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

The The radi radiation

• n do

dose me meas asure rement for the for the cohe

• here

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

• llimator, stopp
• pper, local

al shieldi ding. ng. Ray y Tracing, ng, Mont Monte-Carlo cod

• de: F

FLUKA

• Synchr

hrot

• tron:
• n: hut

hutch, shi hielding ng enc nclosure, exc xclusion zone

• ne. Ana

nalytical code

• de: STAC8
• Less tha

han 0. 0.5µSv/ v/h @a @accessible regi gion

Bremsstrahlung Shielding and PE enclosure

X-ray

Secondary Bremsstrahlung Shielding 15˚

Bremsstrahlung collimator Secondary Bremsstrahlung shielding

The Coherent X-ray Scattering Beamline

The Coherent X-ray Scattering Beamline

The Coherent X-ray Scattering Beamline

1st Survey - Gamma-ray dose rate

0.67@150mA 0.54@200mA 1.60@250mA

Dose rate unit: μSv/h, using 451P ion chamber

End wall: BG Sliding door 0.2↓@150mA 0.2↓@200mA<gap：0.4> 0.6 @250mA<gap：0.9> Downstream of DCM 0.3～0.6 @200mA 0.3～0.7 @250mA Power rack:0.4@250mA

Copper Synchrotron Mask

Gamma-ray dose rate

0.40@200mA slit 4x4 0.25@200mA slit 2x2

• 0.90@300mA slit 4x4

0.60@300mA slit 2x2 0.22@300mA slit 0.5x0.5 1.0@200mA slit 4x4 0.6@200mA slit 2x2

• 2.5@300mA slit 4x4

1.4@300mA slit 2x2 0.3@200mA slit 4x4 0.2@200mA slit 2x2

• 0.8@300mA slit 4x4

0.5@300mA slit 2x2 0.3@300mA slit 0.5x0.5 0.30@200mA slit 4x4 0.20@200mA slit 2x2

• 0.60@300mA slit 4x4

0.50@300mA slit 2x2 0.20@300mA slit 0.5x0.5

Dose rate unit: μSv/h, using 451P ion chamber n+γ detector γ n+γ detector Beam current 200mA and 300 mA, changing front-end slits gap: 0, 0.5, 1, 2, 3, 4mm

Gamma & Neutron dose due to different slit opening and current

Dose @ 90 deg. Dose @ 0 deg.

y = 0.0663x + 0.1123

0.1 0.2 0.3 0.4 0.5 1 2 3 4 5

dose rate (μSv/h) slit opening gap (mm)

Detector at TPS-25A 90° 200mA

gamma neutron

y = 0.1764x + 0.1479

0.2 0.4 0.6 0.8 1 1 2 3 4 5

dose rate (μSv/h) slit opening gap (mm)

Detector at TPS-25A 90° 300mA

gamma neutron

y = 0.2086x + 0.2299

0.2 0.4 0.6 0.8 1 1.2 1 2 3 4 5

dose rate (μSv/h) slit opening gap (mm)

Detector at TPS-25A 0° 300mA

gamma neutron

y = 0.1164x + 0.1046

0.2 0.4 0.6 0.8 1 2 3 4 5

dose rate (μSv/h) slit opening gap (mm)

Detector at TPS-25A 0° 200mA

gamma neutron

Mask shielding for the Coherent X-ray Scattering beamline

Lead 10cm in thickness Lead 5cm in thickness Beam direction 15cm PE next to 5cm Lead

Mask Shielding & Collimator

Beam 300 mA, slit opening in 2 x 2 mm

Dose rate after shielding enhancement

~0.25μSv/h (cryogenic tank)

detector

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

Gamma & Neutron dose rate at lateral position after enhancing shielding

0.2 0.4 0.6 0.8 1 1 2 3 4 5

dose rate (μSv/h) slit opening gap (mm)

Detector at TPS-25A 90° 300mA

gamma neutron total dose

Simulation results – Gamma-ray µSv/h@1ntorr,300mA

0.15±0.7% 0.11±0.25%

• Mea. bg
• Mea. 0.25

0.023±0.36% 0.008±0.67%

Simulation results – Neutron µSv/h@1ntorr,300mA

• Mea. 0.05

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.

Thanks for your attention