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Measurements of the fission fragment properties of 234 U as a function of incident neutron energy A. Al-Adili 1,2 , F.-J. Hambsch 1 , S. Oberstedt 1 , S. Pomp 2 1) European Commission Joint Research Centre IRMM, Belgium 2) Department of Physics and Astronomy, Uppsala University, Sweden. Outline.

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  1. Measurements of the fission fragment properties of234U as a function of incident neutron energyA. Al-Adili1,2, F.-J. Hambsch1, S. Oberstedt1, S. Pomp21) European Commission Joint Research Centre IRMM, Belgium2) Department of Physics and Astronomy, Uppsala University, Sweden

  2. Outline • Introduction • Motivation • Experimental setup • Data analysis • First results • Conclusions and outlook

  3. Introduction MONo-energetic NEutron Tower Quasi mono-energetic neutron source 7 MV Van-de-Graaff accelerator MONNET Beam intensity: <50 μA DC. Neutron flux : n < 109 /s/sr GELINA neutron TOF spectrometer 70 - 140 MeV electron accelerator neutron pulse: 2 s - 1 ns @ FWHM n = 3.4 1013/s @ 800 Hz

  4. Motivation • 234U(n,f) is relevant for nuclear reactor applications through second chance fission of 235U. • 234U(n,f) is relevant for the thorium cycle. IAEA Coordinated Research Project requested more high quality data for the U-Th cycle *. • Important input data for reaction cross section calculations. • Fluctuations of fission fragment properties are expected in sub-barrier region around the vibrational resonance. *Trkov and D. W. Muir, Journal of Nucl. Sci. and Tech., Supp. 2, 1454

  5. Experiments • Targets used: • 7LiF(p,n)7Be 596μg/cm2 • 7LiF(p,n)7Be 619μg/cm2 • TiT(p,n)3He 1930μg/cm2 • Two experimental runs • Uranium samples: • 234UF4 sample on gold coated polyimide, 92.133ug/cm2. Contains >99% 234U • Calibration using 235U(nthermal,f) • Comparison: Analog and Digital data acquisition June & October 2009

  6. Ionisation chamber Neutron Beam Anode 1 Grid 1 1kV A1 G1 Cathode Grid 2 Good side FF1 θ Anode 2 + - - n + + -1.5kV - 234U C - + n + - n - + FF2 Bad side G2 A2 1kV

  7. Electronics

  8. Data Analysis • Primary corrections of raw data • Electronic calibration • Grid inefficiency • Angular calculation Raw data 0.030414 Cos(0o)=1 Cos(90o)=0

  9. Data Analysis • Further corrections • Neutron momentum transfer • Energy losses • Pulse height defect After all corrections 235U(n,f)

  10. Data Analysis • Angular anisotropy • 234U cosine in centre of mass system relative to the isotropic 235U(n,f). • Angular distribution W(θ) fitted with the two first even Legendre polynomials P0 and P2 . • Anisotropy given by:

  11. First results En = 500 keV En = 835 keV

  12. First results

  13. Conclusions and Outlook Thank you for your attention • First results show strong anisotropy around vibrational resonance confirming earlier literature data. • Determination of mass distributions and TKE distributions is ongoing. • Careful comparison of digital and analog data.

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