Berlin, Techn. Univ., Diss., 2002. / Computerdatei im Fernzugriff.

Techn. Universiẗat, Diss., 2000--Berlin.

Universiẗat, Diss., 2007--Würzburg. / Erscheinungsjahr an der Haupttitelstelle: 2006.

Wir studieren die Produktion und den Nachweis von Selektronen mit Massen jenseits der Schwelle zur Paarerzeugung an künftigen Linearbeschleunigern mit Schwerpunktsenergien von 500 GeV und 800 GeV. Hierzu betrachten wir die Produktion von linken und rechten Selektronen in Assoziation mit dem jeweils leichtesten Neutralino oder Chargino durch Elektron-Elektron-, Elektron-Positron- und Elektron-Photon-Streuung im Rahmen des MSSM. Die Produktion durch Elektron-Elektron-Streuung untersuchen wir zusätzlich in zwei erweiterten Modellen, dem NMSSM und einem E6-Modell mit einem zusätzlichen U(1)-Eichfaktor. / We investigate the production and the decay of selectrons with masses beyond the threshold for pair production at future linear colliders with center-of-mass energies of 500 GeV and 800 GeV. For this we study the production of left and right selectrons in association with the lightest neutralino or chargino, respectively, via electron-electron, electron-positron and electron-photon scattering in the framework of the MSSM. Furthermore we analyse the production via electron-electron scattering in two extended models, the NMSSM and an E6-model with an additional U(1) gauge factor.

Techn. Universiẗat, Diss., 2002--Berlin.

Würzburg, University, Diss., 2008.

The radiation source ELBE is a scientific user facility able to generate electromagnetic radiation as well as beams of secondary particles. The figure below shows the layout of the facility. ELBE is based on a superconducting electron linac. The linac consists of two accelerating modules and uses TESLA type nine-cell niobium cavities, two cavities in each module. The cavities were developed at DESY in the framework of the TESLA linear collider project and the X-ray free electron laser (FEL) project. The ELBE linac is designed to operate with an accelerating field gradient of 10 MV/m so that the maximum design electron beam energy at the exit of the second module is 40 MeV. The essential difference of the ELBE linac from the future TESLA and X-ray FEL linacs is that ELBE operates in the continuous wave (CW) mode. ELBE delivers an electron beam with an average current of up to 1 mA. The electron source is a DC thermionic triode delivering beam with energy of 250 keV. The gun beam quality predefines the accelerated beam quality. One application of the electron beam is the generation of bremsstrahlung in the MeV energy range. The bremsstrahlung is used for nuclear spectroscopy experiments. Another application of the electron beam is the generation of quasi-monochromatic X-rays via channeling radiation in a single crystal. Thus X-rays with an energy from 10 keV through 100 keV can be generated. The channeling radiation is used for radio-biological and bio-medical experiments. In the future the ELBE electron beam will be used to produce monoenergetic positrons for material research. One more future application of the beam is the production of neutrons by bremsstrahlung via reactions. The neutrons will be used for material research oriented toward construction of future nuclear fusion reactors. In the author’s opinion, the most exciting and elegant application of the electron beam at ELBE is the infrared FEL. There are two FELs planned to run simultaneously at ELBE. The first one, with an undulator period of 27 mm, is going to operate in the wavelength range from 3 µm through 30 µm. The second one is in the design stage only but it will be built to work at longer wavelengths from 25 µm to 150 µm where the FEL has no competition from conventional quantum lasers. While an infrared FEL makes possible a great variety of experiments it is the device most sensitive to the electron beam quality. This dissertation is dedicated to the development of beam instrumentation and the measurement of electron beam parameters at ELBE. - In Chapter #1 we review fundamentals of FEL operation, discuss the importance of the electron beam quality for the FEL and lay down the requirements imposed by the FEL on the electron beam parameters. - Chapter #2 describes measurements of the transverse emittance we did at ELBE including an explanation of the experimental methods and the measurement error analysis. The transverse emittance was measured with the multislit method in the injector where the beam is space charge dominated. The transverse emittance of the accelerated beam was measured with the quadrupole scan method since the beam is emittance dominated. - Measurements of the electron bunch length, which is in the picosecond range, are described in Chapter #3. The bunch length was estimated from a frequency domain fit of a specially constructed analytical function to the measured power spectrum of the bunch. The power spectrum was obtained as a Fourier transform of the measured autocorrelation function of the coherent transition radiation (CTR). The CTR autocorrelation function was measured with the help of a Martin-Puplett interferometer. - A system of beam position monitors was designed, built, and commissioned in the framework of this effort. The design of our stripline BPM, the corresponding electronics and software is described in Chapter #4 along with the system performance as measured with the ELBE beam.

The radiation source ELBE is a scientific user facility able to generate electromagnetic radiation as well as beams of secondary particles. The figure below shows the layout of the facility. ELBE is based on a superconducting electron linac. The linac consists of two accelerating modules and uses TESLA type nine-cell niobium cavities, two cavities in each module. The cavities were developed at DESY in the framework of the TESLA linear collider project and the X-ray free electron laser (FEL) project. The ELBE linac is designed to operate with an accelerating field gradient of 10 MV/m so that the maximum design electron beam energy at the exit of the second module is 40 MeV. The essential difference of the ELBE linac from the future TESLA and X-ray FEL linacs is that ELBE operates in the continuous wave (CW) mode. ELBE delivers an electron beam with an average current of up to 1 mA. The electron source is a DC thermionic triode delivering beam with energy of 250 keV. The gun beam quality predefines the accelerated beam quality. One application of the electron beam is the generation of bremsstrahlung in the MeV energy range. The bremsstrahlung is used for nuclear spectroscopy experiments. Another application of the electron beam is the generation of quasi-monochromatic X-rays via channeling radiation in a single crystal. Thus X-rays with an energy from 10 keV through 100 keV can be generated. The channeling radiation is used for radio-biological and bio-medical experiments. In the future the ELBE electron beam will be used to produce monoenergetic positrons for material research. One more future application of the beam is the production of neutrons by bremsstrahlung via reactions. The neutrons will be used for material research oriented toward construction of future nuclear fusion reactors. In the author’s opinion, the most exciting and elegant application of the electron beam at ELBE is the infrared FEL. There are two FELs planned to run simultaneously at ELBE. The first one, with an undulator period of 27 mm, is going to operate in the wavelength range from 3 µm through 30 µm. The second one is in the design stage only but it will be built to work at longer wavelengths from 25 µm to 150 µm where the FEL has no competition from conventional quantum lasers. While an infrared FEL makes possible a great variety of experiments it is the device most sensitive to the electron beam quality. This dissertation is dedicated to the development of beam instrumentation and the measurement of electron beam parameters at ELBE. - In Chapter #1 we review fundamentals of FEL operation, discuss the importance of the electron beam quality for the FEL and lay down the requirements imposed by the FEL on the electron beam parameters. - Chapter #2 describes measurements of the transverse emittance we did at ELBE including an explanation of the experimental methods and the measurement error analysis. The transverse emittance was measured with the multislit method in the injector where the beam is space charge dominated. The transverse emittance of the accelerated beam was measured with the quadrupole scan method since the beam is emittance dominated. - Measurements of the electron bunch length, which is in the picosecond range, are described in Chapter #3. The bunch length was estimated from a frequency domain fit of a specially constructed analytical function to the measured power spectrum of the bunch. The power spectrum was obtained as a Fourier transform of the measured autocorrelation function of the coherent transition radiation (CTR). The CTR autocorrelation function was measured with the help of a Martin-Puplett interferometer. - A system of beam position monitors was designed, built, and commissioned in the framework of this effort. The design of our stripline BPM, the corresponding electronics and software is described in Chapter #4 along with the system performance as measured with the ELBE beam.

Elektronen- und Positronenstrahlen mit niedrigsten Emittanzen und hohen Strömen werden in zukünftigen Linearbeschleunigern, wie zum Beispiel dem Compact Linear Collider (CLIC), benötigt, um die geforderte Leuchtkraft für physikalische Experimente bereit zu stellen. Diese Strahlen können in Dämpfungsringen, ausgestattet mit starken, supraleitenden Dämpfungswigglermagneten, erzeugt werden. In dieser Arbeit sind Designkonzepte verschiedener supraleitender Dämpfungswigglermagnete entwickelt worden. Testspulen sowie Modelle sind gebaut und getestet, elektrische Verbindungstechniken entwickelt worden. Eine Wärmelastrechnung für den Betrieb in Dämpfungsringen und ein Designkonzept für den kryogenen Betrieb bei 4.2 K ist erstellt worden. Es konnte theoretisch und experimentell gezeigt werden, dass supraleitende Dämpfungswigglermagnete mit Nb-Ti und Nb3Sn Niedertemperatursupraleitern die magnetischen, mechanischen, elektrischen und thermischen Anforderungen erfüllen und in Dämpfungsringen betrieben werden können.

Elektronen- und Positronenstrahlen mit niedrigsten Emittanzen und hohen Strömen werden in zukünftigen Linearbeschleunigern, wie zum Beispiel dem Compact Linear Collider (CLIC), benötigt, um die geforderte Leuchtkraft für physikalische Experimente bereit zu stellen. Diese Strahlen können in Dämpfungsringen, ausgestattet mit starken, supraleitenden Dämpfungswigglermagneten, erzeugt werden. In dieser Arbeit sind Designkonzepte verschiedener supraleitender Dämpfungswigglermagnete entwickelt worden. Testspulen sowie Modelle sind gebaut und getestet, elektrische Verbindungstechniken entwickelt worden. Eine Wärmelastrechnung für den Betrieb in Dämpfungsringen und ein Designkonzept für den kryogenen Betrieb bei 4.2 K ist erstellt worden. Es konnte theoretisch und experimentell gezeigt werden, dass supraleitende Dämpfungswigglermagnete mit Nb-Ti und Nb3Sn Niedertemperatursupraleitern die magnetischen, mechanischen, elektrischen und thermischen Anforderungen erfüllen und in Dämpfungsringen betrieben werden können.