Spatial profiles of collimated laser Compton-scattering γ\gamma-ray beams

The intensity and energy spatial distributions of collimated laser Compton scattering (LCS) $\gamma$-ray beams and of the associated bremsstrahlung beams have been investigated as functions of the electron beam energy, electron beam phase space distribution, laser optics conditions and laser polarization. We show that the beam halo is affected to different extents by variations in the above listed parameters. In the present work, we have used laser Compton scattering simulations performed with the \texttt{eliLaBr} code (https://github.com/dan-mihai-filipescu/eliLaBr) and real LCS and bremsstrahlung $\gamma$-ray beams produced at the NewSUBARU synchrotron radiation facility. A 500~$\mu$m MiniPIX X-ray camera was used as beamspot monitor in a wide $\gamma$-ray beam energy range between 1.73~MeV and 38.1~MeV

γ-ray strength function for astrophysical applications in the IAEA-CRP

The γ-ray strength function (γSF) is a nuclear quantity that governs photoabsorption in (γ, n) and photoemission in (n, γ) reactions. Within the framework of the γ-ray strength function method, we use (γ, n) cross sections as experimental constraints on the γSF from the Hartree-Fock-Bogolyubov plus quasiparticle-random phase approximation based on the Gogny D1M interaction for E1 and M1 components. The experimentally constrained γSF is further supplemented with the zero-limit M1 and E1 strengths to construct the downward γSF with which (n, γ) cross sections are calculated. We investigate (n, γ) cross sections in the context of astrophysical applications over the nickel and barium isotopic chains along the s-process path

γ-ray strength function for barium isotopes

Photoneutron cross sections were measured for 137 Ba and 138 Ba at energies below two-neutron threshold using quasimonochromatic γ -ray beams produced in laser Compton scattering at the NewSUBARU synchrotron radiation facility. The photoneutron data are used to constrain the γ -ray strength function on the basis of the Hartree-Fock-Bogolyubov plus quasiparticle random phase approximation using the Gogny D1M interaction. Supplementing the experimentally constrained γ -ray strength function with the zero-limit E1 and M1 contributions, which are unique to the deexcitation mode, we discuss radiative neutron capture cross sections relevant to the s-process nucleosynthesis of barium isotopes in the vicinity of the neutron magic number 82

GDR cross sections updated in the IAEA-CRP

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γ-ray strength function for thallium isotopes relevant to the 205Pb−205Tl chronometry

Photoneutron cross sections were measured for 203Tl and 205Tl at energies between the one- and two-neutron thresholds using quasimonochromatic γ -ray beams produced in laser Compton scattering at the NewSUBARU synchrotron radiation facility. Our measurement results in cross sections significantly different from the previously reported bremsstrahlung experiment, leading to rather different giant dipole resonance (GDR) parameters, in particular to lower GDR peak energies and higher peak cross sections. The photoneutron data are used to constrain the γ -ray strength function on the basis of the Hartree-Fock-Bogolyubov plus quasiparticle random-phase approximation using the Gogny D1M interaction. Supplementing the experimentally constrained γ -ray strength function with the zero-limit E1 and M1 contributions for the de-excitation mode, we estimate the Maxwellian-averaged cross section for the s-process branching-point nucleus 204Tl in the context of the 205Pb-205Tl chronometry

Photofission and photoneutron cross sections for

A specific objective of the recent IAEA Coordinated Research Project on Photonuclear Data and Photon Strength Functions (Code F41032; Duration 2016-2019) has been to measure photonuclear cross-section data where needed, for unexplored nuclei and cases of discrepant existing data. A dedicated experimental campaign has been conducted at the laser Compton-scattering γ-ray source of the NewSUBARU synchrotron radiation facility of SPring8, Japan, where photoneutron reactions for 11 nuclei from 9Be to 209Bi have been investigated in the Giant Dipole Resonance energy region. The measurements followed the development of a flat-effi ciency moderated neutron detection array and the associated neutron-multiplicity sorting techniques. The IAEA CRP campaign has been followed at NewSUBARU by new measurements of photofission and photoneutron reactions on 238U and 232Th in the energy range of 5.87 MeV – 20.14 MeV. The neutron-multiplicity sorting of high-multiplicity fission neutron coincidence events has been performed using a dedicated energy dependent, multiple firing statistical treatment. The photoneutron (γ, xn) and photofission (γ, fxn) reactions have been discriminated by considering a Gaussian distribution of prompt-fission-neutrons (PFN) multiplicities predicted by the evaporation theory. We here provide preliminary experimental (γ, n), (γ, 2n) and (γ, F) cross sections, average energies of PFN and of photoneutrons emitted in (γ, n) and (γ, 2n) reactions, as well as the mean number of PFN per fission act. The new 238U cross sections are compared with recent statistical-model calculations performed with the EMPIRE code on existing data

Photon-flux determination by the Poisson-fitting technique with quenching corrections

Single- and multi-photon spectra of pulsed -ray beams produced at 17, 34, and 40 MeV in the laser Compton scattering were measured with an 8” 12” NaI(Tl) detector. By using the experimental single-photon spectra as the probability function of generating random numbers, response functions of the NaI(Tl) detector to -fold photons ( = 2, 3, 4 ...) were constructed. The least-square fits to the experimental multi-photon spectra by the Poisson distribution consisting of the response functions were made. The multi-photon spectra measured at 17 and 34 MeV follow the Poisson distribution. A quenching phenomenon of multi-photon spectra was observed for 40 MeV -rays as a result of the saturation at the photomultiplier tube of the NaI(Tl) detector. The original Poisson distributions were restored from the quenched spectra using a saturation curve in the form of with =e. We discuss the accuracy of photon-flux determination

Photoneutron cross section measurements on

Photoneutron reactions on 208Pb in the Giant Dipole Resonance (GDR) energy range have been investigated at the γ-ray beam line of the NewSUBARU synchrotron radiation facility in Japan. Making use of quasi-monochromatic laser Compton scattering (LCS) γ-ray beams and of a novel flat-efficiency neutron detection system along with associated neutron-multiplicity sorting method, total and partial (γ,xn) photoneutron cross sections with x = 1 to 4 have been measured for 208Pb in a broad energy range covering the neutron threshold up to 38 MeV

Photoneutron Reaction Data for Nuclear Physics and Astrophysics

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Photoneutron Reaction Data for Nuclear Physics and Astrophysics

We discuss the role of photoneutron reaction data in nuclear physics and astrophysics in conjunction with the Coordinated Research Project of the International Atomic Energy Agency with the code F41032 (IAEA-CRP F41032)