IPAC2011 - List of Authors (De Maria, R.)

Paper

Title

Page

Suppression of Emittance Growth by Excited Magnet Noise with the Transverse Damper in LHC in Simulations and Experiment

508

W. Höfle, G. Arduini, R. De Maria, G. Kotzian, D. Valuch
CERN, Geneva, Switzerland
V.A. Lebedev
Fermilab, Batavia, USA

The LHC transverse dampers initially build to control transverse instabilities are also a good remedy to suppress the oscillations causing emittance growth excited by electro-magnetic noises at the frequencies of betatron sidebands. To prevent the emittance growth excited by magnet noise using the damper this system has to have extremely low noise properties. The paper discusses simulation results on the effectiveness of the transverse feedback system to suppress such oscillations and the experimental results from a damper point of view as they were gained during the 2010 LHC run. Possible improvements in the damper system to enhance its effectiveness with respect to the suppression of emittance blow-up are also discussed.

TUPZ034

Impact of Arc Phase Advance on Chromatic Optics in RHIC

1885

R. Calaga, R. Miyamoto, G. Robert-Demolaize, S.M. White
BNL, Upton, Long Island, New York, USA
R. De Maria, R. Tomás
CERN, Geneva, Switzerland
G. Vanbavinckhove
NIKHEF, Amsterdam, The Netherlands

Funding: This work is partially supported by the US Department of Energy through the LHC Accelerator Research program (LARP).
The phase advance between the two interaction points in RHIC is optimized for dynamic aperture for a initial design beta-star. This may not hold true as RHIC presently operates with a considerably reduced beta-star. Additionally the reduction of the available beam aperture due to an enlarged chromatic beta-beating is evident. Results from phase advance scans between the two IPs to reduce the chromatic beta-beating in model and measurements are presented. Impact on the single beam lifetime and momentum aperture is compared to the nominal optics.

THOBA01

Electron Cloud Observations in LHC

2862

G. Rumolo, G. Arduini, V. Baglin, H. Bartosik, P. Baudrenghien, N. Biancacci, G. Bregliozzi, S.D. Claudet, R. De Maria, J. Esteban Muller, M. Favier, C. Hansen, W. Höfle, J.M. Jimenez, V. Kain, E. Koukovini, G. Lanza, K.S.B. Li, G.H.I. Maury Cuna, E. Métral, G. Papotti, T. Pieloni, F. Roncarolo, B. Salvant, E.N. Shaposhnikova, R.J. Steinhagen, L.J. Tavian, D. Valuch, W. Venturini Delsolaro, F. Zimmermann
CERN, Geneva, Switzerland
C.M. Bhat
Fermilab, Batavia, USA
U. Iriso
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
N. Mounet, C. Zannini
EPFL, Lausanne, Switzerland

Operation of LHC with bunch trains different spacings has revealed the formation of an electron cloud inside the machine. The main observations of electron cloud build-up are the pressure rise measured at the vacuum gauges in the warm regions, as well as the increase of the beam screen temperature in the cold regions due to an additional heat load. The effects of the electron cloud were also visible as a strong instability and emittance growth affecting the last bunches of longer trains, which could be improved running with higher chromaticity and/or larger transverse emittances. A summary of the 2010 and 2011 observations and measurements and a comparison with existing models will be presented. The efficiency of scrubbing and scrubbing strategies to improve the machine running performance will be also briefly discussed.

Slides THOBA01 [2.911 MB]

THPZ013

A Proposal for the Optics and Layout of the HL-LHC with Crab-cavities

3711

R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland

The LHC Upgrade studies have been recently formalized into the so-called HL-LHC project. This project relies on the availability of new technologies such as crab-cavities which would be installed in the interaction region (IR) of the new ATLAS and CMS experiments, and high-field and large aperture inner triplet quadrupoles equipped with Nb3Sn super-conducting cables. This paper presents and analyzes a possible layout and optics for the new IRs, with a beta* squeezed down to 15 cm in collision using the ATS scheme*.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for the LHC Upgrade”, these proceedings.

Paper	Title	Page
MOPO013	Suppression of Emittance Growth by Excited Magnet Noise with the Transverse Damper in LHC in Simulations and Experiment	508
	W. Höfle, G. Arduini, R. De Maria, G. Kotzian, D. Valuch CERN, Geneva, Switzerland V.A. Lebedev Fermilab, Batavia, USA
	The LHC transverse dampers initially build to control transverse instabilities are also a good remedy to suppress the oscillations causing emittance growth excited by electro-magnetic noises at the frequencies of betatron sidebands. To prevent the emittance growth excited by magnet noise using the damper this system has to have extremely low noise properties. The paper discusses simulation results on the effectiveness of the transverse feedback system to suppress such oscillations and the experimental results from a damper point of view as they were gained during the 2010 LHC run. Possible improvements in the damper system to enhance its effectiveness with respect to the suppression of emittance blow-up are also discussed.

TUPZ034	Impact of Arc Phase Advance on Chromatic Optics in RHIC	1885
	R. Calaga, R. Miyamoto, G. Robert-Demolaize, S.M. White BNL, Upton, Long Island, New York, USA R. De Maria, R. Tomás CERN, Geneva, Switzerland G. Vanbavinckhove NIKHEF, Amsterdam, The Netherlands
	Funding: This work is partially supported by the US Department of Energy through the LHC Accelerator Research program (LARP). The phase advance between the two interaction points in RHIC is optimized for dynamic aperture for a initial design beta-star. This may not hold true as RHIC presently operates with a considerably reduced beta-star. Additionally the reduction of the available beam aperture due to an enlarged chromatic beta-beating is evident. Results from phase advance scans between the two IPs to reduce the chromatic beta-beating in model and measurements are presented. Impact on the single beam lifetime and momentum aperture is compared to the nominal optics.

THOBA01	Electron Cloud Observations in LHC	2862
	G. Rumolo, G. Arduini, V. Baglin, H. Bartosik, P. Baudrenghien, N. Biancacci, G. Bregliozzi, S.D. Claudet, R. De Maria, J. Esteban Muller, M. Favier, C. Hansen, W. Höfle, J.M. Jimenez, V. Kain, E. Koukovini, G. Lanza, K.S.B. Li, G.H.I. Maury Cuna, E. Métral, G. Papotti, T. Pieloni, F. Roncarolo, B. Salvant, E.N. Shaposhnikova, R.J. Steinhagen, L.J. Tavian, D. Valuch, W. Venturini Delsolaro, F. Zimmermann CERN, Geneva, Switzerland C.M. Bhat Fermilab, Batavia, USA U. Iriso CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain N. Mounet, C. Zannini EPFL, Lausanne, Switzerland
	Operation of LHC with bunch trains different spacings has revealed the formation of an electron cloud inside the machine. The main observations of electron cloud build-up are the pressure rise measured at the vacuum gauges in the warm regions, as well as the increase of the beam screen temperature in the cold regions due to an additional heat load. The effects of the electron cloud were also visible as a strong instability and emittance growth affecting the last bunches of longer trains, which could be improved running with higher chromaticity and/or larger transverse emittances. A summary of the 2010 and 2011 observations and measurements and a comparison with existing models will be presented. The efficiency of scrubbing and scrubbing strategies to improve the machine running performance will be also briefly discussed.
	Slides THOBA01 [2.911 MB]

THPZ013	A Proposal for the Optics and Layout of the HL-LHC with Crab-cavities	3711
	R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland
	The LHC Upgrade studies have been recently formalized into the so-called HL-LHC project. This project relies on the availability of new technologies such as crab-cavities which would be installed in the interaction region (IR) of the new ATLAS and CMS experiments, and high-field and large aperture inner triplet quadrupoles equipped with Nb3Sn super-conducting cables. This paper presents and analyzes a possible layout and optics for the new IRs, with a beta* squeezed down to 15 cm in collision using the ATS scheme. S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for the LHC Upgrade”, these proceedings.