This thesis describes the development of metallic magnetic calorimeters (MMCs) for high resolution spectroscopy. MMCs are energy dispersive particle detectors based on the calorimetric principle which are typically operated at temperatures below 100 mK. The detectors make use of a paramagnetic temperature sensor to transform the temperature rise upon the absorption of a particle in the detector into a measurable magnetic flux change in a dc-SQUID. The application of MMCs for neutrino mass measurements and their advantages with respect to other approaches are discussed. In view of this application the development of an MMC optimized for β-endpoint spectroscopy on 187-rhenium is presented. A fully micro-fabricated X-ray detector is characterized and performs close to design values. Furthermore, a new technique to more efficiently couple rhenium absorbers mechanically and thermally to the sensor was developed and successfully tested. By employing a metallic contact, signal rise times faster than 5 μs could be observed with superconducting rhenium absorbers. In addition to the single pixel detectors, an alternative approach of reading out multiple pixels was developed in this work, too. Here, the individual absorbers have a different thermal coupling to only one temperature sensor resulting in a distribution of different pulse shapes. Straightforward position discrimination by means of rise time analysis is demonstrated for a four pixel MMC and a thermal model of the detector is provided. Unprecedented so far, an energy resolution of less than ∆E_FWHM < 5 eV for 5.9 keV X-rays was achieved across all absorbers.
The PreProcessor of the ATLAS Level-1 Calorimeter Trigger provides digital values of transverse energy in real-time to the subsequent object-finding processors. The input comprises more than 7000 analogue signals of reduced granularity from the calorimeters of the ATLAS detector. The Level-1 trigger decision must be verified. For this, the PreProcessor transmits copies of the real-time digital data to the Data Acquisition (DAQ) system. In addition, the PreProcessor system provides a standard VMEbus interface to the computing infrastructure of the experiment, on which configuration data is loaded and control or monitoring data are read out. A dedicated system that ensures both the transfer of event data to storage in ATLAS and the data transfer over the VME was implemented on the 124 modules of the PreProcessor system in the form of a "Readout Manager". The "Field Programmable Gate Array" (FPGA) is located on each module. The first part of this work describes the algorithms developed to meet the functionality of the Readout Manager. The second part deals with the tests that were carried out to ensure the proper functionality of the modules before they were installed at CERN in the ATLAS cavern.
The subject of this work is the setup of an experiment to study immersed quantum systems using bosonic 23Na and fermionic 6Li. Bose-Einstein condensation of 23Na has been achieved in two di erent magnetic trap con gurations, namely the plugged quadrupole trap and the cloverleaf trap. Both are compared with respect to their suitability for a two-species experiment using this particular isotopes. In such a mixture, it should be possible to investigate polarons, which are quasiparticles, emerging when one of components of the mixture has only a very rare concentration. Furthermore, a theoretical study of the polaron will be discussed. A mean- eld calculation has been carried out in order to simulate the impurity behavior in the presence of a large bosonic background gas.
CMOS - Based Peptide Arrays Peptide arrays are an important tool in proteomics and peptidomics, allowing a large number of peptides to be synthesized on a common support and exposed to a solution of target molecules in parallel. In particle-based synthesis, the amino acids for in situ synthesis of peptides are transported to synthesis loci in solid particles and released upon melting, allowing an increase in density over liquid-based systems. This thesis focuses on the development of application-specific high voltage integrated circuits for electrostatic deposition of charged amino acid particles and their integration into a combinatorial peptide synthesis system. Transfer of amino acid particles from the aerosol to synthesis loci on the chip surface was investigated for a pixel pitch between 45 µm and 100 µm, and compatibility between the chips, particle transfer and the poly(ethylene glycol)methacrylate - based surface modifi¬cations was established. The first combinatorial syntheses on CMOS chips were performed with over 16,000 distinct synthesis sites per chip, at a density of 10,000 spots per cm2, which is a 25-fold increase over the 400 spots per cm2 currently available on laser-printed glass slides. For FLAG and HA peptide epitopes, immonostaining showed regular spots of comparable signal intensity over the whole chip area.
Frequenzverdopplung (SHG) von Licht kann durch verschiedene wichtige Proteinstrukturen in biologischen Proben selbst hervorgerufen werden. Zu diesen zählen vor allem das extrazelluläre Matrixprotein Collagen und das Motorprotein Myosin in der quergestreiften Muskulatur. Mit Hilfe von Kurzpulslasern und Laser-Scanning Mikroskopie können die SHG Signale dazu genutzt werden, um diese Proteinstrukturen ohne den Zusatz externer Marker hochauflösend darzustellen. Das Hauptziel dieser Arbeit ist eine biomolekulare und physikalische Charakterisierung des SHG Signals von Muskelpräparaten und eine Diskussion von Anwendungsmöglichkeiten an der Haut im Kontext von Hautkrebs und Sklerodermie. Am Muskel wurde speziell die Orientierungsabhängigkeit des SHG Signals von der Polarisation des Lasers untersucht. Komplementär dazu wurden theoretische Modelle zur quantitativen Beschreibung und zum Verständnis der beobachteten Effekte entwickelt. Erstmals wurde hier auch ein Modell der Verteilung des elektrischen Feldes im Objektivfokus in die Berechnungen mit einbezogen. Das zentrale Ergebnis dieser Experimente ist, dass die SHG Polarisationsabhängigkeit im Muskel in den physiologischen Zuständen Relaxed und Rigor unterschiedlich ist. Auf diese Weise lässt sich also der funktionale molekulare Zustand der Myosinmoleküle aus der SHG Signalcharakteristik ablesen. An der Haut konnte durch SHG und Autofluoreszenz Signale die Struktur der obersten Hautschichten in vivo mit hoher Auflösung dreidimensional abgebildet werden. Die SHG Mikroskopie verspricht eine besondere Eignung als nicht-invasives Werkzeug zum Studium von Hauterkrankungen.
Vizinale Silizium-(111)-Oberflächen wurden als Substrat für das Wachstum sowohl von Blei-Nanodrähten als auch von atomaren Ketten aus Gold und Indium verwendet. Die Morphologie der Au-Atomketten wurde mittels Rastertunnelmikroskopie (STM) und Beugung hochenergetischer Elektronen (RHEED) untersucht. Die In-Ketten wurden mittels Infrarotspektroskopie mit Polarisation des elektrischen Feldes parallel und senkrecht zu den Drähten untersucht. Es wird gezeigt, dass die In-Ketten bei Raumtemperatur eine plasmonische Absorption entlang der Drähte, jedoch nicht senkrecht dazu aufweisen. Weiterhin zeigte sich beim Kühlen zur Temperatur flüssigen Stickstoffs ein Metall-Isolator-Übergang. Mit RHEED wurde dabei auch eine strukturelle Veränderung gefunden. Durch die mit Infrarotspektroskopie gefundenen Ergebnisse für die Blei-Nanodrähte ist es nun möglich, die durchschnittliche Länge von parallelen Nanodrähten durch die Kontrolle von vier experimentellen Parametern zu kontrollieren. Diese sind die Bleibedeckung, die Verdampfungsrate, die Substrattemperatur und die Oberflächenbeschaffenheit. Das System zeigt im Tieftemperaturbereich eine Verstärkuing der Absorption bei der Antennenfrequenz. Diese Beobachtung wird mit der Reduktion der Elektron-Phonon-Streuung infolge der tiefen Temperatur erklärt.
Interferometry is the most precise measurement technique known today. It is based on interference and therefore on the wave-like nature of the resources – photons or atoms – in the interferometer. As given by the laws of quantum mechanics the granular, particle-like features of the individually independent atoms or photons are responsible for the precision limit – the shot noise limit. However this “classical” bound is not fundamental and it is the aim of quantum metrology to overcome it by employing quantum correlations – entanglement – among the particles. We report on the realization of spin squeezed states suitable for atom interferometry based on two external modes of a Bose-Einstein condensate. We detect manybody entangled states which allow – in principle – for a precision gain of 35% over the shot noise limit in atom interferometry. We demonstrate a novel non-linear atom interferometer for Bose-Einstein condensates whose linear analog – the Ramsey interferometer – is used for the definition of the time standard. Within the non-linear interferometer we detect a large entangled state of 170 inseparable atoms. A measurement with this interferometer outperforms its ideal linear analog by 15% in phase estimation precision showing directly the feasibility of non-linear atom interferometry with Bose-Einstein condensates beyond “classical” precision limits.
Der noch gar nicht so richtig vergangene Winter hatte Eiseskälte mit Temperaturen von minus 20 Grad und mehr gebracht. Professor Christian Enss am Kirchhoffinstitut für Physik der Universität Heidelberg hat aber für diese Temperaturen nur ein Lächeln übrig. Er verfügt über ein Gerät, das den Weltrekord für die bis heute jemals erzielte tiefste Temperatur hält: Nur ein Millionenstel Grad über dem absoluten Nullpunkt von Minus 273,15 Grad.
The higher order and spatial organisation of the genome is closely related to gene’s transcriptional activity. With the numerous results reported in this area, little is known about the precise information of specific chromatin structure, especially the dynamic during physiological changes and tumorigenesis, in the well-preserved tissue sections. In this work, thin tissue cryosections (about 200 nm in thickness) from the mammary gland of transgenic mice were used to study the genome organisation during the tumorigenesis process. Stereological methods were used to estimate the three-dimensional genome structure from the two-dimensional nuclear profiles. It was found that the whole genome-wide chromatin condensation state varies significantly during the tumorigenesis process. The existence of the extremely large as well as the highly condensed nuclei in the mammary tumor cryosections indicates the unique situation of malignancy. The relative volume fraction of chromosome 11 in the nucleus becomes smaller in the tumorigenesis process, while the nuclear radial position of the chromosome stays the same in this process. The central position of chromosome 11 is in good agreement with the gene density related chromosome radial positioning theory. Besides, some preliminary studies regarding the nuclear position and the condensation state of the viral oncogene SV40Tag have been demonstrated. In conclusion, this work presents the first effort to investigate genome organisation during the tumorigenesis process combining fluorescent in situ hybridisation and tissue cryosections. The parameters of specific genome structure measured in this work are the most precise values one can get from tissue sections so far.