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Cherenkov Detector for Fusion Power Monitoring Yury Verzilov* and Takeo Nishitani** * Moscow Engineering Physics Institute, Russia ** FNS, Japan Atomic.

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Presentation on theme: "Cherenkov Detector for Fusion Power Monitoring Yury Verzilov* and Takeo Nishitani** * Moscow Engineering Physics Institute, Russia ** FNS, Japan Atomic."— Presentation transcript:

1 Cherenkov Detector for Fusion Power Monitoring Yury Verzilov* and Takeo Nishitani** * Moscow Engineering Physics Institute, Russia ** FNS, Japan Atomic Energy Agency, Japan Neutron WG Meeting, 10 ITPA, April 11, 2006, Moscow, RUSSIA

2 Research Motivation  Development of a Neutron Monitoring System: Providing an alternative method compare to Systems based on a Fission Chamber; Sensitive to Virgin D-T Neutrons; Combining NAM advantages with Temporal Resolution Ability; Basing on a Light Processing Technology.  Progress in Fiber Optic Development

3 Outline  Two fusion power monitor approaches based on activation of flowing water;  Proof-of-approach experiment: Designing a water Cherenkov radiator with fiber readout systems; Testing detectors inside and outside the D-T neutron source limits; Evaluating temporal parameters;  Concept of the Cherenkov Monitor for ITER

4 Water Activation in a Fusion Environment Two Approaches for Registration 16 O(n,p) 16 N - Dominant activation reaction Major  -decay branches of 16 N (T 1/2 = 7.13 s) 16 N 16 O 0 MeV 6.1 MeV 7.1 MeV 4.8% 66% 28% Registration by Scintillator Registration by Cherenkov detector 10.4 MeV  -rays  -rays Water E  >0.26MeV

5 Fusion Power Monitor Based on Activation of Flowing Water Water transfers the Neutron Pulse Information to the remote Detector Light transfers the Neutron pulse Information to the remote Detector D-T Plasma Pulse Proposed Technique Present Technique BGO  -Detector  ~ 10% Cherenkov Detector  max ~ 90% Optical Fiber Advantages:  Good time resolution;  Absence of Time delay;  The remote detector may be located anywhere Registration of  -rays (E  6.1 and 7.1 MeV) Disadvantages:  Insufficient time resolution;  Time delay;  Location of the remote detector is limited Cherenkov Light by  -rays from 16 N (E max =10.4 MeV)

6 PMT response Cherenkov spectrum Quantum efficiency of the PMT Electron energy (MeV) Theoretical Aspects of the Cherenkov Detector (non-focusing type) Photon yield of electrons in water for region of nm Intensity (relative value) Wavelength (nm)

7 PMT Response to Cherenkov Photons from  -rays of 16 N and 32 P in water 32 P 1709 keV / 100% {E  max / I  } Intensity (relative value) Channel 16 N 4290 keV / 66.2%; keV / 28.0% 100% Light collection 2% Light collection

8 Water Cherenkov Detector with Wavelength-Shifting (WLS) Fiber Readout WLS fiber twined round the quartz tube Quartz tube to PMT Clear fiber bundle Reflector WLS fiber Water flow

9 Experimental Setup for Measurement of Detector Parameters Target room Measurement room D-T Neutron Source Water reservoir Pump Flow meter Detector position B Shielding 3.5 m 8.9 m Detector position A

10 Water Cherenkov Detector with WLS Fiber Readout (Outside the D-T Source Limits)  Tests with pulsed and direct D-T neutron modes were completed;  Detector has demonstrated reasonable characteristics of: light collection efficiency; temporal resolution.  Temporal resolution of the detector can be improved by increasing water flow velocity;  Detector can not be used around the D-T source, due to high  - sensitivity of WLS fiber;  New Design of the detector with quartz fiber is proposed. V H2O flow ~ 2 cm/sec Intensity (relative value) Time (s) V H2O flow ~ 10 cm/sec Neutron Pulse / Detector response

11 Water Cherenkov Detector with a Quartz Fiber Readout Water flow SS tube to PMT Quartz Fiber bundles Reflector

12 Water Cherenkov Detector with Quartz Fiber Readout Quartz Fiber Bundle Water Flow Designs and the experimental setup are not optimized for best performance; Main objective: Gain experimental data that will serve as a basic guideline for further elaboration upon detector development.

13 Detector Response to the Pulsed Neutron Flux (Outside the D-T source limits) Neutron Pulse “Ideal” Response Detector Response Delay Detector Position “B” (8.9 m) Pulsed Mode: step - 20 sec; duty – 50% V H2O flow ~ 1.67 m/sec

14 Detector Response to the Pulsed Neutron Flux Experiment Calculation (Based on the laminar flow model)

15 Time Spectrum for the Detector located inside the D-T Source Limits A and B - the chance coincidence rate of uncorrelated events, when fiber bundles were connected and then disconnected from the radiator. C - the coincidence rate of correlated events from the 16 N decay. H 2 O flow 4 L/min H 2 O flow 0 L/min

16 Detector Response to the Pulsed Neutron Flux (Inside the D-T source limits) Intensity (relative value) Time (s) V H2O flow ~ 0.08 m/s V H2O flow ~ 0.26 m/s Neutron Pulse Detector Response Response components: A - Prompt source gamma; B - Prompt source gamma + 16 N C - 16 N A B C

17 Concept of the Neutron Monitor based on Cherenkov Light for ITER D-T Plasma First Wall & Blanket ~ 40cm Vacuum Vessel ~ 75cm Parameters: Delay – 0 sec; Resolution – 10 ms H 2 O Radiator (D-2.5cm, L-5cm) V H2O flow – 5 m/s Quartz Fiber Bundle

18  Cherenkov Detector has demonstrated the ability to work properly in a radiation environment;  Temporal detector parameters can be improved by optimizing the Cherenkov detector design;  The present study elaborates upon the feasibility and effectiveness of utilizing the Cherenkov Detector as a Fusion Power Monitor with activation of flowing water. Conclusion


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