Excited states in107Ag from the decay of107Cd

The decay of¹⁰⁷Cd has been studied with Ge(Li) and Si(Li) detectors. Thirty three gamma rays were observed in this decay of which nine for the first time. Gammagamma directional correlation techniques employing a Ge(Li)-NaI(Tl) system were used to determine spins and mixing ratios. A decay scheme has been constructed with firmly established excited states at 93.13(7/2⁺), 125.4(9/2⁺), 324.8(3/2^?), 423.0(5/2^?), 786.7(3/2^?), 922.1(5/2⁺), 949.7(5/2^?), 972.9(7/2^?, 5/2^?), 1143.0(5/2^?), 1223.0(5/2⁺), 1258.8(5/2^?), 1325.7(5/2^?) keV. A tentative level has been introduced at 1389.8(7/2⁺) keV. The results are compared with the predictions of the theoretical calculations of Paar [10].     

Mössbauer studies and nuclear quadrupole moments of186, 188, 189, 190 Os

Mössbauer transmission experiments with the 137, 155, 69 and 187 keV gamma rays of^{186, 188, 189, 190}Os, respectively, yielded the electric quadrupole splitting of these gamma resonance lines in OsO₂ and OsP₂. From the results the following ratios of quadrupole moments were derived:Q ₂ ⁺(¹⁸⁶Os, 137 keV):Q ₂ ⁺(¹⁸⁸Os, 155keV):Q ₂ ⁺(¹⁹⁰Os, 187 keV):Q _3/2 ^?(¹⁸⁹Os, g.s.)=(+1.100±0.020): 1.0:(+0.863±0.051): (?0.586±0.011) andQ _5/2 ^?(¹⁸⁹Os, 69 keV)/Q _3/2 ^?(¹⁸⁹Os, g.s.)=?0.735 ±0.012. The ratios for^{180, 188, 190}Os are, within their limits of error, in agreement with the expectation of the rotational model, indicating that the pairing-plusquadrupole model calculations of Kumar and Baranger predict too rapid a transition form rotational to vibrational nuclei. Applying this argument to¹⁸⁶Os in particular and using the measured ratios, one obtains a set of values for the quadrupole moments themselves, namelyQ ₂ ⁺ (¹⁸⁶Os)=?(1.50 ± 0.10)b,Q ₂ ⁺(¹⁸⁸Os)=?(1.36± 0.09) b,Q ₂ ⁺ (¹⁹⁰Os)=?(1.18 ± 0.08) b,Q _3/2 ^?(¹⁸⁹Os)=+ (0.80 ± 0.06) b, andQ _5/2 ^? (¹⁸⁹Os)=? (0.59 ± 0.05) b. For the electric field gradient at Os nuclei in Re metal a value ofV _zz=?(3.3 ± 0.6) · 10¹⁷ V/cm² was found. A measurement with a magnetically split source yielded δ=+ 0.685 ± 0.025 for theE2/M1 mixing parameter of the 69 keV transition of¹⁸⁹Os,g _5/2 ^?/g _3/2 ^?=0.895 ± 0.006 for the ratio of theg-factors of the 69 keV state and the groundstate, andH _i=?(1135 ± 20) kOe for the hyperfine field at Os nuclei in an iron matrix.     

Der Zerfall von Tm174 und Tm175

The radioactive isotopes Tm¹⁷⁴ and Tm¹⁷⁵ were produced by the reactions Yb¹⁷⁶ (γ, np) Tm¹⁷⁴ and Yb¹⁷⁶(γ,p) Tm¹⁷⁵ respectively, with bremsstrahlung of 54 MeV maximum energy. TheΒ- andγ-radiations from the decay of these isotopes were investigated using scintillation counters, solid state detectors and coincidence methods. The decay scheme proposed for Tm¹⁷⁴ is similar to those proposed by previous investigations. The spin assignment of the isomeric 1520 keV level was revised to beI=7. The decay of Tm¹⁷⁵, which was until now rather unknown, has a half-life of of 15.2±0.5 min. The suggested decay scheme shows excited levels at 105 (9/2^?), 511 (1/2^?), 553 (3/2^?), 598 (5/2^?), 643 (5/2^?, 7/2^?), 816 (3/2^?), 873, 990, 1454 (1/2⁺), 1496 (3/2⁺), 1505, 1810 and 1881 keV. The results are discussed using the Nilsson model.     

On the decay of116gIn

The decay of the 1⁺, 14 s ground state of¹¹⁶In produced by neutron capture has been reinvestigated using Ge(Li) detectors. It is found that besides the ground state of¹¹⁶Sn, excited levels at 1293.6 (2⁺), 1756.9 (0⁺), 2225.3 (2⁺), 2545.7 (0⁺, 1⁺, 2⁺), 2649.8(2⁺), 2790.7(2⁺) and 2844.6(2⁺) keV are populated, while no evidence could be obtained for the population of the 0⁺ and 2⁺ levels at 2030 and 2112.4 keV, respectively. The activation cross-section for^116m2In (2.16s,I ^π = 8^?) has been deduced as 83±8 b.     

Levels of 190Os populated in the decays of 3.3 h 190mRe and 12 d 190Ir and in the 189Os(d,p)190Os reaction

The level structure of ¹⁹⁰Os has been investigated by the techniques of radioactive decay and neutron transfer reaction spectroscopy. The existence of 3.3 h ^190mRe has been confirmed; it decays ≈ 49% by isomeric transitions and ≈ 51% by β^? decay to levels in ¹⁹⁰Os with spins $\text{\$}\text{?}\text{= 5}$. In a re-investigation of the 12 d ¹⁹⁰Ir decay, a virtually complete decay scheme has been established and discrepancies between the I^π values assigned to several ¹⁹⁰Os levels by earlier workers have been resolved. The reaction ¹⁸⁹Os(d, p)¹⁹⁰Os has been studied and information about the locations of two-quasiparticle states involving the $\text{3}\text{2}\text{[512]ν}$ orbital and about the microscopic compositions of collective excitations has been derived. Various aspects of the ¹⁹⁰Os level structure are discussed in the light of the combined radioactivity and transfer reaction results.     

The binary and ternary fission of thorium,lead and platinum induced by 12.2 GeV protons

We have investigated the decay of^123g+mIn to excited states of¹²³Sn.¹²³In was produced by the¹²⁴Sn(y,p)¹²³In reaction on an enriched SnO₂ target. The isomeric transition to the¹²³In ground state was not observed. In the beta decay of^123m In excited states at 24, 150.9, 920.5, 1194, 2621, 3151, 3256 and 3306 keV in¹²³Sn withJπ values 3/2⁺, 1/2⁺, (5/2⁺), 5/2⁺, 1/2⁺, (1/2⁺, 3/2⁺), 3/2⁺ and (l/2⁺, 3/2⁺), are fed. In the β decay of the¹²¹In ground state only the 7/2⁺ level at 1154 keV in¹²³Sn is observed.     

Levels of118Sn populated in the decay of118In and118Sb isomers

Gamma-rays in the disintegration of 5.0 s (1⁺), 8.5 s (7^?, 8^?), and 4.4 min (4⁺, 5⁺)¹¹⁸In isomers and of 3.5 min (1⁺) and 5.1 h (8^?)¹¹⁸Sb isomers have been investigated using Ge(Li) detectors and Ge(Li)-NaI(Tl) coincidence spectrometers. The decay schemes of these isomers have been constructed incorporating 17 levels in the product nucleus,¹¹⁸Sn, at the following energies (in keV): 0 (0⁺), 1229.5 (2⁺), 1757.5 (0⁺), 2043.1 (2⁺), 2056.4 (0⁺), 2280.3 (4⁺), 2321.3 (5^?), 2326.4 (1⁺, 2⁺), 2402.7 (4⁺), 2488.8 (4⁺), 2496.5 (0⁺), 2575.2 (7^?), 2677.3, 2733.7 (2⁺), 2929.8, 2963.5 (4⁺), and 3137.1 (0⁺). The structure of¹¹⁸Sn is briefly discussed in view of results from recent quasiparticle-model calculations.     

Level structure of120Sn from the decay of120In and120Sb isomers

Gamma rays in the decay of the 3.2 s (1⁺) and 44 s (4, 5⁺)¹²⁰In isomers and the 15.9 min (1⁺) and 5.8 d (8^?)¹²⁰Sb isomers have been investigated using Ge(Li) spectrometers and prompt and delayed Ge(Li)-NaI(Tl) coincidence techniques. The constructed level scheme of¹²⁰Sn contains 18 levels at the following energies (keV): 0 (0⁺), 1171.6 (2⁺), 1875.6 (0⁺), 2096.9 (1, 2, 3), 2160.7 (0⁺), 2195.0 (4⁺), 2284.8 (5^?), 2355.6 (2⁺), 2421.2 (1, 2, 3), 2466.3 (4⁺), 2482.1 (7^?), 2643.5 (4⁺), 3058.6 (4⁺), 3179.7 (4⁺), 3349.9 (3, 4⁺), 3440 (3, 4⁺), 3447.6 (5, 6⁺) and 3777 (4⁺). The levels are compared with the levels obtained from recent charged-particle reaction studies and the structure of¹²⁰Sn is briefly discussed in view of the latest quasiparticle calculations.     

The decay of 189W

¹⁸⁹W was produced by bombarding natural osmium targets with 14.7 MeV neutrons. The W activities were chemically separated from Os and Re. Gamma-ray spectra were obtained by employing a high resolution detector. A total of 22 γ-rays in the separated tungsten fractions was found which could be assigned to the decay of ¹⁸⁹W. Eighteen of these γ-rays were previously unreported.     

Gamma decay of the lowly excited states of 189Re

189W activities were produced via the 192Os(n, α) reaction using irradiation of isotopically enriched 192Os metallic powder of ～100 mg/cm2 with 14 MeV neutrons. The X-γ and γ-γ coincidence measurements were made so as to obtain γ rays from 189W decay and its coincidence relations. A new simple decay scheme of 189W including three γ rays of 210.2, 229.6 and 260.2 keV is proposed. Two new levels of 189Re at 470.4 and 489.8 keV are assigned.     

Studies of γ-ray transitions in171Yb

The decay of¹⁷¹ Lu(t_1/2=8.2 day) to the levels of¹⁷¹Yb has been studied using large volume high resolution Ge(Li), x-ray Ge(Li) and NaI(Tl) detectors.γ-γ coincidence and directional correlation experiments have been performed. Spin-parity of 5/2^?, 7/2⁺, 5/2^?, 9/2⁺, 7/2^?, 7/2^?, 11/2⁺, 9/2^?, 9/2^? and 5/2^? have been assigned to the 75.87, 95.26, 122.37, 167.62, 208.00, 230.61, 259.02, 835.21, 948.37 and 1024.87 keV levels respectively. Several new coincidence relations have been observed in the present work. Two newγ-transitions at 141.45 and 821.30 keV observed and two levels at 766 and 944 keV been proposed. Multipolarity assignments have been made for most of theγ-transitions from theK-shell internal conversion coefficients obtained using the presentγ-ray intensities and the published conversion electron intensities. A revised level scheme for¹⁷¹Yb has been proposed and compared with published data. Radioactivity¹⁷¹Lu; measuredT _1/2,E _γ ,I _γ ,γγ coin,γγ (θ), I.C.C.,¹⁷¹Yb deduced levels,J, γ-mixing,π. Enriched targets, Ge(Li) detectors.     

Collective and two-quasiparticle states in 158Gd observed through study of radiative neutron capture in 157Gd

The level structure of ¹⁵⁸Gd has been studied using the prompt γ-rays and conversion electrons emitted following neutron capture in ¹⁵⁷Gd. The γ-ray energy and intensity measurements were made using both Ge(Li) detectors and a curved-crystal spectrometer. Conversion-electron energy and intensity measurements were made using two separate magnetic spectrometers: one to measure the primary electron spectrum and the other to measure the lower energy secondary electron spectrum. Some γ-γ coincidence measurements were also made among the secondary γ-rays. From these data, a neutron separation energy of 7937.1 ± 0.5 keV has been determined for ¹⁵⁸Gd. A level scheme containing 59 excited states with energies < 2.25 MeV, for which de-excitation modes have been identified, is proposed for ¹⁵⁸Gd. Many of these states have been grouped into rotational bands. A total of thirteen excited rotational bands with band-head energies below 2.0 MeV are contained in the level scheme. Features of the proposed level scheme include: the K^π = 0^?, 1^? and 2^? octupole-vibrational bands with band-head energies of 1263, 977 and 1793 keV, respectively; the γ-vibrational band at 1187 keV; three excited K^π = 0⁺ bands with band-head energies of 1196, 1452 and 1743 keV; several two-quasiparticle bands with band-head energies in keV (and K^π assignments) of 1380 (4⁺), 1636 (4^?), 1847 (1⁺), 1856 (1^?), 1920 (4⁺) and 1930 (1⁺). An analysis of (d, p) reaction data is presented which permits definite two-quasiparticle configuration assignments to be made to most of these latter bands. Evidence is presented which suggests strong mixing of some two-neutron and two-proton bands. A phenomenological four-band mixing analysis is made of the energy and E2 transition-probability data for the ground-state band and the three lowest-lying excited collective positive-parity bands. Good agreement with experiment is obtained. A Coriolis-mixing analysis of the octupole bands has been carried out and good agreement with the data on level energies and E1 transition probabilities to the ground-state band has been achieved. Values of Z, the ratio of the E1 transition matrix element with ΔK = 1 to that with ΔK = 0, involving the octupole bands and the first four 0⁺ bands are derived. For three of these 0⁺ bands, absolute values of these matrix elements are deduced. An interesting alternation in the sign of Z is observed for these four 0⁺ bands.     

Mössbauer study of the electromagnetic properties of the 69.6-keV level in Os 189

The 69.6-keV level with spin 5/2^? in¹⁸⁹Os was investigated by the recoilless resonance absorption technique. Its magnetic moment was found to beμ (5/2)=(0.977±0.014)μ _N. From the measured ratio of the excited and ground-state electric quadrupole moments,Q(5/2)/Q(3/2)=?0.79±0.09, the excited-state quadrupole momentQ(5/2)=?(0.72±0.11)b could be derived. TheE2/M1 mixing parameter of the 69.6-keV ground-state transition was found to beδ=+0.69±0.10. The results are interpreted in terms of two low-energy rotational bands with strong Coriolis mixing.     

High-spin states in189Hg

High-spin levels in¹⁸⁹Hg have been populated via the¹⁷⁵Lu(¹⁹F, 5n) reaction. A rotation-aligned band built on a 13/2⁺ state originating from theνi _13/2 subshell is identified which is interpreted within the framework of “quasiparticle+rotor” models. A negative parity band built on a 21/2^? state which can be accounted for by a three quasi-particle state is also observed.     

Nuclear structure of 189Tl states studied via \beta^{{+}}_{} /EC decay and laser spectroscopy of 189m+gPb

The /EC decay of ^{189m, g}Pb has been studied at the ISOLDE facility using nuclear spectroscopy and in-source laser spectroscopy. A level scheme of ¹⁸⁹Tl has been built from - coincidence relationships and information on the feeding of some excited levels of ¹⁸⁹Tl provided by the hyperfine spectra obtained from laser ionization. The half-lives of both the 13/2⁺ and 3/2^{- 189}Pb isomers have been estimated to be T _1/2 = 50±3 s and T _1/2 = 39±8 s, respectively. Calculations have been performed for different oblate and prolate nuclear deformations using an axial-rotor coupled to one-quasiparticle model, a structure has been suggested for the low-lying levels of the ¹⁸⁹Tl nucleus.     

New levels observed in188Os from the decay of188Re

The level structure of¹⁸⁸Os has been investigated following the decay of 17h¹⁸⁸Re. The energies and relative intensities of 41 gamma rays were determined using large volume high resolution Ge(Li) detectors. The decay was observed to populate the 0⁺ states at 1478 and 1704 keV which were recently observed in (p, t) reaction studies. Additional states at 1414 and 1843 keV were also observed in the decay.     

The decay of121g+m In to levels in121Sn

The decay of¹²¹ g+m In to the excited states of¹²¹Sn was investigated.¹²¹In was produced by the¹²²Sn(γ,p)¹²¹In reaction on an enriched SnO₂ target. Strong indications of the isomeric transition of 321 keV to the¹²¹In ground state were found. In the beta decay of^121m In excited states at 60.1, 908.9, 1101.9, 1120.4, 1403.0, 2864.1, 3119.8 and 3228 keV in¹²¹Sn withJ ^π values 1/2⁺, 3/2(5/2)⁺, 3/2⁺, 5/2⁺, 5/2⁺ and 1/2⁺ or 3/2⁺ for the three levels around 3 MeV, are fed. In the decay of the¹²¹In ground state only the 7/2⁺ level in¹²¹Sn at 925.3 keV is fed.     

Levels in 156Gd studied in the (n, γ) reaction

Levels up to 2.3 MeV in ¹⁵⁶Gd have been studied using the (n, γ) reaction. Energies and intensities of low-energy γ-rays and electrons emitted after thermal neutron capture have been measured with a curved-crystal spectrometer, Ge(Li) detectors and a magnetic electron spectrometer. High-energy (primary) γ-rays and electrons have been measured with Ge(Li) detectors and a magnetic spectrometer. The high-energy γ-ray spectrum has also been measured in thermal neutron capture in 2 keV resonance neutron capture. The neutron separation energy in ¹⁵⁶Gd was measured as S_n = 8535.8 ± 0.5 keV.About 600 transitions were observed of which ~50% could be placed in a level scheme containing more than 50 levels up to 2.3 MeV excitation energy. 42 of these levels were grouped into 15 excited bands. In addition to the β-band at 1050 keV we observe 0⁺ bands at 1168, 1715 and 1851 keV. Other positive-parity bands are: 1⁺ bands at 1966, 2027 and 2187 keV; 2⁺ bands at 1154 (γ-band) and 1828 keV; and 4⁺ bands at 1511 and 1861 keV. Negative-parity bands are observed at 1243 keV (1^?), 1366 keV (0^?), 1780 keV (2^?) and 2045 keV (4^?). Reduced E2 and E0 transition probabilities have been derived for many transitions. The ground band, the β- and γ-bands and the 0⁺ band at 1168 keV have been included in a phenomenological four-band mixing calculation, which reproduces well the experimental energies and E2 transition probabilities.The lowest three negative-parity (octupole) bands of which the 0^? and the 1^? bands are very strongly mixed, were included in a Coriolis-coupling analysis, which reproduces well the observed energies. The E1 transition probabilities to the ground band are also well reproduced, while those from the higher-lying 0⁺ bands to the octupole bands are not reproduced. Absolute and relative transition probabilities have been compared with predictions of the IBA model and the pairingplus-quadrupole model. Both models reproduce well the E2 transitions from the γ-band, while strong disagreements are found for the E2 transitions from the β-band. The IBA model predicts part of the decay features of the higher lying 2⁺₂, 4⁺₁ and 2^?₁ bands.     

Das Kernquadrupolelement des Os189

The hyperfine structure of 11 Os I-lines in the violet and ultraviolet spectral range was investigated by a digital recording Fabry Perot spectrometer. An enriched sample of Os¹⁸⁹ was used in the hollow cathode light source. The recorded structures were analyzed on a computer. The quadrupole coupling constants of the states 5d ⁶6s ^{2 5} D ₂,⁵ D ₃,⁵ D ₄ and 5d ⁷6s ⁵ F ₅ or linear combinations of these coupling constants were deduced from the measurements. With these results the nuclear quadrupole moment of Os¹⁸⁹ was determined to beQ(Os¹⁸⁹)=(0.91 ± 0.10) · 10^?24 cm². This was done using the eigenfunctions ofGluck, Bordarier, Bauche andVan Kleef, which have been calculated for intermediate coupling considering configuration interaction.     

Quasi-gamma bands in even-mass Xe AND Ba nuclei

Low-lying excited states of ^124,126Xe and ¹³²Ba have been studied by means of in-beam γ-ray spectroscopy in (p, xny) reactions. Excitation functions, angular distributions and γ-γ coincidence spectra were obtained. The 2₂⁺ , 3⁺, 4₂⁺ and 5⁺ levels were observed at the following excitation energies in keV: 846.4(2₂⁺), 1247.5(3⁺), 1437.3 (4₂⁺), 1836.6(5⁺) in ¹²⁴Xe, 879.7(2₂⁺), 1317.3(3 ⁺), 1488.2(4₂⁺), 1903.1(5 ⁺) in ¹²⁶Xe and 1032.1(2₂⁺), 1511.3(3⁺), 1729.9(4₂⁺) in ¹³²Ba. The 2214.3 and 2561.7 keV levels in ¹²⁶Xe were tentatively assigned as the 6₂⁺ and 7⁺ levels, respectively. These 2₂⁺, 3 ⁺, 4₂⁺, 5⁺, 6₂⁺and 7⁺ levels are interpreted as members of a quasi-γ band. The E2/M1 mixing ratios of the 2₂⁺ → 2₁⁺ transitions in ^124,126Xe and ¹³²Ba were obtained as + 6.3^+5.3_?2.0 + 10.8^7.8_?3.2 and + 8.3^+4.9_?2.2, respectively.