Search

We demonstrate a new technique for obtaining fission data for nuclei away from β stability. These types of data are pertinent to the astrophysical r process, crucial to a complete understanding of the origin of the heavy elements, and for developing a predictive model of fission. These data are also important considerations for terrestrial applications related to power generation and safeguarding. Experimentally, such data are scarce due to the difficulties in producing the actinide targets of interest. The solenoidal-spectrometer technique, commonly used to study nucleon-transfer reactions in inverse kinematics, has been applied to the case of transfer-induced fission as a means to deduce the fission-barrier height, among other variables. The fission-barrier height of U239 has been determined via the U238(d,pf) reaction in inverse kinematics, the results of which are consistent with existing neutron-induced fission data indicating the validity of the technique. We demonstrate a new technique for obtaining fission data for nuclei away from $\beta$-stability. These types of data are pertinent to the astrophysical \textit{r-}process, crucial to a complete understanding of the origin of the heavy elements, and for developing a predictive model of fission. These data are also important considerations for terrestrial applications related to power generation and safeguarding. Experimentally, such data are scarce due to the difficulties in producing the actinide targets of interest. The solenoidal-spectrometer technique, commonly used to study nucleon-transfer reactions in inverse kinematics, has been applied to the case of transfer-induced fission as a means to deduce the fission-barrier height, among other variables. The fission-barrier height of $^{239}$U has been determined via the $^{238}$U($d$,$pf$) reaction in inverse kinematics, the results of which are consistent with existing neutron-induced fission data indicating the validity of the technique.

Absolute cross sections for the addition of $s$- and $d$-wave neutrons to $^{14}$C and $^{14}$N have been determined simultaneously via the ($d$,$p$) reaction at 10 MeV/u. The difference between the neutron and proton separation energies, $\Delta S$, is around $-20$ MeV for the $^{14}$C$+$$n$ system and $+8$ MeV for $^{14}$N$+$$n$. The population of the $1s_{1/2}$ and $0d_{5/2}$ orbitals for both systems is reduced by a factor of approximately 0.5 compared to the independent single-particle model, or about 0.6 when compared to the shell model. This finding strongly contrasts with results deduced from intermediate-energy knockout reactions between similar nuclei on targets of $^{9}$Be and $^{12}$C. The simultaneous technique used removes many systematic uncertainties., Comment: 6 pages, 4 figures

The occupancies and vacancies of the valence neutron orbitals across the stable tin isotopic chain from $112\leq A\leq 124$ have been determined. These were inferred from the cross sections of neutron-adding and -removing reactions. In each case, the reactions were chosen to have good angular-momentum matching for transfer to the low- and high-$\ell$ orbitals present in this valence space. These new data are compared to older systematic studies. The effective single-neutron energies are determined by combining information from energy centroids determined from the adding and removing reactions. Two of the five orbitals are nearly degenerate, below $N=64$, and approximately two MeV more bound than the other three, which are also degenerate., Comment: 11 pages, 10 figures

7 pags., 5 figs., 2 tabs., The single-particle properties of Mg29 have been investigated via a measurement of the Mg28(d,p)Mg29 reaction, in inverse kinematics, using the ISOLDE Solenoidal Spectrometer. The negative-parity intruder states from the fp shell have been identified and used to benchmark modern shell-model calculations. The systematic data on the single-particle centroids along the N=17 isotones show good agreement with shell-model predictions in describing the observed trends from stability toward O25. However, there is also evidence that the effect of the finite geometry of the nuclear potential is playing a role on the behavior of the p orbitals near the particle-emission threshold., This work wassupported by the U.K. Science and Technology Facilities Council [Grants No. ST/P004598/1, No. ST/N002563/1, No. ST/M00161X/1 (Liverpool), No. ST/P004423/1 (Manchester), No. ST/P005314/1 (Surrey), the ISOL-SRS Grant (Daresbury), No. ST/R004056/1 (Ernest Rutherford Fellowship - Gaffney), and No. ST/T004797/1 (Ernest Rutherford Fellowship - Sharp)], the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contracts No. DE-AC02-06CH11357 (ANL) and No. DE-SC-0014552 (UConn), the European Union’s Horizon 2020 Framework research and innovation program under Grant Agreement No. 654002 (ENSAR2), the Marie Skłodowska-Curie Grant Agreement No. 665779, the Research Foundation Flanders (FWO, Belgium), the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement No. 617156, and the Spanish Ministry of Science and Innovation under Grants No. PGC2018-095640- B-I00“ELEGANT” and No. PID2019-104390GB-I00. This research used targets provided by the Center for Accelerator Target Science at Argonne National Laboratory. The FSU shell-model calculations were performed using the computational facility of the nuclear physics theory group, Florida State University, supported by grants from the U.S. Department of Energy, Office of Science (DE-SC-0009883 (FSU).

Nucleon-transfer sum rules have been assessed via a consistent reanalysis of cross-section data from neutron-adding ($d$,$p$) and -removing ($d$,$t$) reactions on well-deformed isotopes of Gd, Dy, Er, Yb, and W, with $92\leq N\leq108$, studied at the Niels Bohr Institute in the 1960s and 1970s. These are complemented by new measurements of cross sections using the ($d$,$p$), ($d$,$t$), and ($p$,$d$) reactions on a subset of these nuclei. The sum rules, defined in a Nilsson-model framework, are remarkably consistent. A single overall normalization is used in the analysis, which appears to be sensitive to assumptions about the reaction mechanism, and in the case of sums using the ($d$,$t$) reaction, differs from values determined from reactions on spherical systems., 7 pages, 4 figures

A systematic study of neutron-hole strength in the N = 81 nuclei 137Ba, 139Ce, 141Nd and 143Sm is reported. The single-neutron removal reactions (p,d) and (3He,) were measured at energies of 23 and 34 MeV, respectively. Spectroscopic factors were extracted from measured cross sectionsthrough a distorted-wave Born approximation analysis and centroids of single-particle strength have been established. The change in these centroid energies as a function of proton number have been compared to calculations of the monopole shift for the s1=2 and h11=2 orbitals, where the majorityof the strength has been observed. Signicant fragmentation of strength was observed for the d and g7=2 orbitals, particularly for the latter orbital which is deeply bound, with summed strengths that indicate a signicant amount lies outside of the measured excitation energy range.

The nuclei below lead but with more than 126 neutrons are crucial to an understanding of the astrophysical r process in producing nuclei heavier than A∼190. Despite their importance, the structure and properties of these nuclei remain experimentally untested as they are difficult to produce in nuclear reactions with stable beams. In a first exploration of the shell structure of this region, neutron excitations in ^{207}Hg have been probed using the neutron-adding (d,p) reaction in inverse kinematics. The radioactive beam of ^{206}Hg was delivered to the new ISOLDE Solenoidal Spectrometer at an energy above the Coulomb barrier. The spectroscopy of ^{207}Hg marks a first step in improving our understanding of the relevant structural properties of nuclei involved in a key part of the path of the r process. ispartof: Physical Review Letters vol:124 issue:6 ispartof: location:United States status: published

The pairing properties of the neutrinoless double-$\beta$ decay candidate $^{116}$Cd have been investigated. Measurements of the two-neutron removal reactions on isotopes of $^{114,116}$Cd have been made in order to identify 0$^+$ strength in the residual nuclei up to $\approx$3 MeV. No significant $L=0$ strength has been found in excited states indicating that the Bardeen-Cooper-Schrieffer (BCS) approximation is a reasonable basis to describe the neutrons in the ground state. This approximation avoids complications in calculations of double-$\beta$ decay matrix elements that use the quasiparticle random-phase approximation (QRPA) techniques. However this is not the case for the protons, where pair vibrations are prevalent and the BCS approximation is no longer valid, complicating the use of traditional QRPA techniques for this system as a whole.

Excited states in the neutron-rich 70 Fe nucleus were populated in a one-proton removal reaction from 71 Co projectiles at 87 MeV/nucleon. A new transition was observed with the γ -ray tracking array GRETINA and shown to feed the previously assigned 4+ 1 state. In comparison to reaction theory calculations with shell-model spectroscopic factors, it is argued that the new γ ray possibly originates from the 6+ 1 state. It is further shown that the Doppler-reconstructed γ -ray spectra are sensitive to the very different lifetimes of the 2+ and 4+ states, enabling their approximate measurement. The emerging structure of 70 Fe is discussed in comparison to LNPS-new large-scale shell-model calculations.

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of $ 0^{+}_{1,2}$01,2+, $ 2^{+}_{1,2}$21,2+and $ 4^{+}_{1}$41+states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions. The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of $ 0^{+}_{1,2}$01,2+, $ 2^{+}_{1,2}$21,2+and $ 4^{+}_{1}$41+states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions. ispartof: The European Physical Journal A - Hadrons and Nuclei vol:55 issue:8 pages:130-130 status: published

International audience; Excited states of the rubidium isotopes$_{37}^{87, 89, 91}$Rb have been studied at the INFN Legnaro National Laboratory. Measurements of the $\gamma$ -ray decay of fragments produced in binary grazing reactions resulting from the interaction of a beam of 530 MeV$^{96}$Zr ions with a$^{124}$Sn target have been complemented by studies of the $\gamma$ -ray decay of fission fragments produced in the interaction of a beam of 230 MeV$^{36}$S ions with a thick$^{176}$Yb target. The structure of the yrast states of$_{37}^{87, 89, 91}$Rb has been discussed within the context of spherical shell-model and cranked Nilsson-Strutinsky calculations.

The energy levels and γ-ray decay scheme of the positive-parity states in the Tz=12 nucleus As67 have been studied by using the Ca40(Ar36,2αp)As67 reaction at a beam energy of 145 MeV. Two new band structures have been identified which can be connected to the previously known levels. The results for these bands are compared with configuration-dependent cranked Nilsson-Strutinsky calculations. The good level of agreement between theory and experiment suggests that these structures can be interpreted in terms of configurations that involve three g92 particles and that both possess noncollective terminating states.

Introduction Simulation is increasingly used throughout medicine. Within ultrasound, simulators are more established for learning transvaginal and interventional procedures. The use of modern high-fidelity transabdominal simulators is increasing, particularly in centres with large trainee numbers. There is no current literature on the value of these simulators in gaining competence in abdominal ultrasound. The aim was to investigate the impact of a new ultrasound curriculum, incorporating transabdominal simulators into the first year of training in a UK radiology academy. Methods The simulator group included 13 trainees. The preceding cohort of 15 trainees was the control group. After 10 months, a clinical assessment was performed to assess whether the new curriculum resulted in improved ultrasound skills. Questionnaires were designed to explore the acceptability of simulation training and whether it had any impact on confidence levels. Results Trainees who had received simulator-enriched training scored higher in an objective clinical ultrasound assessment, which was statistically significant ( p = 0.0463). End confidence scores for obtaining diagnostic images and demonstrating pathology were also higher in the simulation group. All trainees stated that transabdominal simulator training was useful in early training. Conclusions This initial study shows that embedded into a curriculum, transabdominal ultrasound simulators are an acceptable training method that can result in improved ultrasound skills and higher confidence levels. Using simulators early in training could allow trainees to master the basics, improve their confidence, enabling them to get more educational value from clinical ultrasound experience while reducing the impact of training on service provision.

The rearrangements of protons and neutrons amongst the valence single-particle orbitals during double-$\ensuremath{\beta}$ decay of $^{100}\mathrm{Mo}$ have been determined by measuring cross sections in ($d,p$), ($p,d$), ($^{3}\mathrm{He},\ensuremath{\alpha}$), and ($^{3}\mathrm{He},d$) reactions on $^{98,100}\mathrm{Mo}$ and $^{100,102}\mathrm{Ru}$ targets. The deduced nucleon occupancies reveal significant discrepancies when compared with theoretical calculations; the same calculations have previously been used to determine the nuclear matrix element associated with the decay probability of double-$\ensuremath{\beta}$ decay of the $^{100}\mathrm{Mo}$ system.

Author(s): Vogt, A; Siciliano, M; Birkenbach, B; Reiter, P; Hadynska-Klȩk, K; Wheldon, C; Valiente-Dobon, JJ; Teruya, E; Yoshinaga, N; Arnswald, K; Bazzacco, D; Blazhev, A; Bracco, A; Bruyneel, B; Chakrawarthy, RS; Chapman, R; Cline, D; Corradi, L; Crespi, FCL; Cromaz, M; De Angelis, G; Eberth, J; Fallon, P; Farnea, E; Fioretto, E; Fransen, C; Freeman, SJ; Fu, B; Gadea, A; Gelletly, W; Giaz, A; Gorgen, A; Gottardo, A; Hayes, AB; Hess, H; Hetzenegger, R; Hirsch, R; Hua, H; John, PR; Jolie, J; Jungclaus, A; Karayonchev, V; Kaya, L; Korten, W; Lee, IY; Leoni, S; Liang, X; Lunardi, S; MacChiavelli, AO; Menegazzo, R; Mengoni, D; Michelagnoli, C; Mijatovic, T; Montagnoli, G; Montanari, D; Muller-Gatermann, C; Napoli, D; Pearson, CJ; Podolyak, Z; Pollarolo, G; Pullia, A; Queiser, M; Recchia, F; Regan, PH; Regis, JM; Saed-Samii, N; Sahin, E; Scarlassara, F; Seidlitz, M; Siebeck, B; Sletten, G; Smith, JF; Soderstrom, PA; Stefanini, AM; Stezowski, O; Szilner, S; Szpak, B; Teng, R; Ur, C; Warner, DD; Wolf, K; Wu, CY; Zell, KO | Abstract: The transitional nuclei Xe132 and Xe133 are investigated after multinucleon-transfer (MNT) and fusion-evaporation reactions. Both nuclei are populated (i) in Xe136+Pb208 MNT reactions employing the high-resolution Advanced GAmma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA, (ii) in the Xe136+Pt198 MNT reaction employing the GAMMASPHERE spectrometer in combination with the gas-detector array CHICO, and (iii) as an evaporation residue after a Te130(α,xn)Xe134-xn fusion-evaporation reaction employing the HORUS γ-ray array at the University of Cologne. The high-spin level schemes are considerably extended above the Jπ=(7-) and (10+) isomers in Xe132 and above the 11/2- isomer in Xe133. The results are compared to the high-spin systematics of the Z=54 as well as the N=78 and N=79 chains. Furthermore, evidence is found for a long-lived (T1/2â‰1μs) isomer in Xe133 which closes a gap along the N=79 isotones. Shell-model calculations employing the SN100PN and PQM130 effective interactions reproduce the experimental findings and provide guidance to the interpretation of the observed high-spin features.

The high-spin structures of the N = 81 isotones 135Xe and 137Ba are investigated after multinucleontransfer (MNT) and fusion-evaporation reactions. Both nuclei are populated in (i) 136Xe+238U and (ii) 136Xe+208Pb MNT reactions employing the high-resolution Advanced Gamma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA, (iii), in the 136Xe+198Pt MNT reaction employing the -ray array GAMMASPHERE in combination with the gas detector array Chico, and (iv) via a 11B+130Te fusion-evaporation reaction. The high-spin level schemes of 135Xe and 137Ba are considerably extended to higher energies. The 2058-keV (19=2 ) state in 135Xe is identified as an isomer, completing the systematics for the N = 81 isotones. Its half-life is measured to be 8.6(10) ns, corresponding to a transition probability of B(E2; 19=2 ! 15=2 ) = 0:539(69) W.u. Latest shell model calculations considering 132Sn as a closed core reproduce the experimental findings and provide guidance to the interpretation of the new levels. The experimentally deduced reduced quadrupole transition probabilities of the isomeric states are compared to shell-model predictions.

Multi-quasiparticle high-K states, several of which are isomeric, were observed in Hf-180 with the Gammasphere array. We determined the lifetimes in the ns-μs range using centroid-shift and decay measurements within a mu s coincidence time window. The configurations of high-K states involve two and four quasiparticles, with states up to Kπ = (18-) established. High-K excitations are found to be progressively more favored with increasing excitation energy. The K quantum number is quite robust up to the highest spins observed, as evidenced by the large values of the reduced hindrance for isomeric decays. Furthermore, rotational bands built on three high-K states are identified, and the measured branching ratios in these sequences enable the assignment of underlying configurations. Multi-quasiparticle calculations using the Lipkin-Nogami approach for pairing, with blocking included, reproduce the observed high-K energies quite well.

Objectives To compare image quality on computed tomographic (CT) images acquired with filtered back-projection (FBP), adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) techniques in CT kidney/ureter/bladder (KUB) examination. Methods Eighteen patients underwent standard protocol CT KUB at our institution. The same raw data were reconstructed using FBP, ASIR and MBIR. Objective [mean image noise, contrast-to-noise ratio (CNR) for kidney and mean attenuation values of subcutaneous fat] and subjective image parameters (image noise, image contrast, overall visibility of kidneys/ureters/bladder, visibility of small structures, and overall diagnostic confidence) were assessed using a scoring system from 1 (best) to 5 (worst). Results Objective image measurements revealed significantly less image noise and higher CNR and the same fat attenuation values for the MBIR technique (P 0.05), while there was a significant difference between ASIR vs. MBIR (P

In neutrinoless double-$\ensuremath{\beta}$ decay such as ${}^{136}$Xe to ${}^{136}$Ba, two neutrons become two protons, thus rearranging the occupancy of protons and neutrons in the ground states of the parent and daughter nuclei. From precision measurements of the cross sections of single-neutron adding and -removing reactions, the authors extract the change in ground-state neutron occupancies between ${}^{136}$Xe and ${}^{136}$Ba. Along with recent results on the proton occupancies, the new experimental neutron occupancies disagree with those used in existing theoretical calculations of the rate of this elusive $\ensuremath{\beta}$-decay mode, and provide a \hskip-0.22em \hskip-0.22embasis for improved estimates of the uncertainties for new calculations.

The change in the configuration of valence protons between the initial and final states in the neutrinoless double-$\beta$ decay of $^{130}$Te $\rightarrow$ $^{130}$Xe and of $^{136}$Xe $\rightarrow$ $^{136}$Ba has been determined by measuring the cross sections of the ($d$,$^3$He) reaction with 101-MeV deuterons. Together with our recent determination of the relevant neutron configurations involved in the process, a quantitative comparison with the latest shell-model and interacting-boson-model calculations reveals significant discrepancies. These are the same calculations used to determine the nuclear matrix elements governing the rate of neutrinoless double-$\beta$ decay in these systems.

Acta physica Polonica / B 47(3), 627 - 636(2016). doi:10.5506/APhysPolB.47.627, Published by Inst. of Physics, Jagellonian Univ., Cracow

© 2015 Elsevier B.V. It is planned to install the heavy-ion, low-energy ring TSR, currently at the Max-Planck-Institute for Nuclear Physics in Heidelberg, at the HIE-ISOLDE facility in CERN, Geneva. Such a facility will provide a capability for experiments with stored, cooled secondary beams that is rich and varied, spanning from studies of nuclear ground-state properties and reaction studies of astrophysical relevance, to investigations with highly-charged ions and pure isomeric beams. In addition to experiments performed using beams recirculating within the ring, the cooled beams can be extracted and exploited by external spectrometers for high-precision measurements. The capabilities of the ring facility as well as some physics cases will be presented, together with a brief report on the status of the project. ispartof: Nuclear Instruments & Methods in Physics Research B vol:376 pages:270-274 ispartof: location:Grand Rapids: MI status: published

A. Vogt et al. ; 12 págs.; 9 figs.; 1 tab., Detailed spectroscopic information on the N∼82 nuclei is necessary to benchmark shell-model calculations in the region. The nuclear structure above long-lived isomers in Xe134 is investigated after multinucleon transfer (MNT) and actinide fission. Xenon-134 was populated as (i) a transfer product in Xe136+U238 and Xe136+Pb208 MNT reactions and (ii) as a fission product in the Xe136+U238 reaction employing the high-resolution Advanced Gamma Tracking Array (AGATA). Trajectory reconstruction has been applied for the complete identification of beamlike transfer products with the magnetic spectrometer PRISMA. The Xe136+Pt198 MNT reaction was studied with the γ-ray spectrometer GAMMASPHERE in combination with the gas detector array Compact Heavy Ion Counter (CHICO). Several high-spin states in Xe134 on top of the two long-lived isomers are discovered based on γγ-coincidence relationships and information on the γ-ray angular distributions as well as excitation energies from the total kinetic energy loss and fission fragments. The revised level scheme of Xe134 is extended up to an excitation energy of 5.832 MeV with tentative spin-parity assignments up to 16+. Previous assignments of states above the 7- isomer are revised. Latest shell-model calculations employing two different effective interactions reproduce the experimental findings and support the new spin and parity assignments., The research leading to these results has received funding from the German BMBF under Contract No. 05P12PKFNE TP4, from the European Union Seventh Framework Programme FP7/2007–2013 under Grant Agreement No. 262010 - ENSAR, from the Spanish Ministerio de Ciencia e Innovación under Contract No. FPA2011-29854-C04, from the Spanish Ministerio de Economía y Competitividad under Contract No. FPA2014-57196-C5, from the Bonn-Cologne Graduate School of Physics and Astronomy (BCGS), from the UK Science and Technology Facilities Council (STFC), and from the US National Science Foundation (NSF). One of the authors (A. Gadea) has been supported by the Generalitat Valenciana, Spain, under Grant No. PROMETEOII/2014/019 and EU under the FEDER program.

Background: Neutron-rich, even-mass chromium and iron isotopes approaching neutron number $N=40$ have been important benchmarks in the development of shell-model effective interactions incorporating the effects of shell evolution in the exotic regime. Odd-mass manganese nuclei have received less attention, but provide important and complementary sensitivity to these interactions.Purpose: We report the observation of two new $\ensuremath{\gamma}$-ray transitions in $^{63}\mathrm{Mn}$, which establish the $(9/{2}^{\ensuremath{-}})$ and $(11/{2}^{\ensuremath{-}})$ levels on top of the previously known $(7/{2}^{\ensuremath{-}})$ first-excited state. The lifetime for the $(7/{2}^{\ensuremath{-}})$ and $(9/{2}^{\ensuremath{-}})$ excited states were determined for the first time, while an upper limit could be established for the $(11/{2}^{\ensuremath{-}})$ level.Method: Excited states in $^{63}\mathrm{Mn}$ have been populated in inelastic scattering from a $^{9}\mathrm{Be}$ target and in the fragmentation of $^{65}\mathrm{Fe}$. $\ensuremath{\gamma}\ensuremath{\gamma}$ coincidence relationships were used to establish the decay level scheme. A Doppler line-shape analysis for the Doppler-broadened $(7/{2}^{\ensuremath{-}})\ensuremath{\rightarrow}5/{2}^{\ensuremath{-}}$, $(9/{2}^{\ensuremath{-}})\ensuremath{\rightarrow}(7/{2}^{\ensuremath{-}}),$ and $(11/{2}^{\ensuremath{-}})\ensuremath{\rightarrow}(9/{2}^{\ensuremath{-}})$ transitions was used to determine (limits for) the corresponding excited-state lifetimes.Results: The low-lying level scheme and the excited-state lifetimes were compared with large-scale shell-model calculations using different model spaces and effective interactions in order to isolate important aspects of shell evolution in this region of structural change.Conclusions: While the theoretical $(7/{2}^{\ensuremath{-}})$ and $(9/{2}^{\ensuremath{-}})$ excitation energies show little dependence on the model space, the calculated lifetime of the $(7/{2}^{\ensuremath{-}})$ level and calculated energy of the $(11/{2}^{\ensuremath{-}})$ level reveal the importance of including the neutron ${g}_{9/2}$ and ${d}_{5/2}$ orbitals in the model space. The LNPS effective shell-model interaction provides the best overall agreement with the new data.

Yrast and near-yrast states in 30 Al and 30 Si have been populated to high spin with the O 18 + C 14 fusion–evaporation reaction in inverse kinematics. The level schemes for these two isobars have been extended up to J ∼ 9 ℏ at 9.4 and 15.5 MeV, respectively. Their decay schemes indicate that cross-shell excitations dominate at high spin, where negative-parity structures exist. Positive-parity states are compared to the results of shell-model calculations using the USD, USDA, and USDB effective interactions. The negative-parity levels are compared to predictions of the WBP interaction and the recently-developed WBP-a Hamiltonian, by allowing 1p–1h excitations to fp -shell orbitals. The results suggest that single-neutron excitations to the 0 f 7 / 2 orbital play a significant role at high spin.

This paper describes the implementation and commissioning of a device based on a new concept for measurements of nuclear reactions in inverse kinematics. The HELIcal Orbit Spectrometer, HELIOS, was commissioned at Argonne National Laboratory by studying the 28Si(d,p)29Si reaction in inverse kinematics. This experiment served as a proof of principle for this previously untested concept, and was used to verify the response and performance characteristics of HELIOS.

Quasistatic strain imaging is a form of elastography that can produce qualitative images of tissue stiffness with only software modifications to conventional ultrasound hardware. Unlike current commercial offerings, the novel strain-imaging system that is the subject of this paper displays regions of signal decorrelation using an overlaid colour mask and can also produce three-dimensional (3D) strain images. In illustrative studies of the breast, testis and thyroid, the colour mask is seen to reduce the potential to misinterpret noise as meaningful stiffness information, and also helps to differentiate cystic and solid lesions. High-quality imaging of the testis in vivo demonstrates that 3D strain imaging is feasible.

The near-term radioactive beam capabilities of ATLAS include radioactive beams produced in flight in a gas cell, or starting in the fall of 2009, re-accelerated beams of 252 Cf fission fragments provided by the new CARIBU injector. The availability of such exotic beams will allow for detailed studies of the single-particle aspects of nuclear structure in neutron-rich nuclei reaching out to the astrophysical r-process path by employing light-ion reactions in inverse kinematics. The HELIOS spectrometer is based on a new concept that is especially well suited for such studies. This concept was recently demonstrated using the reactions D (28 Si , p )29 Si with a (stable) 168 MeV 28 Si beam. Since then D (12 B , p )13 B , D (17 O , p )18 O , and D (15 C , p )16 C have been studied successfully. The combination of neutron-rich beams from CARIBU and the HELIOS spectrometer opens a fertile research area of precision studies of the single particle strengths and collective excitations in exotic nuclei, and is likely to have applications in other reactions as well.

Large area position-sensitive planar germanium wafers are increasingly being used for a variety of gamma-ray imaging and tracking tasks. Position sensitivity can be achieved through measuring charge collected on orthogonal strip electrodes, and by digital pulse shape analysis. However, the development of this detector technology has been slow, and criteria to measure improved performance have not been well established. We have studied 93 and 88 mm square segmented detectors of 20 mm thickness made with conventional boron and lithium electrodes, and two 100 mm circular segmented detectors of 14 mm thickness with amorphous germanium contacts. We have compared these detectors with a planar detector of 15 mm thickness. Conventional energy resolution tests of individual strips are insufficient to fully categorize the performance of the position sensitive detectors. We propose some basic tests which can rapidly quantify any segmented detector characteristics, and show potential inadequacies which become important when imaging or tracking is attempted.

Zhu, S. Janssens, R. V. F. Fornal, B. Freeman, S. J. Honma, M. Broda, R. Carpenter, M. P. Deacon, A. N. Kay, B. P. Kondev, F. G. Krolas, W. Kozemczak, J. Larabee, A. Lauritsen, T. Liddick, S. N. Lister, C. J. Mantica, P. F. Otsuka, T. Pawlat, T. Robinson, A. Seweryniak, D. Smith, J. F. Steppenbeck, D. Tomlin, B. E. Wrzesinski, J. Wang, X.

Background: Shape coexistence in heavy nuclei poses a strong challenge to state-of-the-art nuclear models, where several competing shape minima are found close to the ground state. A classic region for investigating this phenomenon is in the region around Z=82 and the neutron midshell at N=104. Purpose: Evidence for shape coexistence has been inferred from α-decay measurements, laser spectroscopy, and in-beam measurements. While the latter allow the pattern of excited states and rotational band structures to be mapped out, a detailed understanding of shape coexistence can only come from measurements of electromagnetic matrix elements. Method: Secondary, radioactive ion beams of Rn202 and Rn204 were studied by means of low-energy Coulomb excitation at the REX-ISOLDE in CERN. Results: The electric-quadrupole (E2) matrix element connecting the ground state and first excited 21+ state was extracted for both Rn202 and Rn204, corresponding to B(E2;21+→01+)=29-8+8 and 43-12+17 W.u. respectively. Additionally, E2 matrix elements connecting the 21+ state with the 41+ and 22+ states were determined in Rn202. No excited 0+ states were observed in the current data set, possibly owing to a limited population of second-order processes at the currently available beam energies. Conclusions: The results are discussed in terms of collectivity and the deformation of both nuclei studied is deduced to be weak, as expected from the low-lying level-energy schemes. Comparisons are also made to state-of-the-art beyond-mean-field model calculations and the magnitude of the transitional quadrupole moments are well reproduced., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

Excited states up to I π = 8 + in the neutron-rich nucleus 58Cr have been identified by using a new experimental setup composed of the large acceptance magnetic spectrometer PRISMA and the highly efficient γ-detector array CLARA. Interestingly, the excitation energy sequence of the ground-state band follows the one expected by the E ( 5 ) dynamical symmetry for a nucleus at the critical point of the shape phase transition from a spherical vibrator ( U ( 5 ) ) to a γ-soft rotor ( O ( 6 ) ). For the first time, in the same physical system, large scale shell-model calculations in the full fp shell are compared to the E ( 5 ) analytical model results and to the Interacting Boson Model. The theoretical results are in excellent agreement with the present data.

Excited states have been identified in the very neutron-deficient 122Ce nucleus. This is the first observation of this nucleus and its excited states. The ground-state rotational band has been observed up to spin 14 ℏ. The band has been assigned to 122Ce by detecting gamma rays in coincidence with evaporated charged particles and neutrons. The E ( 2 1 + ) value suggests a rather large ground-state deformation of β 2 = 0.35 , in good agreement with Hartree–Fock–Bogoliubov (HFB) mean-field calculations. The aligned angular momentum of the band has been studied and is compared with those of the neighboring even–even cerium isotopes, and to Woods–Saxon cranking calculations. The non-observation of the π ( h 11 / 2 ) 2 alignment until at least 0.4 MeV/ℏ is consistent with the extracted value of β 2 .

The low-lying levels in 59,60Cr have been populated with 13,14C(48Ca, 2p) reactions using a beam energy of 130 MeV. Prompt electromagnetic radiation was detected using the Gammasphere array, in coincidence with recoiling ions measured with the Fragment Mass Analyzer. The residues were selected and identified on the basis of charge-to-mass ratio, energy-loss and time-of-flight measurements. Preliminary results for 60Cr, when compared to lighter even-even isotopes, indicate a softness in shape which increases with neutron number. The low-lying structure of 59Cr is clearly inconsistent with the results of a spherical shell-model calculation and requires the inclusion of the νg9/2 orbital. The sequence of states can be understood within the Nilsson model assuming a moderate oblate ground-state deformation. This is in contrast to lighter odd-Cr nuclei where there is evidence for prolate deformation after excitation of g9/2 neutrons.

Excited states in 57 Cr have been populated to high spin in the C 14 ( Ca 48 , α n ) reaction at a beam energy of 130 MeV. A regular sequence of stretched quadrupole transitions has been established above the yrast 9 / 2 + level. This sequence is interpreted as a rotational band associated with prolate deformation induced by the excitation of the odd neutron into the 1 / 2 + [ 440 ] orbital. Total Routhian surface calculations, which follow this configuration to high spin, reproduce the observed features of the band. They are also able to account for a similar, but less well developed structure in 55 Cr. In contrast, the isomeric yrast 9 / 2 + state in 59 Cr appears to be a band-head state dominated by the 9 / 2 + [ 404 ] configuration, which is favoured at oblate deformations. Such a marked difference presents a significant challenge for theoretical descriptions, but is consistent with features exhibited by the low-lying negative-parity states in 59 Cr.

A study of high spin states in the odd-neutron isotones 239 Pu and 237 U is reported. Striking differences were found in the high-spin properties of rotational bands built on the 1 /2 + [631] ground states in these two nuclei. These differences mirror those observed in the even–even Pu and U immediate neighbors and appear to be related to the strength of octupole correlations.

Clinical examination and urinalysis are usually insufficient for diagnosis in patients with loin pain.Although the majority of renal stones are radioopaque, plain film radiography is not sufficiently accurate in the identification of ureteric stones to be used as the only imaging investigation.Intravenous urography is good for diagnosing ureteric obstruction but is limited in its demonstration of ureteric stones when compared with CT.Ultrasound, incorporating Doppler techniques, is able to diagnose ureteric obstruction with a high degree of accuracy but cannot directly demonstrate ureteric calculi in most cases.Ultrasound, proceeding to MRI in selected cases, is the investigations of choice in pregnant patients with loin pain.Unenhanced CT is the investigation of choice for most patients with loin pain owing to its unrivalled accuracy, speed and ability to demonstrate other renal and non-renal pathologies.Low-dose techniques should be routinely applied to CT KUB examinations.Stone size and location are th...

A seven-quasiparticle isomer with $K^{\pi} = (49 /2^ + )$ and T 1/2 = 53 ( + 3 -7) ns has been identified in 179Ta. By comparing its excitation energy with results from multi-quasiparticle calculations that include the effects of blocking and residual nucleon-nucleon interactions, the isomer is assigned the $\pi^{3}$ (5/2 + [402], 7/2 + [404], $9/2^{-}[514]) \otimes \nu^{4}$ (5/2-[512], 7/2-[514], 7/2-[503], 9/2 + [624]) configuration. The decay of this isomer is found to be unusually fast, a feature that is attributed to a mixing with a specific collective level. The interaction strength is found to be orders of magnitude lower than that observed between interacting collective levels.

A multi-nucleon transfer reaction using an 850 MeV 136Xe beam incident on a 198Pt target was used to populate high-spin states in 184W, 14 nucleons from the target. A 4-quasiparticle isomer with \(t_{1/2} = 188 \pm 38\) ns has been observed for the first time and its de-excitation through collective and intrinsic structures studied. The results are compared with predictions of blocked BCS Nilsson calculations. Observation of this metastable state completes the tungsten 4-quasiparticle isomer systematics from A = 176 to 186. Mapping out the most yrast 4-quasiparticle isomers in these even-even tungsten isotopes suggests the existence of a highly favoured state in 188W, within reach of current experimental set-ups.

The fusion–evaporation reaction 10 B( 12 C, 2 n ) was used to make the first observation of in-beam γ decays from the astrophysically important nucleus 20 Na, lying adjacent to the proton drip-line. All states below the proton threshold in 20 Na were populated and identified in the experiment. These include new levels, previously unresolved levels, and states located with improved energy precision. The level structure of 20 Na, and its γ transitions, are compared to the mirror partner 20 F measured simultaneously in this experiment. In particular, a high degree of energy stability is found for all negative parity states. These results are discussed in the context of the nuclear shell model.

This paper reports on recent work using multi-nucleon transfer reactions to populate metastable states in neutron-rich, rare-earth and transitional nuclei with A∼180-200. The use of a position sensitive gas-filled detector, CHICO, allowed the directions of the binary fragments to be measured, thereby enabling event-by-event Doppler corrections to be made for the prompt, in-beam transitions depopulating the nuclei of interest. By using the temporal calibration provided by (i) the measurement of the binary reaction fragments and (ii) the natural pulsing of the cyclotron beam, transitions from metastable states with lifetimes in the nano-to-microsecond regime could be identified. The complementarity of this technique with the novel use of relativistic projectile fragmentation reactions is outlined, together with potential future avenues for this research, with a particular emphasis on the population of exotic isomeric states at high angular momentum and excitation energy values.

Long-lived high- K states have been identified in 177 Lu, including an isomer with τ >10 μs, placed at 3530 keV and associated with the yrast K π =39/2 − , 5-quasiparticle state predicted in multi-quasiparticle-state calculations. The γ -decay of the isomer exposes the rotational band based on the 160-day 23/2 − isomer, 177m Lu , with band properties which support its proposed configuration. A 90-ns isomer at 1325 keV is associated with the predicted 3-quasiparticle K π =25/2 + state while a 5-quasiparticle 33/2 + , 902-ns isomer with highly-hindered decays is identified at 2771 keV. Both exhibit rotational bands whose properties are used to support the assigned configurations. The possibility that the K π =39/2 − isomer found in this work should be identified with a β -decaying isomer, proposed recently to populate the 51-min 37/2 − isomer in 177 Hf, is discussed in terms of the implied log ft values, configuration changes, and hindrances for K -forbidden γ -decays.

The GREAT spectrometer is designed to measure the decay properties of reaction products transported to the focal plane of a recoil separator. GREAT comprises a system of silicon, germanium and gas detectors optimised for detecting the arrival of the reaction products and correlating with any subsequent radioactive decay involving the emission of protons, α particles, β particles, γ rays, X-rays or conversion electrons. GREAT can either be employed as a sensitive stand-alone device for decay measurements at the focal plane, or used to provide a selective tag for prompt conversion electrons or γ rays measured with arrays of detectors deployed at the target position. A new concept of triggerless data acquisition (total data readout) has also been developed as part of the GREAT project, which circumvents the problems and limitations of common dead time in conventional data acquisition systems.

Lifetime measurements have been performed for yrast rotational states of 100Zr and 104Mo using a 252Cf source in a differential plunger arrangement, together with the EUROBALL and SAPHIR multi-detector arrays. The system has been proved capable of covering a range of lifetimes from a nanosecond to a picosecond. The transition quadrupole moments are found to decrease by around 20% between I = 4 and I = 8 in the case of 104Mo while remaining constant in 100Zr. The origin of this effect lies either in a rotation-induced shape change, or in the strong mixing between the ground and s-bands in 104Mo.

High-spin states in the neutron-deficient isotope Cd-104 were populated using the Cr-50(Ni-58,4p)Cd-104 reaction at a beam energy of 250 MeV The level scheme has been extended using triple gamma-ray coincidences to a spin of 29h and an excitation energy of 18.2 MeV. Several collective structures involving the excitation of h(11/2) neutrons have been observed to spins approaching 30h. The high-spin structure has been compared to the results of cranked Nilsson-Strutinsky calculations.