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t—The mass–energy distributions of fission fragments of excited 180,190Hg nuclei formed in 36Ar + 144,154Sm reactions are measured at incident 36Ar energies of 158, 181, and 222 MeV using the double-arm time-of-flight spectrometer CORSET. The asymmetric fission of 180,190Hg with the most probable masses of light and heavy fragments of 79 and 101 amu, and 84 and 106 amu, respectively, is observed in mass distributions of 180,190Hg at energies of excitation of up to 75 MeV. Two components manifesting the symmetric and asymmetric fission modes are observed in the kinetic energy distributions.

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.

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.

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.

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.

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.

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 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.

The structure of $^{34}$Si was studied through $\gamma$ spectroscopy separately in the $\beta^-$ decays of $^{34}$Mg and $^{34}$Al at the ISOLDE facility of CERN. Different configurations in $^{34}$Si were populated independently from the two recently identified $\beta$-decaying states in $^{34}$Al having spin-parity assignments $J^\pi = 4^-$ dominated by the normal configuration $\pi (d_{5/2})^{-1} \otimes \nu (f_{7/2})$ and $J^\pi = 1^+$ by the intruder configuration $\pi (d_{5/2})^{-1} \otimes \nu (d_{3/2})^{-1}(f_{7/2})^{2}$. The paper reports on spectroscopic properties of $^{34}$Si such as an extended level scheme, spin and parity assignments based on log($ft$) values and $\gamma$-ray branching ratios, absolute $\beta$ feeding intensities and neutron emission probabilities. A total of 11 newly identified levels and 26 transitions were added to the previously known level scheme of $^{34}$Si. Large scale shell-model calculations using the {\sc sdpf-u-mix} interaction, able to treat higher order intruder configurations, are compared with the new results and conclusions are drawn concerning the predictive power of {\sc sdpf-u-mix}, the $N=20$ shell gap, the level of mixing between normal and intruder configurations for the 0$_1^+$, 0$_2^+$ and 2$_1^+$ states and the absence of triaxial deformation in $^{34}$Si.

Mean lifetimes of yrast states of the isotopes 174,176,178,180Hf have been measured using fast- electronic scintillation timing. Excited states of 74,176,178Hf were populated via β decay, while 180Hf was populated via Coulomb excitation. The lifetimes of the 2+ 1 and 4+ 1 states of all isotopes and the lifetimes of the 6+ 1 states of 174,178Hf were measured, using the slope and the centroid shift methods. The mean lifetime, τ (4+ 1 ) = 85(13) ps, of 178Hf has been determined for the first time. In addition, the mean lifetimes of the 2− 1 and the 3− 1 states of 176Hf have been determined. Systematic uncertainties on the evolution of data as a function of neutron number were reduced by using the same setup for all the isotopes of interest. The data are in agreement with other recent lifetime measurements where available and shows a shift of the maximum of collectivity for the Hf isotopic chain from neutron midshell at N = 104 to N = 100.

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.

Lifetimes of yrast band states of \(^{174,176,178,180}\)Hf have been measured using fast-electronic scintillation timing or Coulomb excitation. The lifetimes of the \(2^+_1\), \(4^+_1\) states and apart from \(^{176}\)Hf also of the \(6^+_1\) states have been determined, using the slope and the centroid shift methods. By using the same setup for all isotopes of interest systematic uncertainties were reduced.

The ROmanian array for SPectroscopy in HEavy ion REactions (ROSPHERE) has been designed as a multi-detector setup dedicated to γ-ray spectroscopy studies at the Bucharest 9 MV Tandem accelerator. Consisting of up to 25 detectors (either Compton suppressed HPGe detectors or fast LaBr3(Ce) scintillator detectors) together with a state of the art plunger device, ROSPHERE is a powerful tool for lifetime measurements using the Recoil Distance Doppler Shift (RDDS) and the in-beam Fast Electronic Scintillation Timing (FEST) methods. The array's geometry, detectors, electronics and data acquisition system are described. Selected results from the first experimental campaigns are also presented.

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.

Lifetimes of several short-lived excited states in Nd138 were measured with the ROSPHERE array at IFIN-HH, Bucharest, using the recoil-distance Doppler shift technique following the Sb123(F19,4n) reaction. The resulting electromagnetic transition probabilities are compared to large-scale shell model calculations and to constrained Hartree-Fock-Bogoliubov calculations with the Gogny D1S interaction, configuration mixing, and a five-dimensional collective Hamiltonian formalism. The onset of collectivity in Nd isotopes below the N=82 shell closure and the deformation induced by the alignment of protons and neutron holes in the h11/2 orbitals are discussed.

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.

The ( J , T ) = ( 1 , 1 ) parity doublet in 20 Ne at 11.26 MeV is a good candidate to study parity violation in nuclei. However, its energy splitting is known with insufficient accuracy for quantitative estimates of parity violating effects. To improve on this unsatisfactory situation, nuclear resonance fluorescence experiments using linearly and circularly polarized γ -ray beams were used to determine the energy difference of the parity doublet Δ E = E ( 1 − ) − E ( 1 + ) = − 3.2 ( ± 0.7 ) stat ( − 1.2 + 0.6 ) sys keV and the ratio of their integrated cross sections I s , 0 ( + ) / I s , 0 ( − ) = 29 ( ± 3 ) stat ( − 7 + 14 ) sys . Shell-model calculations predict a parity-violating matrix element having a value in the range 0.46–0.83 eV for the parity doublet. The small energy difference of the parity doublet makes 20 Ne an excellent candidate to study parity violation in nuclear excitations.

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.

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.

Cross sections for 147,149 Sm(p,n) 147,149 Eu and 147,149 Sm(p, γ ) 148,150 Eu were measured using the activation method. The results are compared to the predictions of the Hauser-Feshbach statistical model. Different γ -ray strength functions have been tested against the experimental values. In the case of 150 Eu, in order to reproduce the experimental isomeric population cross sections, various scenarios for unknown branching ratios of certain discrete states have been discussed. The results provide constraints for the optical model parameters dedicated to this insufficiently known area of isotopes. Such cross sections for (p, γ ) reactions at energies below the Coulomb barrier are valuable for p -process nucleosynthesis calculations.

© 2019 Jagellonian University. All Rights Reserved. The breaking of isospin symmetry caused by the Coulomb interaction can be measured by the study of E1 γ decay. The Isovector Giant Dipole Resonance (IVGDR) was measured in 60 Zn and 62 Zn at two different excitation energies E ∗ = 47 MeV and E ∗ = 58 MeV with the goal of deducing the isospin mixing term. A fusion–evaporation reaction, with a beam of 32 S and a target of 28 Si, was used to produce 60 Zn. We also produced the compound nucleus 62 Zn using the reaction 32 S + 30 Si. This last reaction is required because, for the produced nucleus, the statistical model analysis is much less sensitive to the isospin mixing, and this allows to extract the GDR parameters and use them for isospin mixing sensitive reaction populating neighboring nucleus with N = Z. The experimental setup was composed of GALILEO array (germanium detectors) coupled to the large-volume LaBr 3 :Ce detectors for the γ-rays measuring and by two ancillary arrays, EUCLIDES and the Neutron Wall for the detection of particles and neutrons, respectively. An overview on the ongoing analysis and on preliminary results is presented. ispartof: ACTA PHYSICA POLONICA B vol:50 issue:3 pages:481-486 ispartof: location:POLAND, Zakopane status: published

This work aims at investigating the projectile binding energy influence on the reaction dynamics, introducing new results and new data analysis methods in order to overcome some typically encountered problems, such as the identification of reaction products differing by few mass units and the discrimination of direct reaction processes. The $^{17}\mathrm{O}+^{58}\mathrm{Ni}$ collision was studied at five near-barrier energies employing a compact experimental setup consisting of four double-sided silicon strip detectors (DSSSDs). Different reaction processes, namely the elastic and inelastic scattering and the $1n$ stripping, were discriminated by means of a detailed analysis of the experimental energy spectra based on Monte Carlo simulations. The elastic scattering angular distributions were investigated within the framework of the optical model using Woods-Saxon and double-folding potentials. The total reaction cross sections were extracted and the reduced cross sections compared with those obtained for $^{17}\mathrm{F}$ (${S}_{p}=0.600$ MeV), the mirror nucleus of $^{17}\mathrm{O}$ (${S}_{n}=4.143$ MeV), and for the tightly bound $^{16}\mathrm{O}$ projectile. The $^{17}\mathrm{O}+^{58}\mathrm{Ni}$ total reaction cross sections were larger than those for $^{16}\mathrm{O}$ on the same target at the lowest energies studied, becoming identical, within errors, as the incident energy increased above the Coulomb barrier. This behavior was related to a strong contribution from the $1n$-stripping channel at the lowest energies.

For simulating more accurately neutron or proton production from photonuclear reactions, a data-based photonuclear reaction simulation algorithm has been developed. Reliable photonuclear cross sections from evaluated or experimental database are chosen as input data. For checking the validity of the use of the data-based photonuclear algorithm, benchmarking simulations are presented in detail. We calculate photonuclear cross sections or reaction yield for 9Be, 48Ti, 133Cs, and 197Au and compare them with experimental data in the region of incident photon energy below ~30 MeV. While Geant4 can hardly reproduce photonuclear experimental data, results obtained from the data-based photonuclear algorithm are found in good agreement with experimental measurements. Potential application in estimation of specific activity of radioisotopes is further discussed. We conclude that the developed data-based photonuclear algorithm is suitable for an accurate prediction of photon-induced neutron or proton productions.

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.

The $1{i}_{\frac{13}{2}}\ensuremath{\rightarrow}1{h}_{\frac{9}{2}}\phantom{\rule{0.16em}{0ex}}(M2)$ and $3{s}_{\frac{1}{2}}\ensuremath{\rightarrow}2{f}_{\frac{7}{2}}\phantom{\rule{0.16em}{0ex}}(E3)$ reduced proton transition probabilities in $_{83}^{209}\mathrm{Bi}$ have been determined from the direct half-life measurements of the ${\frac{13}{2}}_{1}^{+}$ and ${\frac{1}{2}}_{1}^{+}$ states using the Romanian array for $\ensuremath{\gamma}$-ray SPectroscopy in HEavy ion REactions (RoSPHERE). The ${\frac{13}{2}}_{1}^{+}$ and ${\frac{1}{2}}_{1}^{+}$ states were found to have ${T}_{\frac{1}{2}}=0.120(15)$ ns and ${T}_{\frac{1}{2}}=9.02(24)$ ns respectively. Angular distribution measurements were used to determine an $E3/M2$ mixing ratio of $\ensuremath{\delta}=\ensuremath{-}0.184(13)$ for the 1609 keV $\ensuremath{\gamma}$-ray transition deexciting the ${\frac{13}{2}}_{1}^{+}$ state. This value for $\ensuremath{\delta}$ was combined with the measured half-life to give reduced transition probabilities of $B(E3,{\frac{13}{2}}_{1}^{+}\ensuremath{\rightarrow}{\frac{9}{2}}_{1}^{\ensuremath{-}})=12(2)\ifmmode\times\else\texttimes\fi{}{10}^{3}\phantom{\rule{4.pt}{0ex}}{e}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{fm}}^{6}$ and $B(M2,{\frac{13}{2}}_{1}^{+}\ensuremath{\rightarrow}{\frac{9}{2}}_{1}^{\ensuremath{-}})=38(5){\ensuremath{\mu}}_{N}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{fm}}^{2}$. These values are in good agreement with calculations within the finite Fermi system. The extracted value of $B(E3,{\frac{1}{2}}_{1}^{+}\ensuremath{\rightarrow}{\frac{7}{2}}_{1}^{\ensuremath{-}})=6.3(2)\ifmmode\times\else\texttimes\fi{}{10}^{3}\phantom{\rule{4.pt}{0ex}}{e}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{fm}}^{6}$ can be explained by a small ($\ensuremath{\sim}6%$) admixture in the wave function of the ${\frac{1}{2}}_{1}^{+}$ state.

We report Monte Carlo simulations of the pro- duction of radioisotopes of medical interest through photo- neutron reactions using the high-brilliance γ-beam of the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility. The specific activity for three benchmark radioiso - topes, 99 Mo/ 99m Tc, 225 Ra/ 225 Ac and 186 Re, was obtained as a function of target geometry, irradiation time and γ-beam energy. Optimized conditions for the generation of these radioisotopes of medical interest with the ELI-NP γ-beams were discussed. We estimated that a saturation specific activity of the order of 1-2 mCi/g can be achieved for thin targets with about one gram of mass considering a γ-beam flux of 10 11 photons/s. Based on these results, we suggest that the ELI-NP facility can provide a unique possibility for the production of radioisotopes in sufficient quantities for nuclear medicine research.

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.

We report on the measurement of the half-life of the yrast I π = 5 − state in the transitional nucleus 136 Ce using a combined HPGe-LaBr3(Ce) scintillator gamma-ray detection array. The measured value for the E 1 decay is approximately half a nanosecond, which corresponds to an E 1 decay strength of approximately 2 × 10 − 6 Wu. This value is in line with single-particle type E 1 decays in this mass region and suggests no sign of additional K-hindrance associated with axially symmetric quadrupole deformations observed for lighter cerium isotopes.

ELISSA is an array of silicon strip detectors under construction at the ELI-NP facility for measurements of photodissociation reactions using high-brilliance, quasi monoenergetic gamma beams. The detection system consists of 35 single-sided position-sensitive X3 detectors arranged in a cylindrical configuration and eight QQQ3 detectors as end-caps. A batch of forty X3 detectors have been tested at ELI-NP. The energy and position resolution, ballistic deficit, leakage currents, and depletion voltage were measured and analyzed. Measurements of the energy resolution were carried out using two read-out electronic chains, one based on multichannel preamplifiers and another based on multiplexers.

Low-energy isomeric states of 86Y were populated in the reaction 73Ge + 16O at 57MeV and were investigated by means of delayed n $ \gamma$ and $ \gamma$ $ \gamma$ coincidences. A half-life of 70(7)ns was measured for the 5- state at 208keV, yielding an exceptionally small B(M1) value of 2.0(7)×10-5 W.u. and a B(E2) value of 0.34(+24 -13) W.u. For the other three known isomeric states at 218, 243, and 302keV, the half-lives extracted from the present experimental data are in very good agreement with previous measurements. Given the newly observed isomeric character of the 5- 208keV state, the re-analysis of earlier experimental data on the 302keV isomer led to a new spin-parity assignment, 6+, for this state. In addition, this re-evaluation provided two g -factors, -0.083(3) and +0.63(2) , for the 208 and 302keV states, respectively. The results are discussed in terms of spherical-shell model calculations performed with a truncated space of configurations built on the f 5/2 , p 3/2 , p 1/2 , and g 9/2 valence orbitals. Effective spin, orbital, and “tensor” g -factors were determined empirically for protons and neutrons in the considered configuration space.

We report on efforts to develop reliable photonuclear cross section and photon strength function data by measuring, compiling, assessing, evaluating the available data, and producing tables of Giant Dipole Resonance parameters and global models for use in basic sciences and applications., SCOPUS: cp.p, info:eu-repo/semantics/published

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)., SCOPUS: cp.p, info:eu-repo/semantics/published

Photon activation technique using bremsstrahlug with end-point energy 55.6 MeV is used to induce photonuclear reactions in a 209Bi target. Absolute yields and integrated cross sections of multiparticle reactions (γ, 2n-6n), (γ, 4n1p), and (γ, 5n1p) are obtained. The results are compared to predictions of statistical models using systematical and microscopic description of photoabsorption and to the result of evaluation of the partial photoneutron reaction cross sections. Based on a comparison with existing experimental photoneutron cross sections and model calculations, we make a conclusion that neutron multiplicity assignment in available photoneutron cross sections on 209Bi can be corrected and evaluated cross sections of (γ, 1n) and (γ, 2n) are obtained that are in an agreement with the obtained experimental results.

The low-lying positive- and negative-parity states in $^{168}\mathrm{Yb}$ have been investigated by means of the $(\ensuremath{\alpha},2\mathrm{n}\ensuremath{\gamma})$ fusion evaporation reaction. Using the coincidence method, the level scheme was corrected and extended up to 3 MeV, for both the positive- and negative-parity states. Using the new branching ratios determined in the present experiment, the $K$ quantum number was proposed for two negative-parity bands by direct comparison with the Alaga rule. Like in some other nuclei, one negative-parity band was established, decaying predominantly to the $\ensuremath{\gamma}$-vibrational band. In a second experiment, the lifetimes of the low-lying excited states up to ${J}^{\ensuremath{\pi}}={6}^{+}$ in the ground-state band were measured by using the in-beam fast-timing method with the Bucharest mixed high-purity germanium (HPGe) and ${\mathrm{LaBr}}_{3}$:Ce detector array using the triple-$\ensuremath{\gamma}$ coincidence method. Reduced $E2$ transition probabilities were extracted from the measured lifetimes and compared with the corresponding observables in neighboring isotopes, showing a smooth behavior with increasing mass. The positive- and negative-parity states as well as $E1$ and $E2$ transition probability ratios revealed by these experiments are compared with the interacting boson model in the $sd$ and $spdf$ boson space, and with the confined beta-soft rotor model, and are found to be in good agreement.

The half-lives o fthe I=5- and 7- yrast stateys with Ex=1978 kev and Ex=2307 keV in the N=78 isotone 136Ce have been measured to be 496(23) ps and 270(24) ps respectively , using the concident fast-timing spectroscopy technique following population by a 124Sn(16O,4n) fusion-evporation reaction at an incident beam energy of 68 MeV.

Using Geant4, a complex simulation code of the interaction between laser photons and relativistic electrons was developed. We implemented physically constrained electron beam emittance and spacial distribution parameters and we also considered a Gaussian laser beam. The code was tested against experimental data produced at the γ-ray beam line GACKO (Gamma Collaboration Hutch of Konan University) of the synchrotron radiation facility NewSUBARU. Here we will discuss the implications of transverse missallignments of the collimation system relative to the electron beam axis.

The results of the IS530 experiment at ISOLDE revealed new information concerning several nuclei close to the N ≈ 20 'Island of Inversion' - 34Mg, 34Al, 34Si. The half-life of 34Mg was found to be three times larger than the adopted value (63(1) ms instead of 20(10) ms). The beta-gamma spectroscopy of 34Mg performed for the first time in this experiment, led to the first experimental level scheme for 34Al, also showing that the full beta strength goes through the predicted 1+ isomer in 34Al [1] and/or excited states that deexcite to it. The subsequent beta-decay of the 1+ isomer in 34Al allowed the observation of new gamma lines in 34Si, (tentatively) associated with low-spin high-energy excited states previously unobserved.

Photoneutron cross sections for seven samarium isotopes, 144Sm, 147Sm, 148Sm, 149Sm, 150Sm, 152Sm and 154Sm, have been investigated near neutron emission threshold using quasimonochromatic laser-Compton scattering γ-rays produced at the synchrotron radiation facility NewSUBARU. The results are important for nuclear astrophysics calculations and also for probing γ-ray strength functions in the vicinity of neutron threshold. Here we describe the neutron detection system and we discuss the related data analysis and the necessary method improvements for adapting the current experimental method to the working parameters of the future Gamma Beam System of Extreme Light Infrastructure - Nuclear Physics facility.

Photoneutron cross sections were measured for the seven stable samarium isotopes ${}^{144,147,148,149,150,152,154}\mathrm{Sm}$ near the neutron threshold with quasi-monochromatic laser-Compton scattering $\ensuremath{\gamma}\phantom{\rule{0.28em}{0ex}}\mathrm{rays}$. Our photoneutron cross sections are found to be low by 20%--37% relative to existing data. The photoneutron data are analyzed with the talys reaction code by considering the Skyrme Hartree-Fock-Bogoliubov (HFB) plus quasiparticle random phase approximation (QRPA) model and the axially symmetric deformed Gogny HFB plus QRPA model of the $E1$ $\ensuremath{\gamma}\text{\ensuremath{-}}\mathrm{ray}$ strength. Using the $\ensuremath{\gamma}\text{\ensuremath{-}}\mathrm{ray}$ strength function constrained by the present photoneutron data, we made a thorough analysis of the reverse $(n,\ensuremath{\gamma})$ cross sections including the radioactive nucleus $^{151}\mathrm{Sm}$ with a half-life of 90 yr. The radiative neutron capture cross section for $^{153}\mathrm{Sm}$ with the half-life of 1.928 d is deduced with the $\ensuremath{\gamma}\text{\ensuremath{-}}\mathrm{ray}$ strength function method.

The Extreme Light Infrastructure-Nuclear Physics (ELI-NP) facility, under construction in Magurele near Bucharest in Romania, will provide high-intensity and high-resolution gamma ray beams that can be used to address hotly debated problems in nuclear astrophysics. For this purpose, a silicon strip detector array (named ELISSA) will be realized in a common effort by ELI-NP and INFN-LNS (Catania, Italy), in order to measure excitation functions and angular distributions over a wide energy and angular range. A prototype of ELISSA was built and tested at Laboratori Nazionali del Sud (INFN-LNS) in Catania with the support of ELI-NP. On this occasion, we carried out experiments with alpha sources and with a 11 MeV 7Li beam. Thanks to our approach, the first results of those tests show up a very good energy resolution (better than 1%) and very good position resolution, of the order of 1 mm. Below 1 MeV, a resolution of the order of 6 mm is found, still good enough for the measurement of angular distribution and the kinematical identification of the reactions induced on the target by gamma beams.

Position-sensitive silicon strip detectors represent one of the best solutions for the detection of charged particles as they provide good energy and position resolution over a large range of energies. A silicon array coupled with the gamma beams at the ELI-NP facility would allow measuring photodissociation reactions of interest for Big Bang Nucleosynthesis and on heavy nuclei intervening in the p-process. Forty X3 detectors for our ELISSA (ELI-NP Silicon Strip Detectors Array) project have been recently purchased and tested. We investigated several specifications, such as leakage currents, depletion voltage, and detector stability under vacuum. The energy and position resolution, and ballistic deficit were measured and analyzed. This paper presents the main results of our extensive testing. The measured energy resolution for the X3 detectors is better than results published for similar arrays (ANASEN or ORRUBA).

Absolute cross sections for the 86 Sr(α,n)89 Zr reaction at energies close to the Gamow window are reported. Three thin SrF2 targets were irradiated using the 9 MV Tandem facility in IFIN-HH Bucharest that delivered α beams for the activation process. Two high-purity Germanium detectors were used to measure the induced activity of 89 Zr in a low background environment. The experimental results are in very good agreement with Hauser-Feshbach statistical model calculations performed with the TALYS code.

New data of total and partial (γ,xn) cross sections with x = 1–3 are proposed to be measured by direct neutron multiplicity sorting using Laser Compton scattering (LCS) gamma ray beams at the ELI-NP to solve long standing discrepancies between existing Lawrence Livermore National Laboratory (USA) and France Centre d'Etudes Nucleaires de Saclay photonuclear data. Pioneering experiments are currently performed at the NewSUBARU facility. We present here preliminary results on 209 Bi(g,xn) cross section measurements.