Download SLHCRadiationPlanAug08Final

Oxford Radiation Exposure Plans
For passive optical components
B. Todd Huffman
Oxford University
10/04/08
Items to be tested
• New GRIN optical fibre
– Infinicor SX+ fibre
– Bandwidth 10Gpbs over 150m
– 50mm core
– For use at 850nm wavelength
• Single Mode fibre
– CMS fibre; has shown previous high tolerance
to radiation
– For use at 1310nm wavelength
Items to be tested
• Multi-mode optical splitters (850nm only)
– Fused taper (using Infinicor fibre)
– PLCC
• Planar Lightwave Circuit Chip
• Low profile connectors
– Multimode (at l=850nm)
– Single mode (at l=1310nm)
Exposure Details
• SCK-CEN is a test reactor near Antwerp
• Gamma sources 60Co
• Up to 25 kGy/hr (BRIGITTE)
60Co
Relative Intensity
– 1.2 kGy/hr (RITA)
- spectrum
 Energy (MeV)
Large irradiation volume
at high dose-rate
BRIGITTE



60Co
Side view
- spectrum
B
 Energy (MeV)
900 mm
Relative Intensity
Dose Rate
0.5 => 25 kGy/h
Amb. Temp. ~60 °C
Inert gas or air
On-line instrumentation facilities
220 mm
Container open
RITA
Large irradiation volume
with moderate dose-rate
Relative Intensity
Dose Rate
0.5 => 1.5 kGy/h



60Co
Under water facility
- spectrum
380 mm
 Energy (MeV)
Temperature up to 150 °C
Inert gas or air
On-line instrumentation facilities
600 mm
Technical Details of Sources
Dose Rate
Avail. volume
Useful volume
BRIGITTE
Position B
0.5 – 25 kGy/h
RITA
Dia. 220mm
Height 900mm
Dia. 220mm
Height 600mm
Dia. 420mm
Height 600mm
Dia. 380mm
Height 400mm
0.1 – 1800 Gy/h
Dose rate will be measured prior to exposure at both locations.
Temperature will be ambient but for high dose rate should stabilise at 55 deg. C.
Intention is to stay at both locations for the time required to reach 600kGy
integrated dose at BRIGITTE.
Test set-up: Fibre exposure
Fibre Section exposed
In rad. area
Optical Patch cables
Conn.
Single Laser source
Splitter
Reference
Power supply
&
Measurement
Light-sensitive diode
current Measurements
Fibre under
test
Fibre Test system details
• VME-based system (6u crate)
– Controlled by USB through PC using Labview and
a CAEN VME controller.
• Integrating amplifier card
– Integration times from 500ms to 16,000ms
– Reads voltages; 750ms is unity gain.
– 16 bit ADC with 8v input range at unity gain.
• Photodiode card (6u but not VME controlled)
• Laser card all laser channel currents
adjustable. (Eventually VME settable?)
Test Setup  Connector-loss Test
Test channel
Laser
Splitter
Reference channel
ST
ST
Connector
ST
Patch Cables
ST
Photodiode+
Amplifier
Radiation exposure Vol.
Test Setup  Splitter test
Photodiode+
Amplifier
Splitter
Patch Cables
ST
ST
Splitter
ST
ST ST
Laser
Radiation exposure Vol.
Loading Vessel  Brigitte
Fibre coils on a teflon spool
which slips into this disk.
220mm dia
Measurement Plans
• Dose Measurements at both locations
• Temperature monitoring in vessels
• 50m under test
– Attenuation
– Anealing and anti-anealing @ Highest dose rate
• 2m reference fibres will be contained at the
top of the vessel
– Out of the main radiation volume
• Connectors and splitters will only receive
high dose measurement.
Amplifier Card Stability
– Not a problem
• Voltage sensed across a
precision resistor in a
voltage divider chain.
• Resistor chain is
connected to a linear DC
power supply
• Integration time set to
obtain a Gain of 1.0
• Room temp. variations
• RMS/Mean = 0.00085
• Flat long-term stability
Signal Range Estimates
• Laser power
• 300mW
• Laser splitter loss
• 3.6dB
• Connector losses
• 1.5dB
• Responsivity
• 0.4 A/W
• Est. ADC signal after
Radiation
– 454 ADC counts
• Laser Power
• 500mW
• Laser splitter loss
• 3.0dB
• Connector losses
• 1.0dB
• Responsivity
• 0.6 A/W
• Est. ADC signal prior
to Radiation
– 14610 ADC counts
Schedule
• Through June ’08
– System assembly and shake-down
•
•
•
•
Purchase components
Make disks
Assemble VME cards and test
Patch cable assembly and test
• June-July
– Pre-radiation characterization of all tests described
• August 10th go to Belgium
– 11th-15th buy beer
• Maybe run a radiation test in between beer runs.
• Sept. - present results at TWEPP’08
Some Important Final Things
• Jingbo Ye, Annie Chu Xiang (SMU) are
also performing a fibre test at BNL
– Dose rate 0.3 kGy/h
– Test on 10/04/08 (as we speak)
• Oxford and SMU in full communication
– Common purchases
• Fibres, connectors
– Common test procedures
• Goal is to enable comparison of dose-rate
effects.