Experimental demonstration of novel beam characterization using a polarizable X-band transverse deflection structure.

The PolariX TDS (Polarizable X-Band Transverse Deflection Structure) is an innovative TDS-design operating in the X-band frequency-range. The design gives full control of the streaking plane, which can be tuned in order to characterize the projections of the beam distribution onto arbitrary transverse axes. This novel feature opens up new opportunities for detailed characterization of the electron beam. In this paper we present first measurements of the Polarix TDS at the FLASHForward beamline at DESY, including three-dimensional reconstruction of the charge-density distribution of the bunch and slice emittance measurements in both transverse directions. The experimental results open the path toward novel and more extensive beam characterization in the direction of multi-dimensional-beam-phase-space reconstruction.

Intrinsic emittance reduction of an electron beam from metal photocathodes.

Electron beams in modern linear accelerators are now becoming limited in brightness by the intrinsic emittance of the photocathode electron source. Therefore it becomes important for large scale facilities such as free electron lasers to reduce this fundamental limit. In this Letter we present measurements of the intrinsic emittance for different laser wavelength (from 261 to 282 nm) and for different photocathode materials such as Mo, Nb, Al, Cu. Values as low as 0.41±0.03 mm·mrad/mm laser spot size (rms) were measured for a copper photocathode illuminated with a 282 nm laser wavelength. The key element for emittance reduction is a uv laser system which allows adjustment of the laser photon energy to match the effective work function of the cathode material and to emit photoelectrons with a lower initial kinetic energy. The quantum efficiency over the explored wavelength range varies by less than a factor of 3.

Frequency and temperature dependence of electrical breakdown at 21, 30, and 39 GHz.

A TeV-range e(+)e(-) linear collider has emerged as one of the most promising candidates to extend the high energy frontier of experimental elementary particle physics. A high accelerating gradient for such a collider is desirable to limit its overall length. Accelerating gradient is mainly limited by electrical breakdown, and it has been generally assumed that this limit increases with increasing frequency for normal-conducting accelerating structures. Since the choice of frequency has a profound influence on the design of a linear collider, the frequency dependence of breakdown has been measured using six exactly scaled single-cell cavities at 21, 30, and 39 GHz. The influence of temperature on breakdown behavior was also investigated. The maximum obtainable surface fields were found to be in the range of 300 to 400 MV/m for copper, with no significant dependence on either frequency or temperature.

[Fiberscopic obliteration of esophageal varices (author's transl)]. / Fiberendoskopische Verödung von Oesophagusvaricen.

We are reporting our 2 years experience in the fiberscopic sclerotherapy of esophageal varices. 170 patients from 15-83 years of age were treated (61 females and 109 males), the majority being around 50 years of age. In 162 cases, the cause of the portal hypertension was cirrhosis of the liver and in 8 cases thrombosis of the splenic or portal vein. 47 patients were treated during acute bleeding, 101 in the interval, and 22 prophylactically. Using the modified intravascular technique, most varices could be sclerosed after a maximum of three treatments. In 83%, acute hemorrhages were stopped. The hospital mortality amounted to 30%, while in the interval group only it was 5%. None of the prophylactically treated patients died during their stay in hospital. The mortality after an average of 11.2 months amounted to 11.8%: The main cause was liver failure. Bleeding reoccurred in 11.2% and resulted in death in every fifth case. The most common complication, namely stenosis, arose in 16 cases and 4 of these necessitated dilation therapy. Esophagothoracic fistulae occurred in 2 cases and could be cured by siphon drainage. The rate of complication amounted to 10.6%, without any lethal outcome.

[Corelations between thrombocyte count, clinical diagnosis, and liver pathology in chronic liver diseases]. / Beziehungen zwischen Thrombozytenzahl, klinischer Diagnose und histologischem Leberbefund bei chronisch Leberkranken

In 1488 cases of chronic liver disease thrombocyte content of peripheral blood, clinical diagnosis and histologic findings of the liver biopsy were correlated. Ranging from fatty infiltration to fatty cirrhosis or from slightly active chronic hepatitis to active postnecrotic cirrhosis, according to the extent of the liver injury a significant decrease of thrombocyte-count was evaluated. In case of non-active liver disease and posthepatitic status a thrombocytopenia also could be found. Cirrhotic transformation or proliferation of the connective tissue mainly in the periportal fields and inflammatory activity showed a significant correlation to the frequency of a thrombocyte decrease. A pathogenetic relation is ascribed to an increased thrombocyte storage in the spleen depending on the extent of the liver injury and the alteration of the portal blood stream up to a portal hypertension. Our results indicate such correlations of liver injury, portal pressure and platelet-pooling to thrombocyte-count even if the causal dependency cannot be proved.

[Thrombocytopenia in hepatitis-B-antigenemia (author's transl)]. / Thrombozytopenie bei Hepatitis BS-Antigenämie

Determination of hepatitis-B-antigen and thrombocytes in 1488 cases of liver diseases, 173 of whom had been treated with immunsuppressive drugs. There was no significant relation between hepatitis-B-antigenemia and thrombocyte-count, nor could an influence of the immunsuppressive therapy be evaluated. The thrombocyte-count was correlated with high significance only to the degree of the liver injury.