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International Fusion Materials Irradiation Facility-DEMO-Oriented NEutron Source (IFMIF-DONES) is a high-intensity neutron irradiation facility for qualification of fusion reactor materials, which is being designed as part of the European roadmap to fusion-generated electricity. Its main purpose is to study the behavior of materials properties under irradiation in a neutron flux able to simulate the same effects in terms of relevant nuclear responses as those expected in the first wall of the DEMO reactor which is envisaged to follow ITER. It is thus a key facility to support the design, licensing and safe operation of DEMO as well as of the fusion power plants that will be developed afterwards. The start of its construction is foreseen in the next few years. In this contribution, an overview of the IFMIF-DONES neutron source is presented together with a snapshot of the current engineering design status and of the relevant key results achieved within the EUROfusion Work Package Early Neutron Source (WPENS) as part of the 2014–2020 EURATOM Research and Training Programme, complementary to the EU Horizon 2020 Framework Programme (FP8). Moreover, some information on the future developments of the project are given.

The need of a neutron source for the qualification of materials to be used in future fusion power reactors have been recognized in the European (EU) fusion program for many years. The construction ...

International audience; Abstract IFMIF-DONES is a powerful neutron irradiation facility for the study and qualification of materials planned as part of the European roadmap to fusion-generated electricity. Its main goal is to study properties of materials under severe irradiation in a neutron field similar to the one in a fusion reactor first wall. It is a key facility to prepare for the construction of the DEMO power plant envisaged to follow ITER. The decision to start the construction of IFMIF-DONES is expected imminent. In this paper we present and discuss several key technical studies and decisions to improve and optimize the engineering design of IFMIF-DONES which were carried out as part of the activities in the framework of the EUROfusion Early Neutron Source work package (2015–2020). The following topics are discussed in this paper: the new layout of the IFMIF-DONES SRF LINAC accelerator and high-energy beam transport line, 7Be impurity management approach for the lithium loop, a maintainable test cell concept, a revised layout of the access cell for the remote maintenance operations, and facilities for complementary experiments.

International Fusion Materials Irradiation Facility — DEMO Oriented Neutron Source (IFMIF-DONES) is a planned powerful neutron source, which will generate an intense flux of neutrons (up to ∼1015n/s/cm2) with a fusion-relevant energy spectrum. It will be an accelerator source based on deuteron beam - lithium target reactions. The engineering design of IFMIF-DONES is elaborated in the frame of the Early Neutron Source work package of the EUROfusion consortium. The facility will be dedicated to the irradiation of suitable structural materials planned for the construction of future fusion reactors such as DEMO (Demonstration Fusion Power Plant). Start-up Monitoring Module (STUMM) is designed to monitor radiation and thermal conditions during the commissioning phase of IFMIF-DONES, characterize the produced neutron flux and validate neutronic modeling of the facility. The conceptual design of STUMM is prepared by a team of physicists and engineers from the Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN) and the National Centre for Nuclear Research (NCBJ), Poland. This paper presents the concept of STUMM, the proposed design of the module, and selected measuring systems.

International audience; Lifetimes of low-lying states in 73Ga and 70,72,74Zn were measured using the Recoil Distance Doppler Shift (RDDS) method. These nuclei were produced in deep-inelastic reactions in inverse kinematics with a 208Pb beam impinging on a 76Ge target. Prompt γ rays were detected using the AGATA tracking array coupled to the VAMOS++ spectrometer. Lifetime of the 5/2 − state in 73Ga, measured for the first time, provides additional evidence for the existence of a 1/2 −, 3/2 − ground-state doublet. The lifetimes of the 4 + states in 70,72,74Zn were remeasured in an attempt to understand the discrepancies observed between earlier measurements. Our results are in agreement with those of previous plunger experiments.

The nucleus ${}^{208}$Pb provides an iconic test of the nuclear shell model because its 82 protons and 126 neutrons are both magic numbers. When excited levels are discovered and characterized, this nucleus provides a means to investigate the mechanisms responsible for the generation of angular momentum and, ultimately, for the development of collectivity. This experiment is a tour de force that reveals extensive new information on ${}^{208}$Pb about high-angular-momentum states, isomeric states, and collective states of octupole nature; thus it serves as a showcase for shell-model descriptions. Many of the states explored show good overall agreement with theory, but others at the highest energies reveal discrepancies, pointing to the need for improved calculations. Above the highest-lying ${28}^{-}$ isomer $\ensuremath{\gamma}$ transitions arising from yet higher spin levels could be identified in two separate experiments as displayed in the figure.

$\ensuremath{\beta}$ decay of neutron-rich nuclide $^{94}\mathrm{Kr}$ was reinvestigated by means of a high resolution on-line mass separator and $\ensuremath{\beta}\ensuremath{-}\ensuremath{\gamma}$ spectroscopy. In total 22 $\ensuremath{\gamma}$-ray transitions were assigned to the decay of $^{94}\mathrm{Kr}$, and a new isomeric state was identified. The new information allows us to build detailed levels systematics in a chain of odd-odd rubidium isotopes and draw conclusions on nuclear structure for some of the observed states. The discussed level structure affects the evolution of $\ensuremath{\beta}$-decay half-lives for neutron-rich selenium, krypton, and strontium isotopes.

Excited states with seniority $\ensuremath{\nu}=3$, 5, and 7 have been investigated in odd neutron-rich $^{119,121,123,125}\text{Sn}$ isotopes produced by fusion-fission of 6.9-MeV/$A\phantom{\rule{4pt}{0ex}}^{48}\text{Ca}$ beams with $^{208}\text{Pb}$ and $^{238}\text{U}$ targets and by fission of a $^{238}\text{U}$ target bombarded with 6.7-MeV/$A\phantom{\rule{4pt}{0ex}}^{64}\text{Ni}$ beams. Level schemes have been established up to high spin and excitation energies in excess of 6 MeV, based on multifold gamma-ray coincidence relationships measured with the Gammasphere array. In the analysis, the presence of isomers was exploited to identify gamma rays and propose transition placements using prompt and delayed coincidence techniques. Gamma decays of the known $27/{2}^{\ensuremath{-}}$ isomers were expanded by identifying new deexcitation paths feeding $23/{2}^{+}$ long-lived states and $21/{2}^{+}$ levels. Competing branches in the decay of $23/{2}^{\ensuremath{-}}$ states toward two $19/{2}^{\ensuremath{-}}$ levels were delineated as well. In $^{119}\text{Sn}$, a new $23/{2}^{+}$ isomer was identified, while a similar $23/{2}^{+}$ long-lived state, proposed earlier in $^{121}\text{Sn}$, has now been confirmed. In both cases, isomeric half-lives were determined with good precision. In the range of $\ensuremath{\nu}=3$ excitations, the observed transitions linking the various states enabled one to propose with confidence spin-parity assignments for all the observed states. Above the $27/{2}^{\ensuremath{-}}$ isomers, an elaborate structure of negative-parity levels was established reaching the ($39/{2}^{\ensuremath{-}}$), $\ensuremath{\nu}=7$ states, with tentative spin-parity assignments based on the observed deexcitation paths as well as on general yrast population arguments. In all the isotopes under investigation, strongly populated sequences of positive-parity ($35/{2}^{+}$), ($31/{2}^{+}$), and ($27/{2}^{+}$) states were established, feeding the $23/{2}^{+}$ isomers via cascades of three transitions. In the $^{121,123}\text{Sn}$ isotopes, these sequences also enabled the delineation of higher-lying levels, up to ($43/{2}^{+}$) states. In $^{123}\text{Sn}$, a short half-life was determined for the ($35/{2}^{+}$) state. Shell-model calculations were carried out for all the odd Sn isotopes, from $^{129}\text{Sn}$ down to $^{119}\text{Sn}$, and the results were found to reproduce the experimental level energies rather well. Nevertheless, some systematic deviations between calculated and experimental energies, especially for positive-parity states, point to the need to improve some of the two-body interactions used in calculations. The computed wave-function amplitudes provide for a fairly transparent interpretation of the observed level structures. The systematics of level energies over the broad $A$ = 117--129 range of Sn isotopes displays a smooth decrease with mass $A$, and the observed regularity confirms most of the proposed spin-parity assignments. The systematics of the $B(E2)$ reduced transition probabilities extracted for the $23/{2}^{+}$ and $19/{2}^{+}$ isomers is discussed with an emphasis on the close similarity of the observed $A$ dependence with that of the $E2$ transition rates established for other $\ensuremath{\nu}=2$, 3, and 4 isomers in the Sn isotopic chain.

Excited states above the seniority $\ensuremath{\nu}=2$ isomers have been investigated in even neutron-rich ${}^{118--128}$Sn isotopes produced by fusion-fission of 6.9 MeV/$A$ $^{48}\mathrm{Ca}$ beams with $^{208}\mathrm{Pb}$ and $^{238}\mathrm{U}$ targets and by fission of 6.7 MeV/$A$ $^{64}\mathrm{Ni}$ beams on a $^{238}\mathrm{U}$ target. Level schemes up to excitation energies in excess of 8 MeV have been established based on multifold $\ensuremath{\gamma}$-ray coincidence relationships measured with the Gammasphere array. Isotopic identification of crucial transitions was achieved through a number of techniques, including prompt and delayed cross-coincidence methods. As a result, seniority $\ensuremath{\nu}=4$, 15${}^{\ensuremath{-}}$, and 13${}^{\ensuremath{-}}$ isomers were observed and their half-lives determined. These long-lived states in turn served as steppingstones to delineate the isomeric decays and to locate higher-lying states with good sensitivity. As the observed isomeric decays feed down to 10${}^{+}$ and 7${}^{\ensuremath{-}}$ isomers, firm spin-parity assignments could be proposed for most of the seniority $\ensuremath{\nu}=4$ states. Higher-lying, seniority $\ensuremath{\nu}=6$ levels were assigned tentatively on the basis of the observed deexcitation paths as well as of general yrast population arguments. Shell-model calculations were carried out down to $^{122}\mathrm{Sn}$ in the ${g}_{7/2}$, ${d}_{5/2}$, ${d}_{3/2}$, ${s}_{1/2}$, and ${h}_{11/2}$ model space of neutron holes with respect to a $^{132}\mathrm{Sn}$ core. Effective two-body interactions were adjusted such that satisfactory agreement with data was achieved for $^{130}\mathrm{Sn}$. The results reproduce the experimental level energies and spin-parity assignments rather well. The intrinsic structure of the states is discussed on the basis of the calculated wave functions which, in many instances, point to complex configurations. In a few cases, the proposed assignments lead to unresolved issues. The smooth, systematic decrease of the level energies with mass $A$ is accompanied by the similarly regular behavior with $A$ of the reduced transition probabilities extracted from the isomeric half-lives. This $A$ dependence is discussed for the $E1$ and $E2$ transitions in the decay of the seniority $\ensuremath{\nu}=4$ isomers and is compared to that determined in earlier work for the $E2$ transition rates from the $\ensuremath{\nu}=2,3$ isomers.

Thick target γγ coincidence measurements for the system 130 Te + 275 MeV 64 Ni have been performed using the GASP Ge detector array at Legnaro. For the isotopic assignments of previously unknown γ-ray cascades, prompt γγ coincidences observed between Te and Ni partner products were of vital importance. The results yield much new information about excited states of moderate spins in A = 126–131 tellurium nuclei, especially about yrast excitations of the little studied odd- A isotopes 127 Te, 129 Te, and 131 Te. Level systematics of tellurium nuclei are presented, and both single-particle and collective aspects of the level spectra are discussed.

Neutron-rich sdf shell nuclei have been produced in deep-inelastic processes during collision of 230 MeV {sup 37}Cl ions on a thick {sup 208}Pb target. The in-beam as well as off-beam {gamma}-{gamma} coincidence data yielded new spectroscopic information on some hard-to-access N=18,19 isotones. A new 27 ns isomer at 5583 keV in {sup 32}Si has been located. A candidate for the negative parity state 4{sup {minus}} has been identified above the 200 ns isomer in {sup 32}Al. {copyright} {ital 1997} {ital The American Physical Society}

The $^{68}\mathrm{Ni}$ nucleus has been identified among the products of deep-inelastic reactions of $^{64}\mathrm{Ni}$ projectiles bombarding $^{130}\mathrm{Te}$ and $^{208}\mathrm{Pb}$ targets. Three new states, including the high-lying ${2}^{+}$ (2033 keV) and the 0.86 ms ${5}^{\ensuremath{-}}$ isomer, indicate a substantial subshell closure at neutron number $N=40$. The level structure and the observed very slow $E3$ transition speed are discussed within the shell model.

Recent calculations suggest that the rate of neutron capture by 130Sn has a significant impact on late-time nucleosynthesis in the r-process. Direct capture into low-lying bound states is expected to be significant in neutron capture near the N=82 closed shell, so r- process reaction rates may be strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, the (d, p) reaction has been studied in inverse kinematics using a 630 MeV beam of 130Sn (4.8 MeV/u) and a (CD2)n target. An array of Si strip detectors, including SIDAR and an early implementation of the ORRUBA, was used to detect reaction products. Results for the 130Sn(d, p)131Sn reaction are found to be very similar to those from the previously reported 132Sn(d, p)133Sn reaction. Direct-semidirect (n, ) cross section calculations, based for the first time on experimental data, are presented. The uncertainties in these cross sections are thus reduced by orders of magnitude from previous estimates.

The low-spin level scheme of ${}^{68}$Ni was investigated with the Gammasphere array following reactions between a ${}^{70}$Zn beam and ${}^{238}$U, ${}^{208}$Pb, and ${}^{197}$Au targets. Spin assignments for some states have been verified through $\ensuremath{\gamma}$-ray angular correlations, including the ${0}^{+}$ assignment for the 2511-keV level. Two previously unknown states at 3302 and 3405 keV have been identified. No evidence was found for a recently reported 216-ns, ${0}^{+}$ isomer at 2202 keV that was attributed to a proton two-particle, two-hole intruder configuration, despite experimental conditions similar to those used in the measurement reporting its discovery.

Excited states in ${}^{67}$Ni were populated in deep-inelastic reactions of a ${}^{64}$Ni beam at 430 MeV on a thick ${}^{238}$U target. A level scheme built on the previously known 13-$\ensuremath{\mu}$s isomer has been delineated up to an excitation energy of 5.3 MeV and a tentative spin and parity of (21/2${}^{\ensuremath{-}}$). Shell model calculations have been carried out using two effective interactions in the ${f}_{5/2}p{g}_{9/2}$ model space with a ${}^{56}$Ni core. Satisfactory agreement between experiment and theory is achieved for the measured transition energies and branching ratios. The calculations indicate that the yrast states are associated with rather complex configurations, herewith demonstrating the relative weakness of the $N=40$ subshell gap and the importance of multi-particle-hole excitations involving the ${g}_{9/2}$ neutron orbital.

The $\ensuremath{\beta}$ decay of the $N=51$ nucleus $^{81}\mathrm{Zn}$ was studied by means of $\ensuremath{\beta}$-$\ensuremath{\gamma}$ spectroscopy and from isotopically pure beams produced at the Holifield Radioactive Ion Beam Facility (HRIBF). We observe several competing $\ensuremath{\beta}$ transitions populating $^{81}\mathrm{Ga}$ that are interpreted as allowed Gamow-Teller decays to positive parity, core excited states, and first-forbidden decays to negative parity states. The measured $\ensuremath{\beta}$-decay pattern suggests an assignment of ${I}^{\ensuremath{\pi}}=5/{2}^{+}$ for the $^{81}\mathrm{Zn}$ ground state. The systematics of core excited states in $N=50$ isotones indicate a strengthening of the $N=40$ subshell gap near $^{78}\mathrm{Ni}$.

Excited states in the N=30 neutron-rich isotope {sup 49}K have been studied using multinucleon transfer reactions with thin targets and the PRISMA-CLARA spectrometer combined with thick-target {gamma}-coincidence data from Gammasphere. The d{sub 3/2} proton-hole state is located 92 keV above the s{sub 1/2} ground state, and the proton-particle f{sub 7/2} state is suggested at 2104 keV. Three other levels are established as involving the coupling to 2{sup +} of two neutrons above the N=28 shell. The measured or estimated lifetimes served to reinforce the interpretation of the observed level structure, which is found to be in satisfactory agreement with shell-model calculations.

Lifetimes of low-lying excited states of the neutron-rich $^{44,46}\mathrm{Ar}$ nuclei, populated via multinucleon transfer reactions, are measured by means of the differential recoil distance Doppler shift method. The extracted electromagnetic transition probabilities are compared with previous intermediate-energy Coulomb-excitation measurements and with large-scale shell-model calculations. The increase in the deduced $B$($E2;{2}^{+}\ensuremath{\rightarrow}{0}^{+}$) transition probability from $^{44}\mathrm{Ar}$ to the closed-shell nucleus $^{46}\mathrm{Ar}$ contradicts the earlier results of Coulomb-excitation experiments. Shell-model calculations using different effective interactions agree with the new measured values.

The lifetimes of the first excited states of the Z=18, 44Ar and 46Ar isotopes have been determined using a novel technique that combines the Recoil Distance Doppler Shift method, with the CLARA-PRISMA spectrometers for Multinucleon Transfer Reactions. The B(E2) values extracted for the 2+ to 0+ transitions in both nuclei, as well as for higher excited states in 44Ar, are discussed and compared with the available experimental results and with the new large-scale shell-model calculations.

The yrast structure of the neutron-rich nucleus $^{97}\mathrm{Zr}$ has been studied using fission of targetlike products in the reaction of a $^{48}\mathrm{Ca}$ beam on a thick $^{238}\mathrm{U}$ target. The level scheme, known from previous studies up to an excitation energy and spin-parity of approximately 4619 keV and $23/{2}^{\ensuremath{-}}$, has been extended by about 3 MeV and a few units of angular momentum. Two states fed in the $\ensuremath{\beta}$ decay of the $27/{2}^{\ensuremath{-}}$ high-spin isomer in $^{97}\mathrm{Y}$ were identified at 5570 and 5606 keV. The located level structure can be discussed in terms of shell-model configurations.

The beta-delayed neutron branching ratios (P{betan}) for nuclei near doubly magic 78Ni have been directly measured using a new method combining high-resolution mass separation, reacceleration, and digital beta-gamma spectroscopy of 238U fission products. The P{betan} values for the very neutron-rich isotopes ;{76-78}Cu and 83Ga were found to be much higher than previously reported and predicted. Revised calculations of the betan process, accounting for new mass measurements and an inversion of the pi2p{3/2} and pi1f{5/2} orbitals, are in better agreement with these new experimental results.

Neutron transfer reactions were performed in inverse kinematics using radioactive ion beams of 132Sn, 130Sn, and 134Te and deuterated polyethylene targets. Preliminary results are presented. The Q‐value spectra for 133Sn, 131Sn and 135Te reveal a number of previously unobserved peaks. The angular distributions are compatible with the expected lf7/2 nature of the ground state of 133Sn, and 2p3/2 for the 3.4 MeV state in 131Sn.

Neutron transfer (d, p) reactions have been measured with neutron‐rich fission fragment beams of 130,132Sn and 134Te populating l = 1 and l = 3 excitations above the N = 82 shell gap. Preliminary results and future prospects are discussed.

The distributions of products of {sup 208}Pb+350 MeV {sup 64}Ni, {sup 130}Te+275 MeV {sup 64}Ni and {sup 208}Pb+345 MeV {sup 58}Ni collisions have been determined in thick target gamma-ray coincidence experiments. Analysis of gamma cross-coincidence data allowed to account for neutron evaporation to reconstruct primary product distributions. For the three studied systems the neutron-to-proton ratio equilibration as a function of the mass transfer have been obtained from the experimental data and compared to a simple Liquid Drop energy minimization.

The 82Ge, 84Se, 132Sn, 130Sn, and 134Te (d,p) reactions have been measured with {approx}4-5-MeV-A rare isotope beams and CD2 targets at the HRIBF at ORNL. Energies and spectroscopic strengths have been measured for excitations in 83Ge and 85Se. Direct neutron capture calculations on 82Ge are presented. Preliminary results for single-neutron excitations in 131Sn, 133Sn, and 135Te are reported.

Production of nuclei above $^{100}\mathrm{Sn}$ in fusion-evaporation reactions between $^{58}\mathrm{Ni}$ and $^{54}\mathrm{Fe}$ ions was studied at Oak Ridge National Laboratory by means of the recoil mass spectrometer and charged particle detection. The beam energy was varied to optimize the yields for the two-, three- and four-particle evaporation channels. Experimental results verified the predictions of the statistical model code HIVAP. The optimum energy for the $^{54}\mathrm{Fe}$($^{58}\mathrm{Ni}$,$4n$)$^{108}\mathrm{Xe}$ reaction channel that allows one to study the $^{108}\mathrm{Xe}$-$^{104}\mathrm{Te}$-$^{100}\mathrm{Sn}$ \ensuremath{\alpha} decay chain is deduced as 240 MeV.

The lifetimes of the first excited states of nuclei around the doubly‐magic nucleus 48Ca have been determined using a novel method that combines the Recoil Distance Doppler Shift (RDDS) method with the CLARA‐PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron‐rich nuclei populated via a multinucleon transfer reaction. This novel method and some preliminary results on lifetimes are presented.

An alpha-decay branch of (1.4+/-0.4) x 10(-4) has been discovered in the decay of 109I, which predominantly decays via proton emission. The measured Q(alpha) value of 3918+/-21 keV allows the indirect determination of the Q value for proton emission from 105Sb of 356+/-22 keV, which is approximately of 130 keV more bound than previously reported. This result is relevant for the astrophysical rapid proton-capture process, which would terminate in the 105Sn(p,gamma)106Sb(p,gamma)107Te(alpha decay)103Sn cycle at the densities expected in explosive hydrogen burning scenarios, unless unusually strong pairing effects result in a 103Sn(p,gamma)104Sb(p,gamma)105Te(alpha decay)101Sn) cycle.

Fine structure in proton emission from the deformed states 141g.s.Ho (T1/2 = 4.1 ms) and 141mHo (T1/2 = 7.4 μs) has been discovered at Oak Ridge by detecting fusion evaporation residues with the Recoil Mass Spectrometer, Si‐detectors and digital signal processing electronics. The branching ratios to the first 2+ excited state in 140Dy were measured to be Ipg.s.(2+) = 0.9±0.1% and Ipm(2+) = 1.7±0.5%. A comparison of the available calculations to the experimental values calls for further development of the theoretical models.

The alpha decay chain 109Xe→105Te→101Sn was first identified at the Holifield Radioactive Ion Beam Facility. Recent developments in digital electronics enabled the detection of both alpha decays despite the short half‐life of 105Te. The development of the software algorithm responsible for extracting the double‐alpha events from the experimental data is ongoing. The possibility of using the derivative of the double‐alpha pulse to selectively identify double alpha pulses shows promise and is being developed.

Production of nuclei above 100Sn in fusion‐evaporation reactions between 58Ni beam and 54Fe target was investigated. Reaction products were studied at Oak Ridge by means of the Recoil Mass Spectrometer and charged particle detection. The yields for the 2n, pn, 3n, p2n, 2pn, p3n and 2p2n fusion‐evaporation channels were measured. These experimental results were used to verify the predictions of the statistical model code HIVAP. The optimum energy for the 54Fe(58Ni,4n)108Xe reaction allowing detection of the 108Xe‐104Te‐100Sn alpha decay chain is deduced as 240 MeV.

High-spin states with the seniority v ≥ 2 have been investigated in the neutron-rich 118,120,122,124,126Sn isotopes. They were produced in fusion-fission processes following 48Ca + 208Pb, 48Ca + 238U reactions and via fission of target nuclei in the 64Ni + 238U system. By employing techniques of delayed- and cross-coincidences, it was possible to establish level schemes up to an 8 MeV excitation energy. The 13− and 15− states were identified as being isomeric and their half-lives were determined. The reduced transition probabilities extracted for isomeric transitions behave very regularly with the mass number A. The spin-parity values assigned to or suggested for the identified states were supported by shell-model calculations and by systematics.

The structure of the $^{56,58,60}\mathrm{Cr}$ nuclei was investigated at Gammasphere using both deep inelastic and fusion-evaporation reactions. As a result of this work, expanded level schemes are now available for these three neutron-rich, even-even isotopes. Experimental signatures were found for both single-particle and collective excitations whose relative importance varies with neutron number. Together with recent structural information on the odd-$A$ $^{55,57,59}\mathrm{Cr}$ neighbors, the present data highlight the changing role of the ${g}_{9/2}$ orbital with neutron number. Comparisons with shell-model calculations using the recently developed GXPF1A interaction and with total Routhian surface calculations are presented.

Two new alpha emitters 109Xe and 105Te were identified through the observation of the 109Xe --105Te --101Sn alpha-decay chain. The 109Xe nuclei were produced in the fusion-evaporation reaction 54Fe(58Ni,3n)109Xe and studied using the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. Two transitions at Ealpha = 4062 +/- 7 keV and Ealpha = 3918 +/- 9 keV were interpreted as the l = 2 and l = 0 transitions from the 7/2+ ground state in 109Xe (T1/2 = 13 +/- 2 ms) to the 5/2+ ground state and a 7/2+ excited state, located at 150 +/- 13 keV in 105Te. The observation of the subsequent decay of 105Te marks the discovery of the lightest known alpha-decaying nucleus. The measured transition energy Ealpha = 4703 +/- 5 keV and half-life T1/2 = 620 +/- 70 ns were used to determine the reduced alpha-decay width delta2. The ratio delta105Te(2)/delta213Po(2) of approximately 3 indicates a superallowed character of the alpha emission from 105Te.

High-spin excited states have been identified in the N=Z+1 nucleus {sup 91}Rh with the reaction {sup 54}Fe({sup 40}Ca,p2n{gamma}) at 130 MeV, using the GASP array, the ISIS silicon array, and the n-ring detector system. Two structures have been observed, the positive-parity yrast sequence above the (9/2{sup +}) ground state and a sequence assigned to negative parity that is built on a possible (1/2{sup -}) isomeric state. The observed structures are compared with various shell-model calculations in the (p{sub 1/2},g{sub 9/2}) space.

Data from three gamma spectroscopy experiments using deep-inelastic heavy ion reactions provided new information on high-spin states in the Ca-48 core nucleus and in the N=30, Ca-50 and Sc-51 isotones. Shell model calculations restricted to neutron excitations only are shown to reproduce with good accuracy some of the experimental levels. It is demonstrated that proton excitations not accounted in these calculations are abundantly present in the observed yrast structures. High energy of the 4(+) state in Ca-50 underlines the validity of the N=32 shell closure.

The possible occurrence of sub‐shell gaps at N = 32 and N = 34 in neutron‐rich titanium isotopes is discussed in light of new experimental results from (i) deep‐inelastic reactions measured with Gammasphere at the ATLAS facility at Argonne National Laboratory and from (ii) intermediate‐energy Coulomb excitation performed at the National Superconducting Cyclotron Laboratory at Michigan State University.

The gamma-ray decay of the giant dipole resonance (GDR) in the compound nucleus {sup 216}Rn formed with the reaction {sup 18}O+{sup 198}Pt at the bombarding energy of 96 MeV was investigated. High-energy gamma-ray spectra in coincidence with both prompt and delayed low-energy transitions were measured. The obtained GDR width at the average temperature {approx_equal}1 MeV was found to be larger than that at T=0 MeV and to be approximately constant as a function of spin. The measured width value of 7 MeV is found to be consistent with the predictions based on calculations of the nuclear shape distribution using the newest approach for the treatment of the fission barrier within the liquid drop model. The present study is the first investigation of the giant dipole resonance width from the fusion-evaporation decay channel in this nuclear mass range.

Gamma rays from neutron-rich nuclei in the vicinity of $Z=20$, $N=28$ have been studied at Gammasphere using deep-inelastic reactions induced by a $330\text{\ensuremath{-}}\mathrm{MeV}$ $^{48}\mathrm{Ca}$ beam on a thick $^{238}\mathrm{U}$ target. The yrast $\ensuremath{\gamma}$-ray cascade of $^{56}\mathrm{Ti}$ was identified for the first time and the location in energy of the ${2}^{+}$, ${4}^{+}$, and ${6}^{+}$ states was determined. The low-spin $^{56}\mathrm{Ti}$ yrast structure does not support the presence of a subshell closure at $N=34$ as suggested on the basis of other data on nuclei in the region as well as shell model calculations with a recently proposed interaction.

High-spin excited states have been identified for the first time in the $N=Z+1$ nucleus $^{89}\mathrm{Ru}$ with the reaction $^{54}\mathrm{Fe}(^{40}\mathrm{Ca},\ensuremath{\alpha}n\ensuremath{\gamma})$ at 130 MeV, using the GASP array, the ISIS Silicon array, and the $n$-Ring detector system. The observed structure is discussed within systematics of the $N=45$ isotones and is compared with shell model calculations.

The mass A = 140 products of the 54Fe (315 MeV) + 92Mo reaction were selected by a recoil mass spectrometer and studied in a recoil ‐ delayed γ‐γ coincidence experiment. A new 7 μs isomer was identified in the drip line nucleus 140Dy. Five cascading γ transitions were assigned to the decay of the Iπ = 8− {v9/2−[514] ⊗ v7/2+[404]} K isomer via the ground state band transitions. The established structure of 140Dy is discussed with reference to the fine structure in proton decay of 141Ho.

The yrast band of the $N=Z$ nucleus ${}^{84}\mathrm{Mo}$ has been extended up to the ${10}^{+}$ state. Its moment of inertia varies smoothly up to this state (rotational frequency 0.6 MeV). The new data confirm the systematic delay of the particle alignment frequency in $N=Z$ nuclei with respect to the neighboring $NgZ$ nuclei, which has been suggested as a signature of the neutron-proton pairing interaction. Projected shell model calculations performed for the heaviest $N=Z$ nuclei studied so far, ${}^{84}\mathrm{Mo}$ and ${}^{88}\mathrm{Ru},$ predict that the confirmation of a possible enhancement of the neutron-proton residual interaction requires the observation of still higher spins in these nuclei.

The emission of two coincident energetic (E≥8 MeV) gamma rays has been observed in the 187 MeV 37Cl+ 120Sn reaction by using the cluster detectors of the EUROBALL III array. Those events are attributed to the decay of the double giant dipole resonance built on highly excited states.

Author(s): Chiara, CJ; Walters, WB; Janssens, RVF; Broda, R; Albers, M; Alcorta, M; Bertone, PF; Carpenter, MP; Hoffman, CR; Lauritsen, T; Rogers, AM; Seweryniak, D; Zhu, S; Kondev, FG; Fornal, B; Krolas, W; Wrzesinski, J; Larson, N; Liddick, SN; Prokop, C; Suchyta, S; David, HM; Doherty, DT | Abstract: The level schemes of 68Ni and 67Co were extended following 70Zninduced deep-inelastic reactions. No evidence for a previously reported proton intruder 0+ state at 2202 keV in 68Ni was found. In 67Co, two new states at 3216 and 3415 keV have been established; additional states associated with the intruder configuration have yet to be identified.

The superheavy nucleus 108 272 Hs and its evaporation daughters have been produced using the reaction 232 Th( 40 Ar,γxn) with beam energies 10.5 and 15.0 MeV/ A . The Giant Dipole Resonance γ-radiation from the hot conglomerate system prior to fission has been isolated using a differential method. The pre-fission component shows a strong dipole angular distribution relative to the spin direction. A saturation of the GDR strength is observed for the highest excitation energies.