The impact of low energy proton damage on the operational characteristics of EPIC-MOS CCDs

The University of Tübingen 3.5 MeV Van de Graaf accelerator facility was used to investigate the effect of low energy protons on the performance of the European Photon Imaging Camera (EPIC), metal–oxide semiconductor (MOS), charge coupled devices (CCDs). Two CCDs were irradiated in different parts of their detecting areas using different proton spectra and dose rates. Iron-55 was the calibration source in all cases and was used to measure any increases in charge transfer inefficiency (CTI) and spectral resolution of the CCDs. Additional changes in the CCD bright pixel table and changes in the low X-ray energy response of the device were examined. The Monte Carlo code Stopping Range of Ions in Matter (SRIM) was used to model the effect of a 10 MeV equivalent fluence of protons interacting with the CCD. Since the non-ionising energy loss (NIEL) function could not be applied effectively at such low proton energies. From the 10 MeV values, the expected CTI degradation could be calculated and then compared to the measured CTI changes

Direct measurement of sub-pixel structure of the EPIC MOS CCD on-board th e XMM/NEWTON satellite

We have used a mesh experiment in order to measure the sub-pixel structure of the EPIC MOS CCDs on-board the XMM/NEWTON satellite. The EPIC MOS CCDs have 40 $\mu$m-square pixels which have an open electrode structure in order to improve the detection efficiency for low-energy X-rays. We obtained restored pixel images for various X-ray event grades (e.g. split-pixel events, single pixel events, etc.) at various X-ray energies. We confirmed that the open electrode structure results in a distorted horizontal pixel boundary. The open electrode region generates both single pixel events and vertically split events, but no horizontally split events. Because the single pixel events usually show the best energy resolution, we discuss a method of increasing the fraction of single pixel events from the open electrode region. Furthermore, we have directly measured the thickness of the electrodes and dead-layers by comparing spectra from the open electrode region with those from the other regions: electrodes, electrode finger and channel stop. We can say that EPIC MOS CCDs are more radiation hard than front-illumination chips of ACIS on-board Chandra X-ray Observatory because of their extra absorption thickness above the charge transfer channel. We calcurated the mean pixel response and found that our estimation has a good agreement with that of the ground calibration of EPIC MOS CCD.Comment: 20pages including 2 tables, 10 figures,Accepted for publication in : Nuclear Instruments and Methods in Physics Research

In-orbit performance of the EPIC-MOS detectors on XMM-Newton

XMM-Newton was launched into space on a highly eccentric 48 hour orbit on December 10th 1999. XMM-Newton is now in its fifth year of operation and has been an outstanding success, observing the Cosmos with imaging, spectroscopy and timing capabilities in the X-ray and optical wavebands. The EPIC-MOS CCD X-ray detectors comprise two out of three of the focal plane instruments on XMM-Newton. In this paper we discuss key aspects of the current status and performance history of the charge transfer ineffiency (CTI), energy resolution and spectral redistribution function (rmf) of EPIC-MOS in its fifth year of operation.Comment: 8 pages, 10 figures, SPIE Glasgow 21-25 June 2004, Session 548

Diseño de una lista de chequeo para la orientación psicojurídica en víctimas de asalto sexual (L.O.P.V.A.S)

Curso Especial de Interés : Victimología y CriminologíaLa siguiente propuesta, contiene la información necesaria en el diseño un instrumento que permita determinar y analizar los factores que están involucrados en este tipo de violencia. El objetivo de esta investigación es diseñar una lista de chequeo en atención Psicojurídica para la orientación en la denuncia en víctimas de abuso sexual a partir del reconocimiento de patrones conductuales y el modus operandi del agresor. Esta lista de chequeo nos permite la orientación a víctimas de asalto sexual para el establecimiento de la denuncia, esta guía brinda a los funcionarios públicos la oportunidad de reconocer las necesidades de la víctima de asalto sexual y a partir de la información lograr tipificar la conducta de asalto sexual y a partir de ello generar estrategias de planificación en prevención y promoción de violencia sexual bajo los criterios de las políticas públicas.1. Resumen 2. Justificación 3. Marco Teórico 4. Marco Legal 5. Marco Ético 6. Objetivos 7. Estudio de Mercadeo 8. Presentación del Producto 9. Variables Psicológicas que lo componen 10. Clientes 11. Competencia 12. Resultados 13. Conclusiones 14. ReferenciasPregradoPsicólog

The X-ray lightcurve of Sgr A* over the past 150 years inferred from Fe-Ka line reverberation in Galactic Centre molecular clouds

We examine the temporal and spectral properties of nine Fe-Ka bright molecular clouds within about 30 pc of Sgr A*, in order to understand and constrain the primary energising source of the Fe fluorescence. Significant Fe-Ka variability was detected, with a spatial and temporal pattern consistent with that reported in previous studies. The main breakthrough that sets our paper apart from earlier contributions on this topic is the direct measurement of the column density and the Fe abundance of the MCs in our sample. We used the EW measurements to infer the average Fe abundance within the clouds to be 1.6$\pm$0.1 times solar. The cloud column densities derived from the spectral analysis were typically of the order of 10$^{23}$ cm$^{-2}$, which is significantly higher than previous estimates. This in turn has a significant impact on the inferred geometry and time delays within the cloud system. Past X-ray activity of Sgr A* is the most likely source of ionisation within the molecular clouds in the innermost 30 pc of the Galaxy. In this scenario, the X-ray luminosity required to excite these reflection nebulae is of the order of 10$^{37}-10^{38}$ erg s$^{-1}$, significantly lower than that estimated for the Sgr B2 molecular cloud. Moreover, the inferred Sgr A* lightcurve over the past 150 years shows a long-term downwards trend punctuated by occasional counter-trend brightening episodes of at least 5 years duration. Finally, we found that contributions to the Fe fluorescence by X-ray transient binaries and cosmic-ray bombardment are very likely, and suggest possible ways to study this latter phenomenon in the near future.Comment: 23 pages, 14 figures, accepted for publication in Astronomy & Astrophysic

The European Photon Imaging Camera on XMM-Newton: The MOS Cameras

The EPIC focal plane imaging spectrometers on XMM-Newton use CCDs to record the images and spectra of celestial X-ray sources focused by the three X-ray mirrors. There is one camera at the focus of each mirror; two of the cameras contain seven MOS CCDs, while the third uses twelve PN CCDs, defining a circular field of view of 30 arcmin diameter in each case. The CCDs were specially developed for EPIC, and combine high quality imaging with spectral resolution close to the Fano limit. A filter wheel carrying three kinds of X-ray transparent light blocking filter, a fully closed, and a fully open position, is fitted to each EPIC instrument. The CCDs are cooled passively and are under full closed loop thermal control. A radio-active source is fitted for internal calibration. Data are processed on-board to save telemetry by removing cosmic ray tracks, and generating X-ray event files; a variety of different instrument modes are available to increase the dynamic range of the instrument and to enable fast timing. The instruments were calibrated using laboratory X-ray beams, and synchrotron generated monochromatic X-ray beams before launch; in-orbit calibration makes use of a variety of celestial X-ray targets. The current calibration is better than 10% over the entire energy range of 0.2 to 10 keV. All three instruments survived launch and are performing nominally in orbit. In particular full field-of-view coverage is available, all electronic modes work, and the energy resolution is close to pre-launch values. Radiation damage is well within pre-launch predictions and does not yet impact on the energy resolution. The scientific results from EPIC amply fulfil pre-launch expectations.Comment: 9 pages, 11 figures, accepted for publication in the A&A Special Issue on XMM-Newto

High-tech composites to ancient metals

Neutron diffraction methods offer a direct measure of the elastic component of strain deep within crystalline materials through precise characterisation of the interplanar crystal lattice spacing. The unique non-destructive nature of this measurement technique is particularly beneficial in the context of engineering design and archaeological materials science, since it allows the evaluation of a variety of structural and deformational parameters inside real components without material removal, or at worst with minimal interference. We review a wide range of recent experimental studies using the Engin-X materials engineering instrument at the ISIS neutron source and show how the technique provides the basis for developing improved insight into materials of great importance to applications and industry. © 2009 Elsevier Ltd. All rights reserved

The ME Bandwagon and other labels: Constructing the authentic case in talk about a controversial illness

This paper examines the discourse of morality surrounding ‘ME’ as a contested illness, looking at how GPs and ME group members differentiate between the category of ‘genuine ME sufferer’ and the ‘bandwagon’. ‘Jumping on the bandwagon’ is a metaphor commonly used to describe the activity of ‘following the crowd’ in order to gain an advantage. This discursive analysis shows how ‘bandwagon’ categories are constructed in contrast to the category of genuine sufferer. People who jump on the bandwagon are accused of matching their symptoms to media stereotypes, adopting trendy illnesses (‘fads’,) or using ‘tickets’ to avoid facing up to psychological illnesses. Both GPs and ME group members construct a differential moral ordering of physical and psychological illness categories, where the latter assumes a lesser status. The paper concludes that against a background of medical uncertainty and controversy, the ‘bandwagon’ and other derogatory labels function as contrast categories that work to establish the existence of ‘ME’ as a genuine illness