IPAC2012 - List of Authors (Scott, D.J.)

Paper	Title	Page
MOPPC018	Single/Few Bunch Space Charge Effects at 8 GeV in the Fermilab Main Injector	163
	D.J. Scott, D. Capista, I. Kourbanis, K. Seiya, M.-J. Yang Fermilab, Batavia, USA
	For Project X, it is planned to inject a beam of 3 10¹¹ particles per bunch into the Main Injector. Therefore, at 8 GeV, there will be increased space charge tune shifts and an increased incoherent tune spread. In preparation for these higher intensity bunches exploratory studies have commenced looking at the transmission of different intensity bunches at different tunes. An experiment is described with results for bunch intensities between 20 and 172 10⁹ particles. To achieve the highest intensity bunches coalescing at 8 GeV is required, resulting in a longer bunch length. Comparisons show that similar transmission curves are obtained when the intensity and bunch length have increased by factors of 3.2 and 3.4 respectively, indicating the incoherent tune shifts are similar, as expected from theory. The results of these experiments will be used in conjugation with simulations to further study high intensity bunches in the Main Injector.

MOPPC019	Secondary Electron Yield Measurements of Fermilab’s Main Injector Vacuum Vessel	166
	D.J. Scott, D. Capista, K.L. Duel, R.M. Zwaska Fermilab, Batavia, USA S. Greenwald, W. Hartung, Y. Li, T.P. Moore, M.A. Palmer CLASSE, Ithaca, New York, USA R.E. Kirby, M.T.F. Pivi, L. Wang SLAC, Menlo Park, California, USA
	We discuss the progress made on a new installation in Fermilab’s Main Injector that will help investigate the electron cloud phenomenon by making direct measurements of the secondary electron yield (SEY) of samples irradiated in the accelerator. In the Project X upgrade the Main Injector will have its beam intensity increased by a factor of three compared to current operations. This may result in the beam being subject to instabilities from the electron cloud. Measured SEY values can be used to further constrain simulations and aid our extrapolation to Project X intensities. The SEY test-stand, developed in conjunction with Cornell and SLAC, is capable of measuring the SEY from samples using an incident electron beam when the samples are biased at different voltages. We present the design and manufacture of the test-stand and the results of initial laboratory tests on samples prior to installation.

THPPP021	6 Batch Injection and Slipped Beam Tune Measurements in Fermilab’s Main Injector	3776
	D.J. Scott, D. Capista, I. Kourbanis, K. Seiya, M.-J. Yang Fermilab, Batavia, USA
	During Nova operations it is planned to run the Fermilab Recycler in a 12 batch slip stacking mode. In preparation for this, measurements of the tune during a six batch injection and then as the beam is slipped by changing the RF frequency, but without a 7th injection, have been carried out in the Main Injector. The coherent tune shifts due to the changing beam intensity were measured and compared well with the theoretically expected tune shift. The tune shifts due to changing RF frequency, required for slip stacking, also compare well with the linear theory, although some nonlinear affects are apparent at large frequency changes. These results give us confidence that the expected tunes shifts during 12 batch slip stacking Recycler operations can be accommodated.

THPPP022	Coalescing at 8 GeV in the Fermilab Main Injector	3779
	D.J. Scott, D. Capista, I. Kourbanis, K. Seiya, M.-J. Yang Fermilab, Batavia, USA
	For Project X, it is planned to inject a beam of 3 10¹¹ particles per bunch into the Main Injector. To prepare for this by studying the effects of higher intensity bunches in the Main Injector it is necessary to perform coalescing at 8 GeV. The results of a series of experiments and simulations of 8 GeV coalescing are presented. To increase the coalescing efficiency adiabatic reduction of the 53 MHz RF is required, resulting in ~70% coalescing efficiency of 5 initial bunches. Data using wall current monitors has been taken to compare previous work and new simulations for 53 MHz RF reduction, bunch rotations and coalescing, good agreement between experiment and simulation was found. Possible schemes to increase the coalescing efficiency and generate even higher intensity bunches are discussed. These require improving the timing resolution of the low level RF and/or tuning the adiabatic voltage reduction of the 53 MHz.

Paper

Title

Page

Single/Few Bunch Space Charge Effects at 8 GeV in the Fermilab Main Injector

163

D.J. Scott, D. Capista, I. Kourbanis, K. Seiya, M.-J. Yang
Fermilab, Batavia, USA

For Project X, it is planned to inject a beam of 3 10¹¹ particles per bunch into the Main Injector. Therefore, at 8 GeV, there will be increased space charge tune shifts and an increased incoherent tune spread. In preparation for these higher intensity bunches exploratory studies have commenced looking at the transmission of different intensity bunches at different tunes. An experiment is described with results for bunch intensities between 20 and 172 10⁹ particles. To achieve the highest intensity bunches coalescing at 8 GeV is required, resulting in a longer bunch length. Comparisons show that similar transmission curves are obtained when the intensity and bunch length have increased by factors of 3.2 and 3.4 respectively, indicating the incoherent tune shifts are similar, as expected from theory. The results of these experiments will be used in conjugation with simulations to further study high intensity bunches in the Main Injector.

MOPPC019

Secondary Electron Yield Measurements of Fermilab’s Main Injector Vacuum Vessel

166

D.J. Scott, D. Capista, K.L. Duel, R.M. Zwaska
Fermilab, Batavia, USA
S. Greenwald, W. Hartung, Y. Li, T.P. Moore, M.A. Palmer
CLASSE, Ithaca, New York, USA
R.E. Kirby, M.T.F. Pivi, L. Wang
SLAC, Menlo Park, California, USA

We discuss the progress made on a new installation in Fermilab’s Main Injector that will help investigate the electron cloud phenomenon by making direct measurements of the secondary electron yield (SEY) of samples irradiated in the accelerator. In the Project X upgrade the Main Injector will have its beam intensity increased by a factor of three compared to current operations. This may result in the beam being subject to instabilities from the electron cloud. Measured SEY values can be used to further constrain simulations and aid our extrapolation to Project X intensities. The SEY test-stand, developed in conjunction with Cornell and SLAC, is capable of measuring the SEY from samples using an incident electron beam when the samples are biased at different voltages. We present the design and manufacture of the test-stand and the results of initial laboratory tests on samples prior to installation.

THPPP021

6 Batch Injection and Slipped Beam Tune Measurements in Fermilab’s Main Injector

3776

D.J. Scott, D. Capista, I. Kourbanis, K. Seiya, M.-J. Yang
Fermilab, Batavia, USA

During Nova operations it is planned to run the Fermilab Recycler in a 12 batch slip stacking mode. In preparation for this, measurements of the tune during a six batch injection and then as the beam is slipped by changing the RF frequency, but without a 7th injection, have been carried out in the Main Injector. The coherent tune shifts due to the changing beam intensity were measured and compared well with the theoretically expected tune shift. The tune shifts due to changing RF frequency, required for slip stacking, also compare well with the linear theory, although some nonlinear affects are apparent at large frequency changes. These results give us confidence that the expected tunes shifts during 12 batch slip stacking Recycler operations can be accommodated.

THPPP022

Coalescing at 8 GeV in the Fermilab Main Injector

3779

D.J. Scott, D. Capista, I. Kourbanis, K. Seiya, M.-J. Yang
Fermilab, Batavia, USA

For Project X, it is planned to inject a beam of 3 10¹¹ particles per bunch into the Main Injector. To prepare for this by studying the effects of higher intensity bunches in the Main Injector it is necessary to perform coalescing at 8 GeV. The results of a series of experiments and simulations of 8 GeV coalescing are presented. To increase the coalescing efficiency adiabatic reduction of the 53 MHz RF is required, resulting in ~70% coalescing efficiency of 5 initial bunches. Data using wall current monitors has been taken to compare previous work and new simulations for 53 MHz RF reduction, bunch rotations and coalescing, good agreement between experiment and simulation was found. Possible schemes to increase the coalescing efficiency and generate even higher intensity bunches are discussed. These require improving the timing resolution of the low level RF and/or tuning the adiabatic voltage reduction of the 53 MHz.