The electric quadrupole moment of the 6+ state of 112Sn

The spectroscopic quadrupole moment of the isomeric 6⁺' (2552 keV) state of ¹¹⁷Sn has been derived from TDPAD measurements in a Cd metal host target at 500 K as $\text{Q}{}_{\mathrm{<mtext>I</mtext>}}\text{(6}{}^{\mathrm{+}}\text{,}{}^{112}\text{Sn}\text{) = ± 0.29(6)}\text{b}$. The calibration of the effective field gradient for Sn in Cd at 500 K, given by Herrlander et al. has been used. A comparison of the results with shell model estimates makes a mixed configuration of $\text{|(}\text{g}\text{7}\text{2}\text{)}{}^{\mathrm{?2}}\text{6}{}^{\mathrm{+}}\text{〉)}\text{and}\text{(}\text{g}\text{7}\text{2}{}^{\mathrm{?1}}\text{d}\text{5}\text{2}{}^{\mathrm{?1}}\text{)6}{}^{\mathrm{+}}\text{〉)}$ for the 6⁺ state most likely.     

Quadrupole moment of the first excited state of 32S

The static quadrupole moment and B(E2; 0⁺ → 2⁺) value for the first excited state of ³²S were measured using the reorientation effect in Coulomb excitation of ³²S projectiles. Silicon surface barrier detectors were used to detect ³²S ions scattered from ²⁰⁸Pb at mean laboratory angles of 90° and 174°, for bombarding energies in the range 122 to 160 MeV. The results for constructive (destructive) interference from the second 2⁺ state in ³²S are QP_2⁺ = ?16.0±2.2 (?13.3±2.2) e·fd² and B(E2; 0⁺ → 2⁺) = 292±17 (307±17) e²·fm⁴     

The static quadrupole moment of the first excited state of 198Hg

The first direct evidence of oblate nuclear deformation in the even-A mercury isotopes has been obtained by measurement of the static quadrupole moment of the first excited state of ¹⁹⁸Hg using the reorientation effect in Coulomb excitation.     

Static quadrupole moments of the first excited states of 200Hg and 202Hg

The static quadrupole moments Q_2⁺ and B(E2; 0⁺ → 2⁺) values of the 2⁺ first excited states of ²⁰⁰Hg and ²⁰²Hg have been determined using the reorientation effect in Coulomb excitation. An annular silicon surface-barrier detector was used to detect backscattered ⁴He, ¹²C and ¹⁶O projectiles. It is found that for ²⁰⁰Hg, Q_2⁺ = +1.07 ± 0.19 e · b(+0.98 ± 0.19 e · b) for destructive (constructive) interference from the 2^+′ state, and B(E2; 0⁺ → 2⁺) = 0.853 ± 0.007 e² · b². For ²⁰²Hg, we find Q_2⁺ = +1.01 ± 0.13 e · b (+0.87 ± 0.13 e · b) and B(E2; 0⁺ → 2⁺) = 0.605 ± 0.005 e² · b². The Q_2⁺ value obtained for ²⁰⁰Hg is in agreement with previous work, but that for ²⁰²Hg is not. The results obtained are compared with the predictions of various nuclear models, and the mass dependence of Q_2⁺ in the region 182 ≦ A ≦ 206 is examined.     

Electric moments of the first excited state of 18O

The static quadrupole moment Q_2⁺ and the B(E2; 0⁺ → 2⁺) value of the first excited state of ¹⁸O at e_x = 1.982 MeV have been determined using the reorientation effect in Coulomb excitation. Surface-barrier detectors at laboratory angles of 90° and 174° were used to detect ¹⁸O ions elastically and inelastically scattered from ²⁰⁸Pb. At both angles, we determined experimentally the maximum bombarding energies at which nuclear interference effects were negligible. It is found that Q_⁺ = ?0.023 ± 0.021 e · b (?0.052 ± 0.021 e · b) for destructive (constructive) interference from higher states. This result is in good agreement with theoretical expectation. For the transition moment we find B(E2; 0⁺ → 2⁺) = 0.00390 ± 0.00018 e² · b² (0.00371 ± 0.00018 e² · b²) for destructive (constructive) interference.     

Static moments of the first excited states of 32, 34S and 204, 206Pb

The reorientation effect in Coulomb excitation has been used to measure the following static quadrupole moments: $\text{Q}{}_2\text{+ (}{}^{32}\text{S}\text{) = ?0.066 ± 0.017}\text{b}\text{, Q}{}_2\text{+ (}{}^{34}\text{S}\text{) = 0.026 ± 0.023}\text{b}\text{, Q}{}_2\text{+ (}{}^{204}\text{Pb}\text{) = 0.19 ± 0.14}\text{b}$. Interference effects from higher excited states have been included in the analysis, with the signs of the E2 matrix elements taken from an anharmonic model. The value obtained for $\text{Q}{}_2\text{+ (}{}^{32}\text{S}\text{)}$ is in disagreement with two previous measurements. We attribute the discrepancy to the smaller internucleon separation distances involved in the previous experiments, which can cause deviations from Coulomb excitation cross sections. The other quadrupole moments have not been measured previously. The B (E2: 0⁺ → 2⁺) measured were: $\text{0.0305 ± 0.0016 e}{}^2\text{·}\text{b}{}^2\text{(}{}^{32}\text{S}\text{), 0.025 ± 0.004 e}{}^2\text{·}\text{b}{}^2\text{(}{}^{34}\text{S}\text{),}\text{and}\text{0.166 ± 0.009 e}{}^2\text{·}\text{b}{}^2\text{(}{}^{204}\text{Pb}\text{)}$. From the angular distribution of the de-excitation γ-rays of the Pb nuclei following recoil into vacuum, we have determined the following $\text{g-}\text{factors}\text{: ¦g}{}_2\text{+ (}{}^{204}\text{Pb}\text{)¦ < 0.08}$ (two standard deviations), $\text{¦g}{}_2\text{+ (}{}^{206}\text{Pb}\text{)¦ = 0.07}{}^{\mathrm{+\; 0.07}}{}_{\mathrm{?\; 0.03}}$. Our value of $\text{g}{}_2\text{+ (}{}^{206}\text{Pb}\text{)}$ is in agreement with a previous measurement.     

The g-factors of the first excited states in 78Br and 80Br

Low-lying states of the doubly odd Br isotopes were populated by means of the nuclear reactions ^{78, 80, 82}Se(p, n)^{78, 80, 82}Br. The g-factors of the first excited 2^? states in ⁷⁸Br and ⁸⁰Br were measured with the pulsed beam DPAD method and were found to be $\text{g(}{}^{78}\text{Br}\text{) = ? 0.56 ± 0.02}$ and $\text{g(}{}^{80}\text{Br}\text{) = ? 0.83 ± 0.06}$.     

The quadrupole moment of 26Mg as a test of shell-model interactions

The static quadrupole moment Q_21⁺, and the B(E2; 0₁⁺ → 2⁺₁) value of the first excited state of²⁶Mg have been measured using the reorientation effect in Coulomb excitation of ²⁶Mg projectiles. It is found that Q_21⁺ = ?13.6±3.0 (?9.5±3.0) e ·fm² and B(E2; 0⁺₁ → 2⁺₁) = 322±16 (328±16) e² ·fm⁴ for constructive (destructive) interference from higher states. The result for Q₂ clearly differentiates among several alternative effective interactions which have been used in shell-model calculations.     

Magnetic moment of the 2543 keV 7+ state in 40K

The nuclear g-factor of the 2543 keV, 7⁺ state ⁴⁰K has been measured as g = 0.59 ± 0.10. Time-integral perturbed angular distributions were measured in an external magnetic field and, after implantation, in the hyperfine field at potassium in nickel. The experimental value is discussed within the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^2\text{and}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?2}}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^2$, configurations.     

The half-lives of the first and second excited states in 66Ga

The half-lives of the first and second excited states at 43.9 and 66.3 keV in ⁶⁶Ga were determined by measuring the time dependence of the 43.9 and 22.4 keV γ-transition intensities. The levels in ⁶⁶Ga were populated by the ⁶⁶Za(p, n)⁶⁶Ga and ⁶³Cu(α, n)⁶⁶Ga reactions. The results are T_{$\text{1}\text{2}$}(43.9 keV) = 16(4) ns and T_{$\text{1}\text{2}$}(66.3 keV) = 23(2) ns. A g-factor measurement reported in the literature is reanalysed.     

Magnetic moments of the 10− isomeric states in 202Bi and 204Bi

The g-factors of the 10^? isomeric states in ²⁰²Bi and ²⁰⁴Bi have been measured by the method of in-beam TDPAD. The experimental values $\text{g = 0.243(14)}\text{for}{}^{202}\text{Bi}\text{and}\text{g = 0.236(23)}\text{for}{}^{204}\text{Bi}$ confirm the previously suggested shell-model configuration.     

The g-factor of the 6+ state in 50Ti

The rotation of the angular distribution pattern of the 524 keV γ-radiation from the 6⁺, 3200 keV state in ⁵⁰Ti was measured in an external magnetic field using the ⁴⁸Ca(α, 2n) reaction. The IPAD method was applied. From the experimental precession angle, the value of the g-factor, g = 1.57 ± 0.17, has been derived.     

A study of the 2H(d,p)3H AND 2H(d,n)3He reactions and the excited state of 4He at 23.9 MeV

The relative differential cross sections have been measured for the ²H(d, p)³H and the ²H(d, n)³He reactions from 300 keV to 700 keV in 50 keV steps. Angular distributions of all charged particles from the reactions were taken from 20° to 160° in the laboratory system. Energy-dependent asymmetry coefficients from the expansion of the centre-of-mass angular distributions in terms of even powers of cos θ were obtained as were the branching ratios between the two reaction modes. The different energy dependences of the moments of the two cross sections were used to test the need for the existence of a recently reported T = 0 state in ⁴He.     

Lifetimes of some excited states in 64Ni, 66Zn and 68Zn

Mean lives and excitation energies of the lowest levels in⁶⁴Ni,⁶⁶Zn and⁶⁸Zn were measured with the aid of the (α, α′γ) and (α, pγ) reactions. The γ-rays were detected in coincidence with the outgoing particles. The following mean lives were determined from DSA measurements: 400 ± 150 fs for the level at E_x = 1.35 MeV in ⁶⁴Ni; 270 ± 100, 210 ± 110, 330 ± 200, 80 ± 70 fs for the levels at E_x = 1.87, 2.45, 2.83, 2.94 MeV in ⁶⁶Zn, and 1300 ± 300, > 160, 600 ± 200 fs for the levels at E_x = 1.08, 1.89 and 2.76 MeV in ⁶⁸Zn, respectively.     

Lifetimes of levels in 25Na and 26, 27Mg excited via the 26Mg bombardment of 3H

Lifetimes have been measured for nine levels in ²⁵Na, the first two excited states of ²⁷Mg, and the First excited state of ²⁶Mg by bombarding a Ti³H target with 40 MeV ²⁶Mg ions. Mean lifetimes were determined by fitting the Doppler-broadened γ-ray lineshapes with lineshapes calculated using experimentally-measured stopping powers. The ²⁵Na results are compared to predictions of recent shell-model calculations.     

Study of the 8Be first T = 2 state with 4He + α and 7Li + p initiated excitation functions

In a high resolution study of the ⁴He + α initiated excitation functions in the region of the ⁸Be first T = 2 state, weak resonance excursions have been observed in some reaction channels yielding the total width Γ = 14.7 ± 4.0 keV. No resonance excursion has been observed in the ⁴He + α elastic scattering yielding the branching ratio Γ_α/Γ ≦ 0.003 for the decay of the ⁸Be first T = 2 state into two α-particles. For the decay to the low-lying states of ⁶Li and ⁷Li lower limits of the branching ratio are given. The reinvestigation of the ⁷Li+p initiated excitation functions revealed no resonance anomaly in the region of the ⁸Be first T = 2 state. The upper limit Γ_p/Γ ≦ 0.023 has been derived for the proton decay to the ⁷Li_g.s.. The results are compared with previous measurements and with shell-model calculations.     

States in 89Sr excited by the 86Kr(α, n)89Sr reaction

The reaction ⁸⁶Kr(α, n) with E_α = 12?16 MeV was used to populate excited states in ⁸⁹Sr. The de-excitation of these states was studied by in-beam γ-ray spectroscopy. DSA lifetime measurements were performed using a solid gas target. A number of new high-spin states was found, and lifetimes of ten states were obtained. Some of the states are discussed within the framework of a particle-anharmonic vibrator model.     

Mass and excited levels of the neutron-rich nuclei 73Zn and 74Zn studied with the 76Ge(14C, 17O) and (14C, 16O) reactions

The ⁷⁶Ge(¹⁴C, ^{16, 17}O)^{74, 73}Zn reactions have been studied at 72 MeV bombarding energy. The mass excesses of ⁷³Zn and ⁷⁴Zn were determined to be ?65.41 ± 0.04 and ?65.62 ± 0.04 MeV, respectively. In addition, previously unknown excited levels were identified in both nuclei. The structure of ⁷³Zn is discussed in terms of HFB calculations.     

The g-factors of the first 2+ states in 50, 54Cr, 54Fe and 70Ge

The gyromagnetic ratios of the first excited J^π = 2⁺ states of ^50,54Cr, ⁵⁴Fe and ⁷⁰Ge have been determined by the ion-implantation perturbed angular correlation technique (IMPAC) with ferromagnetic Gd as stopping material. The g-factors were extracted from the measured precession angles with use of known lifetimes, static hyperfine magnetic fields and transient hyperfine magnetic field data for fast ions traversing ferromagnetic lattices. The deduced values are 0.59 ± 0.10, 0.56 ± 0.10, 1.08±0.19 and 0.38±0.08, respectively. With the exception of ⁵⁴Fe all g-factors are close to the collective value. A re-evaluation of earlier IMPAC data on ^{70, 72, 74, 76}Ge with Fe as stopping material has been performed. The value obtained for ⁷⁰Ge is in good agreement with the one measured in this work.