Paper |
Title |
Page |
TUPZ021 |
The SPS Beam Quality Monitor, from Design to Operation |
1849 |
|
- G. Papotti, T. Bohl, F. Follin, E.N. Shaposhnikova
CERN, Geneva, Switzerland
|
|
|
The SPS Beam Quality Monitor is a system that monitors longitudinal beam parameters on a cycle-by-cycle basis and prevents extraction to the LHC in case the specifications are not met. This avoids losses, unnecessary stress of machine protection components and luminosity degradation, additionally helping efficiency during the filling process. The system has been operational since the 2009 LHC run, checking the beam pattern, its correct position with respect to the LHC references, individual bunch lengths and stability. In this paper the algorithms used, the hardware implementation and the operational aspects are presented.
|
|
|
TUPZ022 |
Longitudinal Beam Measurements at the LHC: The LHC Beam Quality Monitor |
1852 |
|
- G. Papotti, T. Bohl, F. Follin, U. Wehrle
CERN, Geneva, Switzerland
|
|
|
The LHC Beam Quality Monitor is a system that measures individual bunch lengths and positions, similarly to the twin system SPS Beam Quality Monitor, from which it was derived. The pattern verification that the system provides is vital during the injection process to verify the correctness of the injected pattern, while the bunch length measurement is fedback to control the longitudinal emittance blow up performed during the energy ramp. In 2010 the system could for example clearly detect instances of longitudinal instabilities and beam excitation due to excess RF noise. The algorithms used, the hardware implementation and the system integration in the LHC control infrastructure are presented in this paper, along with possible improvements.
|
|
|
TUPZ025 |
Experience with Offset Collisions in the LHC |
1858 |
|
- G. Papotti, R. Alemany-Fernandez, F. Follin, R. Giachino, W. Herr, T. Pieloni, M. Schaumann
CERN, Geneva, Switzerland
- R. Calaga, R. Miyamoto
BNL, Upton, Long Island, New York, USA
|
|
|
To keep the luminosity under control, some experiments require the adjustment of the luminosity during a fill, so-called luminosity leveling. One option is the separate the beams transversely and adjust the separation to the desired collision rate. The results from controlled experiments are reported and interpreted. The feasibility of this method for ultimate luminosities is discussed.
|
|
|
MOPS009 |
Probing Intensity Limits of LHC-type Bunches in the CERN SPS with Nominal Optics |
610 |
|
- B. Salvant, G. Adrian, D.J. Allen, O. Andujar, T. Argyropoulos, J. Axensalva, J. Baldy, H. Bartosik, S. Cettour Cave, F. Chapuis, J.F. Comblin, K. Cornelis, D.G. Cotte, K. Cunnington, H. Damerau, M. Delrieux, J.L. Duran-Lopez, A. Findlay, J. Fleuret, F. Follin, P. Freyermuth, H. Genoud, S.S. Gilardoni, A. Guerrero, S. Hancock, K. Hanke, O. Hans, R. Hazelaar, W. Höfle, L.K. Jensen, J. Kuczerowski, Y. Le Borgne, R. Maillet, D. Manglunki, S. Massot, E. Matli, G. Metral, B. Mikulec, E. Métral, J.-M. Nonglaton, E. Ovalle, L. Pereira, F.C. Peters, A. Rey, J.P. Ridewood, G. Rumolo, J.L. Sanchez Alvarez, E.N. Shaposhnikova, R.R. Steerenberg, R.J. Steinhagen, J. Tan, B. Vandorpe, E. Veyrunes
CERN, Geneva, Switzerland
|
|
|
Some of the upgrade scenarios of the high-luminosity LHC require large intensity per bunch from the injector chain. Single bunch beams with intensities of up to 3.5 to 4·1011 p/b and nominal emittances were successfully produced in the PS Complex and delivered to the SPS in 2010. This contribution presents results of studies with this new intense beam in the SPS to probe single bunch intensity limitations with nominal gamma transition. In particular, the vertical Transverse Mode Coupling Instability (TMCI) threshold with low chromaticity was observed at 1.6·1011 p/b for single nominal LHC bunches in the SPS. With increased vertical chromaticity, larger intensities could be injected, stored along the flat bottom and accelerated up to 450 GeV/c. However, significant losses and/or transverse emittance blow up were then observed. Longitudinal and transverse optimization efforts in the PSB, PS and SPS were put in place to minimize this beam degradation and succeeded to obtain single 2.3·1011 p/b LHC type bunches with satisfying parameters at extraction of the SPS.
|
|
|