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Photo-Nuclear Physics Experiments by using an Intense Photon Beam

Photo-Nuclear Physics Experiments by using an Intense Photon Beam. Toshiyuki Shizuma Gamma-ray Nondestructive Detection Research Group Japan Atomic Energy Research Institute. Nondestructive Isotope Detection. Nuclear resonance fluorescence (NRF). F ingerprint of isotopes. W A N T E D.

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Photo-Nuclear Physics Experiments by using an Intense Photon Beam

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  1. Photo-Nuclear Physics Experiments by using an Intense Photon Beam Toshiyuki Shizuma Gamma-ray Nondestructive Detection Research Group Japan Atomic Energy Research Institute

  2. Nondestructive Isotope Detection Nuclear resonance fluorescence (NRF) Fingerprint of isotopes W A N T E D High energy g rays are used; High penetrability Applicable for identification of materials such as specific nuclear materials, explosives, etc. shielded by heavy metals R.Hajima, et al., J. Nucl. Sci. Tech. 45, 441 (2008).

  3. Laser Compton Scattering g Rays LCS g rays can be generated by scattering of high energy electrons with laser light. M1 Laser light Electron E1 LCSgray LCS beam Highly monochromatic Highly polarized (linearly/circularly) Energy variable Small divergent Vertical polarization: q=90° E1: Horizontally scattered M1: Vertically scattered

  4. Nuclear physics Nuclear astrophysics Physics with LCS Photon Beams Fundamental collective motions via E1 and M1 excitation Pygmy dipole resonance, spin-flip M1, scissors mode, etc PNC observation with circularly polarized photons Long-standing question in nuclear physics Interference between weak-bosons and nucleons A. I. Titov and M. Fujiwara, J. Phys. G 32, 1097 (2006) Nucelosynthesis (g process and n process) Inelastic neutrino scattering cross sections Reliable nuclear model, e.g, shell model predicting M1 response K. Langankeet al., PRL 20501 (2004)

  5. Strength Distribution of Dipole Excitation (g,g') (g,n) NRF GDR Strength Eth～8MeV p n GDR n PDR M1 PDR Sc p 0 Eg ～15MeV En M1 p n p n GDR: Electric giant dipole resonance PDR: Electric pygmy dipole resonance M1: Magnetic spin-flip dipole mode Sc: Magnetic dipole scissors mode (orbital part) Sc p n

  6. M1 Parallel M1 transitions M1 E1 Perpendicular E1 6.5 7.0 7.5 (MeV) NRF Measurements with LCS Photon Beam Obtained by using LCS g rays at AIST, Tsukuba, Japan T. Shizumaet al., Phys. Rev. C 78 061303(R) (2008) • Clear difference observed between different polarization setups • Unambiguous determination of multipole orders (E1/M1) • Observation of the detailed level structure below En in 208Pb --- Tensor force

  7. Measurements above Neutron Emission Energy Neutron time-of-flight (TOF) method Duration between g pulses and neutron signals Neutron emission n Neutron Neutron

  8. Neutron TOF Spectrum Obtained by using LCS g rays at NewSUBARU Preliminary Structures are observed g Neutrons Neutrons Time LCS g Neutron energy

  9. Polarization Effects Neutron K. Horikawa et al., JPS meeting, Sep. 2010 LCS beam

  10. Summary • Small DE/E (10-6～10-4): • Selective excitation of levels • Short pulse duration: • High resolution measurements • High intensity : • Increased flight distance • →High resolution measurements • Rare isotope measurements • Less amount of target materials The information on the states above the neutron emission energy can be optained through the neutron TOF measurement. - Dipole strength distribution, parity, excitation energy etc.

  11. TOF Energy Resolution Assuming detector time resolution = 1 ns and distance = 3m

  12. Estimation Scattering cross section Is=1.2x10-22 cm2eV for Eg=10 MeV and G0=1eV Production yield Y=3.4x105 /sec for I=106 /sec/eV and Nt=1g/cm2 Counting rate R～60 cps fore～10-5 (3m, 1%) and N=20

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