traditionally assumes a common technology across different products and stages of production, letting the issue of poolability unexplored. The appropriateness of this assumption is tested here by estimating a General cost function for samples of UK specialized and sewerage-diversified water utilities. The results show the existence of both aggregate scale economies and diseconomies of scope; more interestingly, the hypothesis that the two groups of water companies share the same technological parameters is rejected. Given the implications of this finding in terms of optimal industry configuration and possible restructuring policies (e.g., mergers and/or divestitures), our test suggests caution in pooling samples when undertaking empirical studies on data which refer to multiproduct technologies.Multiproduct technologies; Water and sewerage utilities; Poolability; General cost function

Optical characterization of proton irradiated diamond

ABSTRACT Manufacturing of miniaturized photonic devices based on diamond technology is possible by implanting the pristine material with highly energetic particles. Here we report on the spectral characterization of the optical constants of proton-irradiated diamond. Absorption of the irradiated zones was estimated in the UV-vis-NIR from direct transmittance measurement using a dedicated setup with enhanced spatial resolution. The OPD data providing an estimation of the thickness of the damaged area and its depth profile, have allowed then evaluation of the extinction coefficient from the transmission measurements. Simultaneous variation of dispersive optical constants makes the modeling significantly more complicated compared to the above cited monochromatic study. Keywords: Optical constants; Diamond crystal; Ion implantation 1. INTRODUCTION Manufacturing of miniaturized photonic devices based on diamond technology is possible by implanting the pristine material with highly energetic particles. Theoretically the optical constants of irradiated material may vary from the values typical for pristine diamond to those of graphite, however only precise knowledge of the optical constants allows calculation of performance of the novel photonic micro- and nano-devices like e.g. diamond-based waveguiding structure

Real-time spatial characterization of micrometer-sized X-ray free-electron laser beams focused by bendable mirrors

A real-time and accurate characterization of the X-ray beam size is essential to enable a large variety of different experiments at free-electron laser facilities. Typically, ablative imprints are employed to determine shape and size of μm-focused X-ray beams. The high accuracy of this state-of-the-art method comes at the expense of the time required to perform an ex-situ image analysis. In contrast, diffraction at a curved grating with suitably varying period and orientation forms a magnified image of the X-ray beam, which can be recorded by a 2D pixelated detector providing beam size and pointing jitter in real time. In this manuscript, we compare results obtained with both techniques, address their advantages and limitations, and demonstrate their excellent agreement. We present an extensive characterization of the FEL beam focused to ≈1 μm by two Kirkpatrick-Baez (KB) mirrors, along with optical metrology slope profiles demonstrating their exceptionally high quality. This work provides a systematic and comprehensive study of the accuracy provided by curved gratings in real-time imaging of X-ray beams at a free-electron laser facility. It is applied here to soft X-rays and can be extended to the hard X-ray range. Furthermore, curved gratings, in combination with a suitable detector, can provide spatial properties of μm-focused X-ray beams at MHz repetition rate

Opportunities for Two-Color Experiments in the Soft X-ray Regime at the European XFEL

X-ray pump/X-ray probe applications are made possible at X-ray Free Electron Laser (XFEL) facilities by generating two X-ray pulses with different wavelengths and controllable temporal delay. In order to enable this capability at the European XFEL, an upgrade project to equip the soft X-ray SASE3 beamline with a magnetic chicane is underway. In the present paper we describe the status of the project, its scientific focus and expected performance, including start-to-end simulations of the photon beam transport up to the sample, as well as recent experimental results demonstrating two-color lasing at photon energies of 805 eV + 835 eV and 910 eV + 950 eV. Additionally, we discuss methods to analyze the spectral properties and the intensity of the generated radiation to provide on-line diagnostics for future user experiments

Expansion cone for the 3-inch PMTs of the KM3NeT optical modules

[EN] Detection of high-energy neutrinos from distant astrophysical sources will open a new window on the Universe. The detection principle exploits the measurement of Cherenkov light emitted by charged particles resulting from neutrino interactions in the matter containing the telescope. A novel multi-PMT digital optical module (DOM) was developed to contain 31 3-inch photomultiplier tubes (PMTs). In order to maximize the detector sensitivity, each PMT will be surrounded by an expansion cone which collects photons that would otherwise miss the photocathode. Results for various angles of incidence with respect to the PMT surface indicate an increase in collection efficiency by 30% on average for angles up to 45 degrees with respect to the perpendicular. Ray-tracing calculations could reproduce the measurements, allowing to estimate an increase in the overall photocathode sensitivity, integrated over all angles of incidence, by 27% (for a single PMT). Prototype DOMs, being built by the KM3NeT consortium, will be equipped with these expansion cones.This work is supported through the EU, FP6 Contract no. 011937, FP7 grant agreement no. 212252, and the Dutch Ministry of Education, Culture and Science.Adrián Martínez, S.; Ageron, M.; Aguilar, JA.; Aharonian, F.; Aiello, S.; Albert, A.; Alexandri, M.... (2013). Expansion cone for the 3-inch PMTs of the KM3NeT optical modules. Journal of Instrumentation. 8(3):1-19. https://doi.org/10.1088/1748-0221/8/03/T03006S1198