Properties of excited levels in102Rh by the102Ru(p,nγ) reaction

The level scheme of¹⁰²Rh has been investigated by the¹⁰²Ru(p, nγ) reaction in the proton energy range 3.1 MeV≦E _p≦6 MeV. Excitation functions,γ-γ coincidences and pulsed beam measurements have been performed and a level scheme including 33 excited states up toE _x≈650 keV has been constructed. Theγ-branchings of several levels have also been measured. The lifetimes of 5 excited states have been determined with the centroid-shift method:τ _m(105.2 keV)=(1.3±0.3) ns,τ _m(123.7 keV)=(0.6±0.3) ns,τ _m(178.6 keV)=(1.5±0.3) ns,τ _m(208.7 keV)=(0.5±0.3) ns,τ _m(359.6 keV)=(0.8±0.4) ns. Upper limits have been placed for the lifetimes of 20 other levels.     

Messung der mittleren Lebensdauern des 748 keV- und des 776 keV-Niveaus in51Cr

Using theγ-radiation of 748 and 28 keV the half-lives of the first two excited states in⁵¹Cr at 748 and 776 keV have been measured by a pulsed beam technique. The interesting states were populated by the reaction⁵¹V(p, nγ)⁵¹Cr at 4 MeV proton energy. The half-lives were found to beT _1/2(⁵¹Cr, 748 keV)=(7.35±0.03) ns andT _1/2(⁵¹Cr, 776 keV)=(5.53±0.07) ns. The influence of the 28 keV transition between the two levels upon the lifetime of the 748 keV state has been investigated. The 776 keV-state populates the 748 keV state only by 8.4%. The lifetime of the 776 keV state, therefore, cannot account for the anomalous long lifetime of the level at 748 keV as has been proposed by Bartholomew et al.     

Lebensdauermessungen am 341,2keV-Zustand und am 404,8 keV-Zustand in131Xe

Lifetime measurements of two excited states in¹³¹Xe populated by the decay of¹³¹I have been carried out. Analysis of data, delivered from a delayed γ-γ-coincidence experiment with a Ge(Li)-Plasticdetector combination, resulted in the following values:T _1/2 of 341.2 keV level in¹³¹Xe: (2.15 ± 0.07) nsT _1/2 of 404.8 keV level in¹³¹Xe: <0.5 ns.     

Lifetime measurements and particle-core coupling calculations in144Sm

Applying the generalized centroid shift method in the¹⁴²Nd(α, 2n)¹⁴⁴Sm reaction the following half-lives have been measured:T _1/2(3,376 keV)=(1.6±0.2) ns,T _1/2(3,460 keV) =(0.5±0.2) ns andT _1/2(5,150 keV)≦0.3 ns. Level energies and electromagnetic transition rates have been calculated within a particle-core coupling approach that is based on the shell model with configuration mixing. The persistence ofl-forbiddenness of M1 transitions between rather complex configurations could be confirmed.     

Study of excited states in49V with the48Ti (p, γ)49V reaction

In the⁴⁸Ti(p, γ)⁴⁹V reaction gamma decays of thirteen resonances betweenE _p =960 and 1570 keV are investigated. Level energies within ±0.5–±2.0 keV andQ-value 6756.8±1.5 keV are obtained. Branching ratios for the resonance states and strongly populated bound states are given. Gamma-ray angular distribution measurements yield the followingJ(keV) assignments of⁴⁹V bound and resonance states:J(1140)=5/2,J ^π(2235)=5/2^(?),J(2264)=(3/2),J(2308)=3/2,J(3912)=3/2,J(8105,Ep=1374keV)=(1/2) andJ ^π(8289,E _p =1564keV)=3/2^(?). Multipolarity mixing ratios for all measured primary and secondary gamma rays are tabulated. Dopplershift attenuation measurements yield the mean lifetimes τ _m (keV) of the following bound states in⁴⁹V:τ _m (748)=(200± ₁₀₀ ⁴⁰⁰ )fs, τ _m (1140)=(250± ₁₀₀ ⁵⁰⁰ )fs, τ _m (1155)>400 fs, τ _m (1515)=(45± ₂₀ ³⁰ )fs, τ _m (1644)=(55± ₂₀ ³⁰ )fs, τ _m (1661)=(25±5)fs, τ _m (1994)>400 fs, τ _m (2235)=(30± ₁₅ ³⁰ )fs, τ _m (2264)=(45± ₁₅ ³⁰ )fs and τ _m (2308)=(20±10)fs.     

Conversion coefficients and E0 transitions in102, 104, 106Pd

In in-beam (p, p′) experiments, electron and γ-spectra were measured in the electron energy range of 500-1840 keV for¹⁰²Pd and¹⁰⁴Pd, and 600–1580 keV for¹⁰⁶Pd. The conversion coefficients of all transitions in this range were obtained with accuracies of about 20%, in some favourable cases 10%. Special attention was given to 0⁺′-0⁺ transitions from the two-phonon triplets to the ground states with the following results for the branching ratios 0⁺′-0⁺ (ground state) to 0⁺′-2⁺ (one-phonon state):¹⁰²Pd:T _k (E0)/T _γ (E2)<(2.1±3.6)·10^{?7 104}Pd:T _k (E0)/T _γ (E2)=(6.0±1.4)·10^{?5 106}Pd:T _k (E0)/T _γ (E2)=(6.0±2.0)·10^?4     

Konversionskoeffizienten und Fluoreszenzausbeuten beim Zerfall des Hg199m

Hg^199m was produced by bombarding natural HgO with fast neutrons. The conversion electrons of the cascade decay were investigated with Si(Li)-counters. By application of the summing technique the conversion coefficients andL-shell fluorescence yields of Hg were determined. The gamma rays were studied with a Ge(Li)-counter. The following results were obtained: half-lifeT _1/2=(42.6± 0.2) min; energies of the transitionsE _γ1=(374.1± 0.1) keV,E _γ1=(158.3± 0.1)keV; intensity ratio of the gamma raysI _γ(158 keV):I _γ(374keV)=(424± 42):100; conversion coefficients α_K158=0.30± 0.03, α_total158=0.94± 0.09, α_K158/α_LM...158=0.47± 0.02, α_L158/α_M...158=3.10± 0.16;α_K374=3.51± 0.28,α_total1374=6.19±0.47,α_K374/α_LM...374=1.32±0.04, α_L374/α_M...374=2.14±0.11;L-shell fluorescence yields \(\bar \omega _L \) =0.40± 0.04, ω_KL=0.41±0.04.     

Transition probabilities and hole-core coupled configurations in107In

The nucleus¹⁰⁷In was studied by in-beam spectroscopic methods in (HI, xn yp) reactions. Spin and parity values of some levels were determined by conversion electron andγ-ray measurements. Using the generalized centroid shift method, the half-lives T_1/2(19/2⁺, 2003.6 keV)=0.6±0.2 ns and T_1/2(17/2⁺, 1853.4 keV)=1.7±0.3 ns were measured. The systematics of the lowest members of the multipletπg ₉ ^2/?1 ×6 ₁ ⁺ in^111,109,107In is discussed     

Accurate determination of the half-lives of95Zr and95Nb

The half-lives of⁹⁵Zr and⁹⁵Nb have been determined byγ-ray counting using a Ge(Li) detector and a NaI(Tl) crystal. Data have been recorded at regular time intervals during time periods up to nine times the respective half-life. The obtained results are T_1/2(⁹⁵Zr)= (64.05±0.06) days and T_1/2(⁹⁵Nb)=(34.97±0.03) days. A detailed discussion of the measurements and the uncertainty assignment is given.     

Transition probabilities and the structure of some negative-parity states in126,130Xe and132Ba

The lifetimes of several negative-parity states in^126,130Xe and¹³²Ba have been determined by means of the generalized centroid-shift method. The reactions^124,128Te(α,2n) and¹²²Sn(¹³C, 3n) have been used. Following results were obtained:T _1/2(2758 keV)=1.3±0.2 ns in¹²⁶Xe,T _1/2(2060 keV)=0.20±0.10 ns,T _1/2(2104 keV)=0.50±0.10 ns,T _1/2(2376 keV)=0.30±0.10 ns andT _1/2(2973 keV)=4.6±0.4 ns in¹³⁰Xe as well asT _1/2(2120 keV)=0.40 _?0.10 ^+0.20 ns in¹³²Ba. A systematics of the B(E2; 7 _? ¹ ?5 ₁ ^? ) values in theN=76 nuclei is presented. Electric dipole and quadrupole transition rates are discussed in terms of octupole and quadrupole collectivity. The structure of the 5 ₁ ^? and 7 ₁ ^? states is considered. Nuclear reactions:^124,128Te(α, 2 _n ),E=26 MeV,¹²²Sn (¹³C, 3n),E=53 MeV; measuredE _γ I _γ , γ-r.f. DeducedT _1/2, B(σL) in^126,130Xe and¹³²Ba. Ge detectors. Generalized centroid-shift analysis.     

Decay studies of131Ba

Bombarding a⁸⁵Rb target by 27 MeVα-particles the following half-lives of excited states in different nuclei have been determined by means of the generalized controid shift method: in⁸⁷Y,T _1/2(2827.1 keV)=0.75±0.10 ns,T _1/2(2675.9 keV)=0.25±0.10 ns,T _1/2(3595.3 keV)=0.5±0.2 ns andT _1/2(2986.9, 3094.4 keV)<0.1 ns; in⁸⁸Y,T _1/2(232.1 keV)=0.8±0.1 ns and in⁸⁵Rb,T _1/2(151.2 keV)=0.6±0.1 ns. In⁸⁷Y, the members of the doublet (vg ₉ ^2/?2 )₈₊ (πp_1/2) are identified. E2 transition rates 21/2⁺? 17/2⁺ in odd A≈ 90 nuclei are shown to represent essentially core transitions. Evidence for the existence of seniority-five configurations is found.     

Decay properties of the 19/2− isomers in113,117Sb

By means of the generalized centroid-shift method, the following half-lives were determined:T _1/2(3045 keV)=3.7±0.3 ns in¹¹³Sb using the reaction¹⁰⁴Pd(¹²C,p2n) as well asT _1/2 (1322.8 keV)=3.5±0.3 ns,T _1/2(2779.8 keV) =0.50±0.15ns,T _1/2(2874.9 keV)<0.2 ns andT _1/2(3072.9 keV)<0.1 ns in¹¹⁷Sb using the¹¹⁶In(α, 2n) reaction. Three-quasiparticle configurations of the type πd _5/2ν(h_11/2 d _3/2) in^113,117Sb are found to dominate in the wave functions of the 19/2^? states at 3045 and 2780 keV in¹¹³Sb and¹¹⁷Sb, respectively. TheB(E2, 19/2^? → 15/2^?) values in^113–119Sb are discussed.     

Lebensdauer- und Spinrotationsmessungen an den ersten angeregten Zuständen in197Pt und197Hg

The magnetic moment of the 134 keV state of¹⁹⁷Hg was measured by the differential angular correlation method. The half life of the state was redetermined and the half life of the 53 keV state in¹⁹⁷Pt was determined. The results are:μ(134 keV state in¹⁹⁷Hg)=+0.950(65) nmT _1/2(134 keV state in¹⁹⁷Hg)=7.3(2) nsT _1/2(53 keV state in¹⁹⁷Pt)=16.5(1.5) ns.     

The study of the ground state rotational bands in U 233 and U 235 by the inelastic scattering of deuterons

The ground state rotational bands in the odd isotopes of uranium U 233 and U 235, were studied by the inelastic scattering of 13.1 MeV deuterons. Seven members of these bands were seen in both nuclei. By fitting the experimental energies of the levels to the relation E(I)= =AI(I+1)+B[I(I+1)]², the parametersA andB were determined. Their values and the upper limits of the quadrupole reduced transition probabilities determined from the cross sections were: U 233:A=(5.93±0.10)keV,B=(?0.002±0.001)keV,B(E2,5/2→7/2)= =(6.51±0.66)×10^?48 e² cm⁴,B(E2,5/2→9/2)=(2.80±0.37) X 10^?48 e² cm⁴. U 235:A=(5.36±0.04)keV,B=(?0.0017±0.0004) keV,B(E2,7/2→9/2)=(8.05±0.71) × × 10^?48 e² cm⁴,B(E2,7/2→11/2)=(2.17±0.39) X 10^?48 e² cm⁴.     

Multipole mixing ratios of transitions in168Er

Time-integral and time-differentialγ-γ directional correlation measurements were performed for cascades in¹⁶⁸Er populated from the electron-capture decay of¹⁶⁸Tm(87d). The¹⁶⁸Tm source was dissolved in HF acid to minimize extranuclear perturbations. The results of the time-differential experiment for the 448-99.3 keV and 448-198 keV cascades showed agreement with time dependent interaction and gaveλ ₂(1094)=(0.79±0.09) ×10⁷ sec^?1. The attenuation factors for the 80 keV level were determined asG ₂₂ (80)=0.90±0.01 and G₄₄(80)=0.94±0.01. OnlyI=4 spin value for the 1094 keV level is consistent with our measurements. The 632, 731, 741, and 816 keV transitions connecting theK=2⁺ andK = 0⁺ rotational bands were found to be of almost pureE2 character. The 99.3, 198, 547, 720, 830, and 1277 keV transitions are of practically pureE1 multipolarity. The 448 keVMl transition has (0.8 _?0.4 ^+2.0 )%E2 admixture. The results for the 1014?80keV cascade give (23±4)%E3 component in the 1014 keV transition.     

Untersuchung der Anregungen von186Re nach der (n, γ)-Reaktion

Prompt and delayedγ-γ-coincidences were measured after slow neutron capture in¹⁸⁵Re by use of Ge(Li)-detectors. New isomers were found at 99.4 keV (T_1/2=27±7ns) and at ≈330keV (T_1/2=17.4±0.7 ns). The evaluation of coincidence data established 10 rotational bands with band heads below 700 keV. The level scheme is discussed in detail: Nilsson assignments are proposed for the band configurations, and calculations of Coriolis mixing andγ-transition probabilities are presented which reproduce the experimental level energies and transition intensities very satisfactorily.     

Die Faktoren der inneren Umwandlung beim35Br80m (4,4 Std)

The intensities of the 37keV- and 49keV-γ-rays of Br^80m have been measured with the aid of Na J-scintillation spectrometers and compared with the intensity of the conversion electrons registered by an anthracene split crystal spectrometer. It was possible to separate the 49 keV-γ-radiation from the intense 37 keV-line by selctive absorption with balanced Sm- and Gd-filters. The internal conversion coefficientsα(49 keV)=298±30 andα (37 keV)=1,59±0,10 are in good agreement with the calculated values for M₃- and E₁-transitions. The half life was measured yielding a value ofT _1/2=(4,40±0,05) h.     

Untersuchung der vier ersten angeregten Zustände des6Li-Kernes durch Elektronenstreuung

Inelastic electron scattering cross sections were measured for energies below 60 MeV and momentum transfersq between 0.2 and 0.6 fm^?1. Ground state radiative widths Γ _γ ⁰ and transition radiiR _tr were deduced. 2.18 MeV: Γ _γ ⁰ (E2)=(4.40±0.34) · 10^?4 eV,R _tr=(4.28±0.39)fm; 3.56MeV: Γ _γ ⁰ (M1)=(8.31±0.36)eV,R _tr=(2.90±0.10)fm; 4.27 MeV: Γ _γ ⁰ (E2)=(5.4±2.8) · 10^?3 eV,R _tr=(3.4±1.2) fm. The excitation of the 5.37 MeV level shows a transverse angular dependence.     

Der Zerfall des125m Xe,des127m Xe und des127g Xe

The decay of^125m Xe produced by the reaction¹²²Te(α, n)^125m Xe using a target enriched in¹²²Te (95.4%) and the decay of^127m Xe produced by the reaction¹²⁷J(d, 2n)^127m Xe have been investigated: ^125m Xe decays with a half-life ofT _1/2=(56±3) sec by ayy- cascade withE _γ1=(140.4 ±0.5) keV andE _γ2=(110.5 ±0.5) keV. The experimental conversion coefficients yield multipolarities ofE3 for the 140.4 keV isomeric transition and predominantlyM1 for the 110.5 keV-transition. ^127m Xe decays with a half-life ofT _1/2=(71±2) sec. The decay also proceeds by aγγ-cascade with an isomeric E3 transition ofE _γ1=(172.5±0.3) keV and a predominantlyM1 transition ofE _γ2=(124.6±0.3) keV. In the decay of^127g Xe an additional branching of the electron capture to a level at (618.1±0.3) keV was observed. The relative probability forK-captureP _K618/P_K375=0.40 ±0.07 yields a total transition energyQ _EC=(664 ±4)keV. A spin of 1/2⁺ was assigned to the ground state.