• S. Henderson
  

The Spallation Neutron Source (SNS) will be the world's leading pulsed neutron source, with design beam power capability of 1.4 MW. The SNS Construction Project was completed in June 2006. The accelerator complex was successfully commissioned during the construction phase of the project in seven discrete commissioning runs. The facility is now in the first of a three year performance ramp-up phase, in which the beam power, reliability and operating time will be increased to the baseline design values of 1.4 MW, 90% and 5000 hours respectively. Meanwhile, neutron scattering instruments are being constructed and commissioned in preparation for full user operations in 2009. The progress toward bringing the SNS to its full capabilities will be presented.

• L. Merminga
  

• A. Novokhatski
  

We describe the method to measure total HOM losses and synchrotron losses in a storage ring based on a straightforward model of beam-cavity interaction and precise knowledge of RF power distribution. This method works well at higher currents. The comparison of the measured HOM losses and estimation for cavity and resistive wall losses is given for both LER and HER rings of the PEP-II B-factory.

• S. V. Benson
  
• K. Beard, G. H. Biallas, J. Boyce, D. B. Bullard, J. L. Coleman, D. Douglas, H. F.D. Dylla, R. Evans, P. Evtushenko, C. W. Gould, A. C. Grippo, J. G. Gubeli, D. Hardy, C. Hernandez-Garcia, C. Hovater, K. Jordan, J. M. Klopf, R. Li, S. W. Moore, G. Neil, M. Poelker, T. Powers, J. P. Preble, R. A. Rimmer, D. W. Sexton, M. D. Shinn, C. Tennant, R. L. Walker, G. P. Williams, S. Zhang
  Jefferson Lab, Newport News, Virginia

Operation of the JLab IR Upgrade FEL at CW powers in excess of 10 kW requires sustained production of high electron beam powers by the driver ERL. This in turn demands attention to numerous issues and effects, including: cathode lifetime; control of beamline and RF system vacuum during high current operation; longitudinal space charge; longitudinal and transverse matching of irregular/large volume phase space distributions; halo management; management of remnant dispersive effects; resistive wall, wake-field, and RF heating of beam vacuum chambers; the beam break up instability; the impact of coherent synchrotron radiation (both on beam quality and the performance of laser optics); magnetic component stability and reproducibility; and RF stability and reproducibility. We discuss our experience with these issues and describe the modus vivendi that has evolved during prolonged high current, high power beam and laser operation.

• H. Harada
  
• K. Furukawa
  KEK, Ibaraki
• H. Hotchi, Y. Irie, F. Noda, H. Sako, H. Suzuki
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• K. Shigaki
  Hiroshima University, Higashi-Hiroshima

• S. Redaelli
  
• R. W. Assmann, P. Gander, M. Jonker, M. Lamont, R. Losito, A. Masi, M. Sobczak
  CERN, Geneva

• R. W. Shaw
  
• M. J. Borden, T. Spickermann
  LANL, Los Alamos, New Mexico
• C. S. Feigerle
  University of Tennessee, Knoxville, Tennessee
• Y. Irie
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• M. A. Plum, L. L. Wilson
  ORNL, Oak Ridge, Tennessee
• I. Sugai, A. Takagi
  KEK, Ibaraki

Diamond stripping foils are under development for the SNS. Free-standing, flat 350 microgram/cm² foils as large as 17 x 25 mm have been prepared. These nano-textured polycrystalline foils are grown by microwave plasma-assisted chemical vapor deposition in a corrugated format to maintain their flatness. They are mechanically supported on a single edge by a residual portion of their silicon growth substrate; typical fine foil supporting wires are not required for diamond foils. Six foils were mounted on the SNS foil changer in early 2006 and have performed well in commissioning experiments at reduced operating power. A diamond foil was used during a recent experiment where 12 microCoulombs of protons, approximately 40% of the design value, were stored in the ring. A few diamond foils have been tested at LANSCE/PSR, where one foil was in service for a period of five months (820 Coulombs of integrated injected charge) before it was replaced. Diamond foils have also been tested in Japan at KEK (650 keV H-) where their lifetimes slightly surpassed those of evaporated carbon foils, but fell short of those for Sugai's new hybrid boron carbon (HBC) foils.

• S. M. Cousineau
  
• S. Assadi, J. A. Holmes, M. A. Plum
  ORNL, Oak Ridge, Tennessee

The SNS ring and associated transport lines, commissioned in January 2006, are designed to accumulate and deliver up to 1.5·10¹⁴, 1 GeV protons at 60 Hz to a liquid mercury target for neutron production. In order to control activation and to allow for routine hands-on maintenance of accelerator components, beam loss in most of the ring must remain below 1 W/m . For the full 1.4 MW beam, this translates to a fractional beam loss limit of 0.01%. Accomplishing this loss limit at full beam power will require successful utilization of the ring's two-stage betatron collimation system. In this paper we present the results of initial collimation experiments. We characterize the collimation-induced beam-loss pattern and compare our results with simulations. In addition, we discuss other existing beam-loss-related challenges in the ring.

• K. A. Drees
  
• L. Ahrens, J. G. Alessi, M. Bai, D. S. Barton, J. Beebe-Wang, M. Blaskiewicz, J. M. Brennan, K. A. Brown, D. Bruno, J. J. Butler, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, W. Fischer, W. Fu, G. Ganetis, J. Glenn, M. Harvey, T. Hayes, H.-C. Hseuh, H. Huang, J. Kewisch, R. C. Lee, V. Litvinenko, Y. Luo, W. W. MacKay, G. J. Marr, A. Marusic, R. J. Michnoff, C. Montag, J. Morris, B. Oerter, F. C. Pilat, V. Ptitsyn, T. Roser, J. Sandberg, T. Satogata, C. Schultheiss, F. Severino, K. Smith, S. Tepikian, D. Trbojevic, N. Tsoupas, J. E. Tuozzolo, A. Zaltsman, S. Y. Zhang
  BNL, Upton, Long Island, New York

After the last successful RHIC Au-Au run in 2004 (Run-4), RHIC experiments now require significantly enhanced luminosity to study very rare events in heavy ion collisions. RHIC has demonstrated its capability to operate routinely above its design average luminosity per store of 2x10²⁶ cm^-2 s^-1. In Run-4 we already achieved 2.5 times the design luminosity in RHIC. This luminosity was achieved with only 40% of bunches filled, and with β* = 1 m. However, the goal is to reach 4 times the design luminosity, 8x10²⁶ cm^-2 s^-1, by reducing the beta* value and increasing the number of bunches to the accelerator maximum of 111. In addition, the average time in store should be increased by a factor of 1.1 to about 60% of calendar time. We present an overview of the changes that increased the instantaneous luminosity and luminosity lifetime, raised the reliability, and improved the operational efficiency of RHIC Au-Au operations during Run-7.

• K. Seiya
  
• T. Berenc, B. Chase, J. E. Dey, P. W. Joireman, I. Kourbanis, J. Reid
  Fermilab, Batavia, Illinois

• G. Franchetti
  

• R. Duperrier
  
• D. Uriot
  CEA, Gif-sur-Yvette

• R. J. Macek, M. J. Borden, A. A. Browman, R. J. Macek, R. C. McCrady, J. F. O'Hara, L. Rybarcyk, T. Spickermann, T. Zaugg
  LANL, Los Alamos, New Mexico
• J. E. Ledford
  TechSource, Santa Fe, New Mexico
• M. T.F. Pivi
  SLAC, Menlo Park, California

Recent beam physics studies on the two-stream e-p instability at LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Experimental results will be presented on various characteristics of electron cloud obtain from experiments using this diagnostic and compared with simulations. Results include data on flux and energy spectra of electrons striking the vacuum chamber, the line density and lifetime of electrons trapped in the quadrupole after the beam has been extracted as well as evidence regarding electrons ejected from the magnet during passage of the proton beam.

• R. Schmidt
  
• R. W. Assmann, E. Carlier, B. Dehning, R. Denz, B. Goddard, E. B. Holzer, V. Kain, B. Puccio, B. Todd, J. A. Uythoven, J. Wenninger, M. Zerlauth
  CERN, Geneva

• C. Omet
  
• D. Hoffmann, P. J. Spiller
  GSI, Darmstadt

Beam loss caused by charge changing process in connection with dynamic vacuum effects may limit the maximum number of accelerated heavy ions with low charge states in the existing synchrotron SIS18 and the planned SIS100/SIS300 of the FAIR project. With the aim to stabilize the vacuum dynamics and to control ionization beam loss, a substantial upgrade program has been defined for SIS18 and is presently realized. For SIS100, a new lattice design concept has been developed, where each lattice cell acts as a charge seperator and thereby enables the local control of beam loss. Simulation, conducted with the code STRAHLSIM, of the time dependent evolution of beam loss, dynamic residual gas pressure and the effect of the proposed dedicated ion catcher systems will be presented.

• H. Akikawa
  
• Z. Igarashi, M. Ikegami, S. Lee
  KEK, Ibaraki
• S. Sato, T. Tomisawa, A. Ueno
  JAEA/LINAC, Ibaraki-ken
• G. B. Shen
  JAEA, Ibaraki-ken

• M. Tomizawa
  
• A. Y. Molodozhentsev, M. J. Shirakata
  KEK, Ibaraki

• M. Tomizawa
  
• A. Y. Molodozhentsev, E. Nakamura, I. Sakai, M. Uota
  KEK, Ibaraki

• P. K. Saha
  
• H. Hotchi, Y. Irie, F. Noda
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

• H. Burkhardt
  
• G. Arduini, S. Bart Pedersen, C. Fischer, JJ. G. Gras, A. Koschik, D. K. Kramer, S. Redaelli
  CERN, Geneva

• V. Kain
  
• E. Carlier, E. H.R. Gaxiola, B. Goddard, M. Gourber-Pace, E. Gschwendtner, M. Meddahi, H. Vincke, H. Vincke, J. Wenninger
  CERN, Geneva

• T. Kramer
  
• G. Arduini, O. E. Berrig, E. Carlier, L. Ducimetiere, B. Goddard, A. Koschik, J. A. Uythoven
  CERN, Geneva

• A. Gomez Alonso
  
• R. Schmidt
  CERN, Geneva

• Th. Weiler
  
• G. Arduini, R. W. Assmann, C. B. Bracco, H.-H. Braun, B. Dehning, P. Gander, E. B. Holzer, M. Jonker, R. Losito, A. Masi, L. Ponce, S. Redaelli, G. Robert-Demolaize, M. Sobczak, J. Wenninger
  CERN, Geneva

• M. A. Clarke-Gayther
  

A description is given of slow-wave chopper structures for the 3.0 MeV, 60 mA, H^- MEBT lines of the CERN Linac 4 and RAL Front-End Test Stands (FETS). Transmission line properties and transverse E-field uniformity for the original European Spallation Source (ESS) designs* have been refined by modelling static, and time dependent electromagnetic fields in the 3D CST 'EM Studio', and 'Microwave Studio' codes**. In addition, the original compact, radiation hard, vacuum compatible designs have been simplified and reconfigured to be compatible with standard NC machining practice. Transmission line properties in the frequency and time domain, together with E-field uniformity in the axial and transverse planes, are presented.

* M. A. Clarke-Gayther, 'Slow-wave electrode structures for the ESS 2.5 MeV fast chopper', Proc. of the 2003 Particle Accelerator Conference (PAC), Portland, Oregon, USA, p. 1473-1475.** www.cst.com

• A. Seville
  
• D. J. Adams, C. W. Appelbee, D. Bayley, N. E. Farthing, I. S.K. Gardner, M. G. Glover, B. G. Pine, J. W.G. Thomason, C. M. Warsop
  STFC/RAL/ISIS, Chilton, Didcot, Oxon

• P. N. Ostroumov
  
• B. Mustapha, J. A. Nolen
  ANL, Argonne, Illinois

The Advanced Exotic Beam Laboratory (AEBL) being developed at ANL consists of an 833 MV heavy-ion driver linac capable of producing uranium ions up to 200 MeV/u and protons to 580 MeV with 400 kW beam power. We have designed all accelerator components including a two charge state LEBT, an RFQ, a MEBT, a superconducting linac, a stripper section and beam switchyard. We present the results of an optimized linac design and end-to-end simulations which include possible machine errors.

• B. C. Brown
  
• P. Adamson, D. Capista, D. E. Johnson, I. Kourbanis, D. K. Morris, M.-J. Yang
  Fermilab, Batavia, Illinois

High intensity operation of the Fermilab Main Injector has resulted in increased activation of machine components. Efforts to permit operation at high power include creation of collimation systems to localize losses away from locations which require maintenance. As a first step, a collimation system to remove halo from the incoming beam was installed in the Spring 2006 Facility Shutdown*. We report on commissioning studies and operational experience including observations of Booster beam properties, effects on Main Injector loss and activation, and operational results.

* B. C. Brown, et al., "Collimation System for the Fermilab Booster to Main Injector Transfer Line", this conference.

• W. Chou
  
• C. L. Bartelson, B. C. Brown, D. Capista, J. L. Crisp, J. DiMarco, J. Fitzgerald, H. D. Glass, D. J. Harding, B. Hendricks, D. E. Johnson, V. S. Kashikhin, I. Kourbanis, W. F. Robotham, T. Sager, M. Tartaglia, L. Valerio, R. C. Webber, M. Wendt, D. Wolff, M.-J. Yang
  Fermilab, Batavia, Illinois

A two-year Large Aperture Quadrupole (WQB) Project was completed in the summer of 2006 at Fermilab.* Nine WQBs were designed, fabricated and bench-tested by the Technical Division. Seven of them were installed in the Main Injector and the other two for spares. They perform well. The aperture increase meets the design goal and the perturbation to the lattice is minimal. The machine acceptance in the injection and extraction regions is increased from 40π to 60π mm-mrad. This paper gives a brief report of the operation and performance of these magnets. Details can be found in Ref**.

* D. Harding et al, "A Wide Aperture Quadrupole for the Fermilab Main Injector," this conference.
** W. Chou, Fermilab Beams-doc-#2479, http://beamdocs.fnal.gov/AD-public/DocDB/DocumentDatabase

• A. I. Drozhdin
  
• B. C. Brown, D. E. Johnson, I. Kourbanis, N. V. Mokhov, I. Rakhno, V. Sidorov
  Fermilab, Batavia, Illinois
• K. Koba
  KEK, Ibaraki

• D. E. Johnson
  

• A. I. Drozhdin
  
• W. Pellico, X. Yang
  Fermilab, Batavia, Illinois

• A. I. Drozhdin
  
• W. Pellico, X. Yang
  Fermilab, Batavia, Illinois

• A. V. Aleksandrov
  
• S. Assadi, W. Blokland, P. Chu, S. M. Cousineau, V. V. Danilov, C. Deibele, J. Galambos, S. Henderson, D.-O. Jeon, M. A. Plum, A. P. Shishlo, M. P. Stockli, Y. Zhang
  ORNL, Oak Ridge, Tennessee

The Spallation Neutron Source accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H^- injector, capable of producing one-ms-long pulses at 60 Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The 2.5 MeV beam from the Front End is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in the Superconducting Linac. With the completion of beam commissioning, the accelerator complex began operation in June 2006 and beam power is being gradually ramped up toward the design goal. Operational experience with the injector and linac will be presented including chopper performance, transverse emittance evolution along the linac, and the results of a beam loss study.

• W. Fischer
  
• N. P. Abreu, R. Calaga, G. Robert-Demolaize
  BNL, Upton, Long Island, New York
• U. Dorda, J.-P. Koutchouk, F. Zimmermann
  CERN, Geneva
• A. C. Kabel
  SLAC, Menlo Park, California
• H. J. Kim, T. Sen
  Fermilab, Batavia, Illinois
• J. Qiang
  LBNL, Berkeley, California

A DC wire has been installed in RHIC to explore the long-range beam-beam effect, and test its compensation. We report on experiments that measure the effect of the wire's electro-magnetic field on the beam's lifetime and tune distribution, and accompanying simulations.

• Y. Hao
  
• V. Litvinenko, C. Montag, E. Pozdeyev, V. Ptitsyn
  BNL, Upton, Long Island, New York

Beam-beam effects present one of major factors limiting the luminosity of colliders. In the linac-ring option of eRHIC design, an electron beam accelerated in a superconducting energy recovery linac collides with a proton beam circulating in the RHIC ring. There are some features of beam-beam effects which require careful examination in linac-ring configuration. First, the beam-beam interaction can induce specific head-tail type instability of the proton beam referred to as kink instability. Thus, beam stability conditions should be established to avoid proton beam loss. Also, the electron beam transverse disruption by collisions has to be evaluated to ensure beam quality is good enough for the energy recovery pass. In addition, fluctuations of electron beam current and/or electron beam size, as well as transverse offset, can cause proton beam emittance growth. The tolerances for those factors should be determined and possible countermeasures should be developed to mitigate the emittance growth. In this paper, a soft Gaussian strong-strong simulation is used to study all of mentioned beam-beam interaction features and possible techniques to reduce the emittance growth.

• S. Wang
  
• F. R. Brumwell, J. C. Dooling, K. C. Harkay, R. Kustom, G. E. McMichael, M. E. Middendorf, A. Nassiri
  ANL, Argonne, Illinois

The Intense Pulsed Neutron Source (IPNS) Rapid Cycling Synchrotron (RCS) accelerates 3.2x 10¹² protons from 50 MeV to 450 MeV at 30 Hz. During the 14.2 ms acceleration period, the RF frequency varies from 2.21 MHz to 5.14 MHz. The beam current is limited by a vertical instability. By analyzing turn-by-turn Beam Position Monitor (BPM) data, large amplitude mode 0 and mode 1 vertical beam centroid oscillations were observed in the later part of the acceleration cycle. The oscillations develop in the tail of the bunch, build up and remain localized in the later part of the bunch. This vertical instability was compared with a head-tail instability that was intentionally induced in the RCS by adjusting the trim-sextupoles to make the horizontal chromaticity positive (below transition). It appears that our vertical instability is not typical head-tail instability. More data analysis and experiments were performed to characterize the instability.

• M. J. Barnes
  
• T. Fowler, G. Ravida
  CERN, Geneva
• A. Ueda
  KEK, Ibaraki

• Y. Zhang
  
• M. S. Champion, P. Chu, S. M. Cousineau, V. V. Danilov, T. W. Hardek, J. A. Holmes, H. Ma, M. F. Piller, M. A. Plum
  ORNL, Oak Ridge, Tennessee

A simulation code has been developed for the study of the Spallation Neutron Source (SNS) ring RF control. The code uses the time-domain solvers to compute beam-cavity interactions, and FFT methods to simulate time responses of the linear RF system. The important ingredients of the system are considered in the simulation model, which include the beam loading, dynamic cavity detuning, circuit bandwidth, loop delay, proportional-integral (P-I) controller for feedback and adaptive feed forward, stochastic noise, with-in-turn RF parameter change, beam current fluctuation and beam bunch leakage, etc. The beam loss in the accumulation ring goes up as the beam power increases, and thus a precise control of bunching voltage phase and amplitude is required to limit beam loss. This simulation tool will help the development a correct RF control and to achieve the goal of minimizing the beam loss.

• M. A. Plum
  

The Spallation Neutron Source accelerator complex consists of a 2.5 MeV H^- front-end injector system, a 186 MeV normal-conducting linear accelerator, a 1 GeV superconducting linear accelerator, an accumulator ring, and associated beam transport lines. The linac was commissioned in five discrete runs, starting in 2002 and completed in 2005. The accumulator ring and associated beam transport lines were commissioned in two runs in February and April 2006. With the completed commissioning of the SNS accelerator, the facility has begun initial low-power operations. In the course of beam commissioning, most beam performance parameters and beam intensity goals have been achieved at low duty factor. A number of beam dynamics measurements have been performed, including emittance evolution, transverse coupling in the ring, beam instability thresholds, and beam distributions on the target. The commissioning results, achieved beam performance and initial operating experience of the SNS will be presented.

• O. R. Jones
  

• W. Blokland
  
• J. G. Patton, T. A. Pelaia, T. R. Pennisi, J. D. Purcell, M. Sundaram
  ORNL, Oak Ridge, Tennessee

The Spallation Neutron Source (SNS) accelerator systems are ramping up to deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. Enhancements or additions have been made to several diagnostics instruments to support the ramp up in intensity, improve reliability, and/or add functionality. The Beam Current Monitors now support increased rep rates, the Harp system now includes charge density calculations for the target, and a new system has been created to collect data for the beam accounting and present the data over the web and to the operator consoles. Many of the instruments are PC-based and a way to manage their instrument configuration files through the Oracle database has been implemented. A new version for the wire scanner software has been developed and is under test. This paper also includes data from the various instruments.

• R. Appleby
  
• D. A.-K. Angal-Kalinin
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• P. Bambade, S. Cavalier, O. Dadoun
  LAL, Orsay
• D. Toprek
  UMAN, Manchester

• A. I. Drozhdin
  
• L. Keller
  SLAC, Menlo Park, California
• N. V. Mokhov, N. Nakao, S. I. Striganov
  Fermilab, Batavia, Illinois

• C. Zhang
  
• M. Busch, H. Klein, H. Podlech, U. Ratzinger
  IAP, Frankfurt am Main

EUROTRANS (EUROpean Research Programme for the TRANSmutation of High Level Nuclear Waste in an Accelerator Driven System) is calling for an efficient high-current CW front-end accelerator system. A combination of RFQ, normal conducting CH^- (Crossbar H-mode) and super-conducting CH-DTL which aims to work at 352MHz and accelerate a 30mA proton beam to 17MeV has been studied as a promising candidate. The preliminary conceptual study results are reported with respect to beam dynamics design.

• K. Ohmi
  
• S. Igarashi, H. Koiso, T. Koseki, K. Oide
  KEK, Ibaraki

• J. Barranco
  
• O. E. Berrig, S. S. Gilardoni, J. B. Jeanneret, Y. Papaphilippou
  CERN, Geneva
• G. Robert-Demolaize
  BNL, Upton, Long Island, New York

• A. Xiao
  
• M. Borland
  ANL, Argonne, Illinois

The Touschek effect is a major concern for lepton storage rings of low emittance (i.e., high bunch density) and low or moderate beam energy, such as third-generation synchrotron light sources. Piwinski's formula, which includes beam shape variation along the beamline and which is suitable for any beam energy, has been incorporated into a program that interoperates with elegant for use in lifetime calculations. The difference between using Piwinski's method and other simplified methods for the APS is shown in this paper. Furthermore, because of the generality of this formula, we also applied it to transport lines to predict beam loss rates and beam loss locations for the first time. An example related to a possible energy recovery linac upgrade of the APS (APS-ERL) is also given in this paper.

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

• Y. Sato
  
• J. A. Holmes
  ORNL, Oak Ridge, Tennessee
• S.-Y. Lee
  IUCF, Bloomington, Indiana
• R. J. Macek
  LANL, Los Alamos, New Mexico

We present ORBIT code simulations to examine the sensitivity of electron cloud properties to different proton beam profiles and to reproduce experimental results from the proton storage ring at Los Alamos National Laboratory. We study the recovery of electron clouds after sweeping, and also the characteristics of two types of electrons signals (prompt and swept) as functions of beam charge. The prompt signal means the peak height of electron sweeper signal before high voltage pulse applied on its electrode and after beam accumulation, and the swept signal means the spike height of electron sweeper signal during the high voltage pulse. To concentrate on the electron cloud dynamics, we use a cold proton bunch to generate primary electrons and electromagnetic field for electron dynamics. However, the protons receive no feedback from the electron cloud. Our simulations indicate that the proton loss rate in the field-free straight section might be an exponential function of proton beam charge and may also be lower than the averaged proton loss rate in a whole ring.

• K. R. Samokhvalova
  
• C. Chen, J. Z. Zhou
  MIT/PSFC, Cambridge, Massachusetts

A warm-fluid theory of a thermal equilibrium for a rotating charged particle beam in a periodic solenoidal focusing magnetic field is presented. The warm-fluid equilibrium equations are solved in the paraxial approximation. It is shown that the flow velocity for the thermal equilibrium corresponds to periodic rigid rotation and radial pulsation. The equation of state for the thermal equilibrium is adiabatic. The beam envelope equation and self-consistent Poisson's equation are derived. The numerical algorithm for solving self-consistent Poisson's equation is discussed. Density profiles are calculated numerically for high-intensity beams. Temperature effects in such beams are investigated, and the validity of the warm-fluid theory is discussed. Examples of electron and ion beams are presented for space-charge-dominated beam and high energy density physics (HEDP) research.

• T. P. Wangler
  
• V. N. Aseev, B. Mustapha, P. N. Ostroumov
  ANL, Argonne, Illinois
• J. H. Billen, R. W. Garnett
  LANL, Los Alamos, New Mexico
• K. R. Crandall
  TechSource, Santa Fe, New Mexico
• M. Doleans, D. Gorelov, X. Wu, R. C. York, Q. Zhao
  NSCL, East Lansing, Michigan
• J. Qiang, R. D. Ryne
  LBNL, Berkeley, California

RIAPMTQ/IMPACT is a pair of linked beam-dynamics simulation codes that have been developed for end-to-end computer simulations of multiple-charge state heavy-ion linacs for future exotic-beam facilities. The simulations can extend from the low-energy beam transport after the ECR source to the end of the linac. The work has been performed by a collaboration including LANL, LBNL, ANL, MSU, and TechSource. The code RIAPMTQ simulates the linac front end including the LEBT, RFQ, and MEBT, and the code IMPACT simulates the main superconducting linac. The codes have been benchmarked for rms beam properties against previously existing codes at ANL and MSU. The codes allow high-statistics runs on parallel supercomputing platforms, such as NERSC at LBNL, as well as runs on desktop PC computers for low-statistics design work. We will show results from 10-million-particle simulations of RIA designs by ANL and MSU, carried out at the NERSC facility. These simulation codes will allow evaluations of candidate designs with respect to beam-dynamics performance including beam losses.

• J. A. Holmes
  
• M. R. Perkett
  Denison University, Granville, Ohio
• M. A. Plum, J.-G. Wang, Y. Zhang
  ORNL, Oak Ridge, Tennessee

Simulations of the transport of H⁰ and H^- beams to the SNS ring injection dump are carried out using the ORBIT code. During commissioning and early operations, beam losses in this region have been the highest in the accelerator and presented the most obvious hurdle to cross in achieving high intensity operation. Two tracking models are employed:

1. a piecewise continuous symplectic representation of the lattice elements in the injection chicane and dump line, and
2. particle tracking in full 3D magnetic fields, as obtained from OPERA code evaluations.

• J.-G. Wang
  

The SNS ring injection dump beam line has been suffering high beam losses since its commissioning. In order to understand the mechanisms of the beam losses, we have built a 3D simulation model consisting of three injection chicane dipoles and one injection dump septum. The magnetic field distributions and the 3D particle trajectories in the model are obtained. The study has clearly shown two design problems causing beam losses in the injection dump beam line. This paper reports our simulation model, particle trajectory calculations, beam losses due to small vertical aperture of the injection dump septum and inadequate focusing down stream. The remedy of the beam losses is also discussed.

• T. S. Dixit
  
• Y. Shimosaki, K. Takayama
  KEK, Ibaraki

* K. Takayama et al., "Experimental Result of the Induction Synchrotron", appear in Phys. Rev. Lett. (2007) and in this conference.

• A. P. Zhukov
  
• S. Assadi
  ORNL, Oak Ridge, Tennessee

We are developing a sophisticated system of beam loss pattern evaluation and residual radiation estimation. We have installed a number of Neutron Detectors and Ionization Chambers along LINAC. In this paper we present our implementation and simulation of the losses by inserting Faraday Cups, using Beam Stops and running Wire Scanners at different energies. The measured losses are simulated by 3-D transport codes (GEANT4, SHIELD, MCNPX). We compare two different sets of Beam Loss Monitors: Ionization Chambers (detecting X-ray and gamma radiation) and Photo-Multiplier Tubes with a neutron converter (detecting neutrons) and outline that such a combination is a better way to measure beam losses than relying on detectors of one type. We interpret the loss signal in terms of beam current lost in the SNS LINAC with accurate longitudinal loss distribution and plan to automate beam steering according to loss monitors readings by using vast Loss Pattern Database developed by simulating different loss scenarios with the transport codes.

• B. Dehning
  
• E. Effinger, J. E. Emery, G. Ferioli, G. Guaglio, E. B. Holzer, D. K. Kramer, L. Ponce, V. Prieto, M. Stockner, C. Zamantzas
  CERN, Geneva

• M. R.W. North
  

• B. Sayyar-Rodsari
  
• W. J. Corbett, M. J. Lee, P. Lui, J. M. Paterson
  SLAC, Menlo Park, California
• E. Hartman, C. A. Schweiger
  Pavilion Technologies, Inc, Austin, Texas

Synchrotron light is used for a wide variety of scientific disciplines ranging from physical chemistry to molecular biology and industrial applications. As the electron beam circulates, random single-particle collisional processes lead to decay of the beam current in time. We report a simulation study in which a combined neural network (NN) and first-principles (FP) model is used to capture the decay in beam current due to Touschek, Bremsstralung, and Coulomb effects. The FP block in the combined model is a parametric description of the beam current decay where model parameters vary as a function of beam operating conditions (e.g. vertical scraper position, RF voltage, number of the bunches, and total beam current). The NN block provides the parameters of the FP model and is trained (through constrained nonlinear optimization) to capture the variation in model parameters as operating condition of the beam changes. Simulation results will be presented to demonstrate that the proposed combined framework accurately models beam decay as well as variation to model parameters without direct access to parameter values in the model.

• J. D. Gilpatrick
  
• B. Blind, M. J. Borden, J. L. Erickson, M. S. Gulley, S. S. Kurennoy, R. C. McCrady, J. F. O'Hara, M. A. Oothoudt, C. Pillai, J. F. Power, L. Rybarcyk, F. E. Shelley
  LANL, Los Alamos, New Mexico

Presently, the Los Alamos National Laboratory is in the process of planning a refurbishment of various sub-systems within its Los Alamos Neutron Science Center accelerator facility. A part of this LANSCE facility refurbishment will include some replacement of and improvement to existing older beam diagnostics instrumentation. While plans are still being discussed, some instrumentation that is under improvement or replacement consideration are beam phase and position measurements within the 805-MHz side-coupled cavity linac, slower wire profile measurements, typically known as wire scanners, and possibly additional installation of fast ionization-chamber loss monitors. This paper will briefly describe the requirements for these beam measurements, what we have done thus far to answer these requirements, and some of the technical issues related to the implementation of these instrumentation.

• W. J. Corbett
  
• X. Huang, M. J. Lee, P. Lui
  SLAC, Menlo Park, California
• B. Sayyar-Rodsari
  Pavilion Technologies, Inc, Austin, Texas

The primary contributing factors to electron beam lifetime in a storage ring are elastic and inelastic gas scattering, and intrabeam scattering. In order to further quantify the relative contributions of each mechanism, a series of measurements using vertical scraper position and rf-voltage sweeps were performed in SPEAR3 with fill patterns featuring different single-bunch and total beam currents. In parallel, an analytic beam-lifetime simulator was developed taking scattering cross-sections, rf-bucket height and bunch lengthening effects into account. In this paper, we compare measured results with the simulated results in an effort to develop a comprehensive model for electron beam lifetime under a variety of operating conditions.

• L. Wang
  
• A. Chao
  SLAC, Menlo Park, California
• J. Wei
  BNL, Upton, Long Island, New York

• E. Pozdeyev
  
• I. Ben-Zvi, P. Cameron, K. A. Drees, D. M. Gassner, D. Kayran, V. Litvinenko, G. J. Mahler, T. Rao
  BNL, Upton, Long Island, New York

The ERL Prototype project is currently under development at the Brookhaven National Laboratory. The ERL is expected to demonstrate energy recovery of high-intensity beams with a current of up to a few hundred milliamps, while preserving the emittance of bunches with a charge of a few nanocoulombs produced by a high-current SRF gun. To successfully accomplish this task the machine will include beam diagnostics that will be used for accurate characterization of the three dimensional beam phase space at the injection and recirculation energies, transverse and longitudinal beam matching, orbit alignment, beam current measurement, and machine protection. This paper outlines requirements on the ERL diagnostics and describes its setup and modes of operation.