Singles Spectra Research Articles

Gamma-ray studies inV45

The level scheme of $^{45}\mathrm{V}$ was studied with the reaction $^{40}\mathrm{Ca}$($^{7}\mathrm{Li}$,$2n$)$^{45}\mathrm{V}$ using $^{7}\mathrm{Li}$ beams of 14-16-MeV energies. Prompt and delayed $n\ensuremath{-}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences revealed a doublet at an excitation energy of about 57 keV with a separation energy of only 800 eV. The half-life of the upper member, a $\frac{3}{{2}^{\ensuremath{-}}}$ state, was measured to be 430\ifmmode\pm\else\textpm\fi{}80 nsec. This state decays strongly via internal conversion to the lower member of the doublet, a $\frac{5}{{2}^{\ensuremath{-}}}$ state. The half-life of the latter level was measured to be \ensuremath{\lesssim}4.2 nsec. Since $^{45}\mathrm{V}$ is a $T=\frac{1}{2}$ nucleus and the mirror of the well-known $^{45}\mathrm{Ti}$ nucleus, Coulomb displacement energies could be deduced. A comparison of these Coulomb displacement energies with those of neighboring nuclei, the measured lifetimes, and the observed $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ and $n\ensuremath{-}\ensuremath{\gamma}$ prompt and delayed coincidence spectra established nearly all the $^{45}\mathrm{V}$ levels expected below the proton separation energy of 1.62 MeV, namely, $\frac{7}{{2}^{\ensuremath{-}}}(\mathrm{g}.\mathrm{s}.)$, $\frac{5}{{2}^{\ensuremath{-}}}(56.4 \mathrm{keV})$, $\frac{3}{{2}^{\ensuremath{-}}}(57.2 \mathrm{keV})$, $\frac{3}{{2}^{+}}(386.1 \mathrm{keV})$, $\frac{5}{{2}^{+}}(796.8 \mathrm{keV})$, and $\frac{7}{{2}^{+}}(1273 \mathrm{keV})$. The expected four highest bound levels, in particular the $\frac{9}{{2}^{\ensuremath{-}}}$ and $\frac{11}{{2}^{\ensuremath{-}}}$ states, are not seen in the present experiment. The latter two states are supposed to decay either completely or predominantly to the ground state and hence are not observable in these $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence studies. The third and fourth levels were not seen in $^{45}\mathrm{Ti}$ $\ensuremath{\gamma}$-ray spectra which exhibit much higher counting rates than those of $^{45}\mathrm{V}$. They are therefore not expected to be observable in the present $^{45}\mathrm{V}$ spectra. $^{45}\mathrm{V}$ gamma rays were also seen in the $^{40}\mathrm{Ca}$($^{6}\mathrm{Li}$,$n$)$^{45}\mathrm{V}$ reaction with a 10- and a 13.5-MeV $^{6}\mathrm{Li}$ beam. This reaction has a smaller production cross section and is therefore less suited for detailed studies.NUCLEAR REACTIONS $^{40}\mathrm{Ca}$($^{7}\mathrm{Li}$,$2n$)$^{45}\mathrm{V}$: singles spectra, prompt and delayed $n\ensuremath{-}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences with ${E}_{^{7}\mathrm{Li}}=14, 15, 16$ MeV. $^{40}\mathrm{Ca}$($^{6}\mathrm{Li}$,$n$)$^{45}\mathrm{V}$ with 10, 13.5 MeV $^{6}\mathrm{Li}$: $n\ensuremath{-}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences. Measurement of ${T}_{\frac{1}{2}}=430\ifmmode\pm\else\textpm\fi{}80$ nsec for the 57.2-keV state and \ensuremath{\lesssim}4.2 nsec for the 56.4-keV state. Deduced ${\frac{7}{2}}^{\ensuremath{-}}(\mathrm{g}.\mathrm{s}.)$; ${\frac{5}{2}}^{\ensuremath{-}}(56.4)$; ${\frac{3}{2}}^{\ensuremath{-}}(57.2)$; ${\frac{3}{2}}^{+}(386.1)$; ${\frac{5}{2}}^{+}(796.8)$; ${\frac{7}{2}}^{+}(1273)$, and $\ensuremath{\gamma}$ decay of these states.

Decay of neutron-deficientIn103andCd103isotopes

The decays of neutron-deficient $^{103}\mathrm{In}$ and $^{103}\mathrm{Cd}$ have been investigated. Sources were produced by ($^{14}\mathrm{N}$, $yp\ensuremath{-}xn$) reactions on a natural Mo target. Singles spectra and various coincidence spectra involving $\ensuremath{\gamma}$ rays, x rays, positrons, and conversion electrons have been performed on mass separated samples. The newly discovered activity $^{103}\mathrm{In}$ (${T}_{\frac{1}{2}}=1.08\ifmmode\pm\else\textpm\fi{}0.11$ min) was found to populate mainly the $\frac{7}{{2}^{+}}$ excited $^{103}\mathrm{Cd}$ state at 188 keV. About 200 lines were attributed to the 7.3 min $^{103}\mathrm{Cd}$ decay. Coincidence relationships are given. A level scheme of $^{103}\mathrm{Ag}$ is proposed.

Excited states of the doubly odd deformed nucleus 160Tm

Abstract The decay of 4.8 min 160 Yb has been investigated by means of Ge(Li) detectors, toroidal and magnetic-lens β-spectrometers and scintillation counters. The singles spectra of γ-rays and conversion electrons as well as prompt and delayed γ-γ and γ-ce coincidences have been measured. The 160 Tm level scheme is proposed including 94.5% of the total γ-ray intensity observed in the 160 Yb decay. The lifetimes of the 42.02, 174.40 and 215.78 keV states have been determined to be 1.6±0.3, 17±1 and 0.65±0.15 ns, respectively. From the analysis of the experimental data, the quantum characteristics of 160 Tm levels are proposed. Experimental γ-ray transition probabilities are compared with Weisskopf and Nilsson estimates, the latter also taking into account pairing correlations.

Levels inGd154populated by the (α, 2nγ) reaction and the decay of the isomers ofTb154

Levels in $^{154}\mathrm{Gd}$ have been studied using the $^{152}\mathrm{Sm}(\ensuremath{\alpha}, 2n\ensuremath{\gamma})$ reaction at an energy of 24 MeV. Singles spectra, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence spectra, and angular distributions were obtained in-beam using Ge(Li) detectors. Among the new levels proposed in $^{154}\mathrm{Gd}$ are as follows: a ${7}^{+}$ state in the $\ensuremath{\gamma}$ band; ${7}^{\ensuremath{-}}$, ${9}^{\ensuremath{-}}$, and ${11}^{\ensuremath{-}}$ states in an odd-spin octupole-vibrational band based at 1241 keV; possible ${7}^{+}$ and ${8}^{+}$ states in the ${K}^{\ensuremath{\pi}}={4}^{+}$ band based at 1646 keV; and ${8}^{\ensuremath{-}}$ and ${9}^{\ensuremath{-}}$ members of a $K=7$ band based on the ${7}^{\ensuremath{-}}$ state at 2138 keV. The results are compared with various theoretical models. $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ directional correlation measurements were also performed on some cascades populated in the radioactive decay of the various isomers of $^{154}\mathrm{Tb}$, and the results confirm the assignment of ${7}^{\ensuremath{-}}$ for the 2137.8 keV state and establish a spin value of 1 for the 2119.7 and 2187.2 keV states.NUCLEAR REACTIONS $^{152}\mathrm{Sm}(\ensuremath{\alpha}, 2n\ensuremath{\gamma})$, $E=24$ MeV, measured ${E}_{\ensuremath{\gamma}}$, ${I}_{\ensuremath{\gamma}}$, $\ensuremath{\gamma}\ensuremath{\gamma}$ (delay), $\ensuremath{\gamma}\ensuremath{\gamma}$ coin, $\ensuremath{\gamma}(\ensuremath{\theta})$ $^{154}\mathrm{Gd}$ deduced levels, $K$, $J$, $\ensuremath{\pi}$, $\ensuremath{\delta}$, $Q$. Enriched targets. Ge(Li) detectors. RADIOACTIVITY $^{154}\mathrm{Tb}$(22.6, 9.0, and 21.4 h) from $^{153}\mathrm{Eu}(\ensuremath{\alpha}, 3n)$ and $^{155}\mathrm{Gd}(p, 2n)$. Measured $\ensuremath{\gamma}\ensuremath{\gamma}(\ensuremath{\theta})$ $^{154}\mathrm{Gd}$ deduced $J$, $\ensuremath{\pi}$, $\ensuremath{\delta}$. Enriched targets. Ge(Li) detectors.

A high-efficiency coincidence method for Coulomb excitation studies of weakly populated vibration-like levels

A high-efficiency coincidence method for Coulomb excitation studies is presented. In the experimental arrangement described, the target is placed very close to a large coaxial Ge(Li) detector, and both are surrounded by a large NaI(Tl) annular detector. In studies of even-even nuclei the 2 1 + → 0 1 + transition is detected by the NaI(Tl) annulus and the coincident transitions as well as the singles spectrum are recorded by the Ge(Li) detector. Due to the large solid angle subtended by the NaI(Tl) annulus, angular correlation effects in the coincidence counting rate are practically completely smeared out. Consequently, the method can easily be applied, e.g., to studies of weakly populated vibration-like levels, which is demonstrated in test measurements of 112, 114Cd and 118Sn. The accuracy of the method in determining excitation cross sections relative to that of the 2 1 + level is in favourable cases about 15%.

Nuclear structure study of 96Tc and multiplet structure in doubly odd Tc and Nb isotopes

Low-lying states in 96Tc excited through the 96Mo(d, 2nγ) reaction have been investigated by means of on-line internal conversion electron and γ-ray spectroscopy. Measured singles spectra and relative excitation functions together with particle-γ and γ-γ coincidences were used to identify and fit the transitions in a level scheme. The low-lying positive-parity states 2 +–7 +and negative-parity states 2 − and 3 − are compared with those appearing systematically in doubly odd 94, 98Tc and 92–96Nb isotopes. Comparison is also made with simple shell-model calculations for those nuclei based on the π( p 1 2 , g 9 2 ) p ν ( d 5 2 ) n configuration space and the tendency of the multiplet structure of the wave functions is discussed.

The decay of neutron deficient97Ag,98Ag, and99g, m Ag

The decays of neutron-deficient 21-sec97Ag, 44.5-sec98Ag, 15-sec99mAg, and 124-sec99gAg nuclides have been investigated with the LISOL facility. Sources were produced by the92Mo(14N, ypxn) reactions on an enriched92Mo target. Positron-, x-, and γ-ray singles spectra have been performed on mass separated samples. The results are consistent with 9/2+ ground state in99Ag and a high (6+ or 7+) spin and parity for98Ag.

Identification of short-lived ruthenium and rhodium isotopes in fission by rapid chemical separations

Short-lived ruthenium and rhodium isotopes were produced via thermal neutron induced fission of 235U, 239Pu and 249Cf and via fast neutron induced fission of 238U. The ruthenium isotopes and their descendants were isolated from the fission product mixtures by means of a rapid chemical separation procedure. Typically 7.6 sec were required from the end of irradiation to the start of counting. The γ-ray singles spectra as well as the γ-γ-coincidences were recorded with Ge(Li)-detectors. New short-lived nuclides were identified on the basis of their decay characteristics, and existing data of the longer lived isotopes were confirmed. Results are presented for the ruthenium isotopes 3.75 min 107Ru, 4.55 min 108Ru, 34.5 sec 109Ru, 12.9 sec 109Ru (isomer), 12.6 sec 110Ru, 3 sec 111Ru, 3.6 sec 112Ru, 3 sec 113Ru, and the rhodium isotopes 17 sec 108Rh, 79.8 sec 109Rh, 3.3 sec 110Rh, 11 sec 111Rh.

Gamma competition in the decay of unbound states in 56Fe produced by the 56Fe(n, n′) reaction with 14 MeV neutrons

Iron was bombarded with 14 MeV neutrons and both the singles spectrum of the secondary neutrons and the coincidence spectrum with the 846 keV γ-line from the decay of the first excited state of 56Fe were measured. From there the ratio of the average γ-width to neutron width in 56Fe could be determined for 56Fe as a function of excitation energy in the energy region 0–3 MeV above the neutron binding energy.

Proton decay of the isobaric analogs of the ground states of207Pb and208Pb

The proton decays\(\tilde p\) of isobaric analog states of207, 208Pb in the reactions207, 208Pb(p, n) have been studied using a neutron-proton coincidence technique. The width anomaly observed in (p, n) [4] and (p, n\(\tilde p\)) singles spectra [11] is resolved in the coincident spectra.

Excited States and Transitions in 106Pd from the Decay of 106Rhg

From the singles spectra of γ-rays following the decay of 106 Rh g measured with high resolution Ge(Li) detectors, the energies and relative intensities of 90 γ-transitions in 106 Pd have been determined. Gamma-gamma coincidence measurements were performed using Ge(Li)–Ge(Li) and Ge(Li)–NaI(Tl) coincidence systems and 87 γ-transitions have been fitted into the level scheme incorporating 38 excited states. The levels at 1909.5, 2484.8, 2626.9, 3249.8, 3300.4, 3376.5 and 3401.8 keV have been newly incorporated following the decay of 106 Rh g . Ambiguities of the decay scheme concerning weak transitions have been dissolved. The experimental β-strength function was calculated which showed increase with excitation energy above 1.5 MeV.

Pre-equilibriumαDecay inO16+Al27Collisions at 65 MeV

The mechanism of the reaction $^{27}\mathrm{Al}(^{16}\mathrm{O}, ^{12}\mathrm{C}\ensuremath{\alpha})^{27}\mathrm{Al}$ at 65.6-MeV incident energy has been examined with use of coincidence techniques. It is shown that the broad bell-shaped peak observed in $^{12}\mathrm{C}$ singles spectra corresponds to an $\ensuremath{\alpha}$-transfer-like process leading to fixed excitation energy in the $\ensuremath{\alpha}$+$^{27}\mathrm{Al}$ system. The $\ensuremath{\alpha}$-$^{12}\mathrm{C}$ angular correlation, however, is forward-peaked along the momentum-transfer direction, suggesting that the decay time of the system is less than required for equilibration into $^{31}\mathrm{P}$.

Energy distributions of 1.12-MeV gamma rays Compton scattered byK-shell electrons of gold, lead, and thorium

Measurements are reported of the pulse-height distributions of photons of initial energy 1.12 MeV after Compton scattering through 60' and 100' by K-shell electrons of Au, Pb, and Th. The energy distributions of scattered photons, obtained in the case of Au and Pb targets by a deconvolution of the detector response function, show a rise for energies lower than about 0.25 MeV, a broadening of the Compton line, and a negligible shift of the Compton peak. On account of natural radioactivity of the Th target, the corresponding pulse-height distributions are not precise enough to make the deconvolution procedure worthwhile. The energy distributions are compared with theoretical calculations based on the nonrelativistic impulse approximation. It is clear that a relativistic calculation incorporating the e6ects of electron binding in intermediate states is required. In the present experiment, a fast-slow coinci- dence system was used with resolving times of 30 nsec and 2 p, sec, respectively. Pulse-height analysis of anode pulses from the y detector was made with the help of a 20-channel analyzer gated by the output of the coincidence circuit. The lin- earity of pulse height was checked not only through the singles spectra of the y rays of different en- ergies but also through the spectra obtained in the coincidence mode. Annihilation quanta from a Na source, and 1.17- and 1.33-MeV y rays from a ~Co source were used for the spectral measure- ments in the coincidence mode. The photopeaks obtained in the coincidence mode agreed 'with the positions of the corresponding peaks in the singles spectra. Therefore, useful linearity and gain stability checks could be made more frequently in the singles mode than would have been possible in the coincidence mode. If a check showed a pulse- height shift of more than 2%, the corresponding data were discarded. Pulse-height distributions of the scattered y rays were studied at 60' and 100' scattering angles. In each case, the pulse-height distribution of false events was determined and subtracted from the measured distribution in order to obtain the true distribution. In all cases, the chance coineidenee rate was less than 1% of the total rate and was con- sidered negligible. The rate in each channel cor- responding to Nz of Eq. (2) in the preceding paper was negligible in the case of the high-Z targets used here. For the reasons mentioned in Sec. II of the pre- ceding paper, the distribution of false events was determined with an equivalent aluminum target in the case of targets of thickness less than 30 mg/cm'. In the case of the thicker lead targets, an equivalent copper target was also used. A cor- rection-had to be made in the case of thorium for its radioactivity. As a result, the errors in the thorium measurements are large.

Excited levels of87Sr

In-beam gamma rays from the reaction 87Rb(p,n gamma )87Sr at an incident proton energy of 3.8 MeV were measured. Ten levels up to an excitation of 2698 keV were proposed, of which the levels at 1228.5, 1253.8, 1770.5, 2110.8 and 2169.3 keV are definitely confirmed from coincidence data. The branching ratios for the proposed are deduced and probable spin-parity assignments are suggested. Lifetimes or lower limits on the lifetimes are obtained for some of the levels by the Doppler-shift attenuation method after a careful centroid-shift analysis of the singles spectra taken at 0 degrees and 90 degrees to the incident beam axis. Values or limits for B(E2), B(M1) and B(E1) are obtained. The level structure is discussed in the light of recent experimental and theoretical investigations.

(α, 2nγ) Studies of γ-vibrational and other side-bands in 162, 164, 166Er

Levels in 162, 164, 166Er have been studied using the (α, 2nγ) reaction at an energy of 24 MeV. Singles spectra, γ-γ coincidence spectra, and angular distributions were obtained using Ge(Li) detectors. Transitions from levels in the γ-vibrational bands up to the 8 +' in 162, 164Er and 10 +' in 166Er were observed and M1/E2 mixtures were determined for many of these transitions. There is a relative shifting upward of the even-spin levels in the γ-band of 166Er while the analogous levels of 162, 164Er are shifted downward with the effect being most pronounced for 162Er. The standard phenomenological band-mixing parameters z 2 and z 02 were obtained from γ-ray branching ratio data and the values are probably correlated with the staggering of levels in the γ-bands. The ratios of the intraband and interband E2 transition strengths which are related to the intrinsic quadrupole moments of the ground-state and γ-bands are discussed. A number of other levels are observed in 162, 164Er and some of these correspond to negative parity states reported in decay studies.

A mobile helium-jet transport system for on-line spectroscopy of short-range spallation products

A mobile helium-jet system has been set up, capable of transporting short-range spallation products (range in ThF 4 ⩽ 66 μg/ cm 2) in a closed loop helium circuit. This system was used for the transport of spallation products produced by 600 MeV protons from a 232Th and a 241Am target in the extracted beam of the CERN Synchrocyclotron (SC). The activity was transported through a 61 m long capillary to a low-background area, where it was collected in a vacuum chamber on a moving tape system. Alpha- and gamma-ray singles spectra, alpha-gamma coincidence spectra, as well as fission spectra could be investigated.

Experimental studies of the level scheme of143Eu and a generalized decoupling model description

Excited levels of143Eu have been investigated by nuclear spectroscopy methods. We measured γ-rays and conversion electron singles spectra as well asγγ-coincidences from mass separated143mGd sources (108 s) prepared after the irradiation of144Sm with 78 MeVα-particles. In addition in-beam data were obtained by measuringγ-ray singles spectra, angular distributions andγγ-coincidences, following the144Sm(α, 4n+ p, γ) reaction. A level scheme for143Eu comprising 19 levels is proposed, spin assignments or at least restrictions are given. The deduced experimental level scheme can be reproduced semiquantitatively by a generalized decoupling model which takes into account an asymmetric deformation of the core and a variable moment of inertia. Additionally, the results are discussed in the limit of the weak coupling model.

Structure ofN=81nuclei: Levels ofNd141andCe139populated in beta decay

The nuclear level structure of $^{141}\mathrm{Nd}$ and $^{139}\mathrm{Ce}$ has been investigated by studying the decay of 20.9-min $^{141}\mathrm{Pm}$ produced via the $^{141}\mathrm{Pr}(^{3}\mathrm{He},3n)$ reaction and the decay of 4.5-h $^{139}\mathrm{Pr}$ produced by the $^{140}\mathrm{Pr}(\ensuremath{\gamma},n)^{139}\mathrm{Pr}$ reaction. For the $^{141}\mathrm{Pm}$ decay, singles and anti-Compton $\ensuremath{\gamma}$-ray spectra and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence measurements were used to deduce a decay scheme that includes nine previously unreported levels in $^{141}\mathrm{Nd}$ and incorporates 67 of the 70 $\ensuremath{\gamma}$ rays attributed to the decay of $^{141}\mathrm{Pm}$. Singles and anti-Compton spectra were taken as a function of time in order to confirm assignment of the $^{139}\mathrm{Pr}$ $\ensuremath{\gamma}$ rays. The level structures of $^{141}\mathrm{Nd}$ and $^{139}\mathrm{Ce}$ are compared to recent measurements in other $N=81$ isotones. The results of this work are in good agreement with theoretical predictions based on the hole-vibrational coupling model for levels below 1.3 MeV. There exist more levels between 1.3 and 2.0 MeV than are predicted by this model, but these excess levels can be explained qualitatively within a weak coupling framework.RADIOACTIVITY $^{141}\mathrm{Pm}$ [from $^{141}\mathrm{Pr}(^{3}\mathrm{He},3n)$] and $^{139}\mathrm{Pr}$ [from $^{140}\mathrm{Pr}(\ensuremath{\gamma},n)$] measured ${E}_{\ensuremath{\gamma}}$, ${I}_{\ensuremath{\gamma}}$, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coin; deduced $^{141}\mathrm{Nd}$ and $^{139}\mathrm{Ce}$ levels, $J$, $\ensuremath{\pi}$, and $log\mathrm{ft}$ values. Natural target, Ge(Li) detectors, anti-Compton spectrometer.

Properties of high-spin states inTc95fromNb93(α, 2n)Tc*95(γ)reaction spectrometry: A test of the cluster-core coupling model

The structure and properties of the high angular momentum states in $^{95}\mathrm{Tc}$ up to 5605 keV of excitation have been investigated via measurements of excitation functions of singles $\ensuremath{\gamma}$ rays and of $\ensuremath{\gamma}\ensuremath{\gamma}$ coincidences following the $^{93}\mathrm{Nb}(\ensuremath{\alpha}, 2n)^{95}\mathrm{Tc}^{*}(\ensuremath{\gamma})$ reaction with $\ensuremath{\alpha}$ particle energies between 17-30 MeV. From these experiments and from high-resolution singles energy, angular-distribution, and Doppler-shift attenuation measurements, the position and the decay properties of many high angular momentum states in $^{95}\mathrm{Tc}$ have been determined. Levels at 626.82 (${\frac{5}{2}}_{1}^{+}$), 882.16 (${\frac{13}{2}}_{2}^{+}$), 927.78 (${\frac{3}{2}}_{1}^{+}$), 957.07 (${\frac{11}{2}}_{1}^{+}$), 1084.95 (${\frac{5}{2}}_{2}^{+}, {\frac{7}{2}}^{+}$), 1178.60 (${\frac{7}{2}}_{2}^{+}$), 1214.53 (${\frac{9}{2}}_{1}^{\ensuremath{-}}$), 1307.19 (${\frac{11}{2}}_{2}^{+}$), 1514.8 (${\frac{17}{2}}_{1}^{+}$), 1549.4 (${\frac{15}{2}}_{1}^{+}$), and 1702.1 (${\frac{13}{2}}_{1}^{\ensuremath{-}}$) with the ${J}^{\ensuremath{\pi}}$ values in parentheses are confirmed. New levels at 2119.4 (${\frac{15}{2}}_{2}^{+}$), 2183.2 (${\frac{19}{2}}_{1}^{+}$), 2231.1 (${\frac{17}{2}}_{2}^{+}$), 2546.4 (${\frac{21}{2}}_{1}^{+}$), 2846.7 (${\frac{21}{2}}_{2}^{+}$ or ${\frac{21}{2}}_{1}^{\ensuremath{-}}$), 2905.8 (${\frac{19}{2}}_{2}^{+}$), 3038.8 (${\frac{19}{2}}_{3}^{+}, {\frac{17}{2}}^{+}$), 3515.2 (${\frac{25}{2}}_{1}^{+}$), 3657.7 (${\frac{25}{2}}_{2}^{+}$ or ${\frac{25}{2}}_{1}^{\ensuremath{-}}$), 3917.5 (${\frac{29}{2}}_{1}^{+}$), 4292.2 (${\frac{27}{2}}_{1}^{+}$), 4455.4 (${\frac{29}{2}}_{2}^{+}$ or ${\frac{29}{2}}_{1}^{\ensuremath{-}}$), 4761.0 ($\frac{29}{2}, \frac{33}{2}$), and 5604.9 ($\frac{33}{2}, \frac{31}{2}$) with the ${J}^{\ensuremath{\pi}}$ values in parentheses are proposed. Possible levels at 2474.2, 3064.9, and 3209.2 (${\frac{21}{2}}_{3}^{+}$) keV are also suggested. The measured angular distributions provided (i) branching ratios, (ii) ${J}^{\ensuremath{\pi}}$ assignments corroborated by deduced angular-distribution attenuation coefficients, level excitation functions, and side-feeding yields, and (iii) multipole mixing ratios $\ensuremath{\delta}(\frac{E2}{M1})$. Lifetimes for nine high-spin levels and limits for four additional ones were obtained by the Doppler-shift attenuation method from measurements with the $^{93}\mathrm{Nb}(\ensuremath{\alpha}, 2n)^{95}\mathrm{Tc}^{*}(\ensuremath{\gamma})$ reaction at 18.5, 20.6, 23.6, and 26.7 MeV. The lifetimes were extracted from singles spectra taken in the presence of standards at 7, 4, 7, and 8 angles, respectively, between 0\ifmmode^\circ\else\textdegree\fi{} and 90\ifmmode^\circ\else\textdegree\fi{} for the four bombardment energies by examining the dependence on ${E}_{\ensuremath{\alpha}}$ of the effective level lifetime. For many transitions $B(E2)$ and $B(M1)$ values were obtained. The present results are compared with calculations based on the coupling of three-quasiparticle ${({g}_{\frac{9}{2}})}^{3}$ configurations to the quadrupole vibrations of the core and remarkable agreement is observed for states up to only ${\frac{19}{2}}_{1}^{+}$. This model fails to explain the properties of the higher-spin states with ${J}^{\ensuremath{\pi}}>~{\frac{21}{2}}^{+}$.NUCLEAR REACTIONS $^{93}\mathrm{Nb}(\ensuremath{\alpha}, 2n)^{95}\mathrm{Tc}^{*}(\ensuremath{\gamma})$, $E=17\ensuremath{-}30$ MeV, monoisotopic targets. Measured ${E}_{\ensuremath{\gamma}}$, ${I}_{\ensuremath{\gamma}}$, ${I}_{\ensuremath{\gamma}}(\ensuremath{\theta})$, $\ensuremath{\sigma}(E)$, $\ensuremath{\Delta}{\overline{E}}_{\ensuremath{\gamma}}(E, \ensuremath{\tau})$, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coin, deduced $^{95}\mathrm{Tc}$ levels, $J$, $\ensuremath{\pi}$, branching ratios, $\ensuremath{\tau}$, $\ensuremath{\delta}(\frac{E2}{E1})$, $B(E2)$, and $B(M1)$ values; Ge(Li) detectors, Ge(Li)-NaI(Tl) anti-Compton spectrometer, 1.9 keV at 1332 keV.

Short-lived activities produced in 70Zn with 14 MeV neutrons

Beta spectra have been studied after 14 MeV neutron irradiation of 70Zn . Beta-ray singles spectra and β−γ coincidences using plastic and NaI(Tl) scintillation counters were measured to determine total decay energies for (1 +) 70acu ( T 1 2 = 4±1 s ) and for (5 −) 70bCu ( T 1 2 = 52±4 s ). The decay energies found are 6.17±0.11 MeV and 6.31±0.11 MeV for 70aCu and 70bCu respectively. Five β-branches and four γ-rays could be placed in the decay scheme. A 3.83±0.09 MeV β-branch belonging to the decay of 67Ni ( T 1 2 = 16±4 s ) has also been found.