Following the main objective of the IAEA Coordinated Research Project on Photonuclear Data and Photon Strength Functions (Code F41032; Duration 2016-2019), new measurements of photoneutron and photofission cross sections in the Giant Dipole Resonance energy region have been performed at the laser Compton-scattering γ-ray source of the NewSUBARU synchrotron radiation facility. Nuclei in a wide mass range spanning from 9 Be to 238 U have been investigated. Quasi-monochromatic γ-ray beams with typical energy resolution 3% in full width at half maximum have been employed. The spectral distributions of the incident γ-ray beams have been modeled with the eliLaBr Monte Carlo simulation code for Compton interaction between continuous, unsynchronized laser and electron beams sent head-on against each other, with realistic modeling of the spatial overlap between the polarized laser and unpolarized electron beams along the interaction region and full modeling of the scattered photon polarization state. The neutron multiplicity sorting has been performed using an energy-dependent statistical treatment of neutron coincidence events associated with a flat-efficiency moderated neutron detection array. We report updates on the experimental technique and methodology and selected experimental results on total photoabsorption cross sections for 208 Pb, 232 Th and 238 U.

The experiments were performed at bremsstrahlung end-point energies of 10-23 MeV with the beam from the MT-25 microtron with the use of the γ-activation technique. The experimental values of relative yields were compared with theoretical results obtained on the basis of TALYS with the standard parameters and the combined model of photonucleon reactions. Including isospin splitting in the combined model of photonucleon reactions allows to describe experimental data on reactions with proton escape in energies range from 10 to 23 MeV. Therefore, taking into account isospin splitting is necessary for a correct description of the decay of the GDR.

Relative yields have been measured in the 40-130 MeV bremsstrahlung induced reactions of 59Co. The experiments have been performed with the beam from the electron linear accelerator LINAC-200 using the activation and off-line γ-ray spectrometric technique. The bremsstrahlung photon flux has been calculated with the Geant4 program. The cross sections were calculated by using computer code TALYS-1.96 with different models and are found to be in good agreement with the experimental data.

For photonuclear research with γ-quanta having energies Eγ ≤ 40 MeV at the source under developing with backward Compton scattering of laser radiation on accelerated electrons, activation experiments are proposed as initial ones. These experiments are important both for developing techniques for tuning and monitoring such γ-beams, and for studying the excitation of pygmy and giant resonances in nuclei at Eγ near the threshold of the (γ, n) reaction, as well as the multiplicity of photoneutrons during deexcitation of giant resonances at Eγ above the threshold of (γ, 2n)-reaction.

To study the E1 giant resonance in atomic nuclei, it is important to study the energy and emission angle distributions of fast neutrons from (γ, n)-reactions. The paper considers some features of such studies on beams of γ-quanta produced by inverse Compton scattering with small spreads of their energy, angles, transverse dimensions, duration, and polarization in these beams. It is proposed to use fast neutron spectrometers using both amplitude and time-of-flight data.

105Rh is one of the promising beta-emitters for therapeutic purposes in nuclear medicine, but its use is limited, due to in part its low availability, which dictates the search for new effective ways to produce it. In this work, the radionuclide composition of a PdCl2 target irradiated by bremsstrahlung photons is determined and a method is proposed for recovery carrier free 105Rh from it using a commercial DGA sorbent, which ensures a high degree of purification of the target isotope. In future, the studies carried out may contribute to the practical application of 105Rh to nuclear medicine.

The possibilities of studying the reaction yields of ^13 C (γ,p)^12 B, ^14 N (γ,2p)^12 B, and ^14 N (γ,2n)^12 N through measurements of induced ( ^12 B, ^12 N) activities with thin Δ E detector telescopes in temporal intervals between electron accelerator pulses have been analyzed. Estimates for the production of ( ^12 B, ^12 N) nuclei and registration of their decay are provided, taking into account the parameters of the electron beam, Ta radiator, irradiated targets made of graphite or NH _4 NO _3 , and telescopes of plastic scintillation Δ E detectors.

The issues are considered for studying the yields of the reactions 13C(γ, p)12B, 14N(γ, 2p)12B, and 14N(γ, 2n)12N with measuring (12B, 12N)-activity by telescopes of ΔE-detectors in time between electron accelerator pulses. For the chosen radiators and targets, the fluxes, and spectra of irradiating bremsstrahlung γ-quanta are found. The influence of the parameters of targets and telescopes of ΔE-detectors on production of (12B, 12N)-nuclei and registration of their decay is estimated.

Based on the analysis of development of photonuclear reaction studding at 𝐸𝛾 ≲ 40 MeV and the unique parameters of the Compton source of 𝛾–quanta under projecting, a program of priority photonuclear research using this source is proposed. The program includes research on: structures of giant E1 resonances and pygmy resonances; cross sections for partial photonucleon reactions; nuclear resonant fluorescence; photofission; problems of astrophysics and nucleosynthesis.

Photoneutron reactions on 208 Pb 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 208 Pb in a broad energy range covering the neutron threshold up to 38 MeV.

The possibilities are analyzed for studying the yields of reactions 13C(𝛾, 𝑝) 12B, 14N(𝛾, 2𝑝) 12B, 14N(𝛾, 2𝑛) 12N by measuring the induced (12B, 12N)-activity with telescopes of thin Δ𝐸–detector in time intervals between electron accelerator pulses. For production of (12B, 12N)- nuclei and registration of their decay, estimates are given taking into account the parameters of the electron beam, Ta–radiator and irradiated targets made from graphite or NH4NO3, as well as the parameters of scintillation Δ𝐸 detector telescopes made from thin plastic plates.

The flux weighted average cross sections 〈σ〉 and cross sections per equivalent photon σq were first measured for the photonuclear multiparticle reactions natSe(γ, xnyp) at end-point bremsstrahlung gamma energies ranging from 20 to 80 MeV. The experiments were performed with the beam from the electron linear accelerator LINAC-200 with the use of the γ-activation technique. The bremsstrahlung photon flux was calculated with the program Geant4. The theoretical values of the flux weighted average cross sections 〈σ〉 and the cross sections per equivalent photon σq were calculated using the partial cross section σ(E) computed with the TALYS package code and the combined model of photonuclear reactions.

Proceeding from the comparison of parameters for the γ -ray source based on backward Compton scattering, which is under development now, and the known methods of monitoring γ -ray beams themselves to monitor the intensity and energy spectrum of γ quanta in the beams from this γ -ray source during photonicuclear research in the energy range from a few megaelectronvolts to ∼ 40 MeV, a system comprising scintillation plastic and inorganic detectors, as well as a magnetic pair spectrometer, has been proposed.

Intense, quasi-monochromatic, polarized y-ray beams with high and tunable energy produced by Compton scattering of laser photons against relativistic electrons are used for fundamental studies and applications. Following a series of photoneutron cross section measurements in the Giant Dipole Resonance (GDR) energy region performed at the NewSUBARU synchrotron radiation facility, we have developed the eliLaBr Monte Carlo simulation code for characterization of the scattered y-ray photon beams. The code is implemented using GEANT4 and is available on the GitHub repository (https://github.com/dan-mihai-filipescu/eliLaBr). Here we report the validation of the eliLaBr code on NewSUBARU LCS y-ray beam flux and spectral distribution data and two applications performed with it for asymmetric transverse emittance profiles electron beams, characteristic for synchrotrons.The first application is based on a systematic investigation of transverse collimator offsets relative to the laser and electron beam axis. We show that the maximum energy of the LCS y-ray beam is altered by vertical collimator offsets, where the edge shifts towards lower energies with the increase in the offset. Secondly, using the eliLaBr code, we investigate the effect of the laser polarization plane orientation on the properties of the LCS y-ray beams produced with asymmetric emittance electron beams. We show that:1. The use of vertically polarized lasers contributes to the preservation of the LCS y-ray beam maximum energy edge by increasing the precision in the vertical collimator alignment.2. Under identical conditions for the electron and laser beams phase-space distributions, the energy spectrum of the scattered LCS y-ray beam changes with the laser beam polarization plane orientation. More precisely, the use of vertically polarized laser beams slightly deteriorates the LCS y-ray beam energy resolution.

The production possibility of 161Tb and 155Tb by irradiating of natural dysprosium with gamma rays obtained by decelerating an electron beam with an energy of 55 MeV has been demonstrated experimentally. The yield of 161Tb was 14.4 x 103 Bq x mu A-1 x h-1 x cm2 x gDy2O3- 1. Simultaneously, upon irradiation, 155Dy is formed with the yield of 25 x 103 Bq x mu A-1 x h-1 x cm2 x gDy2O3- 1, which leads to the formation of 1.6 x 103 Bq x mu A-1 x h-1 x cm2 x gDy2O3- 1 of 155Tb. It has been shown that the isolation of terbium radioisotopes from tens of mg of dysprosium target can be achieved by extraction chromatography, and final separation yield was 39%. The impurity of 160Tb is 7.3% of the 161Tb activity at EOB.

Based on a comparison of the parameters of the projected 𝛾–source from backward Compton scattering and the known ways of monitoring the beams of 𝛾–quanta themselves to monitor the intensity and energy spectrum of 𝛾–quanta in their beams at this 𝛾–source in photonuclear studies in the region from several MeV to ∼40 MeV, a system of scintillation plastic and inorganic detectors, as well as a pair magnetic spectrometer, was proposed.