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Title: Benchmarking of Multiparticle Phase Scan and Acceptance Scan techniques for the Spallation Neutron Source linac

Abstract

The importance of accurately setting the rf field amplitude and phase, called rf set-point is well received for a high intensity proton linac such as the Spallation Neutron Source (SNS) linac. As a technique to set the rf set-point of the SNS Drift Tube Linac (DTL), multiparticle phase scan technique based on realistic multiparticle tracking was applied and compared with the measurement data. The analysis showed an accurate agreement between the measurement and simulation even when the beam bunch is rather long (the Full Width Half Maximum beam bunch length entering the DTL tank 1 is about 27 a). Benchmarking of the multiparticle phase scan against acceptance scan showed an excellent agreement in the rf set-points obtained from the two techniques. The model was based on the realistic multiparticle tracking including space charge effect and the realistic BPM model unlike the previous works based on single particle tracking.

Authors:
 [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
981758
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment; Journal Volume: 578; Journal Issue: 2
Country of Publication:
United States
Language:
English

Citation Formats

Jeon, Dong-O. Benchmarking of Multiparticle Phase Scan and Acceptance Scan techniques for the Spallation Neutron Source linac. United States: N. p., 2007. Web. doi:10.1016/j.nima.2007.06.003.
Jeon, Dong-O. Benchmarking of Multiparticle Phase Scan and Acceptance Scan techniques for the Spallation Neutron Source linac. United States. doi:10.1016/j.nima.2007.06.003.
Jeon, Dong-O. Mon . "Benchmarking of Multiparticle Phase Scan and Acceptance Scan techniques for the Spallation Neutron Source linac". United States. doi:10.1016/j.nima.2007.06.003.
@article{osti_981758,
title = {Benchmarking of Multiparticle Phase Scan and Acceptance Scan techniques for the Spallation Neutron Source linac},
author = {Jeon, Dong-O},
abstractNote = {The importance of accurately setting the rf field amplitude and phase, called rf set-point is well received for a high intensity proton linac such as the Spallation Neutron Source (SNS) linac. As a technique to set the rf set-point of the SNS Drift Tube Linac (DTL), multiparticle phase scan technique based on realistic multiparticle tracking was applied and compared with the measurement data. The analysis showed an accurate agreement between the measurement and simulation even when the beam bunch is rather long (the Full Width Half Maximum beam bunch length entering the DTL tank 1 is about 27 a). Benchmarking of the multiparticle phase scan against acceptance scan showed an excellent agreement in the rf set-points obtained from the two techniques. The model was based on the realistic multiparticle tracking including space charge effect and the realistic BPM model unlike the previous works based on single particle tracking.},
doi = {10.1016/j.nima.2007.06.003},
journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
number = 2,
volume = 578,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The shielding at an accelerator-driven spallation neutron facility plays a critical role in the performance of the neutron scattering instruments, the overall safety, and the total cost of the facility. Accurate simulation of shielding components is thus key for the design of upcoming facilities, such as the European Spallation Source (ESS), currently in construction in Lund, Sweden. In this paper, we present a comparative study between the measured and the simulated neutron background at the Swiss Spallation Neutron Source (SINQ), at the Paul Scherrer Institute (PSI), Villigen, Switzerland. The measurements were carried out at several positions along the SINQ monolithmore » wall with the neutron dosimeter WENDI-2, which has a well-characterized response up to 5 GeV. The simulations were performed using the Monte-Carlo radiation transport code Geant4, and include a complete transport from the proton beam to the measurement locations in a single calculation. An agreement between measurements and simulations is about a factor of 2 for the points where the measured radiation dose is above the background level, which is a satisfactory result for such simulations spanning many energy regimes, different physics processes and transport through several meters of shielding materials. The neutrons contributing to the radiation field emanating from the monolith were confirmed to originate from neutrons with energies above 1 MeV in the target region. The current work validates Geant4 as being well suited for deep-shielding calculations at accelerator-based spallation sources. We also extrapolate what the simulated flux levels might imply for short (several tens of meters) instruments at ESS.« less
  • The shielding at an accelerator-driven spallation neutron facility plays a critical role in the performance of the neutron scattering instruments, the overall safety, and the total cost of the facility. Accurate simulation of shielding components is thus key for the design of upcoming facilities, such as the European Spallation Source (ESS), currently in construction in Lund, Sweden. In this paper, we present a comparative study between the measured and the simulated neutron background at the Swiss Spallation Neutron Source (SINQ), at the Paul Scherrer Institute (PSI), Villigen, Switzerland. The measurements were carried out at several positions along the SINQ monolithmore » wall with the neutron dosimeter WENDI-2, which has a well-characterized response up to 5 GeV. The simulations were performed using the Monte-Carlo radiation transport code Geant4, and include a complete transport from the proton beam to the measurement locations in a single calculation. An agreement between measurements and simulations is about a factor of 2 for the points where the measured radiation dose is above the background level, which is a satisfactory result for such simulations spanning many energy regimes, different physics processes and transport through several meters of shielding materials. The neutrons contributing to the radiation field emanating from the monolith were confirmed to originate from neutrons with energies above 1 MeV in the target region. The current work validates Geant4 as being well suited for deep-shielding calculations at accelerator-based spallation sources. We also extrapolate what the simulated flux levels might imply for short (several tens of meters) instruments at ESS.« less
  • No abstract prepared.
  • The use of superconducting radiofrequency (SRF) cavities in particle accelerator is becoming more widespread. Among the projects that make use of that technology is the Spallation Neutron Source, where H-ions are accelerated to about 1 GeV, mostly making use of niobium elliptical cavities. SNS will use the accelerated short (about 700 ns) sub-bunches of protons to generate neutrons by spallation, which will in turn allow probing structural and magnetic properties of new and existing materials. The SNS superconducting linac is the largest application of RF superconductivity to come on-line in the last decade. The SRF cavities, operated at 805 MHz,more » were designed, built and integrated into cryomodules at Jefferson Lab and installed and tested at SNS. SNS is also the first proton-like accelerator which uses SRF cavities in a pulse mode. Many of the details of the cavity performance are peculiar to this mode of operation, which is also being applied to lepton accelerators (TESLA test facility and X-FEL at DESY and the international linear collider project). Thanks to the low frequency of the SNS superconducting cavities, operation at 4.2 K has been possible without beam energy degradation, even though the cavities and cryogenic systems were originally designed for 2.1 K operation. The testing of the superconducting cavities, the operating experience with beam and the performance of the superconducting linac will be presented.« less
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