2011 Particle Accelerator Conference - List of Keywords (closed-orbit)

Paper	Title	Other Keywords	Page
MOP170	Combining Multiturn and Closed-Orbit Methods for Model-Independent and Fast Determination of Optical Functions in Storage Rings	betatron, storage-ring, dipole, synchrotron	411
	B. Riemann, P. Grete, H. Huck, A. Nowaczyk, T. Weis DELTA, Dortmund, Germany
	Multiturn / turn-by-turn data acquisition is a new source for Twiss parameter determination in storage rings, while closed-orbit measurements are a long-known tool for diagnostics with conventional low-frequency beam position monitor (BPM) systems, being available at almost every storage ring. The presented method aims to join the advantages of multiturn and closed-orbit measurement methods. For uncoupled optics, there are only two correctors per oscillation plane and two multiturn BPMs needed in one drift space in the storage ring for model-independent measurement of beta and betatron phase functions at all BPMs in the ring, including conventional ones. This is a cost-effective alternative to the exclusive usage of multiturn BPMs in a storage ring, resulting in the same amount of information. This method can also be extended to include betatron coupling. In addition, we describe a possible experimental setup needed for multiturn data acquisition using a bunch-by-bunch feedback system. By applying an uncritical coherent excitation to coupled bunch modes, the accuracy of the multiturn data acquisition may be significantly improved, enabling the use of smaller drift spaces.

TUP207	The Effects of the RHIC E-lenses Magnetic Structure Layout on the Proton Beam Trajectory	proton, electron, lattice, solenoid	1202
	X. Gu, W. Fischer, R.C. Gupta, J. Hock, Y. Luo, M. Okamura, A.I. Pikin, D. Raparia BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We are designing two electron lenses (E-lens) to compensate for the large beam-beam tune spread from proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). They will be installed in RHIC IR10. First, the layout of these two E-lenses is introduced. Then the effects of e-lenses on proton beam are discussed. For example, the transverse fields of the e-lens bending solenoids and the fringe field of the main solenoids will shift the proton beam. For the effects of the e-lens on proton beam trajectory, we calculate the transverse kicks that the proton beam receives in the electron lens via Opera at first. Then, after incorporating the simplified E-lens lattice in the RHIC lattice, we obtain the closed orbit effect with the Simtrack Code.

WEP018	Optics Error Measurements in the AGS for Polarized Proton Operation	survey, quadrupole, sextupole, betatron	1534
	V. Schoefer, L. A. Ahrens, K.A. Brown, J.W. Glenn, H. Huang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A large distortion of the vertical beta function became evident in the Brookhaven AGS during the 2010 polarized proton run. This paper describes the beam measurements and model calculations made to verify the distortion of the optics, to infer possible sources and to explore correcting strategies. The optics distortion is only apparent when operating with a betatron tune very near the integer (as required for polarization preservation during acceleration in the AGS) and with the lattice chromaticity sextupoles powered. The measurements indicate a small (on the order of millimeters) unexpected systematic horizontal closed orbit displacement in the sextupoles that is not evident in beam position monitor measurements. Motivated especially by these observations a complete survey of the AGS was performed during the 2010 shutdown period.&nb sp; The results of that survey and their impact on the observed optical errors in the AGS are included.

WEP141	Development of a Stepwise Ray-Tracing Based on-Line Model at AGS	dipole, lattice, multipole, quadrupole	1749
	F. Méot, L. A. Ahrens, K.A. Brown, J.W. Glenn, H. Huang, T. Roser, V. Schoefer, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A model of the Alternating Gradient Synchrotron is being developed based on stepwise ray-tracing numerical tools. It provides a realistic representation of the lattice, and accounts for the two helical partial Siberian snake insertions. The aim is to make this stepwise ray-tracing based model an aid for the understanding of the AGS, in matter of both beam dynamics and polarization transmission.

THP103	Spin Code Benchmarking at RHIC	resonance, simulation, synchrotron, status	2318
	F. Méot, M. Bai, V. Ptitsyn BNL, Upton, Long Island, New York, USA V.H. Ranjbar Tech-X, Boulder, Colorado, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Stepwise ray-tracing methods are being developed at C-AD, BNL, in view of benchmarking of existing spin codes and of spin dynamics simulations at RHIC. A status of that work is reported here.

THP127	Analysis of NSLS-II Touschek Lifetime	betatron, simulation, synchrotron, longitudinal-dynamics	2360
	J. Choi, S.L. Kramer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by DOE contract DE-AC02-98CH10886 As scrapers are adopted for the loss control of NSLS-II storage ring, Touschek lifetime estimations for various cases are required to assure the stable operation. However, to estimate the Touschek lifetime, momentum apertures should be measured all along the ring and, if we want to estimate the lifetime in various situations, it can take extremely long time. Thus, rather than simulating for each case, semi-analytic methods with the interpolations are used for the measurements of the momentum apertures. In this paper, we described the methods and showed the results.

THP132	Beam Diagnostics using BPM Signals from Injected and Stored Beams in a Storage Ring	injection, storage-ring, simulation, betatron	2369
	G.M. Wang, W.X. Cheng, R.P. Fliller, R. Heese, T.V. Shaftan, O. Singh, F.J. Willeke BNL, Upton, Long Island, New York, USA
	Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886 Many modern light sources are operating in top-off injection mode or are being upgraded to top-off injection mode. For top-off injection mode, the storage ring always has the stored beam and injected beam. So the BPM data is the mixture of both beam positions and the injected beam position cannot be measured directly. We propose to use a BPM with special electronics in NSLS II storage ring to retrieve the injected beam trajectory with the SVD method. The BPM has the capability to measure bunch-by-bunch beam position. We also need another system to measure the bunch-by-bunch beam current. The injected beam trajectory can be measured and monitored all the time without dumping the stored beam. We can adjust and optimize the injected beam trajectory to maximize the injection efficiency. We can also measure the storage ring acceptance by mapping the injected beam trajectory.

THP134	Lifetime Measurement with Pseudo Moveable Septum in NSLS X-ray Ring	injection, septum, kicker, vacuum	2375
	G.M. Wang, J. Choi, R. Heese, S.L. Kramer, T.V. Shaftan, X. Yang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886 The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source currently under construction at Brookhaven National Laboratory and starts to commission in 2014. The beam injection works with two septa and four fast kicker magnets in an injection section. To improve the injection stability and reproducibility, we plan to implement a slow local bump on top of the fast bump so that the fast kicker strength is reduced. This bump works as a pseudo movable septum. We can also use this ‘movable’ septum to measure the storage ring beam partial lifetime resulting from the septum edge and possibly increasing the lifetime by moving the stored beam orbit away from the edge. We demonstrate the feasibility of this idea, by implementing DC bump in NSLS X-ray ring. We report the results of beam lifetime measurements as a function of the amplitude of this bumped orbit relative to the septum and the idea of a slow bump that could reduce the fast bump magnet strengths.

Paper

Title

Other Keywords

Page

Combining Multiturn and Closed-Orbit Methods for Model-Independent and Fast Determination of Optical Functions in Storage Rings

betatron, storage-ring, dipole, synchrotron

411

B. Riemann, P. Grete, H. Huck, A. Nowaczyk, T. Weis
DELTA, Dortmund, Germany

Multiturn / turn-by-turn data acquisition is a new source for Twiss parameter determination in storage rings, while closed-orbit measurements are a long-known tool for diagnostics with conventional low-frequency beam position monitor (BPM) systems, being available at almost every storage ring. The presented method aims to join the advantages of multiturn and closed-orbit measurement methods. For uncoupled optics, there are only two correctors per oscillation plane and two multiturn BPMs needed in one drift space in the storage ring for model-independent measurement of beta and betatron phase functions at all BPMs in the ring, including conventional ones. This is a cost-effective alternative to the exclusive usage of multiturn BPMs in a storage ring, resulting in the same amount of information. This method can also be extended to include betatron coupling. In addition, we describe a possible experimental setup needed for multiturn data acquisition using a bunch-by-bunch feedback system. By applying an uncritical coherent excitation to coupled bunch modes, the accuracy of the multiturn data acquisition may be significantly improved, enabling the use of smaller drift spaces.

TUP207

The Effects of the RHIC E-lenses Magnetic Structure Layout on the Proton Beam Trajectory

proton, electron, lattice, solenoid

1202

X. Gu, W. Fischer, R.C. Gupta, J. Hock, Y. Luo, M. Okamura, A.I. Pikin, D. Raparia
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We are designing two electron lenses (E-lens) to compensate for the large beam-beam tune spread from proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). They will be installed in RHIC IR10. First, the layout of these two E-lenses is introduced. Then the effects of e-lenses on proton beam are discussed. For example, the transverse fields of the e-lens bending solenoids and the fringe field of the main solenoids will shift the proton beam. For the effects of the e-lens on proton beam trajectory, we calculate the transverse kicks that the proton beam receives in the electron lens via Opera at first. Then, after incorporating the simplified E-lens lattice in the RHIC lattice, we obtain the closed orbit effect with the Simtrack Code.

WEP018

Optics Error Measurements in the AGS for Polarized Proton Operation

survey, quadrupole, sextupole, betatron

1534

V. Schoefer, L. A. Ahrens, K.A. Brown, J.W. Glenn, H. Huang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A large distortion of the vertical beta function became evident in the Brookhaven AGS during the 2010 polarized proton run. This paper describes the beam measurements and model calculations made to verify the distortion of the optics, to infer possible sources and to explore correcting strategies. The optics distortion is only apparent when operating with a betatron tune very near the integer (as required for polarization preservation during acceleration in the AGS) and with the lattice chromaticity sextupoles powered. The measurements indicate a small (on the order of millimeters) unexpected systematic horizontal closed orbit displacement in the sextupoles that is not evident in beam position monitor measurements. Motivated especially by these observations a complete survey of the AGS was performed during the 2010 shutdown period.&nb sp; The results of that survey and their impact on the observed optical errors in the AGS are included.

WEP141

Development of a Stepwise Ray-Tracing Based on-Line Model at AGS

dipole, lattice, multipole, quadrupole

1749

F. Méot, L. A. Ahrens, K.A. Brown, J.W. Glenn, H. Huang, T. Roser, V. Schoefer, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A model of the Alternating Gradient Synchrotron is being developed based on stepwise ray-tracing numerical tools. It provides a realistic representation of the lattice, and accounts for the two helical partial Siberian snake insertions. The aim is to make this stepwise ray-tracing based model an aid for the understanding of the AGS, in matter of both beam dynamics and polarization transmission.

THP103

Spin Code Benchmarking at RHIC

resonance, simulation, synchrotron, status

2318

F. Méot, M. Bai, V. Ptitsyn
BNL, Upton, Long Island, New York, USA
V.H. Ranjbar
Tech-X, Boulder, Colorado, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Stepwise ray-tracing methods are being developed at C-AD, BNL, in view of benchmarking of existing spin codes and of spin dynamics simulations at RHIC. A status of that work is reported here.

THP127

Analysis of NSLS-II Touschek Lifetime

betatron, simulation, synchrotron, longitudinal-dynamics

2360

J. Choi, S.L. Kramer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract DE-AC02-98CH10886
As scrapers are adopted for the loss control of NSLS-II storage ring, Touschek lifetime estimations for various cases are required to assure the stable operation. However, to estimate the Touschek lifetime, momentum apertures should be measured all along the ring and, if we want to estimate the lifetime in various situations, it can take extremely long time. Thus, rather than simulating for each case, semi-analytic methods with the interpolations are used for the measurements of the momentum apertures. In this paper, we described the methods and showed the results.

THP132

Beam Diagnostics using BPM Signals from Injected and Stored Beams in a Storage Ring

injection, storage-ring, simulation, betatron

2369

G.M. Wang, W.X. Cheng, R.P. Fliller, R. Heese, T.V. Shaftan, O. Singh, F.J. Willeke
BNL, Upton, Long Island, New York, USA

Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886
Many modern light sources are operating in top-off injection mode or are being upgraded to top-off injection mode. For top-off injection mode, the storage ring always has the stored beam and injected beam. So the BPM data is the mixture of both beam positions and the injected beam position cannot be measured directly. We propose to use a BPM with special electronics in NSLS II storage ring to retrieve the injected beam trajectory with the SVD method. The BPM has the capability to measure bunch-by-bunch beam position. We also need another system to measure the bunch-by-bunch beam current. The injected beam trajectory can be measured and monitored all the time without dumping the stored beam. We can adjust and optimize the injected beam trajectory to maximize the injection efficiency. We can also measure the storage ring acceptance by mapping the injected beam trajectory.

THP134

Lifetime Measurement with Pseudo Moveable Septum in NSLS X-ray Ring

injection, septum, kicker, vacuum

2375

G.M. Wang, J. Choi, R. Heese, S.L. Kramer, T.V. Shaftan, X. Yang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886
The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source currently under construction at Brookhaven National Laboratory and starts to commission in 2014. The beam injection works with two septa and four fast kicker magnets in an injection section. To improve the injection stability and reproducibility, we plan to implement a slow local bump on top of the fast bump so that the fast kicker strength is reduced. This bump works as a pseudo movable septum. We can also use this ‘movable’ septum to measure the storage ring beam partial lifetime resulting from the septum edge and possibly increasing the lifetime by moving the stored beam orbit away from the edge. We demonstrate the feasibility of this idea, by implementing DC bump in NSLS X-ray ring. We report the results of beam lifetime measurements as a function of the amplitude of this bumped orbit relative to the septum and the idea of a slow bump that could reduce the fast bump magnet strengths.