The decays of 121g,mCd to 121In

The decay of isotope-separated activities of ¹²¹Cd produced in fission have been studied by γ-ray and conversion-electron spectroscopy. A level scheme of ¹²¹In has been constructed. Transition probabilities between some levels have been deduced from a lifetime measurement. The experimental results are compared to a recent theoretical study of ¹²¹In.     

Seeking the phase transition where Cd, Ag, Pd, Rh, and Ru isotopes become “neutron rich”: Isomeric decay in 125,126,127Cd, 123,124,125Ag, 121Pd, 120Rh, and 117Ru

Gamma rays have been identified in the decay of isomers in ^125,126,127Cd, ^123,124,125Ag, ¹²¹Pd, ¹²⁰Rh, and ¹¹⁷Ru that provide information about the low-energy structures of these nuclei. In turn, comparison of low-energy levels in the Cd and Te isotones reveals that, whereas the yrast structures in the Te isotopes rise smoothly as N approaches the closed shell at 82, the 15/2^- to 11/2^- transitions level off as N exceeds 76. This is identified as the point where the Cd isotopes undergo a phase transition and become “neutron rich”.     

Temperature dependence study of the quadrupole interaction of111Cd in antimony

A power law dependence has been observed for the temperature dependence of the quadrupole interaction of the 247 keV state of¹¹¹Cd in antimony, which is similar to that observed for¹²¹Sb and¹²³Sb in antimony.Supported in part by the US Energy Research and Development Administration.     

Investigation of neutron-deficient isotopes in the barium-region

Bombarding targets of 106Cd,¹⁰⁸Cd and¹¹⁰Cd with¹⁶O ions of 52.5–66.0 MeV neutron deficient barium, cesium and xenon isotopes were produced and have been studied using excitation functions and neutron-gamma, proton-gamma, alpha-gamma and gammagamma coincidence measurements. Partial level schemes for¹²³Ba and¹²¹Ba were proposed. A number of gamma transitions was assigned to the different product nuclei. The measured particle emission probabilities from the compound nuclei are compared with different evaporation models. The models mostly underestimate neutron emission and often overestimate the emission of alpha particles.     

Investigation of neutron-deficient isotopes in the barium-region

Bombarding targets of 106Cd,¹⁰⁸Cd and¹¹⁰Cd with¹⁶O ions of 52.5–66.0 MeV neutron deficient barium, cesium and xenon isotopes were produced and have been studied using excitation functions and neutron-gamma, proton-gamma, alpha-gamma and gammagamma coincidence measurements. Partial level schemes for¹²³Ba and¹²¹Ba were proposed. A number of gamma transitions was assigned to the different product nuclei. The measured particle emission probabilities from the compound nuclei are compared with different evaporation models. The models mostly underestimate neutron emission and often overestimate the emission of alpha particles.     

Non-yrast level structure of121Xe via beta decay of121m+g Cs

The results of measurements of the gamma-ray and conversion-electron singles and coincidence spectra from the decay of the 122 s^121m Cs and the 155 s^121g Cs to levels of¹²¹Xe are reported. TheM 3 multipolarity of the 68.5 keV isomeric transition in¹²¹Cs has been deduced. Numerous low-lying levels below 1.6 MeV excitation energy are found. A negative-parity level at 355.9 keV is observed for the first time. The results supplement the low lying energy level systematics in odd-A xenons. A comparison is made with theN=67 barium isotone.     

Spectroscopy of exotic 121, 123, 125Ag produced in fragmentation reactions

Excited states in the neutron-rich ^{121, 123, 125}Ag were studied via the fragmentation of a ¹³⁶Xe beam at 120MeV/nucleon in a thick ⁹Be target. The levels in ¹²¹Ag were populated in the $ \beta$ decay of ¹²¹Pd while those assigned to ^{123, 125}Ag were identified via isomer spectroscopy. The transitions identified in ¹²¹Ag are consistent with the $ \gamma$ -rays reported in ^{117, 119}Ag . The newly observed transitions were placed in the level schemes of ^{123, 125}Ag based on the analysis of $ \gamma$ - $ \gamma$ coincidences and the systematics. We attribute the onset of isomerism in the ^{123, 125}Ag isotopes to the drop in energy of the negative-parity levels similar to the 5^- state in the even-even Cd cores. The proposed level scheme for ¹²⁵Ag is well described by the NuShellX shell model calculations.     

Rotational analysis of the 1Π-X1Σ+ system of phosphorous antimonide

Seven bands of the ¹Π-X¹Σ⁺ band system of P¹²¹Sb have been analyzed in detail. A large number of strong rotational perturbations in the v = 0 and 1 levels and a vibrational perturbation in the v = 0 level of the Π state have been observed. The term values of the rotational levels and rotational constants for the two isotopic species, P¹²¹Sb and P¹²³Sb, are presented.     

The 110Pd, 116Cd(p,p'γ) reactions

The possibility of extending our knowledge about higher-energy collective-type states among the vibrational nuclei by observing γ-rays from states excited by inelastically scattered protons has been examined. Gamma rays from ¹¹⁰Pd and ¹¹⁶Cd were detected in coincidence with inelastically scattered protons; the incident protons had energies of 12 and 13 MeV. Gamma rays, most of them previously unreported, were observed from 17 levels in ¹¹⁰Pd and 14 levels in ¹¹⁶Cd below ≈ 2.5 MeV. The results are compared to predictions of a phonon- model interpretation of the levels. Evidence is shown for the existence of the three-quadrupole phonon quintet in ¹¹⁰Pd.     

The decay of Ag

The γ-radiation following the decay of ¹¹²Ag has been studied with a Ge(Li) detector. A total of 76 γ-rays was observed. The γ-γ coincidence and angular correlation relations involving the 617 keV 2⁺-0⁺ transition have been measured using Ge(Li)-NaI(Tl) and NaI(Tl)-NaI(Tl) detectors. These results have been used to confirm spins and parities of some levels of ¹¹²Cd in the proposed decay scheme. Cross sections for ¹¹²Ag production by ¹¹⁵In(n,α) and ¹¹²Cd(n, p) reactions have been measured; the ¹¹²Ag half-life has been determined as 3.14 ± 0.02 h.     

Temperature dependence of the electric field gradient for111Cd in antimony

For the temperature dependence of the electric field gradient of¹¹¹Cd in the semimetal antimony the well knownT ^3/2 relationship is valid over a wide temperature range. The slope parameterB differs from that for^{121, 123}Sb in antimony by a factor of about 2.3.     

Muon capture rates in Se and Cd isotopes

Energy and time spectra of γ rays following nuclear capture of negative muons in natural Se and Cd and isotopically enriched ⁷⁶Se and ¹⁰⁶Cd targets have been measured with HPGe detectors. Total muon lifetimes in Se and Cd isotopes and partial μ capture rates to excited levels of ⁷⁶As and ¹⁰⁶Ag are obtained. These results are necessary for calculation of nuclear matrix elements of the 2β decay of ⁷⁶Ge and ¹⁰⁶Cd respectively.     

NMR detected by Mössbauer-effect,applied to the system57CoFe

The ratio of the Larmor frequencies of¹¹¹Cd and²H has been measured in an aqueous solution of CdSO₄ with high accuracy.¹¹¹Cd chemical shifts have been investigated in aqueous solutions of CdCl₂, Cd(NO₃)₂, CdSO₄, and Cd(ClO₄)₂ as a function of concentration. Using these, the ratio of the Larmor frequencies of the¹¹¹Cd nuclei for infinite dilution relative to²H in pure D₂O is given. From this ag _I -factor for¹¹¹Cd has been derived and has been compared with theg _I -factor of an optical pumping experiment. The resulting shielding constant is σ^*(hydrated¹¹¹Cd versus¹¹¹Cd atom)=?1.106(4) · 10^?3. This yields an atomic reference scale for all measured NMR line shifts in the liquid and solid state and the possibility of comparing experimental and theoretical shielding constants. As a consequence, the amount of the Knight shift of metallic cadmium becomes 20% larger.     

Evidence for the coexistence of shapes in even-mass Cd nuclei

A quasi-rotational band built on the known proton four-hole, two-particle 0⁺ level at 1473.07-keV in¹¹⁴Cd has been identified, with 2⁺, 4⁺, and 6⁺ members at 1783.44-, 2250.53- and 2876.75-keV respectively. These levels and their properties are compared with those in other even-mass Cd nuclei to show an increasing average deformation in both the 0 ₁ ⁺ (ground-state) and 0 ₂ ⁺ bands when neutron pairs are added beyond¹¹⁰Cd.     

Yrare bands of 121Xe

High-spin states in ¹²¹Xe have been studied via the ¹⁰⁹Ag (16O, p3n) ¹²¹Xe reaction at a beam energy of 80 MeV. Several rotational bands based on one- and three-quasiparticle excitations have been established. Among them, an unfavoured yrare rotational band with unfavoured signature has been newly identified. Received: 19 November 1998     

High-spin study of odd- A 49In isotopes beyond the neutron mid-shell

The ^{115, 117, 119, 121}In nuclei have been produced as fission fragments in three reactions induced by heavy ions: ¹²C + ²³⁸U at 90MeV bombarding energy, ¹⁸O + ²⁰⁸Pb reaction at 85MeV, and ³¹P + ¹⁷⁶Yb at 152MeV. Their level schemes have been built from gamma-rays detected using the EUROBALL III and IV arrays. High-spin states of ^{117, 119, 121}In nuclei have been identified for the first time. Moreover, isomeric states lying around 2.5MeV have been established in ^{119, 121}In from the delayed coincidences between the fission fragment detector SAPhIR and the gamma array. Most of the observed states can be described by coupling a proton g _9/2 hole to a Sn core, while the intruder band based on an orbital from the π[g _7/2/d _5/2] sub-shells behaves as the ground-state band of neighbouring Cd isotopes. Received: 24 May 2002 / Accepted: 11 June 2002 / Published online: 19 November 2002 RID="a" ID="a"e-mail: porquet@csnsm.in2p3.fr RID="b" ID="b"Present address: CEA-DIF, DAM/DCRE/SDE/LDN, 91680 Bruyères-le-Chatel, France. RID="c" ID="c"Present address: CSNSM IN2P3-CNRS and Université Paris-Sud 91405 Orsay, France. RID="d" ID="d"Present address: CEA/Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette Cedex, France. Communicated by D. Schwalm     

IBFM for Ba isotopes and chaoticity

Fluctuation properties have been analysed for the energy levels predicted by IBFM calculations in the Ba isotopes¹²¹Ba to¹³¹Ba. The results indicate, in general, a situation which is close to the chaotic limit. For the lighter isotopes studied (121 and 123), a phase transition is obtained in the low-spin, positive parity states, from a situation close to regularity at low excitation energies, towards chaoticity at higher excitations.     

Levels and transition probabilities in 124In as observed in the decay of 124Cd

The levels of ¹²⁴In, which are populated in the decay of ¹²⁴Cd, have been investigated at the OSIRIS on-line facility by means of conversion electron and γ-ray spectroscopy. A γ-γ coincidence measurement combined with the deduced transition intensities permitted construction of a unique level scheme. The half-life of the 243 keV level of ¹²⁴In has been determined to be 50 ± 6 ns by the method of delayed coincidences.     

Nuclear level structure of low lying levels of109Cd

Nuclear level structure of low lying levels of¹⁰⁹Cd from¹⁰⁹In decay has been investigated by gamma-gamma angular correlation experiments using a Ge(Li)-NaI(Tl) fast coincidence arrangement. From the measurement on the 347.4?326.3, 347.4–650.1, 287.7–650.1, 203.3–420.5, 203.3–619.3 keV cascades spin-parity assignments of 5/2⁺,1/2⁺,7/2⁺,5/2⁺, 7/2⁺,5/2⁺,9/2⁺, and 9/2⁺, have been made to the ground, 59.5, 203.3, 347.4, 623.8, 673.7, 822.5 and 997.5 keV states, respectively, of¹⁰⁹Cd. The results have been discussed and compared with the previous works.     

High spin states in126Xe

High spin states of¹²⁶Xe have been populated by means of the¹¹⁶Cd(¹³C, 3n) reaction using the OSIRIS-12 detector system. A level scheme consisting of 13 bands has been established. More than 40 new levels were observed and several spin and parity assignments could be made. Experimental Routhians and alignments of selected bands are presented.