Gyromagnetic ratios of excited states in 107, 109Ag

The gyromagnetic ratios of the lowest excited $\text{3}\text{2}{}^{\mathrm{?}}\text{and}\text{5}\text{2}{}^{\mathrm{?}}$ states in ^{107, 109}Ag were simultaneously measured relative to that of the 2₁⁺ level in ¹⁰⁸Pd. The thin-foil, perturbed γ-ray angular distribution technique was employed utilizing the transient hyperfine magnetic field present at the nuclei of these ions as they swiftly recoiled through a thin magnetized Co foil. The states of interest were Coulomb-excited using beams of 100 MeV ³²S ions. The present measurements yielded $\text{g(}\text{3}\text{2}{}^{\mathrm{?}}\text{;}{}^{107}\text{Ag}\text{) = +0.63 ± 0.09, g(}\text{5}\text{2}{}^{\mathrm{?}}\text{;}{}^{107}\text{Ag}\text{) = + 0.37±0.06, g(}\text{3}\text{2}{}^{\mathrm{?}}\text{;}{}^{109}\text{Ag}\text{) = +0.77 ± 0.10,}\text{and}\text{g(}\text{5}\text{2}{}^{\mathrm{?}}\text{;}{}^{109}\text{Ag}\text{) = +0.36 ± 0.05}$. These findings are compared with weak-coupling and other appropriate model calculations.     

The g-factors of short-lived isomeric states in 108Ag and 110Ag

Short-lived isomeric states in ¹⁰⁸Ag and ¹¹⁰Ag were populated by means of (p, n) and (d, p) reactions. The nuclear g-factors of these states were determined with the pulsed beam DPAD method to be $\text{g(}{}^{108}\text{Ag}\text{; 215}\text{keV}\text{) = 1.294(6)}\text{and}\text{g(}{}^{110}\text{Ag}\text{; 119}\text{keV}\text{) = 1.277(15)}$. The results indicate a spin and parity I^π = 2⁺ for ¹⁰⁸Ag and I^π = 3⁺ for ¹¹⁰Ag.     

The yrast spectroscopy of 209Rn

The yrast spectroscopy of ²⁰⁹Rn has been investigated to an excitation energy of over 7 MeV and to a spin of $\text{51}\text{2}$. The existence of six isomers has been established: $\text{1174}\text{keV}\text{(J}{}^{\mathrm{\pi }}\text{=}\text{13}\text{2}{}^{\mathrm{+}}\text{, τ}{}_{\mathrm{<mtext>m</mtext>}}\text{= 19.3 ± 1.9 μ}\text{s}\text{), 1687}\text{keV}\text{(}\text{19}\text{2}{}^{\mathrm{?}}\text{, 1.0 ± 0.3}\text{ns}\text{), 2419}\text{keV}\text{(}\text{21}\text{2}{}^{\mathrm{+}}\text{, 12.6 ± 0.3}\text{ns}\text{20 ± 3}\text{ns}\text{, 3637}\text{keV}\text{(}\text{35}\text{2}\text{, 4.3 ± 0.4 μ}\text{s}\text{)}\text{and}\text{4834}\text{keV}\text{(}\text{41}\text{2}{}^{\mathrm{?}}\text{, 14.4 ± 0.5}\text{ns}\text{)}$. Shell-model calcu are used to explain the observed structure. E3 and M2 transitions in ²⁰⁹Rn and neighbouring nuclei are discussed.     

Transitions,with change in parity,produced in 107,109Ag by coulomb excitation

Some of the low-lying energy levels of ¹⁰⁷Ag and ¹⁰⁹Ag were excited by Coulomb excitation using α-particles from 4.8 to 7.2 MeV. Transitions to the isomeric state ($\text{7}\text{2}{}^{\mathrm{+}}$), involving a parity change, were observed both directly in the singles spectra and indirectly by the decay of the isomer. The isomer in both silver isotopes was populated by transitions from the $\text{5}\text{2}{}^{\mathrm{?}}$ level, which was strongly excited. The observed branching ratio in ¹⁰⁹Ag for the $\text{5}\text{2}{}^{\mathrm{?}}\text{→}\text{7}\text{2}{}^{\mathrm{+}}$ transition was (0.315 ± 0.09) % and for the $\text{5}\text{2}{}^{\mathrm{?}}\text{→}\text{9}\text{2}{}^{\mathrm{+}}$ transition was (0.055±0.03) %. The total rate of populating the $\text{7}\text{2}{}^{\mathrm{+}}$ level from the $\text{5}\text{2}{}^{\mathrm{?}}$ level was (0.215±0.04) % in ¹⁰⁷Ag. The level schemes have been discussed on the weak-coupling model, allowing admixtures of singleparticle wave functions to account for the weaker transitions.     

Pionic X-rays from 12, 13C

The energies and widths of pionic 2p-1s and 3d-2p X-rays have been measured in ^12,13C. Values obtained are

${}^{12}\text{C: 2p-1s E=93.221(55)}\text{keV}\text{, τ=2077(14)}\text{keV}$

$\text{3d-2p E=18.400(6)}\text{keV}\text{, τ=1.17(11)}\text{eV}$

${}^{13}\text{C: 2p-1s E=92.227(27)}\text{keV}\text{, τ=2.59(11)}\text{keV}$

$\text{3d-2p E=18.427(5)}\text{keV}\text{, τ=0.97(10)}\text{eV}$

The muonic 2p-1s X-ray energies in ^12,13C have also been measured. The strong interaction effects are discussed in relation to recent low-energy pion scattering measurements.     

Two-quasiparticle excitations and collectivity in the weakly-deformed transitional isotopes 104, 106, 108Cd

Using the generalized centroid-shift method on the Rutgers tandem, the following half-lives of ¹⁰⁶Cd excited states were measured in the reaction ⁹³Nb(¹⁶O, p2n): $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(3679.0}\text{keV}\text{) = 0.7}{}^{\mathrm{+0.1}}{}_{\mathrm{?0.3}}\text{ns}\text{, T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(3507.8}\text{keV}\text{) = 1.2 ± 0.4}\text{ns}\text{, T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(3044.2}\text{keV}\text{) = 0.4 ± 0.1}\text{ns, and}\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(2330.7}\text{keV}\text{) = 0.6 ± 0.2}\text{ns}$. With the same method applied on the Rossendorf cyclotron, the following half-lives were measured in the reactions ${}^{\mathrm{102,\; 106}}\text{Pd}\text{(α, 2}\text{n}\text{): T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(2902.0}\text{keV}\text{) = 0.8}{}^{\mathrm{+0.2}}{}_{\mathrm{?0.1}}\text{ns}\text{(}{}^{104}\text{Cd}\text{)}$ as well as $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(3737.3}\text{keV}\text{) = 0.2 ± 0.1}\text{ns}$, $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(3223.7}\text{keV}\text{) = 0.2 ± 0.1}\text{ns}$, $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(3057.4}\text{keV}\text{) = 0.10 ± 0.05}\text{ns}$, $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(2975.3}\text{keV}\text{) = 0.15 ± 0.10}\text{ns}$, $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(3110.5}\text{keV}\text{) = 0.3 ± 0.1}\text{ns}$, and $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(2565.2}\text{keV}\text{) = 0.2 ± 0.1}\text{ns}\text{(}{}^{108}\text{Cd}\text{)}$. The results reveal the non-collective (two-quasiparticle) character of several states above 2.9 MeV in ^{104, 106, 108}Cd, in qualitative accordance with predictions of the slightly-deformed-rotor model. They concern completely aligned [h_{$\text{11}\text{2}$}g_{$\text{7}\text{2}$}] (9^??11^?-13^?, etc.) as well as semi-decoupled [h_{$\text{11}\text{2}$}d_{$\text{5}\text{2}$}] (6^?-8^?-10^?, etc.) two-quasineutron band structures. Further, the possible character of 8⁺ (two-quasiproton) excitations, 5⁺ (two-quasineutron) states and of other intrinsic excitations is discussed. The experimental findings present a challenge to current theories of transitional nuclei for a quantitative treatment of absolute γ-ray transition strengths.     

Nuclear orientation study of the excited states of 129I populated in the decay of 129gTe and 129mTe

From the angular distributions of γ-rays emitted by oriented ^129gTe and ^129mTe nuclei implanted in iron by isotope separator, unique spin assignments could be made for the excited states of ¹²⁹I at 487.4 keV $\text{(}\text{5}\text{2}{}^{\mathrm{+}}\text{)}$, 696.0 keV $\text{(}\text{11}\text{2}{}^{\mathrm{+}}\text{)}$, 729.6 keV $\text{(}\text{9}\text{2}{}^{\mathrm{+}}\text{)}$, 768.9 keV $\text{(}\text{7}\text{2}{}^{\mathrm{+}}\text{)}$, 1050.4 keV $\text{(}\text{7}\text{2}{}^{\mathrm{+}}\text{)}$ and 1111.8 keV $\text{(}\text{5}\text{2}{}^{\mathrm{+}}\text{)}$. In addition, E2/M1 amplitude ratios for the following ¹²⁹I γ-rays (energies are in keV) are derived: δ(459.6) = ?(0.076^+0.037_?0.148); δ(487.4) = 0.50^+0.17_?0.10 or δ^? = 0.35^+0.15_?0.09; δ(556.7) = 0.06±0.02 or δ^? = ?(0.10±0.02); δ(624.4) = 0.10±0.26 or δ^? > 0.4; the 696.0 keV γ-ray is pure E2; δ(729.6) = ?(0.34±0.06) or δ^?1 = 0.55±0.05; δ(741.1) = ?(0.27±0.10) or δ^?1 = ?(0.43±0.12); δ(817.2) = 0.46±0.04 or δ^?1 =0.20±0.03 if $\text{I}{}^{\mathrm{\pi }}\text{(845}\text{keV}\text{) =}\text{7}\text{2}{}^{\mathrm{+}}$; δ(1022.6) = ?(0.02 ±0.02) or δ^?1 = ?(0.23±0.02); $\text{δ(1084) = 0.56}{}^{\mathrm{+0.04}}{}_{\mathrm{?0.14}}$; δ(1111.8) = 0.06±0.05 or δ^?1 = ?(0.08±0.05). The anisotropy of the 531.8 keV γ-ray excludes $\text{1}\text{2}{}^{\mathrm{+}}$ as a possible spin assignment for the 559.6 keV level, so that no $\text{1}\text{2}{}^{\mathrm{+}}$ level is fed in the decay from ¹²⁹Te. Anisotropies for the 209, 250.7, 278.4 and 281.1 keV γ-rays are also measured. Comparison of the level scheme is made with theoretical predictions from both the pairing-plus-quadrupole model and the intermediate coupling unified model.     

High spin states in 105Ag

High spin states in ¹⁰⁵Ag have been studied using the ¹⁰³Rh(α, 2nγ)¹⁰⁵Ag reaction. A collective band on the $\text{9}\text{2}{}^{\mathrm{+}}$ state at 53.2 keV and a negative parity band with spins ranging from $\text{15}\text{2}$ to $\text{27}\text{2}$ were observed. Furthermore a $\text{15}\text{2}{}^{\mathrm{+}}$ isomeric state with $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext><mtext>\; =\; 6.0\pm 0.2\; </mtext><mtext>ns</mtext>}}$ at 1733.8 keV was identified. The g-factor deduced for this state is g = 0.58±0.06. A comparison of the experimental results with theoretical calculations indicates that the properties of most of the positive parity states are reasonably well described by the cluster-vibrational model as well as by the triaxial rotator model.     

Interference effects in 12C(p, γ)13N and direct capture to unbound states

Excitation functions of the capture reaction ¹²C(p, γ₀)¹³N have been obtained at θ_γ = 0° and 90° and E_p = 150–2500 keV. The results can be explained if a direct radiative capture process, E1(s and d → p), to the ground state in ¹³N is included in the analysis in addition to the two well-known resonances in this beam energy range $\text{[E}{}_{\mathrm{p}}\text{= 457(}\text{1}\text{2}{}^{\mathrm{+}}\text{)}$ and 1699 $\text{(}\text{3}\text{2}{}^{\mathrm{?}}\text{) keV]}$. The direct capture component is enhanced through interference effects with the two resonance amplitudes. From the observed direct capture cross section, a spectroscopic factor of C²S(l = 1) = 0.49 ± 0.15 has been deduced for the $\text{1}\text{2}{}^{\mathrm{?}}$ ground state in ¹³N. Excitation functions for the reaction ${}^{12}\text{C(p,γ}{}_1\text{p}{}^1\text{)}{}^{12}\text{C}$ have been obtained at θ_γ = 0° and 90° and E_p = 610–2700 keV. Away from the 1699 keV resonance the capture γ-ray yield is dominated by the direct capture process E1 (p → s) to the $\text{2366 (}\text{1}\text{2}{}^{\mathrm{+}}\text{) keV}$ unbound state. Above E_p = 1 MeV, the observed excitation functions are well reproduced by the direct capture theory to unbound states (bremsstrahlung theory). Below E_p = 1 MeV, i.e., E_p → 457 keV, the theory diverges in contrast to observation. This discrepancy is well known in bremsstrahlung theory as the “infrared problem”. From the observed direct capture cross sections at $\text{E}{}_{\mathrm{p}}\text{? 1 MeV}$, a spectroscopic factor of C²S(l = 0) = 1.02 ± 0.15 has been found for the $\text{2366 (}\text{1}\text{2}{}^{\mathrm{+}}\text{) keV}$ unbound state. A search for direct capture transitions to the $\text{3512 (}\text{3}\text{2}{}^{\mathrm{?}}\text{)}$and $\text{3547 (}\text{5}\text{2}{}^{\mathrm{+}}\text{) keV}$ unbound states resulted in upper limits of C²S(l = 1) ≦ 0.5 and C²S(l = 2) ? 1.0, respectively. The results are compared with available stripping data as well as shell-model calculations. The astrophysical aspect of the ¹²C(p, γ₀)¹³N reaction also is discussed.     

Lifetime measurements in 22Ne, 28Si and 31P relevant to the interpretation of the Z2 variation in low velocity DSAM results

Accurate lifetimes have been measured for low-lying levels in ²²Ne, ²⁸Si and ³¹P by bombarding ⁴He implanted targets with beams of ¹⁹F and ²⁸Si ions. Mean lifetimes determined by fitting Doppler-broadened γ-ray lineshapes were $\text{(E}{}_{\mathrm{<mtext>x</mtext>}}\text{in MeV}\text{, τ}\text{in ps}\text{):}{}^{22}\text{Ne}\text{(1.275, 5.15 ± 0.31; 3.357, 0.324 ± 0.009),}{}^{28}\text{Si}\text{(1.779, 0.667 ± 0.035),}{}^{31}\text{P}\text{(1.266, 0.70 ± 0.07; 2.234, 0.363 ± 0.024}$). The lifetime values for the 3.357 MeV level in ²²Ne and the 2.234 MeV level in ³¹P are used to calibrate low velocity DSAM lifetime data for these two levels and to obtain scaling factors to theoretical electronic stopping powers for Ne and P ions.     

High spin states in 57Co

High spin states of ⁵⁷Co have been studied via prompt γ-ray spectroscopy in the reactions ⁴⁸Ti(¹²C, p2n) and ⁵⁴Fe(α, p) at 26–48 MeV and 12–24 MeV, respectively. The energies and decay modes of these levels were determined from the analysis of γ-ray singles and γ-γ coincidence spectra, excitation functions, angular distributions and correlations. The relevant lifetimes were measured by the Doppler-shift attenuation method. The new levels established in this work are at 4037, 4814 and 5918 keV with the most probable J^π assignment of $\text{15}\text{2}{}^{\mathrm{?}}$, if $\text{17}\text{2}{}^{\mathrm{?}}$ and $\text{19}\text{2}{}^{\mathrm{?}}$, respectively. The previously known level at 2524 keV was assigned to have $\text{J}{}^{\mathrm{\pi }}\text{=}\text{13}\text{2}{}^{\mathrm{?}}$. These together with the known $\text{9}\text{2}{}^{\mathrm{?}}$(1224 keV) and $\text{11}\text{2}{}^{\mathrm{?}}$(1690 keV) levels constitute the yrast states of ⁵⁷Co. The measured lifetimes of the above six levels are (in order of increasing energies) 0.085±0.030, 0.32±0.10, 0.16±0.06, 0.10_?0.07^+0.06, 1.5_?0.5⁴ and 0.17_?0.07^+0.08 ps, respectively. Comparisons with some theoretical calculations are presented.     

Nuclear wave functions and mesonic exchange currents in the weak transition 16O(0+) ↔ 16N(0−)

We show that any deviation from the closed-core hypothesis for ¹⁶O(0⁺, g.s.) may strongly affect the theoretical ratio of the transition probabilities for the two inverse processes: ${}^{16}\text{O(0}{}^{\mathrm{+}}\text{, g.s.}\text{) →}{}^{16}\text{N(O}{}^{\mathrm{?}}\text{, 120 keV}\text{)}$ muon-capture) and ${}^{16}\text{N(0}{}^{\mathrm{?}}\text{, 120 keV}\text{) →}{}^{16}\text{O(0}{}^{\mathrm{+}}\text{, g.s.}\text{)}$ (beta-decay). As a consequence, the possible evidence for exchange currents in this transition must be reexamined. Preliminary calculations do not exclude a still large meson exchange effect.     

A new level of 18F

A new $\text{T = 0 level of}{}^{18}\text{F, E}{}_{\mathrm{x}}\text{= 4848.3 ± 0.5}\text{keV}$, has been studied using the ⁶Li(¹⁶O, αγ)¹⁸F reaction. The γ-decay by a 65 ± 4 % branch to the 1121 keV (5⁺) level and 35 ± 4 % to the 3791 keV (3^?) level has been observed and a lifetime limit τ > 2 ps has been given. A tentative assignment J^π = 5^? is proposed which is supported by the α-γ angular correlation measurements. The possible structure of the new level and reasons why it had not been observed in past experiments are discussed.     

Half-life measurements of excited levels in 122I

The half-lives of three low-lying levels in ¹²²I have been measured using delayed coincidence techniques. The following results were obtained: $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(61.8}\text{keV}\text{) = 7.4 ± 0.5}\text{ns}\text{, T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(90.7}\text{keV}\text{) = 1.9 ± 0.3}\text{ns and}\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(148.8}\text{keV}\text{) ≦ 80}\text{ps}$. All transitions depopulating these levels are mainly of M1 multipolarity; they are hindered with factors up to 295 as compared to the single particle estimates.     

Coulomb excitation of 85Rb and 87Rb

Energy levels of ⁸⁵Rb and ⁸⁷Rb have been studied via de-excitation γ-rays following Coulomb excitation with ³⁵Cl ions. In addition to the known negative-parity states at 151.2 keV and 868.2 keV in ⁸⁵Rb, two states at 281.0 keV and 731.8 keV have been found with fourγ-ray transitions of 129.8, 281.0, 450.8 and 731.8 keV. Only one Coulomb excited state at 402.6 keV in ⁸⁷Rb has been observed. The B(E2↑) values (in units e² · b²) have been determined as 0.0035±0.0004 (151.2 keV), 0.0016±0.0002 (281.0 keV), 0.0101 ±0.0010 (731.8 keV), and 0.036±0.004 (868.2 keV) for the states in ⁸⁵Rb, and as 0.0054±0.0006 (402.6 keV) for the state in ⁸⁷Rb. The mean lifetimes of the 731.8 keV and 868.2 keV states have been measured by the Doppler shift attenuation method as 6.4±0.7 psec and 4.2±0.5 psec respectively. Angular distribution measurements allow unique spin and parity assignments of $\text{1}\text{2}{}^{\mathrm{?}}$ and $\text{3}\text{2}{}^{\mathrm{?}}$ to the 281.0 keV and 731.8 keV levels respectively. The spin and parity of the 868.2 keV level has been restricted to $\text{5}\text{2}{}^{\mathrm{?}}$ or $\text{7}\text{2}{}^{\mathrm{?}}$.     

Level structure of 75Se by the 75As(p,nγ)75Se reaction

Excitation functions of γ-rays from the ⁷⁵As(p, n)⁷⁵Se reaction were measured with 2.0 to 3.6 MeV protons to establish the level scheme of ⁷⁵Se up to about 1.5 MeV excitation energy. Internal conversion electrons following the same reaction were measured at 4.5 and 5.0 MeV proton energy. Using theoretical predictions of the statistical compound nucleus model together with deduced internal conversion coefficients, unique spin assignments were obtained for the $\text{112.5(}\text{7}\text{2}{}^{\mathrm{+}}\text{), 427.9(}\text{5}\text{2}{}^{\mathrm{?}}\text{)}$ and $\text{663.9(}\text{5}\text{2}{}^{\mathrm{?}}\text{)}\text{keV}$ levels. Probable spins were proposed to the $\text{286.6 (}\text{3}\text{2}{}^{\mathrm{?}}$ for one of the doublet and $\text{5}\text{2}{}^{\mathrm{?}}$ or $\text{7}\text{2}{}^{\mathrm{?}}$ for the other), 579.4 $\text{(}\text{1}\text{2}{}^{\mathrm{?}}$ or $\text{3}\text{2}{}^{\mathrm{?}}$, $\text{585.8(}\text{9}\text{2}{}^{\mathrm{?}}$ or $\text{11}\text{2}{}^{\mathrm{?}}$ and $\text{747.6 (}\text{5}\text{2}{}^{\mathrm{?}}$ or $\text{7}\text{2}{}^{\mathrm{?}}\text{)}\text{keV}$ levels. Alow-lying $\text{9}\text{2}{}^{\mathrm{+}}$ level was tentatively assigned at 133.2 keV energy. It was found that a low-lying $\text{1}\text{2}{}^{\mathrm{?}}$ level which appears systematically in other odd Se nuclei is absent in ⁷⁵Se.     

Silver-compensated germanium center in α-quartz

A synthetic germanium-doped crystal of α-quartz was subjected to an electro-diffusion process $\text{ca. 600}\text{V}\text{cm}$, 625°K), in which Ag⁺ ions were introduced along the crystal's optic axis (c). A 9800MHz electron paramagnetic resonance spectrum at room temperature, taken after room temperature x-irradiation, revealed the presence of a silver-compensated germanium center A_Ge?Ag with large, almost isotropic ¹⁰⁷Ag and ¹⁰⁹Ag hyperfine splittings (26.078, 30.112 mT for magnetic field B∥c). Measurement of the spin-Hamiltonian (i.e. matrices $\text{g}$, $\text{A}{}^{73}{}_{\mathrm{<mtext>Ge</mtext>}}$, $\text{A}{}^{107}{}_{\mathrm{<mtext>Ag</mtext>}}$ and $\text{A}{}^{109}{}_{\mathrm{<mtext>Ag</mtext>}}\text{)}$ discloses that a suitable model for the observed center utilizes germanium, substituted for silicon, with the accompanying silver interstitial in a nearby c-axis channel, and with electronic structure in which an appreciable admixture Ge⁴⁺?Ag⁰ to Ge³⁺?Ag⁺ exists. Estimates of the unpaired electron orbital are presented.     

The quadrupole moments of the 5− states in 116Sn, 118Sn and 120Sn

The quadrupole interaction frequencies $\text{ω}{}_0\text{=}\text{3eQ}{}_1\text{V}{}_{\mathrm{zz}}\text{41(21-1)}\text{h}\text{?}$ in the 5^? state of ¹¹⁸Sn have been measured by time differential perturbed angular correlation technique in Sn, Sb and (95% Sn+5% Sb) environments. The ω₀ for ¹¹⁶Sn was determined in Sn environment only. With the help of the known electric field gradient ¹) of Sn in a Sn lattice the quadrupole moments have been deduced as $\text{Q(5}{}^{\mathrm{?}}\text{,}{}^{118}\text{Sn}\text{) = ±0.10(4) b}\text{and}\text{Q(5}{}^{\mathrm{?}}\text{,}{}^{116}\text{Sn}\text{) = ±0.165(60)}\text{b}$. These values together with the known²) quadrupole moment of the analogous 5^? state in ¹²⁰Sn are interpreted in terms of the pure single-particle model. The data exhibit the expected strong systematic variation of Q_I with the number of particles in the h_{$\text{11}\text{2}$}. subshell which is being filled with 1, 3 and 5 neutrons in ¹¹⁶Sn, ¹¹⁸Sn, and ¹²⁰Sn, respectively.