Charakterisierung der Ferninfrarot-Detektoren der HERSCHEL/PACS-Spektrometerkamera

Im Rahmen der vorliegenden Dissertation wurden die schwach gedrückten Ferninfrarot-Ge:Ga-Flug- und Flugersatzmodule für die PACS-Spektrometerkamera des HERSCHEL-Weltraumobservatoriums unter repräsentativen Bedingungen charakterisiert und kalibriert. Die Kalibrierung der Detektoren am Boden ist für die Gesamtkalibrierung und das Verständnis des Detektorverhaltens im Weltraum wichtig. Eine genaue absolute Kalibrierung ist unter anderem erforderlich, um genaue Farbtemperaturen und Staubmassen abzuleiten, die z.B. in Modellierungen von Sternentstehungsgebieten eingehen. Die experimentellen und theoretischen Untersuchungen des Antwortverhaltens einer flugrepräsentativen Detektorzeile auf kleine Änderung der Beleuchtungsintensität deuten darauf hin, dass Signaltransienten bei PACS aufgrund des hohen Photonenuntergrunds des ~80 K-warmen Hauptspiegels aller Wahrscheinlichkeit nach keine Rolle spielen werden. Die Auswirkung kosmischer Strahlung auf die Ge:Ga-Detektoren wurde anhand von Replikadetektoren und unter Verwendung einer 137Cs-Strahlungsquelle untersucht. In Abhängigkeit der eingestrahlten Energiedosisleistung, des FIR-Untergrundflusses und der Detektorparameter stellt sich ein Gleichgewichtszustand zwischen Bestrahlungseffekten durch die ionisierende Strahlung und Selbstrelaxation aufgrund des hohen IR-Untergrundflusses ein. Unter L2-repräsentativen Umgebungsbedingungen sowie mit stark reduzierter Vorspannung und geeigneter Datenanalysesoftware besitzen die schwach gedrückten Detektoren in diesem Zustand im Mittel eine um ~30% höhere Empfindlichkeit als ohne Bestrahlung. Die Eichung der Detektoren ist dabei bis auf 1.5% stabil und die Reproduzierbarkeit beträgt ~6%. Auf Basis der im Labor erzielten Ergebnisse wurde unter anderem die Modulreihenfolge für die Integration der einzelnen Detektormodule in die Spektrometerkamera definiert und ein Programm zur Inbetriebnahme der Ge:Ga-Detektoren einschließlich detaillierter Prozeduren zur sukzessiven Feinabstimmung der Detektorparameter sowie Strategien zur Kalibrierung und für den Betrieb der Detektoren im Weltraum entwickelt. Unter Einsatz von optimierten Betriebsparametern wird die erreichbare photometrische Genauigkeit der Spektrometerkamera beim Betrieb auf dem Stromempfindlichkeitsplateau ohne Ausheilung temporärer Strahlungsschäden auf ~12% geschätzt. Die im Rahmen dieser Dissertation entwickelte Betriebsstrategie wurde bei der Inbetriebnahme der Ge:Ga-Detektoren im Weltraum verifiziert und die optimalen Betriebsparameter ähneln den Ergebnissen der Labortests

VADER - A Satellite Mission Concept For High Precision Dark Energy Studies

We present a satellite mission concept to measure the dark energy equation of state parameter w with percent-level precision. The Very Ambitious Dark Energy Research satellite (VADER) is a multi-wavelength survey mission joining X-ray, optical, and IR instruments for a simultaneous spectral coverage from 4microns (0.3eV) to 10keV over a field of view (FoV) of 1 square degree. VADER combines several clean methods for dark energy studies, the baryonic acoustic oscillations in the galaxy and galaxy cluster power spectrum and weak lensing, for a joint analysis over an unrivalled survey volume. The payload consists of two XMM-like X-ray telescopes with an effective area of 2,800cm^2 at 1.5keV and state-of-the-art wide field DEPFET pixel detectors (0.1-10keV) in a curved focal plane configuration to extend the FoV. The X-ray telescopes are complemented by a 1.5m optical/IR telescope with 8 instruments for simultaneous coverage of the same FoV from 0.3 to 4 microns. The 8 dichroic-separated bands (u,g,r,z,J,H,K,L) provide accurate photometric galaxy redshifts, whereas the diffraction-limited resolution of the central z-band allows precise shape measurements for cosmic shear analysis. The 5 year VADER survey will cover a contiguous sky area of 3,500 square degrees to a depth of z~2 and will yield accurate photometric redshifts and multi-wavelength object parameters for about 175,000 galaxy clusters, one billion galaxies, and 5 million AGN. VADER will not only provide unprecedented constraints on the nature of dark energy, but will additionally extend and trigger a multitude of cosmic evolution studies to very large (>10 Gyrs) look-back times.Comment: 14 pages, 7 figures, accepted for publication in the SPIE conference proceeding

Risk of contralateral second primary breast cancer according to hormone receptor status in Germany

Introduction: Hormone receptor (HR) status has become an established target in treatment strategies of breast cancer. Population-based estimates of contralateral breast cancer (CBC) incidence by HR subtype in particular are limited. The aim of this study was to provide detailed data on CBC incidence for Germany. Methods: Invasive breast cancer data were extracted on 49,804 women yielding 594 second primaries from the cancer registries of the Federal States of Brandenburg and Saarland and the area of Munich for the period from 1998 to 2007. Multiple imputation was used on missing values for HR status. We estimated standardized incidence ratios (SIRs) with 95% confidence intervals (95% CIs). Results: SIR estimates of CBC among women diagnosed with an invasive first primary breast cancer (FBC) of any HR subtype ranged from 1.0 to 1.5 in the three registries. Pooling three registries' data, the SIR of HR-positive CBC was 0.7 (95% CI: 0.6 to 0.8) among women with HR-positive FBC. For those women with HR-negative FBC, the SIR of HR-negative CBC was 8.9 (95% CI: 7.1 to 11.1). Among women with FBC diagnosed before the age of 50 years, incidence of CBC was increased, especially for HR-negative FBC (SIR: 9.2; 95% CI: 7.1 to 11.9). Conclusions: HR status of the first primary and age at first diagnosis is relevant for predicting risk of CBC. Particularly, patients with HR-negative FBC had elevated risks

Risk of contralateral second primary breast cancer according to hormone receptor status in Germany

Introduction: Hormone receptor (HR) status has become an established target in treatment strategies of breast cancer. Population-based estimates of contralateral breast cancer (CBC) incidence by HR subtype in particular are limited. The aim of this study was to provide detailed data on CBC incidence for Germany. Methods: Invasive breast cancer data were extracted on 49,804 women yielding 594 second primaries from the cancer registries of the Federal States of Brandenburg and Saarland and the area of Munich for the period from 1998 to 2007. Multiple imputation was used on missing values for HR status. We estimated standardized incidence ratios (SIRs) with 95% confidence intervals (95% CIs). Results: SIR estimates of CBC among women diagnosed with an invasive first primary breast cancer (FBC) of any HR subtype ranged from 1.0 to 1.5 in the three registries. Pooling three registries' data, the SIR of HR-positive CBC was 0.7 (95% CI: 0.6 to 0.8) among women with HR-positive FBC. For those women with HR-negative FBC, the SIR of HR-negative CBC was 8.9 (95% CI: 7.1 to 11.1). Among women with FBC diagnosed before the age of 50 years, incidence of CBC was increased, especially for HR-negative FBC (SIR: 9.2; 95% CI: 7.1 to 11.9). Conclusions: HR status of the first primary and age at first diagnosis is relevant for predicting risk of CBC. Particularly, patients with HR-negative FBC had elevated risks

Cold performance tests of blocked-impurity-band Si:As detectors developed for DARWIN

We report first results of laboratory tests of Si:As blocked-impurity-band (BIB) mid-infrared (4 to 28 um) detectors developed by IMEC. These prototypes feature 88 pixels hybridized on an integrated cryogenic readout electronics (CRE). They were developed as part of a technology demonstration program for the future DARWIN mission. In order to be able to separate detector and readout effects, a custom build TIA circuitry was used to characterize additional single pixel detectors. We used a newly designed test setup at the MPIA to determine the relative spectral response, the quantum efficiency, and the dark current. All these properties were measured as a function of operating temperature and detector bias. In addition the effects of ionizing radiation on the detector were studied. For determining the relative spectral response we used a dual-grating monochromator and a bolometer with known response that was operated in parallel to the Si:As detectors. The quantum efficiency was measured by using a custom-build high-precision vacuum black body together with cold (T ~ 4 K) filters of known (measured) transmission.Comment: 11 pages, 8 figures, to appear in "High Energy, Optical, and Infrared Detectors for Astronomy" SPIE conference Proc. 7021, Marseille, 23-28 June 200

Preparing Herschel's commissioning phase: Ge:Ga detector tuning

The Photodetector Array Camera and Spectrometer (Pacs) instrument aboard the Herschel space observatory contains an integral field spectrometer with two camera channels which consist of 25 linear arrays of 16 stressed Gallium doped Germanium crystals (Ge:Ga) each. The space radiation environment induces changes in the detector performance. Therefore, testing the Ge:Ga detectors under space radiation environment during the commissioning phase (CP) is important for optimization of later detector operation in orbit. The test program for Ge:Ga detector tuning during this phase has been designed according to findings obtained in laboratory experiments: Protons as well as a 137Cs-gamma-source have been used to simulate the space radiation environment and to induce the radiation impacts on the photoconductor arrays. From comparison of the performance of the detectors during CP versus laboratory tests the best strategy for operating the detectors during scientific observations will be derived. This includes annealing, proposals for on-board data reduction algorithms and the best estimated strategy for well-calibrated scientific measurements