Selectivity of the 16O(7Li, α) reaction and states with (sd)3 and (sd)2(fp)1 configurations in 19F

The ¹⁶O(⁷Li, α)¹⁹F reaction has been studied at 35 MeV up to 11 MeV excitation energy. Comparison with the ¹⁶O(⁶Li, ³He)¹⁹F and ¹⁶O(⁶Li, t)¹⁹Ne reactions shows very good agreement up to 5.5 MeV excitation energy and large differences at higher excitation energies which can be explained by different angular momentum matching conditions in the different reactions. The identification of mirror states in A = 19 and of states with (sd)³ and (sd)² (fp)¹ configurations in ¹⁹F are discussed.     

Cross sections for proton induced reactions on 41K and for the reaction 62Ni(α, p)65Cu

Excitation functions have been measured for ⁶²Ni(α, p)⁶⁵Cu in the energy range 6.5–9.0 MeV, for ⁴¹K(p, α)³⁸Ar in the range 0.8–2.6 MeV, for ⁴¹K(p, γ)⁴²Ca, ⁴¹K(p, αγ)³⁸Ar, ⁴¹K(p, nγ)⁴¹Ca, and ⁴¹K(p, p'γ)⁴¹ in the range 0.6–4.0 MeV, and for ⁴¹K(p, n)⁴¹Ca from threshold to 3.0 MeV. Cross sections have been extracted from the data and these are compared with statistical-model calculations based on global optical model parameters. Alternative parameter sets have been tried for the ⁶²Ni(α, p)⁶⁵Cu data and published data for ⁶²Ni(α, γ)⁶⁶Zn and ⁶²Ni(α, n)⁶⁵Zn, and both these and the global parameters have been used in statistical-model calculations of ⁶⁵Cu(p, γ)⁶⁶Zn, ⁶⁵Cu(p, n)⁶⁵Zn and ⁶⁵Cu(p, α)⁶²Ni cross sections, which are compared with published data for these reactions. Both the global and the alternative parameters lead to very good agreement with experiment for all six reactions. Alternative parameters have been tried for the ⁴¹K + p reactions also. The global parameters lead to agreement to within a factor of 2 and the alternative parameters lead to agreement to within a factor of 1.3. The ⁴¹K + p alternative parameters are used in calculations of ⁴¹Ca(n, γ)⁴²Ca, ⁴¹Ca(n, p)⁴¹K and ⁴¹Ca(n, α)³⁸Ar cross sections, and these and the experimental ⁴¹K + p data are used in calculations of thermonuclear reaction rates under stellar conditions for the ⁴¹Ca + n and ⁴¹K + p reactions.     

High resolution study of the reactions 54, 56, 58Fe(16O, 12C)58, 60, 62Ni and a comparison with (6Li,d) α-transfer spectroscopy

Spectra and angular distributions for the reactions ^{54, 56, 58}Fe(¹⁶O, ¹²C)^{58, 60, 62}Ni (E_x = 0.0–4.5 MeV) have been measured at 50 MeV with an energy resolution of 45–80 keV using a Q3D spectrograph. The selectivity of the (¹⁶O, ¹²C) reaction is found to be very similar to the (⁶Li, d) reaction. The close correspondence recently noted between the (⁶Li, d) spectra and levels strongly excited in (t, p) and (³He, n) two-nucleon transfer reactions is also observed to be present for the (¹⁶O, ¹²C) reaction. Relative α spectroscopic factors for (¹⁶O, ¹²C) and (⁶Li, d) obtained in a DWBA analysis assuming direct one-step α-cluster transfer are in very good quantitative agreement. Unnatural parity states, whose excitation is forbidden in the DWBA α-cluster approximation, are observed to be very weakly populated. These results, together with previous work on s-d shell and Ni targets, strongly suggest that the spectroscopic information provided by the (¹⁶O, ¹²C) and (⁶Li, d) reactions is essentially the same and that this information may be reliably extracted by DWBA analysis.     

Collisional relaxation of ionic2 P 3/2 excited states in rare gases

Optical pumping with theD ₂ line is used to study the depolarization of the first excited² P _3/2 states of alkaline earth ions and Yb⁺ ions in collisions with rare gas atoms. The deorientation cross sections for the even isotopes of Ba⁺ and Yb⁺ ions are obtained (in units of 10^?16 cm²): rare gas He Ne Ar Kr Xeσ ₁ (Ba⁺ 6p ² P _3/2) 79(11) 89(13) 123(18) 152(22) 204(30)σ ₁ (Yb⁺ 6p ² P _3/2) 60(10) 62(9) 107(18) 133(17) 167(37) The cross sections are discussed in comparison with theoretical calculations and those of isoelectronic atoms. The comparison of the² P _3/2 relaxation of even and odd (I=3/2) isotopes of Ba⁺ allows to draw conclusions on the nature of the depolarization interaction.     

CH3I: Isotope shift for 129I in the v6 band

The isotope shift in the v₆ band of CH₃I has been measured with high resolution for the radioisotope ¹²⁹I (half-life = 1.6 × 10⁷ y) with respect to the stable ¹²⁷I, using tunable diode laser spectroscopy. The average shift obtained from 30 transitions, free from interference in the ^RQ(J, 3) and ^RQ(J, 4) branches, amounted to (-0.0135 ± 0.0006) cm^-1. The abundance ratio ¹²⁹I/¹²⁷I in the gas mixture was determined spectroscopically on ^RQ(16, 3) and found to be (0.032 ± 0.003), as compared to a mass-spectrometric analysis of (0.030 ± 0.001). The self and air broadening coefficients measured on ^RR(6, 0) of CH₃¹²⁷I were (32 ± 3) MHz Torr^-1 and (10.4 ± 1.5) MHz Torr^-1 respectively. The line strengths for ^RQ(16, 3) were found to be (2.0 ± 0.2) × 10^-21 cm^-1 mol^-1 cm² for both CH₃¹²⁷I and CH₃¹²⁹I.     

Two-nucleon pick-up from spin-12 targets (II). 89Y

The angular distributions for the ⁸⁹Y(p, t), (p, τ), and (d, α) reactions are compared to DWBA predictions and to the data for the ⁹⁰Zr(p, t) and (d, α) reactions. Several new spins are assigned to levels of ⁸⁷Y. A weak coupling model is tested by the comparison between the reactions on ⁸⁹Y and ⁹⁰Zr, and found to fail. The (d, α) reaction is found to populate strongly levels at excitation energies of 2.70 MeV and 3.07 MeV in ⁸⁷Sr, corresponding roughly in Q-value and strength to states formed in ths ⁸⁸Sr(d, α)⁸⁶Rb reaction.     

Ground and γ-vibrational bands in even Os isotopes (A = 182–188) studied by (α, χnγ) and (p, χnγ) reactions

Gamma rays following ¹⁸²W(α, 2n)¹⁸⁴Os, ¹⁸⁴W(α, 2n)¹⁸⁶Os, ¹⁸⁶W(α, 2n)¹⁸⁸Os, ¹⁸⁵Re (p, 2n)¹⁸⁴Os, ¹⁸⁵Re(p, 4n)¹⁸²Os, ¹⁸⁷Re(p, 2n)¹⁸⁶Os and ¹⁸⁷Re(p, 4n)¹⁸⁴Os reactions have been measured to study the ground and γ-vibrational bands in even Os isotopes (A = 182–188). In addition to the ground-state levels the γ-vibrational bands have been identified up to the 5⁺ members. The K = 4 band head is proposed in ¹⁸⁶Os and ¹⁸⁸Os.     

Nuclear-matter radii of 7Be and 7Li and astrophysical S-factors for radiative alpha-capture reactions

The nuclear-matter radii of ⁷Be and ⁷Li measured in high-energy heavy-ion reactions have been calculated and applied to the estimate of astrophysical S-factors for the ³He(α,γ)⁷Be and ³G(α,γ)⁷Li reactions. The absolute S(O) values in the KeV b are constrained to be 0.36<S(0)<0.63 and 0.083<S(0)<015 for the ³He(α,γ)⁷Be and ³H(α,γ)⁷Li reactions, respectively.     

Quadrupole and octupole collectivity in light Po isotopes

The level structure of¹⁹⁶Po has been studied using a¹⁶⁰Dy(⁴⁰Ar, 4n) reaction and a recoil-catcher technique to reduce fission. The results showed a sharp drop off in the first (2⁺) and (4⁺) energies relative to systematics implying an abrupt increase in the quadrupole collectivity at N=112. In addition, second (2⁺) and(4⁺) states were identified at 859 and 1388 keV, respectively, suggesting the discovery of a 4p2h deformed band in Po isotopes which is related to known 2p2h proton bands in several Pb isotopes. A prompt¹⁸³W(²⁰Ne, 5n@#@) experiment located similar second 2⁺ and 4⁺ states at 1039 and 1483 keV in¹⁹⁸Po providing corroboration and extended information on the properties of the new Po deformed bands. A measured halflife of 850 (90) ns for the 2491 keV (11^?) state in¹⁹⁶Po implied collective E3 contributions to the extractedB (@#@ E3; 11^?→8⁺)=27(5) W.u.     

Natural radioactivity and radiation hazards assessment of soil samples from the area of Tuzla and Lukavac,Bosnia and Herzegovina

The results of activity concentration measurements of natural occurring radioactive nuclides ²³⁸U, ²³⁵U, ²³²Th, ²²⁶Ra, and ⁴⁰K in surface soil samples collected in the area of cities Tuzla and Lukavac, northeast region of Bosnia and Herzegovina were presented. Soil sampling was conducted at the localities that are situated in the vicinity of industrial zones of these cities. The measured activity was in the range from (8?±?4) to (95?±?28) Bq kg^–1 for ²³⁸U, from (0.41?±?0.06) to (4.6?±?0.7) Bq kg^–1 for ²³⁵U, from (7?±?1) to (66?±?7) Bq kg^–1 for ²³²Th, from (6?±?1) to (55?±?6) Bq kg^–1 for ²²⁶Ra, and from (83?±?12) to (546?±?55) Bq kg^–1 for ⁴⁰K. In order to evaluate the radiological hazard of the natural radioactivity for people living near industrial zones, the absorbed dose rate, the annual effective dose and the radium equivalent activity have been calculated and compared with the internationally approved values.     

Alpha strength factors in medium nuclei

Alpha strength factors are calculated for use in heavy-ion induced α-transfer reactions and in (α, p) reactions on medium nuclei. Detailed calculations are performed in a weak coupling shell model to study the distribution of α-strength over the nuclear states and to explore the α-clustering amplitudes of j-j coupled basis states. Alpha clustering in a model space with states of good isospin as well as states described in neutron-proton formalism is discussed. It is found that the α-cluster strength contained in the configurations (pf)⁴, (sd)⁴, (pf)³(sd)¹ and (pf)¹(sd)³ fragments among several or many states. For the (pf)²(sd)² configuration, conversely, most of the α-strength exists in the lowest state of the configuration, and such states form a band of positive parity states which exhibits rotational properties. A brief comparison with (α, p) and ⁵⁴Fe (¹⁶O, ¹²C)⁵⁸Ni experiments is made. The α-transfer probability was calculated in a semiclassical model. The effects of correlations which produce enhancements of factors of ten are essential to explain observed enhancements in the α-strengths. Alpha strength factors for the (sd)⁴ configurations for nuclei in the Zr region are also given.     

Activation cross-sections of titanium isotopes at neutron energies of 13.5–14.8 MeV

The cross-sections for ~(46) Ti(n,2 n)~(45) Ti, ~(46) Ti(n,p)~(46 m+g) Sc+~(47) Ti(n,d*)~(46 m+g) Sc, ~(46)Ti(n,p)~(46 m+g) Sc, ~(47) Ti(n,p)~(47) Sc+~(48) Ti(n,d*)~(47) Sc, ~(47) Ti(n,p)~(47) Sc, ~(48) Ti(n,p)~(48) Sc+~(49) Ti(n,d*)~(48) Sc,~(48) Ti(n,p)~(48) Sc, and ~(50) Ti(n,α)~(47) Ca reactions were investigated around neutron energies of 13.5–14.8 Me V by means of the activation technique. Fast neutrons were produced by the~3 H(d,n)~4 He reaction. Neutron energies from different directions in the measurements were obtained in advance using the method of cross-section ratios for ~(90) Zr(n,2 n)~(89 m+g) Zr and ~(93) Nb(n,2 n)~(92 m) Nb reactions. The results obtained are analyzed and compared with the experimental data provided by the literature and verified nuclear data in the JEFF-3.3,CENDL-3.1, ENDF/B-VIII.0 libraries, as well as results calculated by Talys-1.9 code.     

EPR study of Fe3+ and Mn2+ in CeO2 and ThO2

Attempts were made to grow CeO₂ and ThO₂ single crystals doped with transition metal ions. Only Fe³⁺ and Mn²⁺ could be detected by the EPR technique. The EPR spectrum of Fe³⁺ in CeO₂ exhibits the well-known fine structure in cubic fields. The parameters areg=2.0044(1) anda=15.6(1)·10^?4 cm^?1. The hyperfine constantA for⁵⁷Fe in hexahedral coordination was found to be 8.9(1)·10^?4 cm^?1. The EPR spectrum of Mn²⁺ in CeO₂ reveals two cubic Mn²⁺ centers. The parameters for center 1 areg=1.9999(1) andA=86.9(1)·10^?4 cm^?1 and for center 2g=1.9984(1) andA=87.0(1)·10^?4 cm^?1. Heating the Mn doped CeO₂ samples in hydrogen, the Mn²⁺ centers transform from cubic into trigonal centers with approximate values ofg=1.9988(2),A=84.5(6)·10^?4 cm^?1 andD=203(1)·10^?4 cm^?1. The two observed Mn²⁺ centers in ThO₂ exhibita priori axial symmetry with approximate values ofg=2.0006(2),A=88.9(4)·10^?4 cm^?1 andD=33(3)·10^?4 cm^?1.     

Magnetic field effects on electron transfer reactions involving sextet-spin (S = 5/2) intermediates generated on photoexcitation of a Cr(III)-porphyrin complex

The excited trip-sextet (⁶T₁) state of chloro-(3-methylimidazol)-(meso-tetraphenylporphyrinato) chromium(III) (Cr^IIIP) is quenched by 1,1′-dibenzyl-4,4′-bipyridinium (BV²⁺) in acetonitrile through electron transfer to give ⁵(Cr^IIIP^·+) and ²BV^·+. The intermediate is a geminate ion pair in the sextet (Sx) state ⁶[⁵(Cr^IIIP^·+) ²BV^·+], which decays through either the escape from a solvent cage to give the free ions or the spin conversion to the quartet (Qa) state followed by back electron transfer. The free ion yield (Φ_FI) increased with increasing magnetic field from 0 to 4 T and then slightly decreased from 4 T to 10 T. These magnetic field effects are explained as follows. Under low fields where the Zeeman splitting of the spin sublevels is lower than or comparable with the electron spin dipole—dipole interaction within ⁵(Cr^IIIP^·+), this interaction effectively induces the Sx → Qa conversion of [⁵(Cr^IIIP^·+)²BV⁺] to result in low Φ_FI values. Under high fields where the Zeeman splitting is larger than the dipole—dipole interaction, the Sx → Qa conversion is decreased with increasing field to cause higher Φ_FI values. The slight decrease in Φ_FI above 4 T may be due to the Δg mechanism.     

Spectroscopy of 166W and 167W and alignment effects in very neutron-deficient tungsten nuclei

High-spin states in ¹⁶⁶W and ¹⁶⁷W were populated by the reactions ¹⁴²Nd(²⁸Si,4n)¹⁶⁶W, ¹⁴²Nd(²⁸Si,3n)¹⁶⁷W and ¹⁴⁷Sm(²⁴Mg,4n)¹⁶⁷W. From the γ-decay the yrast band and a side band (with assumed negative parity) were identified to high spins. There is evidence for a second side band in ¹⁶⁷W. The observed backbend of the yrast sequences and band-crossing anomalies in the side bands are discussed in conjunction with cranked-shell-model calculations. A systematic comparison is made between the yrast bands of ^166,167,168W in order to understand the structure of the second backbend in ¹⁶⁸W.     

Determination of Trace Mercury by Solid Substrate-Room Temperature Phosphorimetry Quenching Method Based on Catalytic Effect of Hg2+on Formation of the Ion Association Complex [Sn(XO)6]4+·[(Fin)4]

A new method for the determination of trace mercury by solid substrate-room temperature phosphorimetry (SS-RTP) quenching method has been established. In glycine-HCl buffer solution, xylenol orange (XO) can react with Sn⁴⁺ to form the complex [Sn(XO)₆]⁴⁺. [Sn(XO)₆]⁴⁺ can interact with Fin⁻ (fluorescein anion) to form the ion associate [Sn(XO)₆]⁴⁺·[(Fin)₄]⁻, which can emit strong and stable room temperature phosphorescence (RTP) on polyamide membrane (PAM). Hg²⁺ can catalyze H₂O₂ oxidizing the ion association complex [Sn(XO)₆]⁴⁺·[(Fin)₄]⁻, which causes the RTP to quench. The ΔIp value is directly proportional to the concentration of Hg²⁺ in the range of 0.016–1.6 fg spot⁻¹ (corresponding concentration: 0.040–4.0 pg ml⁻¹, 0.40 μl spot⁻¹), and the regression equation of working cure is ΔIp=10.03+83.15 m Hg²⁺ (fg spot⁻¹), (r=0.9987, n=6) and the detection limit (LD) is 3.6 ag spot⁻¹(corresponding concentration: 9.0×10^–15 g ml⁻¹, the sample volume: 0.4 μl). This simple, rapid, accurate method is of high selectivity and good repeatability, and it has been successfully applied to the determination of trace mercury in real samples. The reaction mechanism for catalyzing H₂O₂ oxidizing the ion association complex ([Sn(XO)₆]⁴⁺·[(Fin)₄]⁻) SS-RTP quenching method to determine trace mercury is also discussed.     

12C(12C, 8Be)16O angular distributions and excitation functions between 35 and 69 MeV bombarding energy

An array of eight detectors has been developed for identifying the particle unstable ⁸Be nucleus from nuclear reactions with high detection efficiency. Absolute cross sections have been measured for the reaction ¹²C(¹²C, ⁸Be_g.s.)¹⁶O to the ground state and to several excited states in ¹⁶O. Excitation functions at seven angles from 15° to 45° (lab) in 5° steps have been measured for bombarding energies between E¹²_C(lab) = 35 and 69 MeV. Excitation functions were obtained for the following states in the residual nucleus ¹⁶O which were found to be strongly populated: g.s.(0⁺); 6.1 MeV (0⁺, 3^?); 6.9 MeV (2⁺); 10.4 MeV (4⁺); 11.1 MeV (4⁺); 14.7 MeV (6⁺,…) and 16.3 MeV (6⁺,…). The energy range is covered in 250 keV (c.m.) steps; at certain energy ranges in ¹²⁵ keV or 50keV steps. All excitation functions exhibit a strong energy dependence of the cross section; pronounced gross structures with superimposed fine structures, similar to those observed for ¹²C+¹²C elastic and inelastic scattering at these energies, are observed. At 19.3 MeV, where resonant structures were observed in the reactions ¹²C(¹²C, p)²³Na, ¹²C(¹²C, n)²³Mg and ¹²C(¹²C, d)²²Na, no resonance is found for the reaction studied here. At 60, 61 and 63 MeV angular distributions have been measured in 1° and 2.5°(lab) angular steps. The excitation functions have been analyzed in terms of Ericson fluctuations and cross-correlation functions.     

Systematic study of rotational energy formulae for superdeformed bands in La and Ce isotopes

The experimental rotational spectra of superdeformed(SD) bands of ~(130)La, ~(131)Ce(1,2), ~(132)Ce(1,2,3) and133 Ce(1,2,3) in the A～130 mass region are systematically analyzed with the four parameter formula, power index formula, nuclear softness formula, and VMI model. It is observed that out of all the formulae, the four parameter formula suits best for the study of the ~(130)La, ~(131)Ce(1,2), ~(132)Ce(2,3) and ~(133)Ce(1,2,3) SD bands. The four parameter formula works efficiently in determining the band head spin of the ~(130)La, ~(131)Ce(1,2) ~(132)Ce(2,3) and ~(133)Ce(1,2,3) SD bands. Good agreement is seen between the calculated and observed transition energies whenever the accurate spin is assigned. In ~(132)Ce(1), the power index formula is found to work better than the other three formulae. The dynamic moment of inertia is also calculated for all the formulae and its variation with the rotational frequency is investigated.