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Galambos, J.

Paper Title Page
OPL01 High Intensity Challenges at the Spallation Neutron Source 1
 
  • J. Galambos
    ORNL, Oak Ridge, Tennessee
 
 

The Spallation Neutron Source is designed to produce 1.4 MW of beam power on a mercury target produced in short (1 μSec) pulses at 60 Hz with a 1 GeV beam. Since the initial beam operations in Oct. 2006, the Spallation Neutron Source has operated production runs with beam power up to 520 kW. Apart from equipment issues, the primary challenge in power ramp up is beam loss. Suspected causes of observed beam loss will be discussed. While not contributing to beam loss at present operational parameters, evidence of collective effects is seen at higher intensities, and will be presented. Other issues of interest at high intensity include foil survivability, and maintaining acceptable power density on the neutron production target

 

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WGA15 Orbit Response Matrix Analysis Applied at SNS Ring 89
 
  • Z. Liu
    IUCF, Bloomington, Indiana
  • S.M. Cousineau, J. Galambos, J.A. Holmes, M.A. Plum
    ORNL, Oak Ridge, Tennessee
  • X. Huang
    SLAC, Menlo Park, California
 
 

Recently, discrepancies between model-based and observed linear optics, such as the tune and the closed orbit, have been observed in the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Accurate accelerator modeling is very important for machine control during the ongoing power ramp up. The Orbit Response Matrix (ORM) method is applied here to find and correct errors in the linear optics of the SNS ring. With the closed orbit data (4472 data points), we are able to calibrate the strength of the steering magnets, the BPM gain factors, and 6 quadrupole power supplies. Current results and remaining challenges will be presented and discussed.

 
WGD03 The SNS Power Rampup 338
 
  • J. Galambos
    ORNL, Oak Ridge, Tennessee
 
 

Since the start of neutron production in October of 2006, the average beam power level has increased from ~ 5 kW to over 500 kW. This increased has been realized by increases in the beam current, pulse length and repetition rate. Equipment issues encountered during this ramp-up will be discussed along with mitigation efforts. A major concern in the power ramp up has been minimization of uncontrolled beam loss. The beam loss levels, loss reduction efforts, and experience levels with residual activation will be discussed. Also the operational run cycles will be discussed, with an evolution in emphasis from beam-studies to neutron production.

 

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WGD10 Residual Dose Rate Analyses for the SNS Accelerator Facility 371
 
  • I.I. Popova, P.D. Ferguson, J. Galambos, F. X. Gallmeier
    ORNL, Oak Ridge, Tennessee
 
 

The Spallation Neutron Source accelerator is a neutron scattering facility for materials research that recently started operations and presently is in the process of power ramp-up to reach mega-watt power level within a year in cycles of operations and maintenance and tuning periods. The structural materials inside the accelerator tunnel are activated by protons beam losses and by secondary particles. Secondary particles appear due to spallation reactions caused by the proton losses, and produce the residual radiation after shut down in the tunnel environment. In order to plan maintenance work after each operations period, residual dose measurements are taking at 30 cm distance from the accelerator structures and on contact. During normal operation, beam losses and beam scenario are recorded and used as a source to calculate expected residual dose rates after shut down. Calculation analyses are performed using the transport code MCNPX followed by the activation calculation script, which uses the nuclear inventory code CINDER’90, then converting gammas production spectra and gamma power to the dose rates. Calculated results for various locations are compared with measured data.

 

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WGD13 SNS Beam Commissioning Tools and Experience 382
 
  • A.P. Shishlo, J. Galambos
    ORNL, Oak Ridge, Tennessee
 
 

The paper describes a parallel flow of the Spallation Neutron Source (SNS) linac and ring commissioning and development of commissioning tools. An evolution of the physics control system, its features, problems and solutions are presented. The peculiarities of the SNS project such as a collaboration between six Department of Energy laboratories, an absence of previous experience in large accelerator construction and operation in Oak Ridge National Laboratory, an original upper level of a control system (physics applications) and their effect on SNS commissioning are discussed. SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

 

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WGF13 Extracting Information Content within Noisy, Sampled Profile Data from Charged Particle Beams 479
 
  • C.K. Allen, W. Blokland, S.M. Cousineau, J. Galambos
    ORNL, Oak Ridge, Tennessee
 
 

Charged-particle beam diagnostic devices such as wire scanners and wire harps provide data sets describing the one-dimensional density distributions at a particular location; these data are commonly called profile data. We use these data for further computations, usually beam properties such as position and size. Typically these data require subjective, human, processing to extract meaningful results; this is inefficient and labor intensive. Our ultimate goal is to automate these computations, at least streamline the process. If we hope to implement any type of automation we must make real world considerations. Specifically, we consider information content, noise in the data, and sampling theory. Within this framework we create a general model for the data sets. Using signal processing techniques we identify the minimal sampling requirements for maintaining information content. Using Bayesian analysis we identify the most probable Gaussian signal within the data. We present the major obstacles currently faced concerning robust automation techniques.

 

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CPL04 Commissioning Strategies, Operations and Performance, Beam Loss Management, Activation, Machine Protection 489
 
  • J. Galambos
    ORNL, Oak Ridge, Tennessee
  • T. Koseki
    KEK, Ibaraki
 
 

The working group D covered

  1. commissioning aspects of new high power machines,
  2. operational aspects of existing high power machines, and
  3. comparison of modeling and measurements of residual activation buildup.
During discussions in this working group different institutes shared experiences, which are summarized here.

 

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