IPAC2017 - Classification: 06 Beam Instrumentation, Controls, Feedback and Operational Aspects / T18 Radiation Monitoring and Safety

Paper	Title	Page
TUPAB133	Perturbation Analysis for Beam Trajectories. Determining Local Shielding Containment for LCLS-II	1637
	M. Santana-Leitner SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515 Containment of beam losses by halo and momentum/energy collimators is a well-established practice for normal operation of particle accelerators where tracking codes are applied. However, for exceptional events, such as magnet power failures, severe lattice mis-match, etc., ad-hoc analytical approaches are typically applied. Oftentimes those simplified methods are not automatic; they don't define the full phase-space of mis-steered trajectories and cannot keep up with beam-line upgrades. Moreover, there may exist a disconnect between the teams analyzing consequences of errant beams and those involved in beam-line design. With electron beams exceeding 100 kW, design of LCLS-II at SLAC National Accelerator Laboratory required exhaustive beam-containment studies to avoid potential destruction of components and excessive dose rates. The geometry of the different beam-lines and the nominal optics was built with MadFLUKA [1], and FLUKA [2] Monte Carlo code along with perturbations to magnetic fields was used to inspect failures compatible with beam operations and hardware settings. Consequences of mis-steered rays and the respective mitigations were directly analyzed with FLUKA. [1] M. Santana-Leitner et al., MadFLUKA Beam Line 3D Builder. Simulation of Beam Loss Propagation in Accelerators, IPAC14 proceedings, MOPME040 [2] A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)
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TUPIK043	Upgrade of the Neutron Dose Measurement System at BESSY	1781
	K. Ott, Y. Bergmann, M. Martin, L. Pichl HZB, Berlin, Germany
	Funding: Funded by the Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie and by the Land Berlin Neutron radiation fields at synchrotron light sources are caused by bremsstrahlung from electron losses in accelerator components. Inside the enclosure and in transversal direction neutron and gamma radiation is of the same order of magnitude but high energy neutrons are much more penetrating. This causes outside the shielding neutron spectra with two broad maxima at about 1 MeV and 100 MeV. Standard Anderson-Braun or Leake neutron monitors measure thermalized neutrons in a proportional counter tube by nuclear reactions which limits the measurement range to neutron energies < 10 MeV. This implies two considerable systematic errors: Pulsed neutron beams causes dead-time losses due to the time structure of injections and the moderators are not sufficient to moderate high energy neutrons down to thermal energies. We determined and fixed these measurement errors by faster preamplifiers and by a more effective moderator developed by us, which expands the measurement range up to several GeV. Examples of the application at BESSY are presented.
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TUPIK055	Target Investigation Driven by a 10 MeV Electron Linac for Bremsstrahlung Production	1819
	M. Yarmohammadi Satri, M. Lamehi, H. Shaker IPM, Tehran, Iran F. Ghasemi NSTRI, Tehran, Iran
	IPM E-Linac is a 10 MeV electron linear accelerator presently under construction at Institute for Research in Fundamental Sciences (IPM). It will accelerate electron from 45 keV to 10 MeV along the 160 cm accelerating tube. One of the beam energy measurement devices is designed based on the production of bremsstrahlung radiation. Target of the electron linac presents a key role in the production of bremsstrahlung. In this paper, we present the simulation results for an investigation on the bremsstrahlung radiation production based on target thickness, radius and atomic number, Z. We have applied Fluka Monte Carlo code for collecting the dose equiva-lent of generated bremsstrahlung along the target central axis at 30cm located downstream the target.
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TUPIK066	Beam Loss Simulation and Radiation Shielding for Top-Off Operation of Hefei Light Source	1845
	X. Zhou, J.Y. Li, J.G. Wang, S.W. Wang, W.B. Wu, W. Xu, K. Xuan, Q.B. Zeng USTC/NSRL, Hefei, Anhui, People's Republic of China
	The Hefei Light Source (HLS) is undergoing a series of upgrades to prepare for the top-off operation. To ensure radiation safety in the experimental hall under abnormal beam loss, simulations under various system errors in the HLS storage ring are performed to get in-depth understanding of the induced radiation nature. To make the radiation shielding more effective, a beam scraper is used to decrease the aperture opening of the vacuum chamber, and additional shielding is installed around the scraper. Simulation and beam test results are reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK066
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TUPIK080	Accelerator Personnel Safety Systems for European Spallation Source	1884
	M. Mansouri, S.L. Birch, A. Nordt, D. Paulic, Y.K. Sin, A. Toral Diez ESS, Lund, Sweden
	The European Spallation Source (ESS) is a collabora-tion of 17 European countries to build the world's most powerful neutron source for research. ESS is under con-struction since 2014 and it will produce first neutrons in 2019. The linear proton accelerator is composed of nor-mal conducting sections plus the superconducting linac. When operational, such facilities include various hazards, such as ionizing radiation, high voltage and oxygen defi-ciency. The accelerator Personal Safety System (PSS) limits exposure to them and ensures personnel safety in the accelerator tunnel. It will be developed in accordance with IEC 61508 standard (Functional Safety of Electri-cal/Electronic/Programmable Electronic Safety-related Systems), which has become a good practice in similar facilities to develop safety related systems. This paper gives an overview of the accelerator PSS and its subsys-tems. The progress of the accelerator PSS design and the selected software and hardware technologies will also be described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK080
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TUPIK086	Modelling the Radioactivity Induced by Slow-Extraction Losses in the CERN SPS	1897
	M.A. Fraser, D. Björkman, K. Cornelis, B. Goddard, V. Kain, P.M. Schicho, C. Theis, H. Vincke CERN, Geneva, Switzerland
	Resonant slow extraction is used to provide an intense quasi-DC flux of high-energy protons for the Fixed Target (FT) physics programme at the CERN Super Proton Synchrotron (SPS). The unavoidable beam loss intrinsic to the extraction process activates the extraction region and its equipment. Although the radiation dose to equipment has an impact on availability, the cool-down times required to limit dose to the personnel carrying-out maintenance of the accelerator also pose important restrictions, and ultimately limit the number of protons on target. In order to understand how the extracted proton flux affects the build-up and subsequent cool-down of the induced activation, a model based on a simple empirical relationship has been developed and shown to predict the measured radioactive decay at ionisation chambers located along the extraction region. In this contribution, the empirical model is described, its strengths and limitations discussed, and its application as a predictive tool for estimating cool-down times as a function of extracted proton flux demonstrated.
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TUPVA016	Identification and Analysis of Prompt Dose Maxima in the Insertion Regions IR1 and IR5 of the Large Hadron Collider	2078
	O. Stein, M. Brugger, S. Danzeca, R. Garcia Alia, Y. Kadi, M. Kastriotou, C. Martinella, C. Xu CERN, Geneva, Switzerland
	During the operation of the LHC the continuous particle losses create a radiation field in the LHC tunnel and the adjacent caverns. Exposed electronics and accelerator components show dose dependent accelerated aging effects and stochastic Single Event Effects which can lead to faults and downtime of the LHC. In order to achieve an optimal life duration, the position of the equipment is chosen in dependency of the amplitude of the radiation fields. Therefore, it is crucial to monitor the prompt dose distributions along the whole LHC. By using the LHC beam loss monitor and RadMon systems, the prompt dose during the accelerator operation is continuously monitored. Measurements in the long straight sections and the dispersion suppressors in IR1 (ATLAS) and in IR5 (CMS) have shown that the radiation levels have localised maxima which exceed the base line by 1 to 2 orders of magnitude. The analysis of these radiation peaks will be presented and the underlying loss mechanisms will be discussed. The results will help to identify areas not suitable for radiation sensitive electronics. Implications on the expected radiation levels for High-Luminosity LHC are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA016
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Paper

Title

Page

Perturbation Analysis for Beam Trajectories. Determining Local Shielding Containment for LCLS-II

1637

M. Santana-Leitner
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515
Containment of beam losses by halo and momentum/energy collimators is a well-established practice for normal operation of particle accelerators where tracking codes are applied. However, for exceptional events, such as magnet power failures, severe lattice mis-match, etc., ad-hoc analytical approaches are typically applied. Oftentimes those simplified methods are not automatic; they don't define the full phase-space of mis-steered trajectories and cannot keep up with beam-line upgrades. Moreover, there may exist a disconnect between the teams analyzing consequences of errant beams and those involved in beam-line design. With electron beams exceeding 100 kW, design of LCLS-II at SLAC National Accelerator Laboratory required exhaustive beam-containment studies to avoid potential destruction of components and excessive dose rates. The geometry of the different beam-lines and the nominal optics was built with MadFLUKA [1], and FLUKA [2] Monte Carlo code along with perturbations to magnetic fields was used to inspect failures compatible with beam operations and hardware settings. Consequences of mis-steered rays and the respective mitigations were directly analyzed with FLUKA.
[1] M. Santana-Leitner et al., MadFLUKA Beam Line 3D Builder. Simulation of Beam Loss Propagation in Accelerators, IPAC14 proceedings, MOPME040
[2] A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB133

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK043

Upgrade of the Neutron Dose Measurement System at BESSY

1781

K. Ott, Y. Bergmann, M. Martin, L. Pichl
HZB, Berlin, Germany

Funding: Funded by the Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie and by the Land Berlin
Neutron radiation fields at synchrotron light sources are caused by bremsstrahlung from electron losses in accelerator components. Inside the enclosure and in transversal direction neutron and gamma radiation is of the same order of magnitude but high energy neutrons are much more penetrating. This causes outside the shielding neutron spectra with two broad maxima at about 1 MeV and 100 MeV. Standard Anderson-Braun or Leake neutron monitors measure thermalized neutrons in a proportional counter tube by nuclear reactions which limits the measurement range to neutron energies < 10 MeV. This implies two considerable systematic errors: Pulsed neutron beams causes dead-time losses due to the time structure of injections and the moderators are not sufficient to moderate high energy neutrons down to thermal energies. We determined and fixed these measurement errors by faster preamplifiers and by a more effective moderator developed by us, which expands the measurement range up to several GeV. Examples of the application at BESSY are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK043

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK055

Target Investigation Driven by a 10 MeV Electron Linac for Bremsstrahlung Production

1819

M. Yarmohammadi Satri, M. Lamehi, H. Shaker
IPM, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran

IPM E-Linac is a 10 MeV electron linear accelerator presently under construction at Institute for Research in Fundamental Sciences (IPM). It will accelerate electron from 45 keV to 10 MeV along the 160 cm accelerating tube. One of the beam energy measurement devices is designed based on the production of bremsstrahlung radiation. Target of the electron linac presents a key role in the production of bremsstrahlung. In this paper, we present the simulation results for an investigation on the bremsstrahlung radiation production based on target thickness, radius and atomic number, Z. We have applied Fluka Monte Carlo code for collecting the dose equiva-lent of generated bremsstrahlung along the target central axis at 30cm located downstream the target.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK055

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TUPIK066

Beam Loss Simulation and Radiation Shielding for Top-Off Operation of Hefei Light Source

1845

X. Zhou, J.Y. Li, J.G. Wang, S.W. Wang, W.B. Wu, W. Xu, K. Xuan, Q.B. Zeng
USTC/NSRL, Hefei, Anhui, People's Republic of China

The Hefei Light Source (HLS) is undergoing a series of upgrades to prepare for the top-off operation. To ensure radiation safety in the experimental hall under abnormal beam loss, simulations under various system errors in the HLS storage ring are performed to get in-depth understanding of the induced radiation nature. To make the radiation shielding more effective, a beam scraper is used to decrease the aperture opening of the vacuum chamber, and additional shielding is installed around the scraper. Simulation and beam test results are reported in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK066

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK080

Accelerator Personnel Safety Systems for European Spallation Source

1884

M. Mansouri, S.L. Birch, A. Nordt, D. Paulic, Y.K. Sin, A. Toral Diez
ESS, Lund, Sweden

The European Spallation Source (ESS) is a collabora-tion of 17 European countries to build the world's most powerful neutron source for research. ESS is under con-struction since 2014 and it will produce first neutrons in 2019. The linear proton accelerator is composed of nor-mal conducting sections plus the superconducting linac. When operational, such facilities include various hazards, such as ionizing radiation, high voltage and oxygen defi-ciency. The accelerator Personal Safety System (PSS) limits exposure to them and ensures personnel safety in the accelerator tunnel. It will be developed in accordance with IEC 61508 standard (Functional Safety of Electri-cal/Electronic/Programmable Electronic Safety-related Systems), which has become a good practice in similar facilities to develop safety related systems. This paper gives an overview of the accelerator PSS and its subsys-tems. The progress of the accelerator PSS design and the selected software and hardware technologies will also be described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK086

Modelling the Radioactivity Induced by Slow-Extraction Losses in the CERN SPS

1897

M.A. Fraser, D. Björkman, K. Cornelis, B. Goddard, V. Kain, P.M. Schicho, C. Theis, H. Vincke
CERN, Geneva, Switzerland

Resonant slow extraction is used to provide an intense quasi-DC flux of high-energy protons for the Fixed Target (FT) physics programme at the CERN Super Proton Synchrotron (SPS). The unavoidable beam loss intrinsic to the extraction process activates the extraction region and its equipment. Although the radiation dose to equipment has an impact on availability, the cool-down times required to limit dose to the personnel carrying-out maintenance of the accelerator also pose important restrictions, and ultimately limit the number of protons on target. In order to understand how the extracted proton flux affects the build-up and subsequent cool-down of the induced activation, a model based on a simple empirical relationship has been developed and shown to predict the measured radioactive decay at ionisation chambers located along the extraction region. In this contribution, the empirical model is described, its strengths and limitations discussed, and its application as a predictive tool for estimating cool-down times as a function of extracted proton flux demonstrated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK086

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TUPVA016

Identification and Analysis of Prompt Dose Maxima in the Insertion Regions IR1 and IR5 of the Large Hadron Collider

2078

O. Stein, M. Brugger, S. Danzeca, R. Garcia Alia, Y. Kadi, M. Kastriotou, C. Martinella, C. Xu
CERN, Geneva, Switzerland

During the operation of the LHC the continuous particle losses create a radiation field in the LHC tunnel and the adjacent caverns. Exposed electronics and accelerator components show dose dependent accelerated aging effects and stochastic Single Event Effects which can lead to faults and downtime of the LHC. In order to achieve an optimal life duration, the position of the equipment is chosen in dependency of the amplitude of the radiation fields. Therefore, it is crucial to monitor the prompt dose distributions along the whole LHC. By using the LHC beam loss monitor and RadMon systems, the prompt dose during the accelerator operation is continuously monitored. Measurements in the long straight sections and the dispersion suppressors in IR1 (ATLAS) and in IR5 (CMS) have shown that the radiation levels have localised maxima which exceed the base line by 1 to 2 orders of magnitude. The analysis of these radiation peaks will be presented and the underlying loss mechanisms will be discussed. The results will help to identify areas not suitable for radiation sensitive electronics. Implications on the expected radiation levels for High-Luminosity LHC are also discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA016

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)