IPAC2012 - List of Authors (Rubin, D. L.)

Paper	Title	Page
MOPPR074	Using TE Wave Resonances for the Measurement of Electron Cloud Density	960
	J.P. Sikora, M.G. Billing, D. L. Rubin, R.M. Schwartz CLASSE, Ithaca, New York, USA D. Alesini INFN/LNF, Frascati (Roma), Italy B.T. Carlson CMU, Pittsburgh, Pennsylvania, USA S. De Santis LBNL, Berkeley, California, USA K.C. Hammond Harvard University, Cambridge, Massachusetts, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231. In the past few years, electron cloud density has been measured by means of its effect on TE waves propagated through the accelerator vacuum chamber. This technique has been the object of careful studies and has been used in several laboratories around the world (CERN, SLAC, FNAL, Cornell, INFN-LNF). Recent measurements at CesrTA and DAΦNE show that in a majority of practical cases, the theoretical model that relates the cloud density to the phase shift induced on a TE wave propagating in beam pipe may not be the correct one. Instead, the measurement results have to be analyzed considering the effect of the electron cloud on a standing wave excited between the input and output couplers - typically Beam Position Monitors (BPMs). This standing wave pattern is not confined to the portion of beampipe between the BPMs and must be understood in order to correctly interpret the measurement. In this paper we present evidence that the transmission function near cutoff between two BPMs is the result of coupling to standing waves trapped in the vacuum chamber. This evidence includes measurements at DAΦNE, Cesr-TA, a test waveguide, computer EM simulations, and analytical calculations.

MOPPR079	Horizontal Beam-size Measurements at CESR-TA Using Synchrotron-light Interferometer	972
	S. Wang, J.V. Conway, D.L. Hartill, M.A. Palmer, D. L. Rubin CLASSE, Ithaca, New York, USA R.F. Campbell, R. Holtzapple CalPoly, San Luis Obispo, California, USA
	Funding: DOE Award DE-FC02-08ER41538 NSF Award (PHY-0734867) NSF Award (PHY-1002467) NSF Award (PHY-1068662). A horizontal beam profile monitor utilizing visible synchrotron radiation from a bending magnet has been designed and installed in CESR. The monitor employs a double-slit interferometer which has been successfully implemented to measure horizontal beam sizes over a wide range of beam currents. By varying the separation of the slits, beam sizes ranging from 50 to 500 microns can be measured with a resolution of approximately 5 microns. The method for extracting the horizontal beam size from the interference pattern is presented and its application to intrabeam scattering studies is described. A configuration for measuring the small vertical beam size is also discussed.

TUPPR063	Investigation into Electron Cloud Effects in the ILC Damping Ring Design	1963
	J.A. Crittenden, J.V. Conway, G. Dugan, M.A. Palmer, D. L. Rubin CLASSE, Ithaca, New York, USA L.E. Boon, K.C. Harkay ANL, Argonne, USA M.A. Furman LBNL, Berkeley, California, USA S. Guiducci INFN/LNF, Frascati (Roma), Italy M.T.F. Pivi, L. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy DE-SC0006506 We report modeling results for electron cloud buildup in the ILC damping ring lattice design. Updated optics, wiggler magnet, and vacuum chamber designs have recently been developed for the 5-GeV, 3.2-km racetrack layout. An analysis of the synchrotron radiation profile around the ring has been performed, including the effect of photon scattering on the interior of the vacuum chamber. Operational implications of the resulting electron cloud buildup will be discussed.

TUPPR065	Wiggler Magnet Design Development for the ILC Damping Rings	1969
	J.A. Crittenden, M.A. Palmer, D. L. Rubin CLASSE, Ithaca, New York, USA
	Funding: Work supported by the U.S. Department of Energy DE-SC0006506. The baseline damping ring lattice design for the International Linear Collider employs nearly 60 2.2-m-long superconducting wiggler magnets to provide the damping necessary to achieve the specified horizontal emittance. We describe the OPERA-based finite-element model developed for the 14-pole, 30-cm period, 7.62-cm gap superferric design which meets the 2.1 T peak field requirement. Transfer functions and field uniformity results are discussed. We present results for the accuracy of the optimized analytic model needed for symplectic tracking algorithms, as well as implications for the updated engineering design.

WEPPR015	Intrabeam Scattering Studies at CesrTA	2970
	M. P. Ehrlichman Cornell University, Ithaca, New York, USA F. Antoniou, Y. Papaphilippou CERN, Geneva, Switzerland W. Hartung, M.A. Palmer, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, C.R. Strohman, S. Wang CLASSE, Ithaca, New York, USA R. Holtzapple CalPoly, San Luis Obispo, California, USA
	Funding: NSF Award (PHY-0734867) NSF Award (PHY-1002467) Japan/US Cooperation Program Education and lifelong learning, co-financed by Greece and the European Union Intrabeam scattering dilutes the emittance of low energy, low emittance rings. Because CesrTA can be operated at low energies with low transverse emittances and high bunch intensity, it is an ideal laboratory for the study of IBS effects. Furthermore, CesrTA is instrumented for accurate beam size measurements in all three dimensions, providing the possibility of a complete determination of the intensity dependence of emittances. Models based on classical IBS theories and multi-particle simulations are used to estimate the effect of IBS at CesrTA at different beam emittances, intensities and energies. The first measurements from machine studies at CesrTA are presented.

Paper

Title

Page

Using TE Wave Resonances for the Measurement of Electron Cloud Density

960

J.P. Sikora, M.G. Billing, D. L. Rubin, R.M. Schwartz
CLASSE, Ithaca, New York, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
B.T. Carlson
CMU, Pittsburgh, Pennsylvania, USA
S. De Santis
LBNL, Berkeley, California, USA
K.C. Hammond
Harvard University, Cambridge, Massachusetts, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231.
In the past few years, electron cloud density has been measured by means of its effect on TE waves propagated through the accelerator vacuum chamber. This technique has been the object of careful studies and has been used in several laboratories around the world (CERN, SLAC, FNAL, Cornell, INFN-LNF). Recent measurements at CesrTA and DAΦNE show that in a majority of practical cases, the theoretical model that relates the cloud density to the phase shift induced on a TE wave propagating in beam pipe may not be the correct one. Instead, the measurement results have to be analyzed considering the effect of the electron cloud on a standing wave excited between the input and output couplers - typically Beam Position Monitors (BPMs). This standing wave pattern is not confined to the portion of beampipe between the BPMs and must be understood in order to correctly interpret the measurement. In this paper we present evidence that the transmission function near cutoff between two BPMs is the result of coupling to standing waves trapped in the vacuum chamber. This evidence includes measurements at DAΦNE, Cesr-TA, a test waveguide, computer EM simulations, and analytical calculations.

MOPPR079

Horizontal Beam-size Measurements at CESR-TA Using Synchrotron-light Interferometer

972

S. Wang, J.V. Conway, D.L. Hartill, M.A. Palmer, D. L. Rubin
CLASSE, Ithaca, New York, USA
R.F. Campbell, R. Holtzapple
CalPoly, San Luis Obispo, California, USA

Funding: DOE Award DE-FC02-08ER41538 NSF Award (PHY-0734867) NSF Award (PHY-1002467) NSF Award (PHY-1068662).
A horizontal beam profile monitor utilizing visible synchrotron radiation from a bending magnet has been designed and installed in CESR. The monitor employs a double-slit interferometer which has been successfully implemented to measure horizontal beam sizes over a wide range of beam currents. By varying the separation of the slits, beam sizes ranging from 50 to 500 microns can be measured with a resolution of approximately 5 microns. The method for extracting the horizontal beam size from the interference pattern is presented and its application to intrabeam scattering studies is described. A configuration for measuring the small vertical beam size is also discussed.

TUPPR063

Investigation into Electron Cloud Effects in the ILC Damping Ring Design

1963

J.A. Crittenden, J.V. Conway, G. Dugan, M.A. Palmer, D. L. Rubin
CLASSE, Ithaca, New York, USA
L.E. Boon, K.C. Harkay
ANL, Argonne, USA
M.A. Furman
LBNL, Berkeley, California, USA
S. Guiducci
INFN/LNF, Frascati (Roma), Italy
M.T.F. Pivi, L. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy DE-SC0006506
We report modeling results for electron cloud buildup in the ILC damping ring lattice design. Updated optics, wiggler magnet, and vacuum chamber designs have recently been developed for the 5-GeV, 3.2-km racetrack layout. An analysis of the synchrotron radiation profile around the ring has been performed, including the effect of photon scattering on the interior of the vacuum chamber. Operational implications of the resulting electron cloud buildup will be discussed.

TUPPR065

Wiggler Magnet Design Development for the ILC Damping Rings

1969

J.A. Crittenden, M.A. Palmer, D. L. Rubin
CLASSE, Ithaca, New York, USA

Funding: Work supported by the U.S. Department of Energy DE-SC0006506.
The baseline damping ring lattice design for the International Linear Collider employs nearly 60 2.2-m-long superconducting wiggler magnets to provide the damping necessary to achieve the specified horizontal emittance. We describe the OPERA-based finite-element model developed for the 14-pole, 30-cm period, 7.62-cm gap superferric design which meets the 2.1 T peak field requirement. Transfer functions and field uniformity results are discussed. We present results for the accuracy of the optimized analytic model needed for symplectic tracking algorithms, as well as implications for the updated engineering design.

WEPPR015

Intrabeam Scattering Studies at CesrTA

2970

M. P. Ehrlichman
Cornell University, Ithaca, New York, USA
F. Antoniou, Y. Papaphilippou
CERN, Geneva, Switzerland
W. Hartung, M.A. Palmer, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, C.R. Strohman, S. Wang
CLASSE, Ithaca, New York, USA
R. Holtzapple
CalPoly, San Luis Obispo, California, USA

Funding: NSF Award (PHY-0734867) NSF Award (PHY-1002467) Japan/US Cooperation Program Education and lifelong learning, co-financed by Greece and the European Union
Intrabeam scattering dilutes the emittance of low energy, low emittance rings. Because CesrTA can be operated at low energies with low transverse emittances and high bunch intensity, it is an ideal laboratory for the study of IBS effects. Furthermore, CesrTA is instrumented for accurate beam size measurements in all three dimensions, providing the possibility of a complete determination of the intensity dependence of emittances. Models based on classical IBS theories and multi-particle simulations are used to estimate the effect of IBS at CesrTA at different beam emittances, intensities and energies. The first measurements from machine studies at CesrTA are presented.