1. 2007-DEC-13AAP 20070 Prospects for the Use of Large Water- Based Anti-neutrino Detectors for Monitoring Fission Bomb Detonations AAP 2007 2007-DEC-13 Eugene Guillian, Queen’s University

2. 2007-DEC-13AAP 20071 Monitoring Rogue Nuclear Activity with Anti-neutrino Detectors Two types rogue nuclear activities that have anti-neutrinos as a by-product ObjectiveActivity to Achieve Objective Production of weapons-grade plutonium Operation of breeder-reactor Fission bomb design testsDetonation of fission bomb Signatures of the above activities: Breeder Reactor Anti-neutrinos produced at a steady rate Reactor fuel is replaced prematurely to avoid poisoning with 240 Pu Fission Bomb Almost all anti-neutrinos produced in a burst of 10 seconds Accompanied by other signatures (CTBTO monitoring) I shall focus on fission bomb detection in this talk

3. 2007-DEC-13AAP 20072 Anti-neutrinos Produced by a Fission Bomb The bomb yield is typically quoted in TNT-equivalent units: –1 kilo-tonne TNT = 4.184  10 12 Joule The amount of thermal energy released by a single fission event: –  204 MeV  3.3  10 -11 Joule The number of fissions per kilo-tonne of yield: Fission anti-neutrinos are produced in a burst of about 10 seconds A. Bernstein, T. West, & V. Gupta An assessment of Antineutrino Detection as a Tool for Monitoring Nuclear Explosions Fission Rate of a Nuclear Reactor R fiss = 3.1  10 19 fissions/sec/GWt

4. 2007-DEC-13AAP 20073 Anti-neutrino Detection Method The currently available mature technology is based on inverse beta decay on a free proton target Prompt energy deposition Captured after a delay of 10 1 ~ 10 2  s Gamma ray emission produces delayed energy deposition The delayed coincidence greatly reduces the background noise

5. 2007-DEC-13AAP 20074 Anti-neutrino Detection Rate Factors that determine the detection rate: FactorSymbolUnits Bomb YieldEkilo-tonne TNT Distance to Detonation Site R100 km Cross Section of Target  (E ) cm 2 Anti-neutrino Fluence @ 100 km i.e. number of anti-neutrinos per unit area E Thresh. (MeV) Detector Fluence (cm -2 kton -1 ) 0N/A 5  10 8 1.8 Liq. Scint. 2  10 8 3.4 0.5  10 8 3.8 Gd-loaded H 2 O 0.3  10 8 Inverse Beta Cross Section Detection Threshold Most anti-neutrinos are detected in this energy window Cross Section ~ 10 -42 cm 2

6. 2007-DEC-13AAP 20075 Anti-neutrino Detection Rate Detecting a 1 kton bomb at 100 km 0.3  10 8 cm -2 10 -42 cm 2  Number of antineutrinos per cm 2 from bomb above detection threshold Typical interaction cross section ~10 -35 Probability of interacting with a target proton In order to detect ~1 anti-neutrino, the detector needs ~10 35 free protons This is about 1 mega-ton of H 2 O 100 m

7. 2007-DEC-13AAP 20076 Anti-neutrino Detection Rate More precisely: SymbolUnitsDescription Ekton TNTEnergy from bomb N10 35 free protonsNumber of free protons in detector R100 km Distance between the bomb detonation site and the detector Other Factors: Neutrino Survival Probability0.57 Event Selection Cut Efficiency0.86 Combined Rate Reduction Factor0.49

8. 2007-DEC-13AAP 20077 Background Noise

9. 2007-DEC-13AAP 20078 Nuclear Monitoring with Anti-neutrino Detectors The idea has been discussed in the Applied Anti-neutrino Conference since 2004 A pretty comprehensive study of this topic has been done by Sandia scientists: –“An Assessment of Anti-neutrino Detection as a Tool for Monitoring Nuclear Explosions”, by Adam Bernstein, Todd West, Vipin Gupta –Table 10 of this report summarizes the feasibility of monitoring a 1 kt fission explosion at various distances Summary of Table 10 of the Bernstein, West, & Gupta Report RangeApplicationsFeasibility 10 kmCooperative monitoringPossible now 100 kmEntire test sitesLimit of current technology 1000 kmBeyond national bordersPossible with new tech. > 1000 kmRemote monitoringImpossible

10. 2007-DEC-13AAP 20079 My Studies from the Past Few Years