DIA  —  Electron Cloud Diagnostics and Measurements  

Paper	Title	Page
DIA00	Electron Cloud Studies in the Fermilab Main Injector Using Microwave Transmission	173
	J. Thangaraj, N. Eddy, R. Zwaska, K. Seiya, I. Kourbanis, J. Crisp Fermilab
	In this paper, we present recent results from our measurement at the Fermilab Main Injector through microwave transmission in a beam pipe. We present three types of measurement techniques. In the first technique, we use time-resolved direct phase shift measurement to measure the e-cloud density. In the second and third techniques, we look for side bands in the frequency spectrum with or without frequency span by collecting turns of data. Finally, we also discuss the resonant BPM method, where a signal below the waveguide cutoff is sent through a one side of the BPM and is collected on the other side of the BPM to look for phase shift due to electron cloud. We present experimental results taken from MI40 and MI52 section of the main injector.
	Slides
DIA01	TE Wave Measurements at Cesr-TA
	S. De Santis, J. Byrd, G. Penn LBNL J. Sikora Cornell University - CLASSE K. Hammond Harvard University
	TE wave transmission is currently used as a diagnostic tool for measurements of the electron cloud density in several regions of the Cesr-TA ring. While the method is conceptually well established, a number of effects contribute to making a quantitative estimate of the density not straightforward. We report on the measurements currently performed during Cesr-TA experimental runs, describe experimental challenges, and the methods devised to analyze and solve them.
	Slides
DIA02	The Ecloud Measurement Setup in the Main Injector	177
	C. Tan, R. Zwaska, M. Backfish Fermilab
	An ecloud measurement setup was installed in a straight section of the Main Injector in 2009. The goal of the setup was to compare the characteristics of different beam pipe coatings when subjected to proton beam. The setup consists of one coated and one uncoated beam pipe with the same physical dimensions installed at the same location. Four RFAs (retarding field analysers) and two BPMs (used for RF measurements) have been used to measure the ecloud densities. The RFAs have performed very well and have collected both the time evolution and energy distribution of the ecloud for bare and two types of beam pipe coatings.
	Slides
DIA03	Analysis of the Electron Cloud Density Measurement With RFA in a Positron Ring	184
	K. Kanazawa, H. Fukuma KEK P. Jain The Graduate University for Advanced Studies
	In a positron ring such as KEKB LER, clouding electrons receive an almost instantaneous kick from circulating bunches. Therefore, high energy electrons in the cloud are produced just after the interaction with the bunch locally around the beam. The authors gave an estimation of their density using a high energy electron current measured with RFA and a calculated volume neglecting their initial velocity before the interaction with the bunch. To evaluate the accuracy of this estimation, the process of the measurement is analyzed using the phase space density for the motion of electrons in the transverse plane of the beam. The expressions that can evaluate the accuracy of the estimation with the help of simulation are obtained. One of the authors has shown that the accuracy for a drift space is within ±5% error. For other cases such as in a solenoid field, in a quadruple field, the evaluation is not yet given. In addition to this discussion, some examples of the estimation with RFA are shown.
	Slides
DIA04	Status of COLDDIAG: a Cold Vacuum Chamber for Diagnostics	190
	S. Gerstl, T. Baumbach, S. Casalbuoni, A. Grau, M. Hagelstein, D. Saez de Jauregui Karlsruhe Institute of Technology R. Cimino, M. Commisso, B. Spataro, A. Mostacci INFN/LNF J. Clarke, D. Scott Science and Technology Facilities Council (STFC/DL/ASTeC) Daresbury Laboratory Accelerator Science and Technology Centre M. Cox, J. Schouten Diamond Light Source Ltd (Diamond) R. Jones, I. Shinton Cockcroft Institute E. Wallen Lund University - MAX-Lab R. Weigel Max-Planck Institute for Metal Research, Stuttgart V. Baglin CERN C. Boffo, G. Sikler Babcock Noell GmbH (BNG) T. Bradshaw Science and Technology Facilities Council (STFC/RAL) Rutherford Appleton Laboratory
	One of the still open issues for the development of superconducting insertion devices is the understanding of the heat load induced by the beam passage. With the aim of measuring the beam heat load to a cold bore and in order to gain a deeper understanding in the beam heat load mechanisms, a cold vacuum chamber for diagnostics is under construction. We plan to have access with the same set-up to a number of different diagnostics, so we are implementing: i) retarding field analyzers to measure the electron flux, ii) temperature sensors to measure the total heat load, iii) pressure gauges, iv) and mass spectrometers to measure the gas content. The inner vacuum chamber will be removable in order to test different geometries and materials. COLDDIAG is built to fit in a short straight section at ANKA, but we are proposing its installation in different synchrotron light sources with different energies and beam characteristics. A first installation in DIAMOND is planned in June 2011. Here we describe the technical design report of this device and the planned measurements with beam.
	Slides
DIA05	Electron Cloud Generation, Trapping and Ejection from Quadrupoles at the Los Alamos PSR
	R. Macek, A. Browman, R. McCrady, T. Zaugg TechSource, Inc. L. Rybarcyk, T. Spickermann LANL
	Since the ECLOUD’07 workshop, our electron cloud studies have focused on understanding the main sources and locations of electron clouds (EC), which drive the observed e-p instability. Significant EC signals are observed in drift spaces and quadrupole magnets at PSR which together cover ~65% of the ring circumference. Measurements using the EC diagnostic in a quadrupole have also shown significant trapping of electrons in the quadrupole well after the beam is extracted. Results making use of two longitudinal barriers to isolate the drift space electron diagnostic have provided definitive evidence that most of the drift space EC signal is “seeded” by electrons ejected longitudinally by ExB drifts from adjacent quadrupole magnets. Modeling of EC generation in 3D quadrupoles using a modified version of the POSINST code shows that a sizeable fraction of the electrons generated in the quadrupoles are ejected longitudinally into the adjacent drifts. The experimental findings and simulation results of this focus will be presented.
	Slides