The The radi radiation on do dose me meas asure rement for - PowerPoint PPT Presentation

The The radi radiation on do dose me meas asure rement for the for the cohe ohere rent X-ray sca y scatte teri ring ng b beamline mline i in TPS PS A. Y. Chen, J.C. Liu National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan

Phase-I

Beamline shielding  Bremsstrahl hlun ung: g: col ollimator, stopp opper, local al shieldi ding. ng. Ray y Tracing, ng, Mont Monte-Carlo cod ode: F FLUKA  Synchr hrot otron: on: hut hutch, shi hielding ng enc nclosure, exc xclusion zone one. Ana nalytical code ode: STAC8 0.5 µ Sv/  Less tha han 0. v/h @a @accessible regi gion

Bremsstrahlung Shielding and PE enclosure X-ray

Secondary Bremsstrahlung Shielding Secondary Bremsstrahlung shielding Bremsstrahlung collimator 15 ˚

The Coherent X-ray Scattering Beamline

The Coherent X-ray Scattering Beamline

The Coherent X-ray Scattering Beamline

1 st Survey - Gamma-ray dose rate 0.67@150mA 0.54@200mA 1.60@250mA End wall: BG Downstream of DCM 0.3 ～ 0.6 @200mA 0.3 ～ 0.7 @250mA Power rack:0.4@250mA Sliding door 0.2 ↓@ 150mA 0.2 ↓@ 200mA<gap ： 0.4> 0.6 @250mA<gap ： 0.9> Dose rate unit: μ Sv/h, using 451P ion chamber

Copper Synchrotron Mask

Gamma-ray dose rate Beam current 200mA and 300 mA, changing front-end slits gap: 0, 0.5, 1, 2, 3, 4mm n+ γ detector γ 1.0@200mA slit 4x4 0.6@200mA slit 2x2 n+ γ detector --------------------------- 2.5@300mA slit 4x4 1.4@300mA slit 2x2 0.30@200mA slit 4x4 0.3@200mA slit 4x4 0.40@200mA slit 4x4 0.20@200mA slit 2x2 0.2@200mA slit 2x2 0.25@200mA slit 2x2 ------------------------ ------------------------ ------------------------ 0.60@300mA slit 4x4 0.8@300mA slit 4x4 0.90@300mA slit 4x4 0.50@300mA slit 2x2 0.5@300mA slit 2x2 0.60@300mA slit 2x2 0.20@300mA slit 0.5x0.5 0.3@300mA slit 0.5x0.5 0.22@300mA slit 0.5x0.5 Dose rate unit: μ Sv/h, using 451P ion chamber

Gamma & Neutron dose due to different slit opening and current

Dose @ 90 deg. Dose @ 0 deg. Detector at TPS-25A 90° 200mA Detector at TPS-25A 0° 200mA 0.5 0.8 gamma gamma 0.4 dose rate ( μ Sv/h) y = 0.1164x + 0.1046 y = 0.0663x + 0.1123 dose rate ( μ Sv/h) neutron 0.6 neutron 0.3 0.4 0.2 0.2 0.1 0 0 0 1 2 3 4 5 0 1 2 3 4 5 slit opening gap (mm) slit opening gap (mm) Detector at TPS-25A 0° 300mA Detector at TPS-25A 90° 300mA 1.2 1 gamma gamma y = 0.2086x + 0.2299 y = 0.1764x + 0.1479 1 0.8 dose rate ( μ Sv/h) dose rate ( μ Sv/h) neutron neutron 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0 0 0 1 2 3 4 5 0 1 2 3 4 5 slit opening gap (mm) slit opening gap (mm)

Mask shielding for the Coherent X-ray Scattering beamline Lead 5cm in thickness Beam direction Lead 10cm in 15cm PE next thickness to 5cm Lead

Mask Shielding & Collimator

Dose rate after shielding enhancement ~0.25 μ Sv/h (cryogenic tank) detector Beam 300 mA, slit opening in 2 x 2 mm

451P inside optical hutch – gamma-ray dose rate behind the enhanced local shielding

Gamma & Neutron dose rate at lateral position after enhancing shielding Detector at TPS-25A 90° 300mA 1 gamma 0.8 dose rate ( μ Sv/h) neutron total dose 0.6 0.4 0.2 0 0 1 2 3 4 5 slit opening gap (mm)

Simulation results – Gamma-ray µ Sv/h@1ntorr,300mA Mea. bg 0.11 ± 0.25% 0.15 ± 0.7% Mea. 0.25

Simulation results – Neutron µ Sv/h@1ntorr,300mA 0.023 ± 0.36% Mea. 0.05 0.008 ± 0.67%

Conclusion  The preliminary study shows the design of collimator, stopper, hutch and the secondary bremsstrahlung collimator are work.  The modification of the optical elements and components might challenge the effectiveness of the shielding, especially for those narrowing or shaping synchrotron light (also the bremsstrahlung) at collimator upstream.  The mask with a narrow penetration is really the true collimator. For it’s at the beginning part of the hutch, the enhanced shielding is very helpful in mitigating the dose rate around the hutch.  The dose around the authorized TPS beamlines obeys the criteria well after the work.

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