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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2005.06.006 Byline: R.F. Elsner (a), B.D. Ramsey (a), J.H. Waite (b), P. Rehak (c), R.E. Johnson (d), J.F. Cooper (e), D.A. Swartz (f) Keywords: Instrumentation; Experimental techniques; Jupiter; magnetosphere; Io; Europa; Ganymede; Callisto; Aurorae; Abundances; Impact processes Abstract: Remote observations with the Chandra X-ray Observatory and the XMM-Newton Observatory have shown that the jovian system is a source of X-rays with a rich and complicated structure. The planet's polar auroral zones and its disk are both powerful sources of X-ray emission. Chandra observations revealed X-ray emission from the Io plasma torus and from the Galilean moons Io, Europa, and possibly Ganymede. The emission from the moons is due to bombardment of their surfaces by highly energetic magnetospheric protons, and oxygen and sulfur ions. These ions excite atoms in their surfaces leading to fluorescent X-ray emission lines. These lines are produced against an intense background continuum, including bremsstrahlung radiation from surface interactions of primary magnetospheric and secondary electrons. Although the X-ray emission from the Galilean moons is faint when observed from Earth orbit, an imaging X-ray spectrometer in orbit around one or more of these moons, operating from 200 eV to 8 keV with 150 eV energy resolution, would provide a detailed mapping of the elemental composition in their surfaces. Surface resolution of 40 m for small features could be achieved in a 100-km orbit around one moon while also remotely imaging surfaces of other moons and Jupiter's upper atmosphere at maximum regional resolutions of hundreds of kilometers. Due to its relatively more benign magnetospheric radiation environment, its intrinsic interest as the largest moon in the Solar System, and its mini-magnetosphere, Ganymede would be the ideal orbital location for long-term observational studies of the jovian system. Here we describe the physical processes leading to X-ray emission from the surfaces of Jupiter's moons and the properties required for the technique of imaging X-ray spectroscopy to map the elemental composition of their surfaces, as well as studies of the X-ray emission from the planet's aurora and disk and from the Io plasma torus. Author Affiliation: (a) NASA Marshall Space Flight Center, XD 12, Huntsville, AL 35812, USA (b) Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109-2143, USA (c) Instrumentation Division 535 B, 20 Technology Street, Brookhaven National Laboratory, Upton, NY 11973, USA (d) Engineering Physics, University of Virginia, Charlottesville, VA 22901, USA (e) Space Physics Data Facility, Code 612.4, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA (f) Universities Space Research Association, NASA Marshall Space Flight Center, XD 12, Huntsville, AL 35812, USA Article History: Received 14 September 2004; Revised 25 February 2005

Since 2022, there has been a significant increase in the importance of critical entities in terms of critical infrastructure protection. The adoption of the Critical Entities Resilience Directive must in EU member states ensure not only the protection of critical infrastructure, but also a sufficient resilience level of the entities themselves. This directive obliges critical entities to take measures to increase their resilience but does not provide any methodological support. A necessary starting point for fulfilling this obligation is knowledge of the current state of critical entities resilience to small-scale disasters. The results of the resilience assessment will then enable critical entities to identify vulnerabilities on the basis of which adequate technical, security and organisational measures can be defined. Therefore, this article presents an entirely new semi-quantitative method, CERA, which has been developed for the comprehensive assessment of entity and infrastructure resilience of critical entities. At the core of this method is a procedure that allows critical entities to self-assess their internal resilience through individual factors, which are defined in detail in this article. In order to facilitate the assessment process, the authors of the article have created the CERA Support Tool, which is supplementary material to this article. The Results section of the article also includes a presentation of a practical application example of the proposed procedure. [ABSTRACT FROM AUTHOR]

The concept of X-ray active matrix pixel sensor (XAMPS) is introduced. XAMPSs are direct illumination, position sensitive X-ray detectors with the possibility of containing 1 000 000 pixels. They count the number of diffracted X-rays in each pixel by measuring the total charge released by converted X-rays in the body of the sensor. Readout is accomplished with a relatively small number of channels equal to the square root of the number of pixels. The estimated readout time can be about 1 ms. Noise of the readout electronics can be so low that practically no additional fluctuations in the number of incident X-rays per pixel are added and, therefore, the XAMPS performance is very close to that of an ideal detector for X-ray crystallography. Index Terms--Active pixel sensors, protein crystallography, silicon radiation detectors, X-ray imaging.

In this paper we present the working principle and the design criteria of the Controlled-Drift Detector, a novel device suitable for the simultaneous measurement of energy and two-dimensional position of X rays. In the Controlled-Drift Detector the pixel structure typical of a charge-coupled device and the fast readout typical of a silicon drift detector are joined. When the radiation is to be detected, suitable potential barriers are generated to prevent the drift of the signal electrons that are confined within a matrix of integration wells. The potential barrier which prevents the drift is selectively removable to allow the fast transport of the confined signal electrons to the readout electrodes by means of a static drift field. In principle such a device can achieve excellent energy resolution and readout times of some tens of microseconds. Three different confining mechanisms that allow control of the drift of the stored electrons are studied, and their advantages and drawbacks are discussed. First prototypes of the Controlled-Drift Detector are currently in production. Index Terms - Fast read-out, high-energy resolution, silicon detector, X-ray imaging.

A description is given of the principle and experimental verification of a new method which significantly reduces broadening of the position response, due to parallax, for radiation incident on a detector at finite angles of incidence. The technique, which can be implemented in gas-based position-sensitive detectors with planar geometry, substantially improves position resolution for scattering experiments using X-rays and neutrons, and will permit larger angular coverage than has previously been possible. An improvement of nearly a factor four in rms position resolution is predicted, which is confirmed by measurements using a gas proportional X-ray detector with delay-line position encoding.

We have designed a 16-channel preamplifier-shaper for particle tracking using silicon drift detectors (SDD). The preamplifier, which is optimized for a detector capacitance of 0.2 - 0.8 pF, uses two new circuit techniques to achieve a low noise (ENC 120 [e.sup.-] + 62 [e.sup.-]/pF), high linearity (< 0.5% to 50 fC), and good tolerance to process variations and temperature and power supply fluctuations. The circuit is continuously sensitive, has no digital signals on chip, and requires no external components or critical adjustments. The peaking time of the shaper is 50 nsec and the power dissipation, including an off-chip driver, is 6.5 mW/channel. The circuit is fabricated in 1.2[[micro]meter] CMOS and can accomodate detector leakage currents of up to 1.5 uA. Although the circuit was developed for use with particle tracking detectors, these techniques are also well-suited for the design of lower-noise preamplifiers for high-resolution X-ray spectroscopy systems.

We report here an ultra low noise charge sensitive monolithic CMOS amplifier (CSA) suitable for small anode capacitance (200fF), low leakage current solid state detectors. The CSA is continuously sensitive, the charge from the input node being drained by a feedback transistor Mf biased as a resistor with effective values in the G[Omega] range. This very high value was achieved by a novel scheme which tracks threshold variations, and power supply and temperature fluctuations. A good linearity of the CSA conversion gain is achieved (

A new configuration of a resistorless charge sensitive preamplifier with an nJFET as an input device was tested. The dc level of the input of the amplifier was kept constant by a slightly forward-biased np junction connected between the input of the amplifier and ground. A noise level of 22 root mean square (r.m.s.) electrons is measured at 295 K and 15 r.m.s. electrons at 253 K. The dynamic behavior of the amplifier is investigated with different leakage current conditions. The technological benefits and the suitability of the front-end connection for room temperature detectors, particularly multianode drift chambers, are highlighted.

In this paper we present a method to obtain the three-dimensional (3-D) solution of the Laplace equation in closed form suitable for semiconductor detector design. The method applies to planar geometry cases (microstrip detectors, pixel detectors, drift detectors, etc.) with possible mixed boundary conditions on the surfaces of the wafer. The solution inside the detector volume is expressed by a series of elementary functions. The method requires lower CPU time and memory than methods based on 3-D discretization, in particular for the study of 3-D carrier trajectories inside the volume of semiconductor detectors and for inter-electrode capacitance calculations.