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A Coulomb-excitation experiment to study electromagnetic properties of Ca42 was performed using a 170-MeV calcium beam from the TANDEM XPU facility at INFN Laboratori Nazionali di Legnaro. γ rays from excited states in Ca42 were measured with the AGATA spectrometer. The magnitudes and relative signs of ten E2 matrix elements coupling six low-lying states in Ca42, including the diagonal E2 matrix elements of 21+ and 22+ states, were determined using the least-squares code gosia. The obtained set of reduced E2 matrix elements was analyzed using the quadrupole sum rule method and yielded overall quadrupole deformation for 01,2+ and 21,2+ states, as well as triaxiality for 01,2+ states, establishing the coexistence of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in Ca42. The experimental results were compared with the state-of-the-art large-scale shell-model and beyond-mean-field calculations, which reproduce well the general picture of shape coexistence in Ca42.

Relatively neutron-rich thorium isotopes lie at the heart of a nuclear region of nuclei exhibiting octupole correlation effects. The detailed level structure of Th223 has been investigated in measurements of γ radiation following the fusion-evaporation channel of the Pb208(O18,3n)Th223 reaction at 85 MeV beam energy. The level structure has been extended up to spin 49/2, and 33 new γ rays have been added using triple-γ coincidence data. The spins and parities of the newly observed states have been confirmed by angular distribution ratios. In addition to the two known yrast bands based on a K=5/2 configuration, a non-yrast band has been established up to spin 35/2. We interpret this new structure as based on the same configuration as the yrast band in Th221 having dominant K=1/2 contribution. At the highest spin a backbending occurs around a rotational frequency of ℏω=0.23 MeV, very close to the one predicted in Th222, where a sharp transition to a reflection-symmetric shape is expected.

The neutron-rich $^{39}\mathrm{S}$ nucleus has been studied using binary grazing reactions produced by the interaction of a 215-MeV beam of $^{36}\mathrm{S}$ ions with a thin $^{208}\mathrm{Pb}$ target. The magnetic spectrometer, PRISMA, and the $\ensuremath{\gamma}$-ray array, CLARA, were used in the measurements. Gamma-ray transitions of the following energies were observed: 339, 398, 466, 705, 1517, 1656, and 1724 keV. Five of the observed transitions have been tentatively assigned to the decay of excited states with spins up to ($11/{2}^{\ensuremath{-}}$). The results of a state-of-the-art shell-model calculation of the level scheme of $^{39}\mathrm{S}$ using the SDPF-U effective interaction are also presented. The systematic behavior of the excitation energy of the first $11/{2}^{\ensuremath{-}}$ states in the odd-$A$ isotopes of sulfur and argon is discussed in relation to the excitation energy of the first excited ${2}^{+}$ states of the adjacent even-$A$ isotopes. The states of $^{39}\mathrm{S}$ that have the components in their wave functions corresponding to three neutrons in the $1{f}_{7/2}$ orbital outside the $N=20$ core have also been discussed within the context of the 0 $\ensuremath{\hbar}\ensuremath{\omega}$ shell-model calculations presented here.

The neutron decay of the resonant states of light neutron-rich nuclei is an important and poorly explored property, useful to extract valuable nuclear structure information. In the present paper the neutron decay of the C15 resonances populated via the two-neutron transfer reaction C13(O18,O16n) at 84-MeV incident energy is reported for the first time using an innovative technique which couples the MAGNEX magnetic spectrometer and the EDEN neutron detector array. Experimental data show that the resonances below the one-neutron emission threshold decay to the C14 ground state via one-neutron emission with an almost 100% total branching ratio, whereas the recently observed C15 giant pairing vibration at 13.7 MeV mainly decays via two-neutron emission.

We have performed the $^{70}\mathrm{Zn}(d,^{3}\mathrm{He})^{69}\mathrm{Cu}$ proton pick-up reaction in direct kinematics using a deuteron beam at 27 MeV. The outgoing $^{3}\mathrm{He}$ particles were detected at the focal-plane detection system of an Enge split-pole spectrometer. The excitation-energy spectrum was reconstructed up to 7 MeV and spectroscopic factors were obtained after analysis of the angular distributions in the finite-range distorted-wave Born approximation. The results show three new angular distributions for which the $\ensuremath{\pi}{f}_{7/2}$ strength was measured and a lower limit of the centroid is established. State-of-the-art shell-model calculations are performed and predict a $\ensuremath{\pi}{f}_{7/2}$ strength that lies too high in energy in comparison to our experimental results.

R. Chapman et al.; 17 pags.; 18 figs.; 1 tab.; PACS number(s): 23.20.Lv, 25.70.Lm, 27.30.+t

The ${}^{12}$C(${}^{18}$O,${}^{16}$O)${}^{14}$C and ${}^{12,13}$C(${}^{18}$O,${}^{17}$O)${}^{13,14}$C reactions are studied at 84 MeV. Mass distributions and energy spectra of the ejectiles are measured, indicating the selectivity of these reactions to populate two- and one-neutron configurations in the states of the residual nucleus, respectively. The measured absolute cross-section angular distributions are analyzed by exact finite range coupled reaction channel calculations based on a parameter free double-folding optical potential. The form factors for the (${}^{18}$O,${}^{16}$O) reaction are extracted within an extreme cluster and independent particles scheme with shell-model-derived coupling strengths. The results show that the measured cross sections are accurately described for the first time without the need for any arbitrary scaling factor. The (${}^{18}$O,${}^{16}$O) reaction is thus found to be a powerful tool for quantitative spectroscopic studies of pair configurations in nuclear states.

The high-spin states of the two neutron-rich nuclei ${}^{88}$Kr${}_{52}$ and ${}^{89}$Rb${}_{52}$ have been studied from the ${}^{18}$O+${}^{208}$Pb fusion-fission reaction. Their level schemes were built from triple $\ensuremath{\gamma}$-ray coincidence data, and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ angular correlations were analyzed in order to assign spin and parity values to most of the observed states. The two level schemes evolve from collective structures to single-particle excitations as a function of the excitation energy. Comparison with results of shell-model calculations gives the specific proton and neutron configurations which are involved to generate the angular momentum along the yrast lines.

Odd-odd ${}^{136}$Cs nuclei have been produced in the ${}^{18}\mathrm{O}+{}^{208}$Pb and ${}^{12}\mathrm{C}+{}^{238}$U fusion-fission reactions and their $\ensuremath{\gamma}$ rays studied with the Euroball array. The high-spin level scheme was built up to $\ensuremath{\sim}$4.7 MeV excitation energy and spin $I\ensuremath{\sim}16\ensuremath{\hbar}$ from the triple $\ensuremath{\gamma}$-ray coincidence data. The configurations of the three structures observed above $\ensuremath{\sim}$2 MeV excitation energy are first discussed by analogy with the proton excitations identified in the semimagic ${}^{137}$Cs${}_{82}$ nucleus, which involve the three high-$j$ orbits lying above the $Z=50$ gap, $\ensuremath{\pi}{g}_{7/2}$, $\ensuremath{\pi}{d}_{5/2}$, and $\ensuremath{\pi}{h}_{11/2}$. This is confirmed by the results of shell-model calculations performed in this work.

Superdeformed (SD) states of {sup 190}Hg have been studied with the Eurogam Phase 2 {gamma}-ray spectrometer using the {sup 160}Gd({sup 34}S,4{ital n}) reaction. Two new excited SD bands have been found and identified as belonging to this nucleus, bringing the total number of SD bands in {sup 190}Hg to 4. One of the new bands has a dynamic moment of inertia that is very similar to that of the yrast SD band of {sup 190}Hg and most other SD bands in the {ital A}{approximately}190 region. In contrast, the other band has a dynamic moment of inertia which is mainly constant as a function of rotational frequency and exhibits a dramatic increase at the lowest frequencies. The observed dynamic moments of inertia are compared with the results of random phase approximation calculations based on the cranked shell model. Finally, the known excited SD band has been extended towards lower frequencies and new transitions have been found linking this band to the yrast SD band. The extracted {ital B}({ital E}1) values of the new linking transitions give further support for the possible octupole vibrational character of this band. {copyright} {ital 1996 The American Physical Society.}

The six superdeformed bands in {sup 193}Pb have been studied with the EUROGAM 2 {gamma}-ray spectrometer using the {sup 168}Er({sup 30}Si,5{ital n}){sup 193}Pb reaction. The results are discussed in terms of cranked-Hartree-Fock-Bogolioubov-Lipkin-Nogami calculations. From the @FF {sup (2)} moment of inertia behavior as function of the rotational frequency and the {ital M}1 and {ital E}2 decay competition of the superdeformed states, the bands are interpreted as three pairs of signature partners based on quasineutron excitations. Dipole transitions linking two signature partner superdeformed bands have been observed and, for the first time in lead isotopes, the branching ratio {ital B}({ital M}1)/{ital B}({ital E}2)=0.15{plus_minus}0.04 {mu}{sup 2}{sub {ital N}}/{ital e}{sup 2}b{sup 2} has been extracted. {copyright} {ital 1996 The American Physical Society.}

From the observed competition between $M1$ and $E2$ $\ensuremath{\gamma}$ transitions deexciting the states of the two signature partner yrast superdeformed bands in $^{193}\mathrm{Tl}$, the ${i}_{\frac{13}{2}}$ ($\ensuremath{\Omega}=\frac{5}{2}$) intruder proton orbital is found to have $\frac{({g}_{K}\ensuremath{-}{g}_{R})K}{{Q}_{0}}=0.138\ifmmode\pm\else\textpm\fi{}0.008$. A model dependent value of ${g}_{s}^{\mathrm{eff}}=(0.7\ifmmode\pm\else\textpm\fi{}0.2){g}_{s}^{\mathrm{free}}$ is deduced. A saturation of the ${\mathcal{T}}^{2}$ moments of inertia, at rotational frequency $\ensuremath{\hbar}\ensuremath{\omega}g0.32$ MeV, is observed for the two bands. This feature is discussed in terms of exhausted quasineutron alignment in the presence of substantially reduced quasiproton alignment due to Pauli blocking.

An experiment using the Eurogam phase II \ensuremath{\gamma}-ray spectrometer confirms the existence of an excited superdeformed (SD) band in $^{190}\mathrm{Hg}$ and its very unusual decay into the lowest SD band over 3--4 transitions. The energies of the transitions linking the two SD bands have been firmly established, and their angular distributions are consistent with a dipole character. Comparisons with calculations using random-phase approximation indicate that the excited SD band can be interpreted as an octupole-vibrational structure.

Five $N=82$ isotones have been produced in two fusion-fission reactions and their $\ensuremath{\gamma}$ rays studied with the Euroball array. The high-spin states of ${}^{139}$La have been identified, while the high-spin yrast and near-to-yrast structures of the four others have been greatly extended. From angular correlation analysis, spin values have been assigned to some states of ${}^{136}$Xe and ${}^{137}$Cs. Several cascades involving $\ensuremath{\gamma}$ rays of ${}^{139}$La have been found to be delayed; they deexcite an isomeric state with ${T}_{1/2}=315(35)$ ns located at 1800 keV excitation energy. The excited states of these five $N=82$ isotones are expected to be due to various proton excitations involving the three high-$j$ subshells located above the $Z=50$ shell closure. This is confirmed by the results of shell-model calculations performed in this work. In addition, high-spin states corresponding to the excitation of the neutron core have been unambiguously identified in ${}^{136}$Xe, ${}^{137}$Cs, and ${}^{138}$Ba.

We report here the first direct lifetime measurement of the 2(1)(+) state in Zn-72,Zn-74. The neutron-rich beam was produced by in-flight fragmentation of Ge-76 at the Grand Accelerateur National d'Ions Lourds and separated with the LISE spectrometer. The 2(1)(+) state was excited by inelastic scattering and knock-out reaction on a CD2 target and its lifetime was measured by the recoil-distance Doppler-shift method with the Koln plunger device combined with the EXOGAM detectors. The lifetimes of the 2(1)(+) states in Zn-72,Zn-74 were determined to be 17.9(18) and 27.0(24) ps, which correspond to reduced transition probabilities B(E2; 2(1)(+)-> 0(+)) = 385(39) and 370(33) e(2) fm(4), respectively. These values support the idea of a systematic maximum of collectivity at N = 42 for Zn, Ge, and Se nuclei. In addition, the available systematics in the neighboring nuclei point toward a transition from a spherical oscillator at N = 40 to complete gamma-softness at N = 42.

The ${}^{119--126}$Sn nuclei have been produced as fission fragments in two reactions induced by heavy ions: ${}^{12}\text{C}+{}^{238}\text{U}$ at a bombarding energy of 90 MeV and ${}^{18}\text{O}+{}^{208}\text{Pb}$ at 85 MeV. Their level schemes have been built from $\ensuremath{\gamma}$ rays detected using the Euroball array. High-spin states located above the long-lived isomeric states of the even- and odd-$A$ ${}^{120--126}$Sn nuclei have been identified. Moreover, isomeric states lying around 4.5 MeV have been established in ${}^{120,122,124,126}$Sn from the delayed coincidences between the fission fragment detector SAPhIR and the Euroball array. The states located above 3 MeV excitation energy are ascribed to several broken pairs of neutrons occupying the $\ensuremath{\nu}{h}_{11/2}$ orbit. The maximum value of angular momentum available in such a high-$j$ shell, i.e., for midoccupation and the breaking of the three neutron pairs, has been identified. This process is observed for the first time in spherical nuclei.

The structure of the weakly-bound $^{26}_{\;\;9}$F$_{17}$ odd-odd nucleus, produced from $^{27,28}$Na nuclei, has been investigated at GANIL by means of the in-beam $\gamma$-ray spectroscopy technique. A single $\gamma$-line is observed at 657(7) keV in $^{26}_{9}$F which has been ascribed to the decay of the excited J=$2^+$ state to the J=1$^+$ ground state. The possible presence of intruder negative parity states in $^{26}$F is also discussed., Comment: 3 pages, 1 figure, accepted for publication in Physical Review C

The ${}^{83,81}\phantom{\rule{-0.16em}{0ex}}$As nuclei have been produced as fission fragments in the fusion reaction ${}^{18}$O + ${}^{208}$Pb at 85 MeV bombarding energy and studied with the Euroball array. Medium-spin states of ${}^{83,81}\phantom{\rule{-0.16em}{0ex}}$As have been established up to $\ensuremath{\sim}3.5$ MeV excitation energy. From angular correlation analysis, spin values have been assigned to most of the ${}^{81}\phantom{\rule{-0.16em}{0ex}}$As excited states. The behaviors of the yrast structures identified in this work are discussed in comparison with the general features known in the mass region. Then they are compared to the results of two theoretical approaches: the ``rotor + quasiparticle'' for ${}^{81}\phantom{\rule{-0.16em}{0ex}}$As and the shell model using the effective interactions JUN45 for ${}^{83,81}\phantom{\rule{-0.16em}{0ex}}\phantom{\rule{-0.16em}{0ex}}$As.

Yrast states in the neutron-rich S41 nucleus have been studied using binary grazing reactions produced by the interaction of a 215-MeV beam of S36 ions with a thin Pb208 target. The magnetic spectrometer, PRISMA, and the γ-ray array, CLARA, were used in the measurements. γ-ray transitions of energy 449 and 638 keV were observed. Results from published intermediate-energy Coulomb excitation measurements in combination with those from the present work have led to the construction of a new S41 level scheme. Proposed Jπ values are based on experimental observation and on model-dependent arguments. The level scheme and published electromagnetic transition probabilities are discussed within the context of state-of-art shell-model calculations using the SDPF-U effective interaction. In contrast with the excellent agreement observed in earlier published work, here there are significant discrepancies between experiment and the results of shell-model calculations. © 2011 American Physical Society., Supported in part by the EPSRC (UK) and by the European Union under Contract No. RII3-CT- 2004-506065. A.J. acknowledges financial support from the m Spanish Ministerio de Ciencia e Innovacion under Contracts No. FPA2007-66069 and No. FPA2009-13377-C02-02. Zs.D. acknowledges the financial support from OTKA Project No. K68801.

The existence of the giant pairing vibration (GPV) in $^{120}\mathrm{Sn}$ and $^{208}\mathrm{Pb}$ was investigated using the ($p$,$t$) reaction at incident proton energies of 50 MeV and 60 MeV for the scattering angles 0${}^{\ifmmode^\circ\else\textdegree\fi{}}$ and 7${}^{\ifmmode^\circ\else\textdegree\fi{}}$. No clear signature for the GPV was found, providing an upper limit for the cross section of ${\ensuremath{\sigma}}_{\mathrm{max}}$ = 0.2 mb. Theoretical interpretations for the low cross section of the GPV are discussed.

High-spin states in the nucleus [sup 196]Hg were populated in the reaction [sup 192]Os([sup 9]Be,5[ital n]) at a beam energy of 65 MeV. A regular rotational-like [Delta][ital I]=1 band has been observed up to an excitation energy of [ital E][sup *][approx]8.7 MeV and spin [ital I][approx]30[h bar]. This is the second observation of a band of this character in a mercury isotope. The experimental results are compared with mean field calculations and semiclassical estimates based on the Doenau-Frauendorf formalism. The mercury bands show significantly lower [ital B]([ital M]1)/[ital B]([ital E]2) branching ratios as compared with similar bands in light lead nuclei. This difference may be more readily explained by a difference in single-particle structure rather than by large differences in deformation between the lead and mercury configurations.

This work was supported in part by the EPSRC (UK) and by the European Union under Contract No. RII3-CT-2004-506065. Five of us (D.O., M.B., A.H., K.K., and A.P.)acknowledge financial support from the EPSRC. Z.M.W acknowledges support from ORSAS and from the University of the West of Scotland. A.J. acknowledges financial supportfrom the Spanish Ministerio de Ciencia e Innovacion under Contract Nos. FPA2007-66069 and FPA2009-13377-C02-02. Zs.D. acknowledges the financial support from OTKA Project No. K68801.

Yrast states up to (6{sup +}) in the neutron-rich {sup 40}S nucleus have been studied using binary grazing reactions produced by the interaction of a 215 MeV beam of {sup 36}S ions with a thin {sup 208}Pb target. The novel experimental setup that combines the large acceptance magnetic spectrometer, PRISMA, and the high-efficiency gamma-ray detection array, CLARA, was used. A new gamma-ray transition at an energy of 1572 keV was observed and tentatively assigned to the (6{sup +})->(4{sup +}) transition. A comparison of experimental observations and the results of large-scale 0(Planck constant/2pi)omega sd-pf shell-model calculations indicates that one- and two-proton excitations from the 2s{sub 1/2} to the 1d{sub 3/2} orbitals play an important role in reproducing the {sup 40}S yrast level structure and the published B(E2;0{sub g.s.}{sup +}->2{sub 1}{sup +}) value. The structure of the yrast states of the even-A isotopes of sulfur is interpreted in terms of the configurations of valence protons and neutrons within the context of large-scale 0(Planck constant/2pi)omega sd-pf shell-model calculations.

Excited states of $^{38}_{17}$Cl$_{21}$ were populated in grazing reactions during the interaction of a beam of $^{36}_{16}$S$_{20}$ ions of energy 215 MeV with a $^{208}_{82}$Pb$_{126}$ target. The combination of the PRISMA magnetic spectrometer and the CLARA $\gamma$-ray detector array was used to identify the reaction fragments and to detect their decay via $\gamma$-ray emission. A level scheme for $^{38}$Cl is presented with tentative spin and parity assignments. The level scheme is discussed within the context of the systematics of neighboring nuclei and is compared with the results of state-of-the-art shell model calculations.

Transition energies of 25 superdeformed (SD) bands in 13 nuclei of the A=194 region were fitted by the power-series expansion of I in odd powers of ${\mathit{E}}_{\ensuremath{\gamma}}$/2, \ensuremath{\Elzxh}(I+1/2)=2\ensuremath{\alpha}\ensuremath{\omega}+4/3\ensuremath{\beta}${\mathrm{\ensuremath{\omega}}}^{3}$, where ${\mathit{E}}_{\ensuremath{\gamma}}$/2=\ensuremath{\Elzxh}\ensuremath{\omega}, and by the expression for transition energy, ${\mathit{E}}_{\ensuremath{\gamma}}$=E(I+2)-E(I), where E(I)=AI(I+1) +B[I(I+1)${]}^{2}$+C[I(I+1)${]}^{3}$. Results are generally similar, and level spins for these SD bands are given based on expectations of rotational model behavior.

Evidence for collective behavior in the high-spin region of lead nuclei is provided by the observation of two collective structures in $^{197}\mathrm{Pb}$. One of these bands is interpreted as an oblate collective structure built on oblate proton and possibly neutron states. A second more irregular band is suggested to be most likely a triaxial rotational band. Neutron and proton configurations for these bands are suggested from the results of quasiparticle Routhians and total Routhians surface calculations. A partial level scheme up to I\ensuremath{\approxeq}69/2 and ${\mathit{E}}_{\mathit{x}}$\ensuremath{\approxeq}8 MeV is presented.

$\ensuremath{\gamma}$-rays following the $\ensuremath{\beta}$ and $\ensuremath{\beta}\text{\ensuremath{-}}n$ decays of the very neutron rich ${}_{31}^{84}{\mathrm{Ga}}_{53}$ produced by the photofission of $^{238}\mathrm{U}$ have been studied at the newly built ISOL facility of IPN Orsay: ALTO. Two activities were observed and assigned to two $\ensuremath{\beta}$-decaying states: $^{84}\mathrm{Ga}$${}^{g}$, ${I}^{\ensuremath{\pi}}=({0}^{\ensuremath{-}})$ and $^{84}\mathrm{Ga}$${}^{m}$, ${I}^{\ensuremath{\pi}}=({3}^{\ensuremath{-}},{4}^{\ensuremath{-}})$. Excitation energies of the ${2}_{1}^{+}$ and ${4}_{1}^{+}$ states of ${}_{32}^{84}{\mathrm{Ge}}_{52}$ were measured at $E({2}_{1}^{+})=624.3$ keV and $E({4}_{1}^{+})=1670.1$ keV. Comparison with HFB $+$ GCM calculations allows to establish the collective character of this nucleus. The excitation energy of the $1/{2}_{1}^{+}$ state in ${}_{32}^{83}{\mathrm{Ga}}_{51}$ known to carry a large part of the neutron $3{s}_{1/2}$ strength was measured at $247.8$ keV. Altogether these data allow to confirm the new single particle state ordering which appears immediately after the double $Z=28$ and $N=50$ shell closure and to designate $^{78}\mathrm{Ni}$ as a fragile and easily polarized doubly-magic core.

Charged-particle and $\ensuremath{\gamma}$ decays in $^{24}\mathrm{Mg}{}^{*}$ are investigated for excitation energies where quasimolecular resonances appear in $^{12}\mathrm{C}+^{12}\mathrm{C}$ collisions. Various theoretical predictions for the occurrence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are discussed within the measured $^{24}\mathrm{Mg}{}^{*}$ excitation energy region. The inverse kinematics reaction $^{24}\mathrm{Mg}+^{12}\mathrm{C}$ is studied at ${E}_{\mathrm{lab}}(^{24}\mathrm{Mg})=130$ MeV, an energy that enables the population of $^{24}\mathrm{Mg}$ states decaying into $^{12}\mathrm{C}+^{12}\mathrm{C}$ resonant breakup states. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with Euroball IV installed at the Vivitron tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions, and their associated $\ensuremath{\gamma}$ decays studied. Coincident events associated with inelastic and $\ensuremath{\alpha}$-transfer channels have been selected by choosing the excitation energy or the entry point via the two-body $Q$ values. The analysis of the binary reaction channels is presented with a particular emphasis on $^{24}\mathrm{Mg}\text{\ensuremath{-}}\ensuremath{\gamma}$, $^{20}\mathrm{Ne}\text{\ensuremath{-}}\ensuremath{\gamma}$, and $^{16}\mathrm{O}$-$\ensuremath{\gamma}$ coincidences. New information (spin and branching ratios) is deduced on high-energy states in $^{24}\mathrm{Mg}$ and $^{16}\mathrm{O}$, respectively.

Excited states in the very neutron-deficient nucleus {sup 174}Pt have been identified up to spin 14. An irregular yrast sequence was observed beginning with a high 2{sup +}{r arrow}0{sup +} energy. It can be interpreted as the result of a change from a weakly deformed ground-state band, to a well-deformed rotor, near spin 6.

The structure of N19-22 nuclei was investigated by means of in-beam gamma-ray spectroscopic technique using fragmentation reactions of both stable and radioactive beams. Based on particle-gamma and particle-gamma gamma coincidence data, level schemes are constructed for the neutron-rich nitrogen nuclei. The experimental results are compared with shell model calculations. The strength of the N=14 and Z=8 shell closures and the weakening of the shell model interaction WBT are discussed.

The excited states of the neutron-rich nucleus {sub 15}{sup 37}P{sub 22} have been populated in grazing reactions, using a beam of {sup 36}S ions (at 215 MeV) delivered onto a thin {sup 208}Pb target. Emitted {gamma} rays from excited projectile-like nuclei were detected using the CLARA array of 25 escape-suppressed Ge clover detectors in coincidence with reaction products detected and identified with the PRISMA magnetic spectrometer. A level scheme is presented for {sup 37}P together with proposed spin assignments. The level structure of {sup 37}P is discussed within the context of shell-model calculations by using an improved sdpf effective interaction.

Excited states of $N=22$ $^{36}\mathrm{Si}$, populated in deep-inelastic processes produced by the interaction of a 215 MeV beam of $^{36}\mathrm{S}$ ions with a $^{208}\mathrm{Pb}$ target, were studied in the present work. \ensuremath{\gamma} rays from the binary fragments detected using CLARA, an array of 25 Ge Clover detectors, were measured in coincidence with projectile-like fragments detected by PRISMA, a large solid angle magnetic spectrometer. Two new \ensuremath{\gamma}-ray photopeaks at energies of 1442 and 842 keV were observed and tentatively assigned to the ${4}^{+}\ensuremath{\rightarrow}{2}^{+}$ and ${6}^{+}\ensuremath{\rightarrow}{4}^{+}$ transitions, respectively. The systematics of the level structures of $N=22$ isotones are presented, and a comparison is made of the behavior of Si, Mg, and S isotopes. The level structure of $^{36}\mathrm{Si}$ is also compared with the results of $\mathit{sdpf}$ shell model calculations.

The high-spin normally deformed and superdeformed states of ${}^{194}\mathrm{Hg}$ have been populated in an exit channel of the ${}^{16}{\mathrm{O}+}^{186}\mathrm{W}$ reaction at 110 MeV bombarding energy. The Doppler shift analysis of the energies of the \ensuremath{\gamma} transitions de-exciting both normally deformed and superdeformed states in ${}^{194}\mathrm{Hg}$ indicates a lower recoil velocity of the ${}^{194}\mathrm{Hg}$ nucleus compared to that of the ${}^{196}\mathrm{Pb}$ nucleus obtained from the $6n$ exit channel of the complete-fusion compound nucleus. This suggests that incomplete fusion plays the main role in the population of normally deformed and superdeformed states of ${}^{194}\mathrm{Hg}$ in this reaction.

The gamma decay of the nuclei Ba-124,Ba-125 has been investigated by means of the EUROBALL spectrometer, coupled to the DIAMANT array of charged-particle detectors, using the reaction Ni-64 + Ni-64 ...

Nuclear structure of the neutron rich {sup 25-29}Ne nuclei has been investigated through the in-beam {gamma}-ray spectroscopy technique using fragmentation reactions of both stable and radioactive beams. Level schemes have been deduced for these Ne isotopes. In order to examine the importance of intruder fp configurations, they are compared to shell model calculations performed either in the restricted sd or in the larger sdpf valence space. The {sup 25,26}Ne and {sup 27}Ne nuclei were found to be in agreement with the sd shell model calculations, whereas {sup 28}Ne exhibits signatures of the intruder fp shell contribution.

Matière Nucléaire; International audience; Lifetimes have been measured for states in the yrast (band 1) and an excited superdeformed band (band 2) in Pb-196. The excited band is thought to be built on an octupole vibration, rather than a quasiparticle excitation. Centroid shifts and line shapes of transitions in gamma-ray coincidence spectra measured with the EUROBALL spectrometer have been analyzed. The transition quadrupole moments deduced from these data for the yrast and the excited superdeformed band are identical within the experimental uncertainties. This result shows that the excited band is not built on different deformation-driving orbitals compared to band 1. It is compatible with the previous suggestion of an octupole-vibrational excitation for the signature partner bands 2 and 3.

This Comment examines the claim of a lack of evidence for a superdeformed band in [sup 192]Pb. We reaffirm the existence in our data of the superdeformed band in [sup 192]Pb.

The stripping reaction (\ensuremath{\alpha},${\mathrm{}}^{3}$He) at 183 MeV incident energy has been used to study the neutron-particle response function on a $^{208}\mathrm{Pb}$ target nucleus up to 15 MeV excitation energy. Detailed spectroscopic information has been obtained on the low-lying neutron states (0--4 MeV) through angular distribution measurements and standard distorted wave Born approximation analysis. A large enhancement of cross section is observed between 5 and 15 MeV. It appears as a broad bump superimposed on a continuous background which has been analyzed within the framework of the plane wave breakup model. The excitation energies, angular distributions, and strengths of these high-lying transitions suggest that they arise from neutron stripping to high-spin outer subshells, i.e., 2${h}_{11/2}$, 1${k}_{17/2}$, and 1${j}_{13/2}$ in $^{209}\mathrm{Pb}$. The results are compared with predictions from the core-particle model and from the quasiparticle-phonon model.