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Shielding Calculations for NSLS2 Beamlines and Front ends

Shielding Calculations for NSLS2 Beamlines and Front ends. P.K. Job Radiation Physicist Peer Review 2007 March 28, 2007. Outline. Radiation Sources Considered for Calculations Calculational Tools and Procedures Bremsstrahlung Source Design of Front End Safety Shutters

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Shielding Calculations for NSLS2 Beamlines and Front ends

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  1. Shielding Calculations for NSLS2 Beamlines and Front ends P.K. Job Radiation Physicist Peer Review 2007 March 28, 2007

  2. Outline • Radiation Sources Considered for Calculations • Calculational Tools and Procedures • Bremsstrahlung Source • Design of Front End Safety Shutters • First Optics Enclosure Shielding • Mirror as First Optics Element

  3. Radiation Sources Considered for Calculations • Bremsstrahlung (High Energy Photons) • Bremsstrahlung produced Neutrons • Synchrotron Radiation (ID and BM)

  4. Calculational Tools and Procedures • PHOTON for Synchrotron Radiation (xrays) • STAC8 for Synchrotron Radiation (xrays) • Electron Gamma Shower Program (EGS4) • Photoneutron Dose Measurements

  5. Beamline Shielding Design Shielding Design Specifications • Recommendations based upon maximum allowed design dose criteria (100 mrem/year) • Recommendations based upon 2000 work-hours of exposure per year on contact at the exterior of the Beamline shielding • Conservative beam scattering assumptions

  6. Bremsstrahlung Source (Beam Straight path)

  7. Beamlines (Bremsstrahlung Source) Beam Energy = 3.5 GeV, Beam Current = 500 mA Straight Section Path Length = 16 meters Distance to the Dose Point = 20 meters Vacuum = 1 ntorr

  8. Shutter Thickness (EGS4 Calculation)

  9. Safety Shutter Thickness (EGS4 Results)

  10. Safety Shutter Thickness (EGS4 Results)

  11. Neutron Dose Rates from Safety Shutters(APS Measurements- Storage Ring Vacuum = 9 nTorr) NIM A 430 (1999) page 542

  12. First Optics Enclosures (Calculational Geometry) SR is scattered with 0.1 mm Al and Bremsstrahlung with 3 mm Cu

  13. Bremsstrahlung Scattering Results (EGS4)

  14. (Bremsstrahlung Scattering Results) Pb Thickness required to shield to 0.05 mrem/h

  15. Synchrotron Radiation Scattering (ID Parameters)

  16. Synchrotron Radiation Scattering (BM Parameters) • Beam Energy 3.5 GeV • Beam Current 500 mA • Peak Magnetic Field 0.4 T • Critical Energy 3.25 keV • Angular Acceptance 7.5 mrads (horizontal) • Bremsstrahlung St. Path 18.62 cm • Bremsstrahlung Source 2.8 rem/h • Max. Power in FOE 0.102 w/mrad-H / mA • 382.5 watts (at 500 mA)

  17. First Optics Enclosure Shielding(STAC8 Calculations) • 1 m Al and 10 meter air scatterer are used • Beam incident normally on the scatterer • Self absorption is set to zero • Maximum energy of SR is set to 500 keV • The lateral walls are at 1 m from the scatterer • ICRU Tissue used for dose scoring • Dose is scored at 70 degree angle (maximum) • Polarization of SR is ignored • For mono-beam calculations 5 harmonics are considered • Bandwidths are 0.1%, 0.01%, 0.01%, 0.001%, 0.001% correspondingly

  18. First Optics Enclosure Shielding(STAC8 Results) Pb Thickness required to shield to 0.05 mrem/h

  19. First Optics Enclosure Shielding(Summary) Pb Thickness required to shield to 0.05 mrem/h (100 mrem/y)

  20. First Optics Enclosure Shielding(Summary) Pb Thickness required to shield to 0.25 mrem/h (500 mrem/y)

  21. Beam Transports (White and Mono) • 0.05 mrem/h under vacuum (10-8 torr) • 2000 work hours per year • Interlocking the beam transport vacuum (PPS/EPS) • ? mrem/h under loss of vacuum (1 atmos) • SR scattered from a scatterer

  22. Mirror as First Optics Element

  23. Mirror as First Optics Element(EGS4 Calculations)

  24. Bremsstrahlung Scattering from Mirrors Si Substrate

  25. Bremsstrahlung Scattering from Mirrors Cu Substrate

  26. Radiation Shielding Design for NSLS II Shielding Design Documents 1. Linac, NSLS II- TN 12 2. Booster & Storage Ring, NSLS II – TN 13 3. Storage Ring Supplemental Shielding – TN 21 4. Beamlines and Front Ends, NSLS II – TN 14 5. Ray Tracing Standards, NSLS II – TN 20 6. Activation Analysis, NSLS II – TN 15 & 16

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