Th.--Sci. phys.--Nancy--I.N.P.L., 1985.

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Introduction Krypton-81m is a radioactive gas with a half-life of 13 s, and found to be useful in many applications in nuclear medicine, particularly for lung perfusion studies and ventilations. Due to high demands for 81mKr, we have developed an automated Krypton system to be installed in one of the Cyclotron’s beamlines at King Faisal Specialist Hospital and Research Centre (KFSH&RC) and to deliver large activity of the radioactive gas. Material and Methods The effective cross section of producing 81Rb is between 15 and 30 MeV [1]. Therefore, range and stopping power of the effective cross section were calculated with respect to gas density of 0.0185 g/cm3. This value is equivalent to gas density at 5.0 bars at room temperature. SRIM calculations resulted in a range of 589 mm. However, due to limitation in fabricating such long target chamber, the target length is chosen to be 250 mm. Attached to the end of target body is a special water circulating flange ‘back-pool’, its purpose is to absorb the rest of the energy and protons Bragg peak. The target body is made of Aluminum with the inner part being electroplated with nickel. The target body is of conical shape. The target body is electrically isolated from other parts to allow accurate beam current reading. Full access to the target loading/unloading steps is made through touch screen technology (FIG. 2) for user access. Additionally, the target control system is designed to be protected through chain of interlock steps. The production cycle of 81Rb is explained as follow. Target is evacuated to approximately 10−3 mbar before being filled with natKr at pressure of 5 bars. At the end of bombardment, recovery of natKr is done via cryogenic vessel. Finally, the radioactivity is washed with KCl and pushed to Hotcells through the nitrogen gas for chemistry processing. Irradiation time was approximately 30 min. Results and Conclusion Experimental results clearly showed a fairly good activity of 81mKr as shown in TABLE 1. In all experiments, the radionuclidic purity of 81mKr was above 99.59%. 79mKr and 79Kr were also measured with a percentage of, respectively, 0.34 and 0.07 %. Special attention has to be drawn to last experiment where the yield significantly in-creased, due to the period where the KCl left inside the target (10 min) before pushing the solution to the Hotcells

The question of the absolute mass scale of neutrinos is of particular interest for particle physics, astrophysics, and cosmology. The KATRIN experiment (KArlsruhe TRItium Neutrino experiment) aims to address the effective electron antineutrino mass from the shape of the tritium β-spectrum with an unprecedented sensitivity of 0.2 eV/c2 . One of the major systematic effects concerns the experimental energy scale, which has to be stable at the level of only a few parts in a million. For its calibration and monitoring the monoener- getic electrons emitted in the internal conversion of γ-transition of the metastable isotope 83m Kr will be extensively applied. The aim of this thesis is to address the problem of KA- TRIN energy scale distortions and its monitoring in detail. The source of electrons based on 83m Kr embedded in a solid as well as the source based on gaseous 83m Kr are studied. Based on the experimental results an approach for the continuous stability monitoring is proposed. 1

This work describes a study of the gamma rays and beta particles emitted during the decay of the 33-second fission product Krypton-90. Procedures for the analysis of gamma, gamma-gamma coincidence, beta and beta-gamma coincidence experiments are discussed. The application of these analyses to the short-lived Krypton-90 activity yields the prominent features of this decay. The total energy release of this decay was found to be 4.56 ± 0.02MeV, in agreement with beta systematics. A level scheme for the daughter, Rubidium-90, is proposed. / Thesis / Doctor of Philosophy (PhD)

No description available.

Diese Dissertation widmet sich der spektroskopischen Untersuchung verschiedener Aspekte der Strahlungsemis\-sion hochgeladener Krypton-Ionen mit Relevanz für die Fusionsforschung. Die Experimente hierzu erfolgten an der Berliner Elektronenstrahl-Ionenfalle (EBIT). Der erste Teil der Arbeit hat die Messung kanalspezifischer Wirkungsquerschnitte für die dielektronische Rekombination (DR) der KL$n$-Resonanzserie ($n$=2, \ldots, 5) von Helium- bis Kohlenstoff-ähnlichen Kr-Ionen ($\mbox{Kr}^{(34\, \ldots\,30)+}$) zum Inhalt, die relativ zum Wirkungsquerschnitt der nichtresonanten strahlenden Rekombination (RR) bestimmt wurden. Die Anpassung der Anregungskurven durch eine Modellfunktion aus berechneten Resonanzst ärken ermöglichte den Vergleich mit theoretischen DR-Wirkungsquerschnitten. Es zeigt sich, dass Vorhersagen des HULLAC-Atomstrukturcodes für die Resonanz\-st"ar\-ken der Kr-Ionen durch das Experiment innerhalb der Me"sunsicherheiten best"a\-tigt werden. Darüber hinaus wurde auch die Relaxation der einfach angeregten Ionen nach erfolgtem DR-Stabilisierungsübergang analysiert. Die zur Auswertung der DR-Anre\-gungs\-kurven angewandte Technik eröffnet gleichzeitig eine spektroskopische Methode für die Bestimmung der relativen Konzentration hochgeladener Ionen in EBIT. Die Messung der Strahlungskühlungsrate von Krypton, die den zweiten inhaltlichen Schwerpunkt der Dissertation darstellt, wäre ohne diese in situ Diagnostik der Ladungbilanz nicht möglich gewesen. Hier wurde die Ionenfalle so eingestellt, dass sich eine Ladungsverteilung herausbildet, die dem Ionisationsgleichgewicht eines Plasmas bei einer Temperatur von etwa $5\;\mbox{keV}$ entspricht. Die Bestimmung der Strahlungsk"uhlungsrate profitierte von dem Potential einer EBIT, die gefangenen Ionen mit Elektronenenergien aus einem weiten Bereich abzutasten und einzelne Strahlunsprozesse selektiv anzuregen. Die Röntgenemission verschiedener Strahlungskanäle, wie Bremsstrahlung, strahlende Rekombination, dielektronische Rekombination und Linienstrahlung nach direkter Anregung wurde separat erfaßt. Hieraus konnten erstmals kanalspezifische Strahlungskühlungsraten bestimmt werden. Es stellte sich heraus, dass der dominante Beitrag zur Strahlungskühlungsrate durch die direkt angeregte Linienstr ahlung des L-Schalen-Spektrums zustande kommt, die etwa 75\% der gesamten Verlustleistung ausmacht. Beim Vergleich der totalen Strahlungsverlustleistung mit Vorhersagen der Theorie sind Abweichungen festzustellen. Die berechneten Werte sind je nach Modell um einen Faktor 1.5 - 2.0 kleiner als das Ergebnis der Messung. Dieser Unterschied liegt außerhalb der experimentellen Unsicherheit von maximal 30\%. / This thesis deals with the spectroscopic investigation of various aspects of the x-ray emission of highly charged krypton ions with relevance for fusion research. The experiments have been performed at the Berlin electron beam ion trap (EBIT). One part of the work was devoted to the measurement of channel-specific cross sections for dielectronic recombination (DR) via the KL$n$ ($n$=2, \ldots, 5) resonance series of He- to C-like krypton ions ($\mbox{Kr}^{(34\, \ldots\,30)+}$). The DR cross sections were determined relative to the cross section for non-resonant radiative recombination (RR). A fit procedure was used to compare the measured data with theoretical calculations. Predictions of the HULLAC atomic structure code are confirmed within the experimental uncertainties. Additionally, the radiative relaxation mechanism following the stabilizing transition in the DR process was analyzed. The approach used to obtain the DR excitation function opens up a spectroscopic method to determine the relative abundance of the highly charged ions in the trap. This in situ diagnostic of the charge state balance allowed for the measurement of the radiative cooling rates of krypton being the second focus of the thesis. For this purpose EBIT was tuned to a charge state distribution approaching the ionization balance of a plasma at a temperature of about $5\;\mbox{keV}$. EBIT's capability to sample a wide range of electron-beam energies and distinguish between different radiation channels was utilized to determine the cooling rate. The x-ray emission from the various plasma radiation channels, like bremsstrahlung, radiative recombination, dielectronic recombination, and line radiation following electron-impact excitation was analyzed. For the first time, channel-specific cooling rates could be obtained from these data. It was found, that the dominant contribution to the cooling rate is made up by the directly excited x-rays of the L-shell spectra of krypton, producing more than 75\% of the total radiation loss. A difference with theoretical calculations is noted for the total cooling rate. The predicted values are lower by a factor of 1.5 - 2.0, depending on the theoretical model. This discrepancy is clearly beyond the experimental uncertainty of 30\% at maximum.

Ce travail portant sur l’imagerie tomodensitométrique double énergie de la ventilation a permis d’établir les points suivants :• L’irradiation d’un examen thoracique acquis en double énergie peut être abaissée à celle d’un examen acquis en simple énergie, grâce à l’utilisation de la reconstruction itérative.• L’analyse qualitative du parenchyme pulmonaire en imagerie double énergie doit se faire sur les reconstructions monochromatiques 50-55keV.• L’atténuation théorique maximale du Krypton dosé à 80% est modérément inférieure à celle du Xénon dosé à 30%.• La décomposition des matériaux en tomodensitométrie double énergie simple source est possible sur le Xénon et le Krypton.• L’utilisation d’un produit de contraste gazeux n’a pas d’impact significatif sur le Workflow en routine clinique.• Le Krypton est cliniquement sûr à la dose de 80%.• La technique ne permet pas de détecter le Krypton au-delà de la carène de manière satisfaisante, probablement en raison d’une concentration en gaz atteinte insuffisante.• Le recalage élastique augmente les performances diagnostiques de détection de la bronchiolite oblitérante par rapport à une simple analyse visuelle. / This work on dual energy CT ventilation imaging has established the following:• The radiation dose of a dual energy chest CT can be reduced to that of a single energy examination through the use of iterative reconstruction.• The qualitative analysis of the lung parenchyma should be made on the 50-55keV monochromatic reconstructions.• The maximum theoretical attenuation obtained with 80% Krypton is moderately inferior to that of 30% Xenon.• Dual energy material decomposition of Xenon and Krypton is efficient with a single source technique.• The use of a gaseous contrast agent has no significant impact on the workflow in the clinical setting.• The Krypton is safe at 80% concentration.• The technique does not satisfactorily detect Krypton beyond the carina, probably due to insufficient gas concentration.• The elastic registration increases the diagnostic performance of bronchiolitis obliterans syndrome detection, compared to a simple visual analysis.

This thesis presents a series of electron impact ionization measurements on the gas phase targets of argon and krypton. The (e,2e) coincidence technique has been employed to measure the triple differential cross section (TDCS) using a new coincidence spectrometer designed to operate in the low energy regime (2 to 5 times the ionization energy) and in the coplanar geometry. The spectrometer is a conventional device utilizing a non-energy selected electron gun and two 1800 hemispherical electron analysers fitted with channel electron multipliers for detection of the outgoing electrons. A series of TDCS measurements were performed on the 3s inner-valence and 3p valence orbitals of argon employing coplanar asymmetric kinematics. Measurements for both orbitals were performed at an incident energy of 113.5 eV, ejected energies of 10, 7.5, 5 and 2 eV and a scattering angle of -15°. The energy of the scattered electron in each case was chosen to satis~' energy conservation and is dependent on the ionization energies of the different orbitals. The experimental cross sections are compared to theoretical TDCS calculations using the distorted wave Born approximation (DWBA) and variations of the DWBA in an attempt to investigate the role that post collisional interaction (PCI), polarization and electron exchange play in describing the TDCS in the low energy regime. To further extend this analysis, a series of TDCS measurements were performed on the 3s and 4s. orbitals of argon and krypton, respectively, employing coplanar symmetric kinematics. Measurements were performed for the 3s orbital at outgoing energies of 50, 20, 10 and 4eV and for the 4s orbital at outgoing energies of 85, 50, 20 and 10 eV. The kinematics were chosen to coincide with several of the (e,2e) measurements made in the same geometry on the 3p orbital of argon by Rouvellou et al (1998). The experimental results were again compared to a DWBA calculation and similar variations to those employed for the asymmetric measurements.