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The Shanghai Laser Electron Gamma Source (SLEGS) is a powerful gamma source that provides MeV gamma-ray beams for nuclear science and technology. It was developed as one of the 16 beamline stations in the Phase II Project of the Shanghai Synchrotron Radiation Facility. The slant-scattering mode is for the first time systematically employed in laser Compton scattering at SLEGS to produce energy-tunable quasi-monoenergetic gamma-ray beams. The SLEGS officially completed its commissioning from July to December 2021. Gamma rays in the energy range of 0.25–21.7 MeV with a flux of 2.1 × 104–1.2 × 107 photons/s and an energy spread of 2–15% were produced during the test. This paper reports the results from commissioning the SLEGS beamline.

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.

A high-and-flat efficiency moderated neutron detection array of 3He counters has been recently developed for photoneutron cross section measurements at the future ELI-NP gamma-ray beam source. We have designed a three rings geometry of 31 counters with a ˜37% efficiency flat within 5% in the 10 keV to 5 MeV neutron energy interval. A commissioning experiment was performed using proton beams delivered by the 9 MV Tandem accelerator of IFIN-HH. We measured the neutron production cross sections for proton induced reactions on nat Cu and 27Al. The (p, xn) reactions on nat Cu were investigated in the 4.5 MeV to 14 MeV proton energy range with 250 keV steps, using pulsed and continuous proton beams. The low energy measurements below 10 MeV served to validate the detection efficiency calibration against well-known natCu(p, n) cross sections. The 27Al(p, n) reaction was investigated in the 5.8 MeV to 6.75 MeV energy range with 5 keV steps. Preliminary cross section results are here compared with preceding data.

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.

Photo-induced reaction cross section data are of importance for a variety of current or emerging applications, such as radiation shielding design and radiation transport analyses, calculations of absorbed dose in the human body during radiotherapy, physics and technology of fission reactors (influence of photo-reactions on neutron balance) and fusion reactors (plasma diagnostics and shielding), activation analyses, safeguards and inspection technologies, nuclear waste transmutation, medical isotope production and astrophysical applications. To address these data needs the IAEA Photonuclear Data library was produced in 1999, containing evaluated photo-induced cross sections and neutron spectra for 164 nuclides which were deemed relevant for the applications. Since the release of the IAEA Photonuclear Data Library however, new experimental data as well as new methods to assess the reliability of experimental cross sections have become available. Theoretical models and input parameters used to evaluate photo-induced reactions have improved significantly over the years. In addition, new measurements of partial photoneutron cross sections using mono-energetic photon beams and advanced neutron detection systems have been performed allowing for the validation of the evaluations and assessments of the experimental data. Furthermore, technological advances have led to the construction of new and more powerful gamma-beam facilities, therefore new data needs are emerging. We report our coordinated efforts to address these data needs and present the results of the new up-to-date evaluations included in the new updated IAEA Photonuclear Data Library consisting of 219 nuclides. The new library includes 188 new evaluations produced by the CRP evaluators, and one evaluation taken from the JENDL/PD-2016 library, while 20 evaluations were retained from the previous 1999 IAEA Photonuclear Data Library. In most of the cases, the photon energy goes up to 200 MeV. A total of 55 nuclides are new in this library reflecting the progress in measurements but also the developing data needs. In this paper we discuss the new assessment method and make recommendations to the user community in cases where the experimental data are discrepant and the assessments disagree. In addition, in the absence of experimental data, we present model predictions for photo-induced reaction cross section on nuclides of potential interest to medical radioisotope production.

We present the latest development of measuring (γ, n) cross sections and giant dipole resonance (GDR) cross sections in the IAEA photonuclear data project. Photoneutron cross sections were measured for 21 isotopes below 2n threshold to construct the γ-ray strength function (γSF) with the γSF method; (γ, n) cross sections are used as experimental constraints on the model E1 and M1 γSFs from the Hartree–Fock–Bogolyubov plus quasi-particle random phase approximation based on the Gogny D1M interaction supplemented with the M1 upbend. GDR cross sections were measured for 11 nuclei from 9Be to 209Bi by direct neutron-multiplicity sorting with a flat-efficiency neutron detector toward a goal of resolving the long-standing discrepancy between the Livermore and Saclay data. We present γSFs for the Ni isotopic chain and GDR cross sections for 159Tb as well as those updated for 209Bi.

Performance of the ELIGANT-GN array being developed at ELI-NP was evaluated using dedicated GEANT4 simulation code. The array is designed to consist of 17 LaBr3:Ce and 17 CeBr3 detectors as well as 33 BC501A and 29 6Li-glass detectors. The energy and time responses of the detectors were studied giving information on gamma and neutron absolute detection efficiencies of the array. A planned day-one experiment regarding the gamma and neutron decay from GDR in 208Pb is discussed and, based on simulations, the data analysis procedure is proposed. The detection efficiencies as well as the count rates estimations are presented.

Photoneutron measurements in the Giant Dipole Resonance region have been recently performed using quasimonochromatic Laser Compton Scattering γ -ray beams at NewSUBARU (Japan) for 59Co, 89Y, 103Rh, 139La, 159Tb, 165Ho, 169Tm, 181Ta, 197Au and 209Bi. Experimental ( γ , x n ) with x = 1 – 4 photoneutron cross sections have been obtained with a direct neutron-multiplicity sorting method associated to a flat-efficiency neutron detector , which operates under single firing conditions obtained by low reaction rates. In this paper, we discuss recent developments to the neutron-multiplicity sorting procedure dedicated to (i) resolving multiple firing events and to (ii) extracting the average energies of ( γ , x n ) photoneutrons. The method is tested on 159Tb experimental data.

The response function to high energy γ γ -rays of two large volume LaBr 3 :Ce crystals (3.5”x8”) and the linearity of the coupled PMT’s were investigated at the NewSUBARU facility, where γ γ -rays in the energy range 6 –38 MeV were produced and sent into the detectors. Monte Carlo simulations were performed to reproduce the experimental spectra. The photopeak and interaction efficiencies were also evaluated both in case of a collimated beam or an isotropic source.

A novel technique of direct neutron-multiplicity sorting with a flat-efficiency detector is proposed to resolve the long-standing discrepancy between the Livermore and Saclay data of partial photoneutron cross sections. A flat-response neutron detector with the detection efficiency of 36 . 5 ± 1 . 6 % over a neutron energy range 0.01–5.0 MeV was developed by optimizing triple-ring configurations of He proportional counters embedded in a polyethylene moderator. The technique forms a foundation of measuring cross sections with x = 1 − 3 for the photonuclear data project of the International Atomic Energy Agency. The methodology of direct neutron-multiplicity sorting and key experimental elements are presented.

The Coordinated Research Project (CRP) with the code F41032 has been launched by the International Atomic Energy Agency (IAEA) in 2016 as a 5-year project with the scientific goal being two-fold: 1) updating the 2000 photonuclear data library and 2) constructing a reference database of photon strength functions. We report the experimental technique and methodology used for the former goal and selected giant-dipole resonance (GDR) data updated 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.

Photon strength functions describing the average response of the nucleus to an electromagnetic probe are key input information in the theoretical modelling of nuclear reactions. Consequently they are important for a wide range of fields such as nuclear structure, nuclear astrophysics, medical isotope production, fission and fusion reactor technologies. They are also sources of information for widely used reaction libraries such as the IAEA Reference Input Parameter Library and evaluated data files such as EGAF. In the past two decades, the amount of reaction gamma-ray data measured to determine photon strength functions has grown rapidly. Different experimental techniques have led to discrepant results and users are faced with the dilemma of which (if any) of the divergent data to adopt. We report on a coordinated effort to compile and assess the existing experimental data on photon strength functions from the giant dipole resonance region to energies below the neutron separation energy. The assessment of the discrepant data at energies around or below the neutron separation energy has been possible only in a few cases where adequate information on the model-dependent analysis and estimation of uncertainties was available. In the giant dipole resonance region, we adopt the recommendations of the new IAEA photonuclear data library. We also present global empirical and semi-microscopic models that describe the photon strength functions in the entire energy region and reproduce reasonably well most of the experimental data. The compiled experimental photon strengths and recommended model calculations are available from the PSF database hosted at the IAEA (http://www-nds.iaea.org/PSFdatabase)., SCOPUS: re.j, info:eu-repo/semantics/published

Photoneutron cross sections were measured for $^{137}$Ba and $^{138}$Ba at energies below two-neutron threshold using quasi-monochromatic $\gamma$-ray beams produced in laser Compton-scattering at the NewSUBARU synchrotron radiation facility. The photoneutron data are used to constrain the $\gamma$-ray strength function on the basis of the Hartree-Fock-Bogolyubov plus quasi-particle random phase approximation using the Gogny D1M interaction. Supplementing the experimentally constrained $\gamma$-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., Comment: arXiv admin note: substantial text overlap with arXiv:1811.00291, arXiv:1804.07654

The future prospects of photonuclear reactions studies at the new Extreme Light Infrastructure—Nuclear Physics (ELI-NP) facility are discussed in view of the pursuit of investigating the electromagnetic response of nuclei using γ-ray beams of unprecedented energy resolution and intensity characteristics. We present here the features of the γ-ray beam source, the emerging ELI-NP experimental program involving photonuclear reactions cross section measurements and spectroscopy and angular measurements of γ-rays and neutrons along with the detection arrays currently under implementation.

Photoneutron cross sections were measured for $^{203}\mathrm{Tl}$ and $^{205}\mathrm{Tl}$ at energies between the one- and two-neutron thresholds using quasimonochromatic $\ensuremath{\gamma}$-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 $\ensuremath{\gamma}$-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 $\ensuremath{\gamma}$-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 $^{204}\mathrm{Tl}$ in the context of the $^{205}\mathrm{Pb}\ensuremath{-}^{205}\mathrm{Tl}$ chronometry.

Nuclear level densities (NLDs) and \(\gamma \)-ray strength functions (\(\gamma \)SFs) of \(^{91,92}\)Zr have been extracted from particle-\(\gamma \) coincidences using the Oslo method. The extracted \(\gamma \)SF data, combined with photonuclear cross sections, cover the whole energy range from \(E_{\gamma } \approx 1.5\) MeV up to the giant dipole resonance at \(E_{\gamma } \approx 17\) MeV. The wide-range \(\gamma \)SF data display structures at \(E_{\gamma } \approx 9.5\) MeV, compatible with a superposition of the spin-flip M1 resonance and a pygmy E1 resonance. Furthermore, the \(\gamma \)SF shows a minimum at \(E_{\gamma } \approx \) 2–3 MeV and an increase at lower \(\gamma \)-ray energies. The experimentally constrained NLDs and \(\gamma \)SFs are shown to reproduce known (\(n, \gamma \)) and Maxwellian-averaged cross sections for \(^{91,92}\)Zr using the TALYS reaction code, thus serving as a benchmark for this indirect method of estimating (\(n, \gamma \)) cross sections for Zr isotopes.

Photoneutron cross sections were measured for Ni58,Ni60,Ni61, and Ni64 at energies between the one-neutron and two-neutron thresholds using quasimonochromatic γ-ray beams produced in laser Compton scattering at the NewSUBARU synchrotron radiation facility. These photoneutron data are used to extract the γ-ray strength function above the neutron threshold, complementing the information obtained by the Oslo method below the threshold. We discuss radiative neutron-capture cross sections and the Maxwellian-averaged cross sections for Ni isotopes including Ni63, a branching point nucleus along the weak s-process path. The cross sections are calculated with the experimentally constrained γ-ray strength functions from the Hartree-Fock-Bogolyubov plus quasiparticle–random-phase approximation based on the Gogny D1M interaction for both E1 and M1 components and supplemented with the M1 upbend.

The synchrotron radiation facility NewSUBARU with nine beam-lines is operated by the Laboratory of Advanced Science and Technology for Industry, University of Hyogo, Japan. Gamma-ray beams are produced in the beam-line BL01 by laser Compton scattering (LCS) from 0.5–1.5 GeV electron beams in the NewSUBARU storage ring [1]. Lasers with different wavelengths are used to produce the LCS photon beam in the energy range from 0.5 MeV to 76 MeV: a Nd:YVO4 laser (λ = 1064 and 532 nm), a CO2 laser (λ = 10.59 μm), and an Er fiber laser (λ = 1540 nm). A new experimental hutch, GACKO (Gamma Collaboration Hutch of Konan University), was installed in the BL01 in March 2012.

The 77Se (γ, n) cross section was measured for the energy range from 7.6 to 13.8 MeV by using quasi-monochromatic laser-Compton scattering γ-rays. The advanced method to deduce γ-ray strength functions from (γ, n) cross section was developed. By utilizing the method, the γ-ray strength functions of 77, 78, 80Se were deduced so as to reproduce the 77, 78, 80Se (γ, n) cross sections measured in this work and previous systematic measurements. The inverse (n, γ) cross sections for 76, 77, 79Se isotopes were calculated using the statistical model calculation code CCONE with the deduced γ-ray strength functions. The uncertainty of the calculated 79Se(n, γ)80Se cross section was evaluated by comparing the calculations and the experimental data on 76, 77Se (n, γ) cross sections.

The photoneutron cross sections of Dy162,163 have been measured for the first time in an energy region from the neutron threshold (Sn) up to ≈13MeV. The (γ,n) reaction was induced with quasimonochromatic laser Compton-scattered γ rays, produced at the NewSUBARU laboratory. The corresponding γ-ray strength functions (γSF) have been calculated from the photoneutron cross sections. The data are compared to reanalyzed γSFs of Dy160-164, which are measured below Sn. The excellent agreement with the photoneutron data at Sn confirms the principle of detailed balance. Thus, a complete γSF is established covering in total the energy region of 1≤Eγ≤13 MeV. These mid-shell well-deformed dysprosium isotopes all show scissors resonances with very similar structures. We find that our data predict the same integrated scissors strength as (γ,γ′) data when integrated over the same energy range, which shows that the scissors mode very likely is consistent with the generalized Brink hypothesis. Finally, using the γSFs as input in the reaction code talys, we have deduced radiative neutron-capture cross sections and compared them to direct measurements. We find a very good agreement within the uncertainties, which gives further support to the experimentally determined γSFs., SCOPUS: ar.j, info:eu-repo/semantics/published

Single- and multi-photon spectra of pulsed γ -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 j -fold photons ( j = 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 γ -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 y = a ⋅ x η with η =e − b x . We discuss the accuracy of photon-flux determination.

Photoneutron cross sections were measured in the $^{209}\mathrm{Bi}$($\ensuremath{\gamma}, xn$) reaction with $x=1--4$ at energies from the neutron threshold to 40 MeV using quasimonochromatic laser Compton-scattering $\ensuremath{\gamma}$-ray beams. A novel technique of direct neutron-multiplicity sorting with a flat-efficiency detector was used. Results are compared with the positron in-flight annihilation data of Livermore and Saclay as well as with bremsstrahlung data. The present neutron yields are consistent with the latest photoactivation measurement with bremsstrahlung. The giant dipole resonance component of the total photoneutron cross section is reasonably reproduced by model calculations of the Hartree-Fock Bogoliubov plus quasiparticle random phase approximation based on the Gogny D1M interaction for both E1 and M1 components. In contrast, the quasideuteron component of the total photoneutron cross section requires a factor of $\ensuremath{\sim}3$ enhancement of the Levinger parameter. Furthermore, a survival of large $(\ensuremath{\gamma},n)$ cross sections above 20 MeV may indicate the surface effect on the two-component particle-hole state density. The threshold behavior of photoneutron emission is discussed in terms of the average neutron kinetic energy.

We discuss the γ-ray strength function toward a unified understanding of (γ,n) and (n,γ) reactions and propose a novel technique of direct neutron-multiplicity sorting to resolve the long-standing discrepancy between the Livermore and Scalya data of partial photoneutron cross sections., SCOPUS: cp.p, info:eu-repo/semantics/published

Nuclear level densities (NLDs) and $\ensuremath{\gamma}$-ray strength functions ($\ensuremath{\gamma}\mathrm{SFs}$) have been extracted from particle-$\ensuremath{\gamma}$ coincidences of the $^{92}\mathrm{Zr}(p,{p}^{\ensuremath{'}}\ensuremath{\gamma})^{92}\mathrm{Zr}$ and $^{92}\mathrm{Zr}(p,d\ensuremath{\gamma})^{91}\mathrm{Zr}$ reactions using the Oslo method. The new $^{91,92}\mathrm{Zr}\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}\mathrm{SF}$ data, combined with photonuclear cross sections, cover the whole energy range from ${E}_{\ensuremath{\gamma}}\ensuremath{\approx}1.5\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ up to the giant dipole resonance at ${E}_{\ensuremath{\gamma}}\ensuremath{\approx}17$ MeV. The wide-range $\ensuremath{\gamma}\mathrm{SF}$ data display structures at ${E}_{\ensuremath{\gamma}}\ensuremath{\approx}9.5$ MeV, compatible with a superposition of the spin-flip $M1$ resonance and a pygmy $E1$ resonance. Furthermore, the $\ensuremath{\gamma}\mathrm{SF}$ shows a minimum at ${E}_{\ensuremath{\gamma}}\ensuremath{\approx}2--3\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ and an increase at lower $\ensuremath{\gamma}$-ray energies. The experimentally constrained NLDs and $\ensuremath{\gamma}\mathrm{SFs}$ are shown to reproduce known ($n,\ensuremath{\gamma}$) and Maxwellian-averaged cross sections for $^{91,92}\mathrm{Zr}$ using the talys reaction code, thus serving as a benchmark for this indirect method of estimating ($n,\ensuremath{\gamma}$) cross sections for Zr isotopes.

The well-known problem of noticeable disagreements between photoneutron cross sections from various experiments was discussed in detail for 209Bi. Data for partial photoneutron reactions cross sections obtained at Livermore (USA) using quasimonoenergetic annihilation photons and the method of neutron multiplicity sorting were analyzed using the objective physical criteria and the experimental-theoretical method for evaluation. Because of significant systematic uncertainties involved in the method for determining the neutron multiplicity, experimental data do not satisfy the criteria of reliability and differ noticeably from the evaluated data. The new experimental data for 209Bi (γ, in) reactions with i = 1–4 were obtained using quasimonochromatic laser Compton-scattering (LCS) γ-ray beams at the NewSUBARU synchrotron radiation facility and the novel technique of direct neutron-multiplicity sorting with a flat-efficiency detector. It was found that new σ(γ, 1n), σ (γ, 2n), and σ (γ, 3n) contradict noticeably to the Livermore data. It was shown that at the same time the new 209Bi photoneutron cross-sections are in good agreement with data evaluated using experimental-theoretical method and assuring the reliability of those.

Using $\gamma $ -ray beams produced in the inverse Compton scattering between ${\hbox{CO}}_2$ laser photons and relativistic electrons, we have calibrated electron beam energies in the nominal energy range 550–974 MeV at the synchrotron radiation facility NewSUBARU. The laser Compton-scattering (LCS) $\gamma $ -ray beams were produced at energies from 561 to 1728 keV and detected with a high-purity germanium detector. The electron beam energies were determined by reproducing the full energy peaks of the $\gamma $ -ray beams by Monte Carlo simulations. The accuracy of the calibration is $(5.5 - 9.4) \times {10^{ - 5}}$ . The reproducibility of the electron beam energy is excellent in an independent injection and deceleration. The present energy calibration of the electron beams offers a standard for the energy calibration of high-energy LCS $\gamma $ -ray beams produced with a ${\hbox{Nd:YVO}}_4$ laser. As applications of the energy calibration, we investigated the energy linearity of a $3.5^{\prime\prime} \times 4.0^{\prime\prime}$ ${\hbox{LaBr}}_3({\hbox{Ce}})$ detector in the response to $\gamma $ -rays at energies up to 10 MeV and the energy profile of the high-energy LCS $\gamma $ -ray beams.

An update of the NACRE compilation [3] is presented. This new compilation, referred to as NACRE II, reports thermonuclear reaction rates for 34 charged-particle induced, two-body exoergic reactions on nuclides with mass number A 16 , of which fifteen are particle-transfer reactions and the rest radiative capture reactions. When compared with NACRE, NACRE II features in particular (1) the addition to the experimental data collected in NACRE of those reported later, preferentially in the major journals of the field by early 2013, and (2) the adoption of potential models as the primary tool for extrapolation to very low energies of astrophysical S-factors, with a systematic evaluation of uncertainties. As in NACRE, the rates are presented in tabular form for temperatures in the 10 6 ≲ T ⩽ 10 10 K range. Along with the ‘adopted’ rates, their low and high limits are provided. The new rates are available in electronic form as part of the Brussels Library (BRUSLIB) of nuclear data. The NACRE II rates also supersede the previous NACRE rates in the Nuclear Network Generator (NETGEN) for astrophysics. [ http://www.astro.ulb.ac.be/databases.html ]

The $\ensuremath{\gamma}$-ray strength functions and level densities of $^{73,74}\mathrm{Ge}$ have been extracted up to the neutron-separation energy ${S}_{n}$ from particle-$\ensuremath{\gamma}$ coincidence data using the Oslo method. Moreover, the $\ensuremath{\gamma}$-ray strength function of $^{74}\mathrm{Ge}$ above ${S}_{n}$ has been determined from photoneutron measurements; hence these two experiments cover the range of ${\mathrm{E}}_{\ensuremath{\gamma}}\ensuremath{\approx}1$--13 MeV for $^{74}\mathrm{Ge}$. The obtained data show that both $^{73,74}\mathrm{Ge}$ display an increase in strength at low $\ensuremath{\gamma}$ energies. The experimental $\ensuremath{\gamma}$-ray strength functions are compared with $M1$ strength functions deduced from average $B(M1)$ values calculated within the shell model for a large number of transitions. The observed low-energy enhancements in $^{73,74}\mathrm{Ge}$ are adopted in the calculations of the $^{72,73}\mathrm{Ge}(n,\ensuremath{\gamma})$ cross sections, where there are no direct experimental data. Calculated reaction rates for more neutron-rich germanium isotopes are shown to be strongly dependent on the presence of the low-energy enhancement.

We measured pulse-height spectra of 16.7 MeV laser-Compton scattering photons with a 6 in.×5 in. NaI(Tl) detector for blank and three lead materials of 75.8, 50.9, and 25.9% transmissions at the NewSUBARU facility to investigate how the original Poisson distribution of the pulsed photons is modified after passing through thick-target materials. We present a well-prescribed method of determining the number of incident photons within 3.5% accuracy based on the response of the NaI(Tl) detector to the pulsed photon beams.

An indirect method of determining radiative neutron-capture cross sections for unstable nuclei which we refer to as the γ-ray strength function (γSF) method is outlined and applied to Zr and Sn isotopes. Photoneutron cross sections for 91,92,94,96Zr and 117,116Sn near neutron threshold show the presence of extra γ-ray strengths known as giant M1 and pygmy E1 resonances on top of the low- energy γSF of GDR. Based on the γSF method, we present (n,γ) cross sections for two radioactive nuclei, a long-lived fission product, 93Zr with T1/2 = 1.5 × 106 y and an s-process branching point nucleus, 95Zr with T1/2 = 64.0 d.

The (γ, n) cross sections of Se isotopes (76Se,78Se) were measured to supply fundamental data for estimating the inverse reaction cross section, i.e., the 79Se(n, γ)80Se cross section. The enriched samples and a reference 197Au sample were irradiated with laser-Compton scattering (LCS) γ-rays. The excitation function of each (γ, n) cross section was determined for the energy range from each near neutron separation energy to the threshold energy of (γ, 2n) reaction. The energy point corresponding to each cross section was deduced using the accurately determined energy distribution of LCS γ-rays. Systematic (γ, n) cross sections for Se isotopes including 80Se were compared with those calculated by using a statistical model calculation code TALYS.

Photoneutron cross section measurements were made for Au in the entire energy range of the (γ,n) channel based on a direct neutron counting with quasi-monochromatic γ-rays produced in inverse Compton scattering of laser photons with relativistic electrons. The data were analyzed by a least-squares method to deduce photoneutron cross sections. The analysis significantly reduced experimental uncertainties compared with those resulting from the photon difference method. The result is compared with the previous data by direct neutron counting with γ-rays produced in positron annihilation in flight and by photoactivation with bremsstrahlung. The present data are in good agreement with the previous data near the neutron threshold, while there remain some discrepancies between the present and the previous data above 10 MeV.

The 80Se(γ, n)79Se cross section was measured with laser-Compton scattering (LCS) γ-rays to supply fundamental data for the estimation of the inverse reaction cross sections, i.e., the 79Se(n, γ)80Se cross section. An enriched 80Se sample and a reference 197Au sample were irradiated with LCS γ-rays whose maximum energy was varied from 10.5 to 16.0 MeV. The energy distributions of LCS γ-rays were precisely determined using a high-resolution high-energy photon spectrometer (HHS). Emitted neutrons were detected by a high-efficiency 4π-3He detector. The excitation function of the 80Se(γ, n) cross section was determined for the energy range of 10.2–14.6 MeV. The energy point corresponding to each cross section was deduced using the accurately determined energy distribution of LCS γ-rays.

We carried out the β‐decay spectroscopy on 24Si in order to investigate a change in configuration in the wave function induced by Thomas‐Ehrman shift from a perspective of mirror asymmetry of B(GT). We observed two β transitions to low‐lying bound states in 24Al for the first time. In this proceeding, the B(GT) of 24Si is compared with that of the mirror nucleus 24Ne, and the mirror asymmetry of B(GT) is determined. Then the origin of the B(GT) asymmetry is discussed through the comparison with theoretical calculations.

The universe is filled with cosmic microwave background radiation at 2.73 K (Figure 1). It is a relic of the “fire-ball” that the universe once underwent shortly after its birth. This is the lowest-temperature black-body radiation that mankind has ever witnessed. Where can we expect highest-temperature black-body radiations? An answer may be found in the explosion of massive stars. Stars more massive than 10 solar masses that are destined to die as type II supernovae (Figure 2) evolve to form an onion-like pre-supernova structure consisting of multi-layers of hydrogen, helium, carbon, silicon, and the iron core as dominant elements. The gravitational collapse of the iron core triggers the explosion. Typically energy of about 1% (~1051 erg) of the gravitational energy is sufficient to explode massive stars, blowing off the outer layers and leaving neutron-stars (black-holes) as remnants. During the supernova explosion, the shock wave propagates the outer layers and heats material behind it, making, for exa...

The photon mass attenuation coefficients of the important materials for γ-ray detection, Ge and BGO (Bi4Ge3O12) crystals, have been measured for 10.0 MeV γ-rays. The measurement system using the laser-Compton backscattering γ-rays and the high-resolution high-energy photon spectrometer has been developed and utilized. The effectiveness of the system achieving the total systematic uncertainties of 0.5% for the measurements of the photon mass attenuation coefficients was demonstrated. It was shown that the measured photon mass attenuation coefficients, 318.1 ± 1.7 [cm2/g] for the Ge crystal and 425.2 ± 2.4 [cm2/g] for the BGO crystal, agree within the achieved experimental uncertainties with the evaluated values including atomic and nuclear processes at 10.0 MeV.

The cross sections of the 152Sm(γ,n) and 197Au(γ,n) reactions have been measured with the laser-Compton scattering (LCS) γ beam in the 8.3–12.4MeV energy range. The photon difference method has been used for LCS γ rays in the data analysis for the first time. The present data for 197Au measured as the standard are in agreement with the preceding data and the recent recommendation. On the other hand, the preceding data for 152Sm at 8.3 MeV are twice as large as the present data.

Photodisintegration of $^{9}\mathrm{Be}$ through the $1/{2}^{+}$ state near neutron threshold and cluster dipole resonance below giant dipole resonance was measured with quasi-monochromatic $\ensuremath{\gamma}$-ray beams produced in the inverse Compton scattering of laser photons. The cross section for the $1/{2}^{+}$ state is revisited, being consistent with the 2001 data. The cross section for the cluster dipole resonance is consistent with the cluster dipole sum-rule which however degenerates for the two-body $(n\text{\ensuremath{-}}^{8}\mathrm{Be})$ and three-body $(n\text{\ensuremath{-}}\ensuremath{\alpha}\text{\ensuremath{-}}\ensuremath{\alpha})$ configurations.

The perspectives for photonuclear experiments at the new Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility are discussed in view of the need to accumulate novel and more precise nuclear data. The parameters of the ELI-NP gamma beam system are presented. The emerging experimental program, which will be realized at ELI-NP, is presented. Examples of day-one experiments with the nuclear resonance fluorescence technique, photonuclear reaction measurements, photofission experiments and studies of nuclear collective excitation modes and competition between various decay channels are discussed. The advantages which ELI-NP provides for all these experiments compared to the existing facilities are discussed.

Photon-induced reactions play a key role in the nucleosynthesis of heavy neutron-deficient nuclei, the so-called p-nuclei. In this paper we review the present status of experiments on photon-induced reactions at energies of astrophysical importance and their relevance to p-process modeling., Comment: Nucl. Phys. A, in press

Direct determination of photoneutron cross sections of astrophysical importance has recently become possible with use of quasi-monochromatic γ beams produced in laser Compton backscattering (LCS) from relativistic electrons at AIST. The astrophysics to be discussed with the photodisintegration cross section are both stellar and big bang nucleosyntheses regarding the production of p-process and s-process nuclei as well as light elements. Synchrotron radiations from a 10 tesla superconducting wiggler (SCW) at SPring-8 serve as an ideal photon source to determine photoreaction rates. This paper covers the latest cross section measurements with the LCS photon beams and a feasibility study of determining (γ,x) (x = n, p, α) reaction rates with the SCW radiation.

The astrophysical reaction rates of the 16O(a,g)20Ne capture reaction and its inverse 20Ne(g,a)16O photodisintegration reaction are given by the sum of several narrow resonances and a small direct capture contribution at low temperatures. Although the thermal population of low lying excited states in 16O and 20Ne is extremely small, the first excited state in 20Ne plays a non-negligible role for the photodisintegration rate. Consequences for experiments with so-called quasi-thermal photon energy distributions are discussed.

A surface channel formed in a coaxial germanium detector degrades the pulse-height of output signals. The pulse-height degradation gives rise to an enhancement of low pulse-height events in γ -ray response functions at the cost of the full-energy peak. This phenomenon was closely examined for a twin coaxial-germanium detector. It was found that imperfect charge collection is primarily caused by p-type surface channels and supplemented by the n + –i and i– p + boundaries, producing low-energy events both in the valley between the full-energy peak and the Compton edge and on the hill below the Compton edge. It is shown that experimental response functions of the twin Ge can be reproduced with high precision by incorporating the imperfect charge collection in Monte Carlo simulations in a phenomenological way.

Cross sections of the 186W, 187Re, 188Os(γ,n) reactions were measured using quasi monochromatic γ-ray beams from laser Compton scattering (LCS), and results for the latter reaction are presented here. Neutron capture cross sections of the inverse reactions were evaluated by the Hauser-Feshbach statistical calculation where the experimental data were used to constrain the model parameters, especially the E1 strength function. The influence of the neutron capture by the 9.75 keV first excited state in 187Os which is substantially populated in stellar plasmas at typical s-process temperatures is examined in connection with the 187Re-187Os cosmochronology.