Study of122Te(n, γ)123 Te reaction

-rays emitted after thermal neutron capture in¹²²Te have been investigated for the first time. Energies and intensities of 80 transitions assigned to¹²³Te have been determined. Fortyeight of these transitions have been placed in the¹²³Te level scheme among 27 excited levels. Two new levels of 1808·8 and 2092·3 keV,J=(1/2, 3/2), have been observed. The neutron binding energy has been found to be 6929·1±0·5 keV. The role of direct capture mechanism has been examined.     

A study of the125Te(n, γ)126Te reaction with thermal neutrons

The¹²⁵Te(n, )¹²⁶Te reaction has been studied with thermal neutrons. Totally 113 lines in the -ray spectrum were assigned to radiative transitions in the¹²⁶Te isotope. The neutron separation energy of¹²⁶Te was evaluated to be 9113.8±0.1 keV. The experimental values of the partial cross sections of the primary E1-transitions were compared with predictions of the Lane-Lynn theory.     

Study of the187W states excited in the (n, γ) reaction

A singles-ray spectrum and a spectrum of summed amplitudes of coinciding pulses (SACP) were measured in the¹⁸⁶W(n, )¹⁸⁷W reaction experiment on the thermal neutron beam. It was for the first time that the data on¹⁸⁷W-transitions were obtained in the excitation energy region from 1500–2500 keV. The neutron binding energy was determined to beB _n=5467.25 (4) keV (statistical error only). In result the level scheme of¹⁸⁷W was developed in the excitation energy interval 1E _f < 3.4=" mev,=" which=" contained=" 105=" levels=" with=" about=" 70=" of=" them=" being=" identified=" for=" the=" first=" time.=" the=" experimental=" values=" for=" summed=" intensities=" of=" two-step=" cascades=" were=" established=" to=" exceed=" those=" predicted=" by=" the=" modern=" statistical=" theory=" (by=" 36±6%).=" this=" is=" explained=" by=" a=" considerable=" contribution=" of=" few-quasiparticle=" components=" to=" wave=" functions=" of=" compound=" and=" intermediate=">     

Study of 124Te by the 122Sn(α,2nγ) reaction and by the decay of 124I

In-beam γ-ray spectroscopy and the decay of ¹²⁴I were used to study the nuclear structure of ¹²⁴Te. On the basis of γγ-coincidences, a level scheme was constructed with over 100 levels and 170 transitions. The use of excitation functions and angular distributions for the (α, 2n) reaction, and the log(ft) values for the decay, allowed spin assignments for a large number of the levels to be made. The resulting level scheme was interpreted in the framework of the interacting boson model and the particle-core coupling model.     

A study of the low-lying states in 178Hf through the (n, γ) reaction

The nucleus ¹⁷⁸Hf was studied through thermal neutron and averaged resonance neutron capture reactions. The γ-ray and conversion electrons were measured with high resolution spectrometers. A level scheme up to an excitation energy of ∼2.1 MeV was constructed. It includes ∼65 levels, most of which are ordered into 18 rotational bands. The level scheme is complete up to about 1800keV for spins between 2 and 5. The neutron binding energy was established to be at 7626.3 (3) keV. The consistent Q form of the IBA-1 (CQF) was used to describe the low-lying collective γ and K^π = 0⁺ bands. The agreement with the data was found to be excellent for the energies and B(E2) ratios of the ground and γ bands, whereas the agreement was poor for the K^π = 0⁺ bands.     

Study of the reaction 12C(γ, n 3He)2α

The possibility of separating, with the aid of photoemulsion, channels of the reaction ¹²C(γ, n ³He)2α that involve the formation of ⁷Be and ⁸Be intermediate nuclei in excited states is studied. The experimental energy distributions of these nuclei are obtained. The relative yields from these reaction channels are estimated.     

Study of 113Cd by the 110Pd(α,nγ) reaction

The nuclear structure of ¹¹³Cd was studied using in-beam γ-ray spectroscopy. A level scheme, consisting of 65 levels and more than 100 transitions, was constructed on the basis of γγ coincidences using five compton-suppressed Ge detectors. Spins were assigned by means of excitation function slopes and angular distribution analysis. The resulting level scheme was interpreted in the framework of the interacting boson-fermion model.     

Systematical law of (n, γ) reaction cross sections of even-even nuclei

We have derived a formula for the neutron radiative capture cross section in the framework of a statistical model approach to nuclear reactions. Based on this formula, new systematics are established between the (n, γ) reaction cross section and the energy level density of a compound nucleus or a relative neutron excess of an even-even target nucleus for neutron incident energy above the resonance region to MeV. Good agreement with experimental data suggests that this new systematical law is helpful to analyze the experimental data.     

Analysis of average primary gamma-transition intensities and cross sections of the113Cd(n, γ) reaction

A combined analysis of the available data on the primaryγ-ray intensities from the¹¹³Cd(n, γ) reaction atE _n=1.9 and 24.3 keV neutron energies together with the data on¹¹³Cd neutron capture cross sections in theE _n=3–200 keV energy region was carried out. The neutron strength functions were determined asS _n0=(0.260±0.073) 10^?4 and S_n1=(5.06±0.67) 10^?4. No spin-orbit splitting of thep-wave neutron strength function was found. The energy dependence of theE 1 radiative strength function {ie147-01} was fitted by the Kadmenski-Furman model somewhat better than by a standard Lorentzian. TheM 1 giant resonance parameters were obtained as E _G ^{M 1} =8.8±1.6 MeV and Γ _G ^{M 1} = 4.7±2.6 MeV. The neutron capture cross section of¹¹³Cd from its isomeric state ({ie147-02}=11/2^?, E ₁ ^m =263.7 keV) was calculated.     

Investigation of 238U in the (n,n′γ) reaction

An irradiation of ²³⁸U with a beam of reactor fast neutrons permits revealing about 550 gamma transitions associated with the respective (n, n′γ) reaction and with fission fragments. The use of all known data on gamma radiation from fission fragments makes it possible to identify gamma transitions belonging to ²³⁸U with a high probability. The scheme of levels and gamma transitions is composed for ²³⁸U. New levels (including those of spin-parity J ^π = 0⁺) at excitation energies below 2 MeV are proposed. The low-lying levels in the rotational band for two-phonon octupole excitations are determined. It is found that a hybrid state is formed upon the crossing of this band and the band based on two-quasiparticle excitations. This hybrid state must involve excitations of both types. A small value of the rotational-band parameter in the isomer of energy 2559.0(4) keV is explained by the contribution to this state from two-quasiparticle configurations belonging to the 1k _17/2 subshell. The same circumstance may also be responsible for an enhanced yield of ternary fission for this isomer.     

Energy dependence of the calculated yield of 176m Lu isomer in reaction 175Lu(n, γ)

We calculate the yield of ^176m Lu isomer in dependence on neutron energy using the Huizenga-Vandenbosch and Hauser-Feshbach statistical models. The results are compared to experimental data. We discuss the impact of uncertainty in calculating the isomer yield on the isotopic ratio ¹⁷⁶Lu/¹⁷⁵Lu in the core of the Oklo reactor.     

Investigation of 166Er in the respective (n,n′γ) reaction

Physics of Atomic Nuclei - The spectrum, angular distribution, and linear polarization of gamma rays from the (n, n′γ) reaction on 166Er were measured in a beam of reactor fast neutrons....     

Study of the reaction γp → pπ0η

The reaction γp → pπ⁰η has been studied with the CBELSA detector at the tagged photon beam of the Bonn electron stretcher facility. The reaction shows contributions from Δ⁺(1232)η , N(1535)⁺π⁰ and pa ₀(980) as intermediate states. A partial-wave analysis suggests that the reaction proceeds via formation of six Δ -resonances, Δ(1600)P ₃₃ , Δ(1920)P ₃₃ , Δ(1700)D ₃₃ , Δ(1940)D ₃₃ , Δ(1905)F ₃₅ , Δ(2360)D ₃₃ , and two nucleon resonances N(1880)P ₁₁ and N(2200)P ₁₃ , for which pole positions and decay branching ratios are given.     

Measurements of a partial cross section for the reaction 58Ni(n, γ0)59Ni

The partial cross section for radiative neutron capture accompanied by gamma transitions to the ground state of the ⁵⁹Ni nucleus was measured as a function of energy by a new neutron-spectrometry method that employed the shift of a primary gamma transition in response to a change in the energy of the captured neutron. The reaction ⁷Li(p, n)⁷Be was used as source of neutrons for the present measurements. The protons that induced this reaction were accelerated by a Van de Graaff electrostatic generator to energies exceeding the reaction threshold by 60 keV, in which case an appropriate geometry of the experiment permitted irradiation of the sample under study with neutrons whose energy ranged between 10 and 120 keV. The partial widths of some resonances and radiative strength function for hard primary M1 gamma transitions were determined in addition to the above cross sections.     

The level structure of104Rh deduced from the103Rh(n, γ)104Rh reaction

A sensitive, high resolution study of the¹⁰³Rh(n, γ)¹⁰⁴Rh reaction has revealed the presence of 516 transitions in the energy range 3,700 to 7,000 keV. These results have been used to interpret the reaction in terms of a statistical model in which a constant temperature level density is assumed. Previous work which revealed a much simpler level structure is quantitatively explained in terms of resolution and sensitivity. The average reduced radiative width is significantly lower than that reported for nuclides in theA=100 mass region and the width shows an indication of an energy dependence somewhat greater thanE _γ ³ . The neutron separation energy of the reaction is found to be 6,999.0±0.1 keV.     

Angular distributions of γ-rays from four resonances of the55Mn(p, γ)56Fe reaction

Four resonances in the⁵⁵Mn(p, )⁵⁶ Fe reaction at the centre-of-mass proton beam energy E _P ^CM =1320, 1504, 1508 and 1649 keV were studied. Angular distributions for some strong -rays following the radiative decay of the resonances were measured and analysed in terms of the channel-spin formalism. Spin-parity assignmentI _r =3⁺, 4⁺ and 3⁺ was acquired for the 1320, 1504 and 1649 keV resonances, respectively. No definite assignment was established for the 1508 keV resonance and the resonance is assumed to be a very tight multiplet. Analysis of primary transitions to bound states of the Fe final nucleus permited us to assign these states. The 2⁺, 2⁺, 2⁺, 6⁺ and 4⁺ assignments were ascribed to the states at excitation energyE _x =5705, 5303, 4738, 4692 and 4658 keV, respectively, while for the 5132 keV state ambiguous assignment 3⁺ or 4⁺ was found. Multipole mixing ratio was established for some primaries. The coupling of angular momenta of proton and target nucleus in the formation of the 3⁺ resonances was also roughly discussed.Participated partly in the course of his work on diploma thesis.The authors wish to thank the staff of the Van de Graaff accelerator at Charles University in Prague for the efficient operation of the machine. One of us (M. X. T.) acknowledges the staff of the Dept. of Nuclear Physics of Charles University, Prague, for the excellent working conditions.     

Study of the 13N(p, γ)14O reaction at stellar energies in a microscopic coupled-channel approach

We have studied the ¹³N(p, γ)¹⁴O reaction at stellar energies within a microscopic coupled channel approach based on the generator coordinate method. Our calculation improves previous investigations as we explicitly take into account the internal excitation of the ¹³N fragment nucleus. We find that the cross section at stellar energies is mainly dominated by the J^π = 1⁻ resonance at E = 0.547 MeV in ¹⁴O for which we calculate a γ-width of Γ_γ = 1.6 eV. For temperatures T = 10⁸ to 10⁹ K the thermally averaged ¹³N(p, γ)¹⁴O reaction rate is also sensitive to a direct capture contribution which we derive consistently within our microscopic study. Finally we discuss the astrophysical implications of the ¹³N(p, γ)¹⁴O rate for which we adopt a mean value of the various theoretical estimates of the γ-width of the 1⁻ resonance (Γ_γ = 1.8 eV).