PMT Test Facility at MPIK Heidelberg and Double Chooz Super Vertical Slice

Proceedings supplement for conference poster at Neutrino 2010, Athens, Greece

Transit Time and Charge Correlations of Single Photoelectron Events in R7081 PMTs

During the calibration phase of the photomultiplier tubes (PMT) for the Double Chooz experiment the PMT response to light with single photoelectron (SPE) intensity was analysed. With our setup we were able to measure the combined transit time and charge response of the PMT and therefore we could deconstruct and analyse all physical effects having an influence on the PMT signal. Based on this analysis charge and time correlated probability density functions were developed to include the PMT response in a Monte Carlo simulation.Comment: minor changes by referee reques

Green fluorescent protein: applications in cell biology

AbstractThe green fluorescent protein (GFP) of Aequorea victoria is a unique in vivo reporter for monitoring dynamic processes in cells or organisms. As a fusion tag GFP can be used to localize proteins, to follow their movement or to study the dynamics of the subcellular compartments to which these proteins are targeted. Recent studies where GFP technology has revealed new insights regarding physiological activities of living cells are discussed

Transit Time and Charge Correlations of Single Photoelectron Events in R7081 PMTs

During the calibration phase of the photomultiplier tubes (PMT) for the Double Chooz experiment the PMT response to light with single photoelectron (SPE) intensity was analysed. With our setup we were able to measure the combined transit time and charge response of the PMT and therefore we could deconstruct and analyse all physical effects having an influence on the PMT signal. Based on this analysis charge and time correlated probability density functions were developed to include the PMT response in a Monte Carlo simulation.Comment: minor changes by referee reques

Afterpulse Measurements of R7081 Photomultipliers for the Double Chooz Experiment

We present the results of afterpulse measurements performed as qualification test for 473 inner detector photomultipliers of the Double Chooz experiment. The measurements include the determination of a total afterpulse occurrence probability as well as an average time distribution of these pulses. Additionally, more detailed measurements with different light sources and simultaneous charge and timing measurements were performed with a few photomultipliers to allow a more detailed understanding of the effect. The results of all measurements are presented and discussed

Detection of 133^{133}Xe from the Fukushima nuclear power plant in the upper troposphere above Germany

After the accident in the Japanese Fukushima Dai-ichi nuclear power plant in March 2011 large amounts of radioactivity were released and distributed in the atmosphere. Among them were also radioactive noble gas isotopes which can be used as tracers to test global atmospheric circulation models. This work presents unique measurements of the radionuclide $^{133}$Xe from Fukushima in the upper troposphere above Germany. The measurements involve air sampling in a research jet aircraft followed by chromatographic xenon extraction and ultra-low background gas counting with miniaturized proportional counters. With this technique a detection limit of the order of 100 $^{133}$Xe atoms in litre-scale air samples (corresponding to about 100 mBq/m$^3$) is achievable. Our results provide proof that the $^{133}$Xe-rich ground level air layer from Fukushima was lifted up to the tropopause and distributed hemispherically. Moreover, comparisons with ground level air measurements indicate that the arrival of the radioactive plume at high altitude over Germany occurred several days before the ground level plume.Comment: 8 pages, 5 figure

Datenanalyse des Sonnenneutrinoexperiments GALLEX

Datenanalyse des Sonnenneutrinoexperiments GALLEX Das GALLEX-Experiment hat zwischen 1991 und 1997 den Fluss solarer Neutrinos oberhalb einer Energie von 233 keV gemessen. Gegen Ende von GALLEX und während des Nachfolgeexperiments GNO wurden einige der verwendeten Zählrohre neu und mit höherer Genauigkeit geeicht. In den veröffentlichten Ergebnissen wurden diese Werte jedoch noch nicht berücksichtigt. Ferner beruht die bisherige Datenanalyse auf einer relativ einfachen Methode der Ereignisauswahl, die nur einen geringen Teil der in den aufgezeichneten Signalen enthaltenen Informationen verwendet. Ziel dieser Arbeit ist es, durch eine neue Pulsformanalyse den vollständigen Informationsgehalt zu nutzen, um damit eine bestmögliche Auswertung von GALLEX und der dazu gehörenden Quellexperimente unter Berücksichtigung der aktuellen Eichergebnisse durchzuführen. Die existierenden Programme zur GALLEX-Datenanalyse basieren auf einem veralteten Betriebssystem und konnten nicht auf moderne Betriebssysteme übertragen werden. Deshalb wurden alle benötigten Routinen zum Einlesen der Rohdaten, Analysieren der Ereignisse und Auswertung mit der Maximum-Likelihood-Methode neu programmiert. Die Entwicklung einer Pulsformanalyse wird durch die Überlagerung der Daten durch Störungen erheblich erschwert. Die in dieser Arbeit vorgestelle Methode beruht auf einer Entfaltung der Pulse durch ein theoretisches Mustersignal, wodurch man Informationen über die im Zählrohr vorhandene Ladungsverteilung erhält. Diese Methode erweist sich als ausreichend robust gegenüber Störeinflüssen und ermöglicht eine verbesserte Untergrunddiskriminierung. Die auf der Pulsformanalyse basierende Auswertung von GALLEX ergibt [ 73.1 (+6.1) (-6.0) (stat.) (+3.7)(-4.1)(syst.) ] SNU, wodurch der Fehler im Vergleich zu dem bisher veröffentlichten Ergebnis leicht reduziert werden konnte. Ein weiterer Teil der vorliegenden Arbeit ergibt sich aus der Mitarbeit am BNO-LNGS-Experiment im Gran Sasso Labor

Assembly, trafficking and function of gamma-secretase

gamma-Secretase catalyzes the final cleavage of the beta-amyloid precursor protein to generate amyloid-beta peptide, the principal component of amyloid plaques in the brains of patients suffering from Alzheimer's disease. Here, we review the identification of gamma-secretase as a protease complex and its assembly and trafficking to its site(s) of cellular function. In reconstitution experiments, gamma-secretase was found to be composed of four integral membrane proteins, presenilin (PS), nicastrin (NCT), PEN-2 and APH-1 that are essential and sufficient for gamma-secretase activity. PS, which serves as a catalytic subunit of gamma-secretase, was identified as a prototypic member of novel aspartyl proteases of the GxGD type. In human cells, gamma-secretase could be further defined as a heterogeneous activity consisting of distinct complexes that are composed of PS1 or PS2 and APH-1a or APH-1b homologues together with NCT and PEN-2. Using green fluorescent protein as a reporter we localized PS and gamma-secretase activity at the plasma membrane and endosomes. Investigation of gamma-secretase complex assembly in knockdown and knockout cells of the individual subunits allowed us to develop a model of complex assembly in which NCT and APH-1 first stabilize PS before PEN-2 assembles as the last component. Furthermore, we could map domains in PS and PEN-2 that govern assembly and trafficking of the complex. Finally, Rer1 was identified as a PEN-2-binding protein that serves a role as an auxiliary factor for gamma-secretase complex assembly. Copyright (c) 2006 S. Karger AG, Basel

Qualification Tests of 474 Photomultiplier Tubes for the Inner Detector of the Double Chooz Experiment

The hemispherical 10" photomultiplier tube (PMT) R7081 from Hamamatsu Photonics K.K. (HPK) is used in various experiments in particle and astroparticle physics. We describe the test and calibration of 474 PMTs for the reactor antineutrino experiment Double Chooz. The unique test setup at Max-Planck-Institut f\"ur Kernphysik Heidelberg (MPIK) allows one to calibrate 30 PMTs simultaneously and to characterize the single photo electron response, transit time spread, linear behaviour and saturation effects, photon detection efficiency and high voltage calibration