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Describes a technique utilizing analyses of photographs to study planetary motion. (CP)

The beta-decay of Zn-81 to the neutron magic N = 50 nucleus Ga-81, with only three valence protons with respect to Ni-78, was investigated. The study was performed at the ISOLDE facility at CERN by means of gamma spectroscopy. The 81Zn half-life was determined to be T-1/2 = 290(4) ms while the beta-delayed neutron emission probability was measured as P-n = 23(4)%. The analysis of the beta-gated gamma-ray singles and gamma-gamma coincidences from the decay of Zn-81 provides 47 new levels and 70 new transitions in Ga-81. The beta(-)n decay of Zn-81 was observed and a new decay scheme into the odd-odd Ga-80 nucleus was established. The half-lives of the first and second excited states of Ga-81 were measured via the fast-timing method using LaBr3(Ce) detectors. The level scheme and transition rates are compared to large-scale shell-model calculations. The low-lying structure of (81)Gais interpreted in terms of the coupling of the three valence protons outside the doubly magic Ni-78 core.

The existence of two close-lying nuclear states in ⁷³Ga has recently been experimentally determined: a 1/2⁻ spin-parity for the ground state was measured in a laser spectroscopy experiment, while a J_π = 3/2⁻ level was observed in transfer reactions. This scenario is supported by Coulomb excitation studies, which set a limit for the energy splitting of 0.8 keV. In this work, we report on the study of the excited structure of ⁷³Ga populated in the β decay of ⁷³Zn produced at ISOLDE, CERN. Using β-gated, γ-ray singles, and γ –γ coincidences, we have searched for energy differences to try to delimit the ground-state energy splitting, providing a more stringent energy difference limit. Three new half-lives of excited states in ⁷³Ga have been measured using the fast-timing ;method with LaBr₃(Ce) detectors. From our study, we help clarify the excited structure of ⁷³G and we extend the existing ⁷³Zn decay to ⁷³Ga with 8 new energy levels and 35 γ transitions. We observe a 195-keV transition consistent with a γ ray de-exciting a short-lived state in the β-decay parent ⁷³Zn.

gamma-ray and fast-timing spectroscopy were used to study levels in Al-30 populated following the beta(-) decay of Mg-30. Five new transitions and three new levels were located in Al-30. A search was made to identify the third 1(+) state expected at an excitation energy of similar to 2.5 MeV. Two new levels were found, at 3163.9 and 3362.5 keV, that are firm candidates for this state. Using the advanced time-delayed (ATD) beta gamma gamma (t) method we have measured the lifetime of the 243.8-keV state to be T-1/2 = 15(4) ps, which implies that the 243.8-keV transition is mainly of M1 character. Its fast B(M1; 2(+) -> 3(+)) value of 0.10(3) W.u. is in very good agreement with the USD shell-model prediction of 0.090 W.u. The 1801.5-keV level is the only level observed in this study that could be a candidate for the second excited 2(+) state.

The electromagnetic structure of 140Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The 2+ and 4+ states of the ground-state band and a second 2+ state were populated by multistep excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the 2+ 1 state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and algebraic models are also employed to interpret the experimental data. The results indicate that 140Sm shows considerable γ softness, but in contrast to earlier speculation no signs of shape coexistence at low excitation energy. This work sheds more light on the onset of deformation and collectivity in this mass region. 15 pages, 12 figures ispartof: Physical Review C vol:93 issue:5 status: published

NESTER; The fast timing $\beta\gamma\gamma(t)$ method was applied to investigate the level lifetimes in $^{30,31,32}$Mg. Levels in Mg have been populated in $\beta$ and $\beta$-delayed neutron emission of Na at the ISOLDE facility. From the $\gamma\gamma$ coincidences a number of new states have been identified and new level schemes were constructed for $^{30,31,32}$Mg. The following preliminary half lives have been determined: T$_{1/2}$ = 3.9(4) ns for the 1789 keV state in $^{30}Mg, T$_{1/2}$ = 133(8) ps and 10.5(8) ns for the 221 keV and 461 keV states in $^{31}$Mg, respectively, and T$_{1/2}$ = 16(4) ps for the 885 keV level in $^{32}$Mg. The 1789 keV level was established as a candidate for the intruder 0$^+$ configuration in $^{30}$Mg with a possible strong E0 branch to the ground state.

Study of 149Ce levels populated in the beta decay of 149La and the signature splitting of the i13/2 band

International audience; Electromagnetic transition strengths and spectroscopic quadrupole moments for Sm-140 were measured by means of multi-step Coulomb excitation with radioactive beam at the ISOLDE facility at CERN. A complementary experiment was performed at the Heavy Ion Laboratory in Warsaw to assign spins for non-yrast states using the angular correlation technique. Based on the new experimental data previous spin assignments need to be revised.

A new level scheme of 80Ga has been determined. This nucleus was populated following the β− decay of 80Zn at ISOLDE, CERN. The proposed level scheme is significantly different compared to the previously reported one and contains 26 levels up to 3.4 MeV in excitation energy. The present study establishes that the previously identified 1.9-s β− -decaying 6− isomer is the ground state of 80Ga and the 1.3-s β− -decaying 3− isomer lies at an excitation energy of 22.4 keV. A new isomeric level was identified at 707.8 keV and its half-life was measured to be 18.3(5) ns, allowing the 685.4-keV transition de-exciting this state to be assigned anM2 multipolarity. The newly measured spectroscopic observables are compared with shell-model calculations using the jj44bpn and JUN45 interactions.

International audience; The neutron-rich nucleus 81Ga was populated from the β-decay of 81Zn produced at the ISOLDE (CERN) facility. The analysis of β-gated γ-ray singles and γ-γ coincidences permits to extend significantly the level scheme of 81Ga as well as to provide a new half-life for 81Zn. A preliminary upper limit was obtained for the half-life of the first excited state in 81Ga.

The use of a resonance ionization laser ion source at CERN/ISOLDE has made it possible to study the decay of very neutron-rich Sn135-137. The decay of Sn-135 is found to populate low-energy levels in Sb-135 via direct beta decay and the first excited state in Sb-134 by beta-delayed neutron emission. The level structure of Sb-135 Will be discussed and a possible signature for a more diffuse nuclear surface considered.

The fast timing βγγ(t) method has been used to measure lifetimes of the low-lying levels in 231Th populated in the β− decay of 231Ac. The half-life of the K π = 5 2 − band-head at 185.7-keV was measured as T 1 2 = 1073(79) ps , yielding D0 = 1,76(8) × 10−2 e·fm and 1.65(6) × 10−2 e·fm for the E1 transitions to the 7 2 + and 5 2 + members respectively of the K π = 5 2 + ground state band. Furthermore, T 1 2 ⩽ 74 ps and ⩽ 74 ps were measured for the K π = 3 2 + and 1 2 + band-heads at 221.4- and 247.6-keV, and T 1 2 = 503(12) ps and 98(36) ps for the 1 2 − and 3 2 − states at 554.7- and 593.6-keV, members of the K π = 1 2 − band. The latter results consistently yield D0 values of the order of 1.1 × 10−2 e·fm for three transitions connecting the K π = 1 2 ± bands. The observed transition rates have been interpreted within the quasiparticle-phonon model with the inclusion of Coriolis coupling.

Spins and parities for collective states in $^{228}$Ra have been determined from conversion electron measurements with a mini-orange $\beta$-spectrometer. The fast-timing $\beta\gamma\gamma(t)$ method has been used to measure lifetimes of T$_{1/2}$=550(20) ps and 181(3) ps for the $2^{+}_{1}$ and $4^{+}_{1}$ members of the K=0$^{+}$ band, and T$_{1/2} \leqslant$ 7 ps and $\leqslant$ 6 ps for the $1^{-}_{1}$ and $3^{-}_1$ members of the K = $0^{-}$ band, respectively The quadrupole moments, $Q_{0}$ deduced from the B (E2; 2$_{1}^{+} \rightarrow 0_{1}^{+}$) and B (E2; 4$_{1}^{+} \rightarrow 2_1^{+}$) rates are in good agreement with the previously measured value and the systematics of the region. However, the B(E1) rates of $\geqslant$ 4 × 10$^{−4}$ e$^{2}$fm$^{2}$, which represent the first B(E1) measurements for this nucleus, are at least 25 times larger than the value previously suggested for $^{228}$Ra. The new results are consistent with the B(E1) rates recently measured for the neighbouring $^{227}$Ra and reveal octupole correlations in $^{228}$Ra.

The location of several single-neutron states in ${}^{133}\mathrm{Sn}$ has been identified. The ${p}_{3/2}$, ${h}_{9/2}$, and ${f}_{5/2}$ states were found at 853.7, 1560.9, and 2004.6 keV, respectively, by measuring $\ensuremath{\gamma}$ rays in coincidence with delayed neutrons following the decay of ${}^{134}\mathrm{In}$. Crucial for obtaining the new data were the improved yields at the mass-separator facility ISOLDE-PSB at CERN. A semiempirically adjusted Woods-Saxon calculation, based on parameters from the Pb region and normalized on the mass data at ${}^{132}\mathrm{Sn}$, reproduces the new single particle energies with good precision.

The study of the stability of an astrophysically interesting nucleus 73Rb was performed by searching its β+ and proton decay at the ISOLDE facility at CERN. Light rubidium isotopes were produced in a spallation reaction of a niobium target induced by a pulsed 1 GeV proton beam. The previously reported proton-unbound character of 73Rb was confirmed and the upper limit for its production cross-section was reduced by more than one order of magnitude.

We report on the results of the β-decay of 81Zn. The experiment was performed at the CERN ISOLDE facility in the framework of a systematic ultra-fast timing investigation of neutron-rich nuclei populated in the decay of Zn. The present analysis included β-gated γ-ray singles and γ-γ coincidences from the decay of 81Zn to 81Ga and leads to a new and much more extensive level scheme of 81Ga. A new half-life of 81Zn is provided.

The [sup 67]Se and [sup 68]Se isotopes near the proton drip line were produced by spallation of zirconium with 600 MeV protons at CERN. Beta decay properties were determined for the first time using the selectivity of molecular ion beams at the on-line mass separator ISOLDE. Chemically selective production was obtained through separation of the molecular ion COSe[sup +]. The half-lives of [sup 67]Se and [sup 68]Se were measured as 107[plus minus]35 ms and 35.5[plus minus]0.7 s respectively. From [beta]-[gamma] and [gamma]-[gamma] coincidences, and conversion-electron measurements, a decay scheme was obtained for [sup 68]Se. For the [sup 68]As ground state and several excited states, spin and parity are unambiguously determined from [beta]-decay rates and electromagnetic multipolarity assignments. In addition to the strong Fermi branch between the mirror ground states of [sup 67]Se and [sup 67]As [[ital J][sup [pi]]=(5/2)[sup [minus]],[ital T][sub [ital z]]=[plus minus]1/2], a GT branch to an excited state in [sup 67]As is observed. Implications of [sup 67]Se and [sup 68]Se properties in the [ital rp]-process path are considered.

We performed at ISOLDE the spectroscopy of the decay of the ${8}^{\ensuremath{-}}$ isomer in ${}^{136}$Cs by $\ensuremath{\gamma}$ and conversion-electron detection. For the first time the excitation energy of the isomer and the multipolarity of its decay have been measured. The half-life of the isomeric state was remeasured to ${T}_{1/2}=17.5(2)$ s. This isomer decays via a very slow 518-keV $E3$ transition to the ground state. In addition to this, a much weaker decay branch via a 413-keV $M4$ and a subsequent 105-keV $E2$ transition has been found. Thus we have found a new level at 105 keV with spin ${4}^{+}$ between the isomeric and the ground state. The results are discussed in comparison to shell-model calculations.

The 1789 keV state in {sup 30}Mg was identified as the first excited 0{sup +} state via its electric monopole (E0) transition to the ground state. The measured small value of rho{sup 2}(E0,0{sub 2}{sup +}->0{sub 1}{sup +})=(26.2+-7.5)x10{sup -3} implies within a two-level model a small mixing of competing configurations with largely different intrinsic quadrupole deformation near the neutron shell closure at N=20. Axially symmetric configuration mixing calculations identify the ground state of {sup 30}Mg to be based on neutron configurations below the N=20 shell closure, while the excited 0{sup +} state mainly consists of two neutrons excited into the nu 1f{sub 7/2} orbital. The experimental result represents the first case where an E0 back decay from a strongly deformed second to the normal deformed first nuclear potential minimum well has been unambiguously identified, thus directly proving shape coexistence at the borderline of the much-debated 'island of inversion.'

The decay properties of84As have been investigated with mass separated sources. Only one β-decaying state is seen, contradictory to previous observations. The halflife is found to be 4.5±0.2 s. A detailed decay scheme has been constructed, and 33 excited states in84Se have been determined.

The decay of isotope-separated85As has been studied for the first time by means ofγ-ray spectroscopy. A level scheme for85Se has been constructed on the basis ofγγ-coincidence measurements. Spin and parity were then assigned to the lowest excited levels. Two levels, weakly populated in84Se after emission of delayed neutrons, were also identified. The results obtained here differ considerably from previously reported experiments with chemically separated sources.

4 pages, 3 figures, 1 table.-- PACS nrs.: 21.10.Tg; 23.40.−s; 27.40.+z., The Advanced-Time-Delayed method was used to measure lifetimes of the states in Ar-41 populated in the β decay of Cl-41. The nuclei Cl-41 were produced at ISOLDE by 1.4-GeV proton bombardment of a thick UCx target and mass-separated as molecular ions, XeCl+. Our measured half-life of the 167.1-keV state, T(1/2) = 315(15) ps, is significantly lower than the previously measured value of 410(30) ps. We have also determined T(1/2) = 260(80) ps and T(1/2) ≤ 46 ps for the 515.9- and 1867.7-keV states, respectively. These are the shortest lifetimes measured so far with the ultrafast timing method using the new LaBr3(Ce) crystals for γ-ray detection., This work was performed as part of an undergraduate research project (ERW) at the Physics Department of the University of Notre Dame. Fast-timing detectors and electronics were provided by the Fast Timing Pool of Electronics. This study was supported in part by the NSF PHY04-57120, Swedish Research Council, BMBF Grant No. 06KY205I, the Alexander von Humboldt Foundation (WBW), Foundation for Polish Science (AK), the European Union Sixth Framework through RII3-EURONS (Contract No. 506065), and the EURTD project TARGISOL (HPRI-CT-2001-50033).

Lifetimes of excited states in {sup 229}Th, populated in the {beta} decay of {sup 229}Ac, have been measured using the advanced time-delayed {beta}{gamma}{gamma}(t) method. Half-lives of 14 states have been determined including 11 of them for the first time. Twenty-seven new {gamma} lines have been introduced into the {beta}-decay scheme of {sup 229}Ac based on results of {gamma}{gamma} coincidence measurements. Reduced transition probabilities have been determined for more than 70 {gamma} transitions in {sup 229}Th. Average |D{sub 0}| values of 0.029(1), 0.077(3), and 0.024(5) e fm have been deduced for the lowest K{sup {pi}}=1/2{sup {+-}},3/2{sup {+-}}, and 5/2{sup {+-}} parity partner bands, respectively. Excited states in {sup 229}Th and experimental transition rates have been interpreted within the quasiparticle-plus-phonon model. The half-life of the 3.5-eV, 3/2{sup +} isomeric state is predicted to be about 10 h. Potential energy surfaces on the ({beta}{sub 2},{beta}{sub 3}) plane for the lowest single quasiparticle configurations in {sup 229}Th have been calculated using the Strutinsky method.

The \ensuremath{\beta} decay of $^{135}\mathrm{Sn}$ was studied at CERN/ISOLDE using a resonance ionization laser ion source and mass separator to achieve elemental and mass selectivity, respectively. \ensuremath{\gamma}-ray singles and $\ensuremath{\gamma}$-$\ensuremath{\gamma}$ coincidence spectra were collected as a function of time with the laser on and with the laser off. These data were used to establish the positions of new levels in $^{135}\mathrm{Sb}$, including new low-spin states at 440 and 798 keV, which are given tentative spin and parity assignments of $3/{2}^{+}$ and $9/{2}^{+}$, respectively. The observed levels of $^{135}\mathrm{Sb}$ are compared with shell-model calculations using different single-particle energies and different interactions.

The level structure of odd-odd $^{134}\mathrm{Sb}$ has been studied at CERN/ISOLDE following the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{134}\mathrm{Sn}$ and the \ensuremath{\beta}-delayed neutron decay of $^{135}\mathrm{Sn}$. Elemental and isobaric separation were accomplished by use of a resonance ionization laser ion source and an on-line mass separator, respectively. Both \ensuremath{\gamma}-ray singles and $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence data were taken as a function of time. New levels at 279, 441, 555, 617, and 1385 keV have been identified and given proposed spin and parity assignments of ${7}^{\ensuremath{-}}$, ${5}^{\ensuremath{-}}$, ${6}^{\ensuremath{-}}$, ${4}^{\ensuremath{-}}$, and ${5}^{\ensuremath{-}}$, respectively, following \ensuremath{\beta}-delayed neutron decay of $7/{2}^{\ensuremath{-}}$ $^{135}\mathrm{Sn}$. New ${1}^{\ensuremath{-}}$ levels have been identified at 1900, 2170, and 2430 keV following the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of ${0}^{+}$ $^{134}\mathrm{Sn}$. The resulting level structures are compared to shell-model calculations using the CD Bonn interaction and scaled and unscaled Kuo-Herling interactions developed for the $^{208}\mathrm{Pb}$ region. Remarkably enough, the unscaled Kuo-Herling interaction provides the best fit for the levels below 1 MeV.

The decays of the three isomers of $^{131}\mathrm{In}$ and the total decay energies of the two isomers of $^{131}\mathrm{Sn}$ have been studied in high sensitivity experiments at the OSIRIS mass separator. The main purpose of the investigation was to determine the position of the neutron hole ${h}_{11∕2}$ state, since a previous determination appeared to be in error. The present results support a small separation of the ${d}_{3∕2}$ and ${h}_{11∕2}$ neutron hole states. The new value obtained from measurements of decay energies is $69\ifmmode\pm\else\textpm\fi{}14\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$. A more precise value of $65.1\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ may be deduced from the level scheme of $^{131}\mathrm{Sn}$ obtained currently, however without firm support from coincidence data. This relatively low excitation energy of the ${h}_{11∕2}$ state is in agreement with systematics and in disagreement with the previous determination. A re-evaluation of the ${Q}_{\ensuremath{\beta}}$ values and isomer spacings of $^{131}\mathrm{In}$ has been made.

The decay properties of $^{127}\mathrm{In}$ and $^{129}\mathrm{In}$ have been investigated using Isotope Separation On-Line (ISOL) produced samples. In both $^{127}\mathrm{In}$ and $^{129}\mathrm{In}$ new $\ensuremath{\beta}$-decaying isomeric states were observed, with half-lives of $1.04\ifmmode\pm\else\textpm\fi{}0.10$ and $0.67\ifmmode\pm\else\textpm\fi{}0.10\phantom{\rule{0.3em}{0ex}}\mathrm{s}$, respectively, in addition to the previously known isomers of single proton hole ${p}_{1∕2}$ and ${g}_{9∕2}$ character. ${\mathrm{Q}}_{\ensuremath{\beta}}$ measurements show that the new isomeric states are present at energies approaching $2\phantom{\rule{0.3em}{0ex}}\text{MeV}$ above the ground states. The level schemes of $^{127}\mathrm{Sn}$ and $^{129}\mathrm{Sn}$ have been considerably extended. The modes of feeding and decay of the two $\ensuremath{\mu}\mathrm{s}$ isomers in each of the Sn nuclei are fully elucidated, including new half-life determinations. Shell model calculations on $^{127}\mathrm{Sn}$ and $^{129}\mathrm{Sn}$ were performed, giving results in good agreement with the new data.

First $\ensuremath{\beta}$- and $\ensuremath{\gamma}$-spectroscopic decay studies of the $N=82$ $r$-process ``waiting-point'' nuclide $^{130}\mathrm{C}\mathrm{d}$ have been performed at CERN/ISOLDE using the highest achievable isotopic selectivity. Several nuclear-physics surprises have been discovered. The first one is the unanticipatedly high energy of 2.12 MeV for the [$\ensuremath{\pi}{g}_{9/2}\ensuremath{\bigotimes}\ensuremath{\nu}{g}_{7/2}]$ ${1}^{+}$ level in $^{130}\mathrm{I}\mathrm{n}$, which is fed by the main Gamow-Teller transition. The second surprise is the rather high ${Q}_{\ensuremath{\beta}}$ value of 8.34 MeV, which is in agreement only with recent mass models that include the phenomenon of $N=82$ shell quenching. Possible implications of these new results on the formation of the $A\ensuremath{\simeq}130$ $r$-process abundance peak are presented.

The present work is a part of our systematic studies of strong electric octupole correlations in the region of heavy isotopes of barium, lanthanum and cerium. High spin studies of the 149Ce (N = 91) [1,2] and 147La (N = 90) [3] nuclei showed no evidence for octupole deformation in the former nucleus while in the latter one some octupole effects, weakened by alignment phenomena, have been suggested. The new γ-spectroscopic data on the low-lying states in 149Ce and 147La studied in the β-decay of 149La and 147Ba, respectively, at OSIRIS facility at Studsvik in Sweden, provided new information on the low-spin levels and also appeared to be helpful in interpretation of the high-spin level structure of these nuclei.

The decays of the very neutron rich Sn isotopes Sn135-137 were studied at CERN/ISOLDE using isotopic and isobaric selectivity achieved by the use of a resonance ionization laser ion source and mass spectroscopy, respectively. Neutron decay rates, gamma-ray singles, and gamma-gamma coincidence data were collected as a function of time. The half-life (T-1/2) and delayed neutron emission probability (P-n) values of 135 Sn were measured to be 530(20) ms and 21(3)%, respectively. For Sn-136, a T-1/2 of 250(30) ms was determined along with a P-n value of 30(5)%. For Sn-137, a T-1/2 of 190(60) ms and a P-n value of 58(15)% were deduced. Identification of low-energy transitions in Sb-135 was made possible by comparison of laser-on and laser-off gamma-ray spectra. Those data combined with gamma-gamma coincidence spectra were used to construct a level scheme for Sb-135 that includes an unexpectedly low first excited state at 282 keV. A ground state beta branch of 33.2% was measured by following the growth and decay of the Sb-135 daughter. Shell-model calculations are consistent with the observed Sb-135 level structure and can account for a lowered first excited state.

Excited states in the 134Sb nucleus, populated in the β−-decay of 134Sn, have been studied at the mass separator OSIRIS. The 134Sn activity was produced via fast neutron-induced fission of 238U target. A main result was the discovery of a very low-lying first-excited state of 134Sb, at 13 keV, which has led to a strong revision of the level scheme. The new results are compared with different theoretical calculations and with the known data for the analogous neutron and proton two-particle nucleus in the 208Pb region. On the basis of this comparison, the energy of the (πg 7/2νf 7/2)7− isomer is estimated to be about 250 keV, some 100 keV lower than previously reported.

The recently developed methods allowing the experimental studies on new neutron-rich nuclei beyond doubly-magic {sup 208}Pb are briefly described. An identification of new neutron-rich isotopes {sup 215}Pb and {sup 217}Bi, and new decay properties of {sup 216}Bi studied by means of a pulsed release element selective technique at PS Booster-ISOLDE are reported.

The $\gamma$-rays following the $\beta^{-}$-decay of $^{227}$Rn have been investigated by means of $\gamma$-ray singles and $\gamma\gamma$-coincidence measurements using an array of 12 Compton-suppressed Ge detectors. The fast timing $\beta\gamma\gamma$(t) method has been used to measure six level lifetimes. Multipolarities of 32 transitions in $^{227}$Fr have been established by measuring conversion electrons with a mini--orange electron spectrometer. Most of the observed transitions have been placed in a level scheme comprising 38 excited states of $^{227}$Fr. The low-lying levels are interpreted in terms of seven rotational bands. The observed E1 strengths for two transitions connecting the K$^{\pi}$=3/2 bands are consistent with the transitional character of $^{227}$Fr, and confirm the presence of octupole correlations in this nucleus.

The β+/EC decay of the neutron deficient nuclei76,78Sr and79Y was studied employing mass separated molecular beams of SrF+ and YF2+ from the ISOLDE mass separator. The halflives of76,78Sr and79Y were measured as t1/2=8.9(3)s, 159(8)s and 14.4(15)s, respectively, and decay schemes were established for76Sr and79Y. In the78Sr decay 10 new γ-ray transitions were identified.

The branchings (absolute intensities) of γ-rays following the decay of84,85Ge and84,85As have been determined using mass-separated samples. Our results include the first identification of85Ge and the first γ-ray data for84Ge. Values of the delayed neutron emission probabilities, Pn, of84Ge and85As were also deduced from the data, together with a lower limit of this quantity for85Ge. The deduced Pn of about 39 % for the important neutron emitter85As is substantially larger than the values of about 22–23 % obtained in previous indirect determinations.