BIW2012 - List of Authors (Weiland, T.)

Paper	Title	Page
TUPG008	Coupling Methods for the Highly Sensitive Cavity Sensor for Longitudinal and Transverse Schottky Measurements	149
	M. Hansli, A. Angelovski, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany P. Hülsmann, W. Kaufmann GSI, Darmstadt, Germany
	Funding: Work supported by the BMBF: 06DA90351 In order to observe rare isotopes and anti-protons in the Collector Ring (CR) at FAIR, a highly sensitive Schottky cavity sensor is proposed, utilizing the monopole mode for longitudinal and a dipole mode for transverse measurements. Because the charged particle beam excites the dipole mode in the suggested resonator several orders of magnitude smaller than the corresponding monopole mode, it is crucial to extract both components independently without mutual correlation. Particular focus has to be put on the extraction of the dipole mode to sufficiently suppress the strong monopole contribution by taking advantage of a frequency selective coupling mechanism. Utilization of waveguide filters at the measurement frequency of about 300 MHz results in a bulky structure. To reduce the size, different methods for coupling and filtering including dielectric filling of the waveguides are evaluated in this work with respect to their Signal-to-Interference-and-Noise-Ratio. Hereby, key parameters that influence the performance, namely, the shunt impedance of the dipole mode, the suppression of the monopole mode, and the noise behavior of the system are systematically analyzed and optimized.

TUPG042	High Intensity Effects on Betatron Tune at GSI SIS-18	219
	R. Singh, O. Chorniy, P. Forck, R. Haseitl, W. Kaufmann, P. Kowina, K. Lang GSI, Darmstadt, Germany T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: This work is supported by DITANET (novel DIagnostic Techniques for future particle Accelerators: A Marie Curie Initial Training NETwork),Project Number ITN-2008-215080 The tune measurement system (TOPOS) at GSI SIS-18 consists of, a band limited noise exciter which excites coherent betatron oscillations in the bunched beam; Fast ADCs to digitize the BPM signals at 125 MSa/s and FPGAs to calculate position from the digitized BPM signals. Baseband tune is thus determined by Fourier transformation of the individual bunch position data. Several tune measurement campaigns were performed with U⁷³⁺ and Ar¹⁸⁺ ion beam at highest achievable intensities of 2x10⁹ and 2.5x10¹⁰ respectively using TOPOS. The goal of these measurements was to understand the high current effects on the tune spectra. Substantial modification of the tune spectra were observed and attributed to the bunch head tail oscillations after further investigations. Coherent tune shift in dependence of beam intensity were also measured. This contribution reports on the modified tune spectra, corresponding space charge effects and further experimental details.

Paper

Title

Page

Coupling Methods for the Highly Sensitive Cavity Sensor for Longitudinal and Transverse Schottky Measurements

149

M. Hansli, A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
P. Hülsmann, W. Kaufmann
GSI, Darmstadt, Germany

Funding: Work supported by the BMBF: 06DA90351
In order to observe rare isotopes and anti-protons in the Collector Ring (CR) at FAIR, a highly sensitive Schottky cavity sensor is proposed, utilizing the monopole mode for longitudinal and a dipole mode for transverse measurements. Because the charged particle beam excites the dipole mode in the suggested resonator several orders of magnitude smaller than the corresponding monopole mode, it is crucial to extract both components independently without mutual correlation. Particular focus has to be put on the extraction of the dipole mode to sufficiently suppress the strong monopole contribution by taking advantage of a frequency selective coupling mechanism. Utilization of waveguide filters at the measurement frequency of about 300 MHz results in a bulky structure. To reduce the size, different methods for coupling and filtering including dielectric filling of the waveguides are evaluated in this work with respect to their Signal-to-Interference-and-Noise-Ratio. Hereby, key parameters that influence the performance, namely, the shunt impedance of the dipole mode, the suppression of the monopole mode, and the noise behavior of the system are systematically analyzed and optimized.

TUPG042

High Intensity Effects on Betatron Tune at GSI SIS-18

219

R. Singh, O. Chorniy, P. Forck, R. Haseitl, W. Kaufmann, P. Kowina, K. Lang
GSI, Darmstadt, Germany
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: This work is supported by DITANET (novel DIagnostic Techniques for future particle Accelerators: A Marie Curie Initial Training NETwork),Project Number ITN-2008-215080
The tune measurement system (TOPOS) at GSI SIS-18 consists of, a band limited noise exciter which excites coherent betatron oscillations in the bunched beam; Fast ADCs to digitize the BPM signals at 125 MSa/s and FPGAs to calculate position from the digitized BPM signals. Baseband tune is thus determined by Fourier transformation of the individual bunch position data. Several tune measurement campaigns were performed with U⁷³⁺ and Ar¹⁸⁺ ion beam at highest achievable intensities of 2x10⁹ and 2.5x10¹⁰ respectively using TOPOS. The goal of these measurements was to understand the high current effects on the tune spectra. Substantial modification of the tune spectra were observed and attributed to the bunch head tail oscillations after further investigations. Coherent tune shift in dependence of beam intensity were also measured. This contribution reports on the modified tune spectra, corresponding space charge effects and further experimental details.