• R. Bartoldus, I. Aracena, P. Grenier, D.W. Miller, E. Strauss, D. Su
  SLAC, Menlo Park, California
• J. Beringer, P. Loscutoff
  LBNL, Berkeley, California
• H. Burkhardt, S.M. White
  CERN, Geneva
• W. Kozanecki
  CEA, Gif-sur-Yvette
• J. Walder
  Lancaster University, Lancaster

We present results from the measurement of the 3-D luminosity distribution with the ATLAS Inner Detector during early running. The spatial distribution of pp interactions is reconstructed by a dedicated algorithm in the High-Level Trigger that fits tracks and primary event vertices in real time, and by an offline algorithm that takes full advantage of the high tracking efficiency and resolution. The number of vertices provides online monitoring of the instantaneous luminosity, while luminous-centroid motion mirrors IP-orbit and RF-phase drifts. The x, y and z luminous widths reflect the evolution of the transverse and longitudinal emittances. The length scales of the IP orbit bumps, which directly impact the accuracy of the transverse convolved beam sizes measured during van der Meer scans, are calibrated offline against the measured displacement of the luminous centroid; this significantly improves the accuracy of the absolute luminosity calibration. The simultaneous determination, during such scans, of the transverse convolved beam sizes (from the luminosity variation) and of the corresponding luminous sizes can be used to disentangle the transverse IP sizes of the two beams.

• S. Redaelli, M.C. Alabau Pons, M. Giovannozzi, G.J. Müller, F. Schmidt, R. Tomás, J. Wenninger
  CERN, Geneva

The mechanical aperture of the Large Hadron Collider (LHC) is a critical parameter for the operation of the machine due to the high stored beam intensities in the superconducting environment. Betatron and momentum apertures must be therefore precisely measured and optimized. In this paper, we present the results of beam-based measurements of the LHC aperture. The experimental results are compared with the expectations from the as-built model of the LHC aperture, taking into account the optics imperfections of the superconducting magnets. The impact of these measurements on various aspects of the LHC operation are also discussed.

• S.M. White, R. Alemany-Fernandez, H. Burkhardt, M. Lamont
  CERN, Geneva

Once circulating beams have been established in the LHC the first step towards collisions is to remove the physical separation used to avoid collisions during injection and ramp. A residual separation can remain after the collapsing of the separation bumps. The so-called Van Der Meer method allows for a minimization of this unwanted separation by transversally scanning one beam through the other. The beam sizes at the IP can also be determined by this method and used to give an absolute measurement of the luminosity. We report on how this measurement was implemented and performed in the LHC to optimize and calibrate luminosity.

• M.G. Minty
  BNL, Upton, Long Island, New York

In this report we present recent experimental data from the Relativistic Heavy ion Collider (RHIC) illustrating effects resulting from of ~ 10 Hz vibrations of the triplet quadrupole magnets in the interactions regions and evaluate the impact of these vibrations on RHIC collider performance. Measurements revealed modulation of the betatron tunes of appreciable magnitude relative to the beam-beam parameter. Comparison of the discrete frequencies in the spectra of the measured beam positions and betatron tunes confirmed a common source. The tune modulations were shown to result from feed-down in the sextupole magnets in the interaction regions. In addition we show that the distortions to the closed orbit of the two counter-rotating beams produced a modulated crossing angle at the interaction point(s).

• F. Méot
  CEA, Gif-sur-Yvette
• H. Huang, W.W. MacKay, T. Roser
  BNL, Upton, Long Island, New York

To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electro-magnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained.

• T. Baer, B. Araujo Meleiro, T.B. Bogey, J. Wenninger
  CERN, Geneva
• T. Baer
  DESY, Hamburg

The Super Proton Synchrotron (SPS) at CERN with a peak energy of 450GeV is at the top of the LHC preaccelerator-complex. Apart from the LHC, SPS is with Tevatron the accelerator with the largest stored beam energy of up to 2.5MJ. The SPS has a known vulnerability to fast equipment failures that led to an uncontrolled loss of a high intensity beam in 2008, which resulted in major damage of a main dipole. The beam loss was caused by a fast tune decrease towards an integer resonance. Simulations and distinct experimental studies provide clear understanding of the beam dynamics at different SPS tune resonances. Diverging closed orbit oscillations, dispersion explosion and increased beta-beating are the driving effects that lead to a complete beam loss in as little as 3 turns (70μs). Dedicated experiments of fast failures of the main power converters reveal that the current interlock systems are much too slow for an adequate machine protection. To counteract the vulnerability of the SPS, current research focuses on a new fast position interlock system which is planned to become operational in 2010.

• Y. Giboudot, R. Nilavalan
  Brunel University, Middlesex
• T.R. Edgecock
  STFC/RAL, Chilton, Didcot, Oxon
• A. Wolski
  The University of Liverpool, Liverpool

The Non Scaling Fixed Field Alternating Gradient EMMA has a compact linear lattice. Effect of Fringe Field on the beam has to be studied carefully. A numerical magnetic field map is generated by magnet measurements or magnet design softwares. We developed a technique that produces from the numerical field map, a dynamical map for a particle travelling in the entire EMMA cell for a reference energy without acceleration. Since the beam dynamics change with energy, a set of maps have been produce with different reference energies between 10 and 20MeV. For each reference energy, simulated tune and time of flight (TOF) have been compared with results in Zgoubi - tracking directly through numerical field map. The range of validity of a single map has been investigated by tracking particle with large energy deviation. From that, a sensible acceleration scheme has been implemented.

yoel.giboudot@stfc.ac.uk

• Y. Luo
  BNL, Upton, Long Island, New York

SimTrack is a simple C++ library designed for numeric particle tracking in high energy accelerators. It adopts a 4th order symplectic integrator for optical transportat in the magnetic elements. 4-D and 6-D weak-strong beam-beam treatments are included for beam-beam studies. It provides versatile functions to manage elements and lines. New type of elements can be easily created in the library. It calculates Twiss and coupling, fits tunes and chromaticities, and corrects closed orbits. During tracking, the parameters of elements can be changed or modulated on the fly.

• H.H. Li, J. Hou, B.C. Jiang, L.G. Liu, X.Y. Sun, S.Q. Tian, M.Z. Zhang, W.Z. Zhang
  SINAP, Shanghai

The SSRF (Shanghai Synchrotron Radiation Facility) storage ring consisting of 20 Double Bend Achromatic cells with four super-periods is designed with a low emittance of 3.9nm.rad on 3.5GeV beam energy. Commissioning of the storage ring began on Dec. 21st 2007, and the beam was stored within sixty hours. After one and a half years commissioning, all specifications of the storage ring were reached in 2009. In this paper, study of beam dynamics in the SSRF storage ring is presented. Results of the measurement are given in detail, such as model calibration, orbit stability, etc.

• G. Benedetti, D. Einfeld, Z. Martí, M. Muñoz
  CELLS-ALBA Synchrotron, Cerdanyola del Vallès

The commissioning of the booster for the synchrotron light source ALBA should take place in the period December 2009-January 2010. In this paper, the beam dynamics aspects of the commissioning are described, including the studies performed, the main problems find during the commissioning and a comparison of the measured beam parameters to the design one. A description of the software tools used and developed for the task is included.

• G.H. Wei
  KEK/JAEA, Ibaraki-Ken
• A. Ando, Y. Hashimoto, T. Koseki, J. Takano
  J-PARC, KEK & JAEA, Ibaraki-ken
• S. Igarashi, K. Ishii, M. Tomizawa, M. Uota
  KEK, Ibaraki
• P.K. Saha, K. Satou, M.J. Shirakata
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

The beam commissioning of J-PARC (Japan Proton Accelerator Research Complex) MR (Main Ring) was started from May 2008 and is in progress. As usual, injection tuning is in the first stage and strongly related to other tuning items. Starting with design schemes, making adjustment due to leakage field influence from injection septum, doing envelope matching considering dilution of beam profile in Main Ring are reported in this paper. The 'Without bump' scheme was got on June 15th 2008, while 'With bump' scheme on February 15th 2009. Beam orbit betatron oscillation to the MR close orbit which cause by injection error is less than 1 mm both in horizontal and vertical direction. Meanwhile, Beam Optics matching for 3 GeV beam from 350BT to MR has been well done too, which is also very important.

* T. Koseki, Challenges and Solutions for J-PARC Commissioning and Early Operation, in these proceedings

• D.J. Kelliher, S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• S.L. Sheehy
  JAI, Oxford

EMMA - the Electron Model of Many Applications - is to be built at the STFC Daresbury Laboratory in the UK and will be the first non-scaling FFAG ever constructed. The purpose of EMMA is to study beam dynamics in such an accelerator. The EMMA orbit correction scheme must deal with two characteristics of a non-scaling FFAG: i.e. the lack of a well defined reference orbit and the variation with momentum of the phase advance between lattice elements. In this study we present a novel orbit correction scheme that avoids the former problem by instead aiming to maximise both the symmetry of the orbit and the physical aperture of the beam. The latter problem is dealt with by optimising the corrector strengths over the energy range.

• S.I. Tzenov, J.K. Jones, B.D. Muratori
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• Y. Giboudot
  Brunel University, Middlesex

Described in the paper are systematic procedures to inject and keep the beam on the reference trajectory for a fixed energy, as applied to the EMMA non scaling FFAG accelerator. The notion of accelerated orbits in FFAG accelerators has been introduced and some of their properties have been studies in detail.

• G.K. Sahoo, K. Balewski, W. Decking, J. Keil
  DESY, Hamburg

PETRA III is a 6GeV positron light source with a design horizontal beam emittance of 1nm.rad and 1% emittance coupling. This low emittance is achieved with proper correction of horizontal dispersion to its theoretical values in the arcs as well as dispersion free sections. The spurious vertical dispersion, arising due to misalignment and rotational errors of the magnets is also duly corrected as this contributes to the vertical beam size of the photon beam. Here we discuss the method taken to correct the horizontal dispersion using a combined orbit and dispersion correction scheme. In the vertical plane the same procedure can be used as that of horizontal plane or only the dispersion can be corrected using dedicated skew quadrupoles to millimeter level after orbit correction has been done. In this paper we present the methods used and results obtained in correction of dispersions in transverse planes.

• J.-B. Lagrange, Y. Ishi, Y. Kuriyama, Y. Mori, K. Okabe, T. Planche, T. Uesugi, E. Yamakawa
  KURRI, Osaka

Until today, scaling FFAG accelerator were only designed in a ring shape. But a new criteria of the magnetic field configuration satisfying the scaling condition even for straight FFAG beam line has been recently found. Moreover, combining different types of cells can be used to imagine new lattices. Various applications using these recent developments are here examined: inprovements of the PRISM project and the ERIT project, and a zero-chromatic carbon gantry concept are presented.

• S.C. Zhang, W. Fan, G. Feng, W.W. Gao, H. Geng, Z.G. He, W. Li, L. Wang, H. Xu
  USTC/NSRL, Hefei, Anhui

In order to meet the increasing requirements of synchrotron radiation users, an upgrading plan of hefei light source is undergoing by National Synchrotron Radiation Laboratory (NSRL). The emittance of storage ring is reduced from 166nm.rad to 36nm.rad. In this paper, we study the beam close orbit distortions' (COD) sensitivity to the field and alignment errors in magnets. Estimation of the COD from various error sources is investigated. The distribution of beam position monitors and the location of correctors are reported in the paper. Simulation proves that COD can be corrected down to 50 microns level. In the same time the corrector strengths are weaker enough in the correction scheme.

• A.L. Romanov, D.E. Berkaev, I. Koop, A.N. Kyrpotin, E. Perevedentsev, Yu. A. Rogovsky, P.Yu. Shatunov, D.B. Shwartz
  BINP SB RAS, Novosibirsk

Lattice correction based on orbit responses to dipole correctors and orbit correction based on orbit responses to field gradient variations in quads were successfully implemented on VEPP-2000 [*] for the flat-beam lattice. The round-beam lattice involves strong coupling of vertical and horizontal motions that require a full-coupling analysis in the orbit response technique. Programs used were modified to treat this task. Also, automation and speed enhancements were done that enable a routine use of this technique at VEPP-2000. New experimental results from VEPP-2000 are presented.

* Yu.M.Shatunov et al. Project of a New Electron-Positron Collider VEPP-2000, in: Proc. 7th European Particle Accelerator Conf. (EPAC 2000), Vienna, Austria, 439-441

• R.J.L. Fenning, A. Khan
  Brunel University, Middlesex
• T.R. Edgecock
  STFC/RAL, Chilton, Didcot, Oxon
• D.J. Kelliher, S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

A gantry is required for the PAMELA project using non-scaling Fixed Field Alternating Gradient (NS-FFAG) magnets. The NS-FFAG principle offers the possibility of a gantry much smaller, lighter and cheaper than conventional designs, with the added ability to accept a wide range of fast changing energies. This paper will build on previous work to investigate a design which could be used for the PAMELA project.

• V. Ptitsyn, M. Bai, T. Roser
  BNL, Upton, Long Island, New York

Polarized proton beams are accelerated in RHIC to 250 GeV energy with the help of Siberian Snakes. The pair of Siberian Snakes in each RHIC ring holds the design spin tune at 1/2 to avoid polarization loss during acceleration. However, in the presence of closed orbit errors, the actual spin tune can be shifted from the exact 1/2 value. It leads to corresponding shift of locations of higher-order ("Snake") resonances and limits available betatron tune space. The largest closed orbit effect on the spin tune comes from the horizontal orbit angle between the two snakes. During RHIC Run in 2009 dedicated measurements with polarized proton beams were taken to verify the dependence of the spin tune on the local orbits at the Snakes. The experimental results are presented along with the comparison with analytical predictions.

• H.J. Kim, T. Sen
  Fermilab, Batavia

Beam collisions with a crossing angle at the interaction point are often necessary in colliders to reduce the effects of parasitic collisions which induce emittance growth and decrease beam lifetime. The crossing angle reduces the geometrical overlap of the beams and hence the luminosity. Crab cavity offer a promising way to compensate the crossing angle and to realize effective head-on collisions. Moreover, the crab crossing mitigates the synchro-betatron resonances due to the crossing angle. A crab cavity experiment in SPS is proposed as a proof of principle before deciding on a full crab-cavity implementation in the LHC. In this paper, we investigate the effects of a single crab cavity on beam dynamics in the SPS and life time.