High-Spin Level Scheme of Odd-Odd 140Pr Nucleus

High spin level structure of doubly odd nucleus ¹⁴⁰Pr has been investigated using in beam γ spectroscopy techniques by means of the ¹³⁰Te(¹⁴N,4n)¹⁴⁰Pr reaction at beam energy of 58MeV.γ-ray excitation functions,γ-ray singles and γ-γ-t coincidences were measured experimentally.The level scheme of ¹⁴⁰Pr,including 27 new levels and 42 new γ-rays,was established for the first time up to 4717.3keV in excitation energy.Based on the measured γ-ray anisotropies,spin values were suggested to the levels in ¹⁴⁰Pr.Several quasiparticle configurations are discussed on the basis of systematics in the neighboring odd odd nuclei,and interpreted qualitatively.     

Particle-core coupling in 141Nd

High-spin states in 141Nd have been studied using in-beam γ-ray spectroscopic techniques via the 130Te(16O, 5nγ)141Nd reaction. The level scheme of 141Nd has been extended up to an excitation energy of 7614.5 kev including 12 new γ rays deexciting 15 new levels. According to particle-vibrator coupling and semi-empirical shell model calculations, the level structure of 141Nd can be well interpreted by coupling an h11/2 neutron-hole to the respective excited states in 142Nd core.     

First In-beam γ Spectroscopic Experiment at HIRFL

The in-beam γ expedmental setup of HIRFL, which includes SFC(ECR ion source), direct-link-pipe(limit jaws) and in-beam γmeasurement system, was adjusted and tested with its first in-beam γ experiment. All performances, such as neutron and γ backgrounds of the setup have reached to an ideal level. With some special γ-ray spectroscopic techniques, the in=beam γ experiment, including γ single spectrtum. γ excitation funcdon, γ angular distdbudon and γ-γ-t coincidence measurements, was perfomned using reacdon ¹⁶O (¹⁹⁷Au, xn).     

Study of the Low Excited States of 72Ge

The radioactive decay of ⁷²Ga has been investigated by means of NaI-HpGe Compton-suppress spectrometer,and γ-γ coincidence measurements Performed with two HpGe detectors coupled to three-parameter(γ-γ-T) data acquisition system. 2.3×10⁷ coincidence events are collected. A new decay scheme of 72Ga including 26 levels,87 γ-rays is established. The extensive coincidence relationships are used to identify the γrays and levels of 72 Ge, such as new γ-rays of 225. 92, 826.97, 1349.71,1475. 32, 1667.91, 2105.28, 2247.39keV and new levels of 3248.01, 3396.27, 3806.10,3864.56keV. The unsure transitions of 112.59, 937.97, 2402.25, 2939.95keV and level of 2939.83keV are confirmed in thes work. No evidence has been observed for the existences of 113.5, 1155.7, 1192.4keV γ-rays and level of 3707.1keV. The transitiou of 317.72keV γ-ray is moved from 3757.26-3439. 51keV level to 3565.85-3248.01keV level.     

Study of the high-energy part of the spectrum of γ rays from the neutron-induced fission reaction of 235U nuclei

The spectrum of γ rays from the neutron-induced fission reaction of ²³⁵U nuclei has been investigated in the energy range 10–90 MeV. The experiment was performed in the horizontal channel of a nuclear reactor. The energy spectra was measured using a single-crystal NaI(Tl) spectrometer. The data on the energy dependence of the yield of γ rays have been obtained in the energy range 10–36 MeV. The upper limit of the probability of γ-ray emission has been determined for the range 36–90 MeV.     

Nuclear viscosity of hot rotating 240Cf

In a detailed investigation of giant dipole resonance (GDR) γ-ray yield from ²⁴⁰Cf populated in the ³²S + ²⁰⁸Pb reaction, the absolute γ-ray/fission multiplicities are extracted over a wide range of excitation energy and angular momentum. The enhanced yield of GDR decay γ rays has been analyzed within the framework of a modified statistical model containing the nuclear viscosity as a free parameter. The extracted nuclear dissipation coefficient is found to be independent of the temperature. Large constant dissipation during the saddle-to-scission path provides good fits to the γ-ray spectra.     

Results of observations of very high energy Cyg X-3 and Cyg γ-2 sources in Crimea

The observations at the Research Institute “Crimean Astrophysical Observatory” with the GT-48 γ-ray telescope in 2006 revealed very high energy γ rays from the unidentified Cyg γ-2 source and the Cyg X-3 X-ray source with a high confidence level (Q > 4).     

Level Scheme of High-Spin States in 145Tb

High-spin states of ¹⁴³Tb have been studied via the ¹¹⁸Sn(³²S,1p4n)¹⁴⁵Tb reaction by means of in-beam γ-ray spectroscopy. Measurements of γ-ray excitation functions and γ-γ-t coincidences were performed with 12 BGO(AC)HPGe detectors. A level scheme for ¹⁴⁵Tb including 41 γ-rays which come from the deexcitations of the 24 levels, has been established for the first time based on an analysis of the γ-ray excitation functions, γ-γ coincidence relationships, intensity balances and cross-over transitions. The spins for most of the levels in the scheme are assigned according to the results of the measured γ-ray anisotropies. Considering the structure similarity between ¹⁴³Eu and ¹⁴⁵Tb, the low-lying levels in 145Tb are interpreted by coupling a h_9/2 proton to the excited states in ¹⁴⁴Gd core.     

Decay of127Ce to low-lying states in127La

The high-spin states of¹⁹⁸Bi have been studied in the reaction¹⁸⁷Re(¹⁶O, 5n)¹⁹⁸Bi at¹⁶O energies from 85 to 105 MeV. In-beam measurements of γ-ray excitation functions, γ-γ-t coincidences and γ-ray angular distributions were carried out with six BGO(AC)HPGe detectors and one intrinsic Ge planar detector. A level scheme for¹⁹⁸Bi- with 26 γ rays was established for the first time, including a 15⁺ isomer with a measured half-life of 8.0±3.6 ns.     

Decay of 95Ru

1.65h ⁹⁵Ru was produced and studied by y ray spectroscopy of ⁹²Mo(a, n)reaction, 34 of the 130 obversed y rays following ⁹⁵Ru decay are new. According to coincidence relations, 29 new γ rays were flited into level scheme, the placement of 7 γ rays in level scheme were confirmed, 3 new levels were assigned, a modified and expanded decay scheme was proposed.     

Observation of active galactic nuclei on the GT-48 CrAO γ-ray telescope in 2004

The results of observations of active galactic nuclei on the γ-ray telescope GT-48 (Crimean Astrophysical Observatory) in 2004 are reported. Fluxes of very-high-energy γ rays (E ≥ 10¹² eV) from the 3C 66A, Mkn 421, Mkn 501, and 1H 1426 objects have been recorded at a level exceeding 4σ. The upper values of γ-ray fluxes for the active nuclei of the 1ES 1959 and BL Lac galactics are presented. Analysis of the data on the 3C66A object confirmed the existence of γ-ray fluxes from this source. This object was previously discovered in Crimea.     

New Neutron-Rich Nuclide 185Hf

New neutron-rich nuclide ¹⁸⁵Hf has been identified for the first time.The ¹⁸⁵Hf was produced via the ¹⁸⁶W(n,2p)¹⁸⁵Hf reaction by 14MeV neutron irradiation of natural metallic tungsten powder and separated by radiochemical methods.The identification of ¹⁸⁵Hf was based on the observation of decay γ-ray of its daughter ¹⁸⁵Ta.A half-life of 3.5±0.6min was determined for ¹⁸⁵Hf by fitting the measured growth and decay curve of the 177.59keV γ-ray which is the strongest decay γ-ray of ¹⁸⁵Ta.In addition,a new γ-ray of 164.5±0.5keV was found and assigned to ¹⁸⁵Hf.     

New states and γ-transitions in 209Bi observed in the (3He, d*γγ)-subcoulomb-reaction

High-spin states in ¹⁴³Pm have been investigated via the ¹²⁸Te(¹⁹F,4nγ)¹⁴³Pm reaction using techniques of in-beam γ-spectroscopy. γ-ray singles, γ-γ coincidences, γ-ray anisotropies and DCO ratios have been measured. Based on these measurements, the level scheme of ¹⁴³Pm has been extended up to an excitation energy of 10535.4 keV, including 48 new γ-rays deexciting 28 new levels. The yrast levels in ¹⁴³Pm can be understood qualitatively in the framework of a weak-coupling model. Received: 10 July 2000 / Accepted: 12 October 2000     

Precise measurement of the energy of γ rays excited in <Superscript>191</Superscript>Pt decay

The energy differences for 19 pairs of γ rays are measured with a γ spectrometer. The first γ transition in each pair is excited in decay of ¹⁹¹Pt, and the second transition, accompanying the decay of ¹⁸²Ta or ¹⁹²Tr is a third-order nuclear spectroscopic normal. The energies of nine ¹⁹¹Ir levels and 36 γ-ray photons accompanying decay of ¹⁹¹Pt, were determined with high accuracy on the basis of these data.     

Negative-muon capture in <Superscript>150</Superscript>Sm

The energy and time spectra of γ rays emitted during negative-muon capture in ¹⁵⁰Sm were studied. The total muon lifetime in ¹⁵⁰Sm was measured. The yields of several radioactive isotopes in this reaction were determined. The partial γ-ray yield upon muon capture by a ¹⁵⁰Sm nucleus were measured.     

Particle-core coupling in141Nd

High-spin states in¹⁴¹Nd have been studied using in-beam γ-ray spectroscopic techniques via the¹³⁰Te(¹⁶O, 5nγ)¹⁴¹Nd reaction. The level scheme of¹⁴¹Nd has been extended up to an excitation energy of 7614.5 keV including 12 new γ rays deexciting 15 new levels. According to particle-vibrator coupling and semi-empirical shell model calculations, the level structure of¹⁴¹Nd can be well interpreted by coupling an h_11/2 neutron-hole to the respective excited states in¹⁴²Nd core.     

The nuclear structure of 151Pm in the low excitation region < 1 MeV

The level scheme of ¹⁵¹Pm populated by the β-decay of 12 min ¹⁵¹Nd has been studied using Ge(Li) detectors as singles and coincidence γ-ray spectrometers. Most of the new γ-rays have been included in a partial level scheme of ¹⁵¹Pm involving four new levels. Angular correlation measurements on the 170.752–255.678 keV and 170.752–138.882 keV cascades have been made with the result A₂ = 0.088±0.005 and ?0.02 – +0.05, respectively. A PAC measurement on the 170.752–255.678 keV cascade has yielded the g-factor of the 255.676 keV level as g = 1.18 ±0.16. A Nilsson-model calculation including Coriolis coupling has been made and the experimental level energies have been well reproduced by the Nilsson orbitais [413]↓, [411]↑, [420]↑, [532]↑, [541]↑ and [550]↑. Theoretical transition rates, E2/M1 mixing ratios, branching ratios and g-factors are in good agreement with experimental values.     

Identification of New Isotope 238Th

Unreported heavy neutron-rich nuclide ²³⁸Th has been produced via a multinucleon transfer reaction by 60MeVIu ¹⁸0 ions bombardment of natural uranium.Thorium was radiochemically separated from the mixture of uranium and reaction products. ²³⁸Pa as a daughter nucleus of ²³⁸Th has been identified according to the growth and decay of ²³⁸Pa γ rays which has been observed. The half-life of ²³⁸Th was determined to be (9.4 + 2.0) min. At the same time, a new γ ray of (89.0 + 0.3) keV with T_1/2= (8.9 + 1.5)min was found in the γ spectrum gated with the K_α1, X ray of Pa and assigned to ²³⁸Th decay based on the measurements of its transition energy and the half-life.

     

A New Heavy Neutron-rich Isotope 238Th

A new nuclide ²³⁸Th has been produced via multinucleon transfer reaction induced by 60MeV/u ¹⁸O ion irradiation of natural uranium. The thorium was radiochemically separated from the mixture of uranium and its reaction products. The activity of thorium was measured by using a HPGe detector and a planar HPGe detector. The ²³⁸Th has been identified for the first time by measuring the growth and decay of the γ-rays from its daughter ²³⁸Pa. The half-life of 238Th was determined to be (9.4±2.0)min. In addition,a new (89.0±0.3)keV γ-ray with T_1/2=(8.9±1.5)min was observed and assigned to ²³⁸Th decay based on the measurement of transition energy and half life.     

The γ-ray spectrum following the β−-decay of147Nd

The still existing discrepancies in the γ-ray spectrum accompanying the β^?-decay of¹⁴⁷Nd could be cleared up by careful measurements with high-resolution Ge(Li)-detectors. It could be shown that these discrepancies are caused by radioactive impurities of^148m Pm thus excluding several energy levels and γ-ray transitions reported in earlier papers. The experimental level scheme is compared with the predictions of intermediate coupling theory.