Shielding calculations for the design of new Beamlines at ALBA - - PowerPoint PPT Presentation
1 Shielding calculations for the design of new Beamlines at ALBA Synchrotron A. Devienne M.J. Garca-Fust Health & Safety Department, ALBA Synchrotron A. Devienne RADSYNCH17 21/04/17 Content 2 1. Context 2. Material &
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M.J. García-Fusté¹
Health & Safety Department, ALBA Synchrotron
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1.1 ALBA Synchrotron 1.2 Shielding design at ALBA 1.2 Objective
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2.1 Geometry constrains 2.2 Sources 2.3 FLUKA code
3.1 Shielding elements 3.2 Dose maps
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particle accelerator located near Barcelona city generating bright beams of synchrotron radiation. ALBA accelerates electrons up to 3 GeV.
Light Laboratory
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LINAC
Electron beam 110 MeV
BOOSTER
110 MeV to 3 GeV
STORAGE RING
3 GeV stored electron beam 150 mA (currently) - designed for 400 mA
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perimeter 270 m
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microfocus XAIRA and 1 Instrumentation NOTOS) + upgrade the current BLs ALBA
MIRAS and 1 Soft X-Rays LOREA BL) ALBA
Soft X-Rays BLs) P. Berkvens (ESRF)
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Tunnel bunker Hard X-Rays Beamline (NCD) Soft X-Ray Beamline (BOREAS) Infrared Beamline (MIRAS)
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E- Beam (3Gev)
Beam Line Optical Hutch
high-resolution angular photoemission for complex materials (energy range
Tunnel (Concrete Wall)
Experimental Area End Station
3D preliminary design of LOREA Beamline
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code to guarantee public access zone1 outside the shielding in
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1 public access zone: equivalent dose rates below 0.5 μSv/h, derived from the dose limit for
non-exposed workers, assuming 2000 h/year)
LOREA Beamline 3D FLUKA geometry
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LOREA geometry:
1 side wall T (1.5 m normal concrete) 1 side wall S 1 back wall B 1 roof R
Target :
2° inclined Mirror M1 (Copper)
Pipes :
Diameter 70 mm Source
LOREA Optical Hutch FLUKA 2D top view Simplified LOREA Optical Hutch drawing
Target (thickness and material to be defined by calculation)
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Insertion Device Undulator: Radiation depends on the Undulator parameters and directly proportional to the current intensity (mA).
radiation Gas Bremsstrahlung: Electromagnetic cascade produced by the interaction of the e- beam with the residual gas inside the vacuum chamber. It depend on the Current Intensity (mA), the e- Energy (3GeV), the pressure and composition inside the vacuum chamber
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Some FLUKA parameters (cards) of the simulations:
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Molecule Relative pressure (%)
H2 80 CO 10 CO2 5 Noble gas 3 H2O 2
Beam: Electron 3 GeV Target: Residual gas inside a 8.62 m length straight section Average pressure in the straight section: 5.0 × 10-9 mbar (design value) but calculations performed at atmospheric pressure (1 atm) and then scaled at design value (see [4] SLAC–PUB–6410, Nisy E. Ipe, Alberto Fasso) Electron beam
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Photon flux (photons/s) for 400 mA e- beam, scored with USRBDX card at the end of the Storage Ring straight section
The flux obtained is considered as source for the LOREA shielding calculations
1 GeV 1e+08 1 keV
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1.E-08 1.E-05 1.E-02 1.E+01 1.E+04 1.E+07 1.E+10 1.E+13 1.E+16 1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04 1.00E+05 1.00E+06 Flux (Ph/s/0.1%BW) Energy (eV)
Use of hsource.f sub routine to read histogram and use as a souce for the Shielding Calculation with the BL 1st Mirror as main Target
Apple II LOREA Undulator Maximum ID photon flux for each Undulator energy range (analytic calculations by ALBA Accelerator division)
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Shielding thicknesses and material for the LOREA
Corresponding vacuum in straight section for 0.5 μSv/h (mbar) Wall S (side wall) 20 mm lead + 50 mm polyethylene 2.5 × 10-8 Roof 15 mm lead 2.5 × 10-8 Wall B (back wall) 60 mm of lead + 50 mm of lead in central 1 m2 + 105 mm of lead Opt-to-Exp guillotine + 50 mm of lead local screen behind mirror + 20 mm other white beam scattering source 5.0 × 10-8
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# Shielding Elements Height (cm) Width (cm) Thickness (cm) Material
1 Tunnel-to-OH guillotine 35.5 30.5 2 Pb 2 Local Pb screen 1 behind mirror 65 70 5 Pb 3 Local Pb screen 2 behind slits 45 45 2 Pb 4 Central reinforcement Pb screen 2 10 10 2 Pb 5 OH-to-EH guillotine 22 22 10.5 Pb 6 OH backwall central reinforcement 100 100 5 Pb # Shielding Elements Height (cm) Width (cm) Thickness (cm) Material 1 In vacuum Tungsten Beamstop 8 8 5 W 2 Double collimator system 1.4 (aperture) 1.2 (aperture) 5 W
Dimensions defined by basic ray tracing
Reduction of a factor 15 of the scattered bremsstrahlung radiation escaping from the Optical Hutch through the beampipe
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a) Gas Bremsstrahlung source case equivalent dose rate maps (DOSE-EQ) - horizontal view at beam level -
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Photon dose rate map (in µSv/h) Neutron dose rate map (in µSv/h)
Total dose rate map (in µSv/h) from scattered bremsstrahlung with real LOREA geometry and shielding
0.5µSv/h
Beamstop Doble collimation system Lead screen
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Figure Dose rate profile (in µSv/h) from scattered bremsstrahlung outside LOREA as a function of the distance along the wall (in cm) : red curve: photon dose rate; green curve: neutron dose rate; blue curve: total dose rate
Side wall (S) Back wall (S)
a) Gas Bremsstrahlung source equivalent dose rate (DOSE-EQ)
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a) Gas Bremsstrahlung source case equivalent dose rate maps (DOSE-EQ) - transversal view at beam level -
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Total dose rate map (in µSv/h) from scattered bremsstrahlung with real LOREA geometry and shielding
0.5µSv/h
Dose rate profile (in µSv/h) from scattered bremsstrahlung outside LOREA Roof (R) as a function of the distance along the roof (red curve: photon dose rate; green curve: neutron dose rate; blue curve: total dose rate)
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Shielding requirements for scattered synchrotron radiation are largely met by the shielding thicknesses required for scattered bremsstrahlung.
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b) ID Undulator dose rate maps (at 400 mA):
Total dose rate map (in µSv/h) from ID Undulator source
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23 Outside BL Inside BL Gamma dose rate measurements at BOREAS BL compared with storage ring current and FE state Gamma dose rate map (in µSv/h) from scattered bremsstrahlung at LOREA at 400 mA
Results obtained with FLUKA are in agreement with experimental data (Ionizating chamber FHT192) from a similar Beamline at ALBA ( few µSv/h current inside the Optical Hutch - proportional to the electron beam - and background reading outside)
0.5 µSv/h
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1. CPU time vs. Statistical error : 0.3 ms per primary particle, 1e+08 primary sent per cycles, 10 cycles per run
simulations via Batch system to cluster: split into 48 inputs (now integrated in Flair) … (vs. Manpower)
inside the shielding element) could allow better statistic in regions of interest,
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Beam
Simplified (left) and 3D (right) LOREA Optical Hutch drawing with door on backwall
Target
heaviest frame (600 kg)
Door B46 thickness Corresponding vacuum in straight section for 0.5 μSv/h (mbar) 60 mm lead 5.0×10-8 Door B66 thickness 40 mm lead 6.2×10-8
6 (-2) = 4 cm 6 cm 2 (+3) cm
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FLUKA is a powerful code for the design of Synchrotron Beamline shielding (Radioprotection) and will be used at ALBA for the Phase III Beamlines (2017-2020) LOREA Optical Hutch shielding will be installed on October 2017 and commissioned during 2018 Open points can be discussed to optimize the shielding calculations
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Email: adevienne@cells.es ALBA Website: www.albasynchrotron.es
Mª José García Arnaud Devienne José A. Alcobendas
ALBA Radioprotection Service
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[1] "The FLUKA code: Description and benchmarking" G. Battistoni, S. Muraro, P.R. Sala, F. Cerutti, A. Ferrari, S. Roesler, A. Fasso`, J. Ranft, Proceedings of the Hadronic Shower Simulation Workshop 2006, Fermilab 6--8 September 2006, M. Albrow, R. Raja eds., AIP Conference Proceeding 896, 31-49, (2007) [2] "FLUKA: a multi-particle transport code" A. Ferrari, P.R. Sala, A. Fasso`, and J. Ranft, CERN-2005-10 (2005), INFN/TC_05/11, SLAC-R-773 [3] Gas Bremsstrahlung Considerations in the Shielding Design of the Advanced Photon Source Synchrotron Radiation Beam Lines, Nisy E. Ipe, Alberto Fasso , SLAC–PUB–6452 [4] Impact of gas bremsstrahlung on synchrotron radiation beamline shielding at the advanced photon source, Nisy E. Ipe, Alberto Fasso SLAC–PUB–6410 [5] Shielding
Beamlines at ALBA: Comparison between different types
bremsstrahlung, P. Berkvens. ALBA internal report. [6] Comparison of Design and Practices for Radiation Safety among Five Synchrotron Radiation Facilities, James C. Liu, Sayed H. Rokni, Yoshihiro Asano, William R. Casey, Richard J. Donahue, P.K. Job, SLAC-PUB-11139