Elastic scattering of15N on19F,19F on18O and19F on16O at low energies and elastic transfer

The reduced matrix elements for the ground state transitions to the first 2⁺, 3^? and 4⁺ states in¹⁴⁰Ce and¹⁴Ce were determined by DWBA analysis. In the giant resonance region of Ce, La and Pr three broad resonances at excitation energies of 9, 12 and 15 MeV have been found. They are interpreted asM1,E2 andE1 giant resonances. For Ce the total widths are (2.2±0.4) MeV (M1) and (2.8±0.3) MeV (E2) and the groundstate radiative widths (90±45) eV (M1), (100±30) eV (E2) and (5±1) · 10⁴ eV (E1).     

Measurement of mass and lifetime of hadronically produced charmed F mesons

We have observed three unique decays of F mesons into KKπ and five unique decays of D mesons into KKπ using the NA11 spectrometer together with a telescope of high-resolution silicon microstrip detectors. The mass value obtained for the F meson is (1975 ± 4) MeV, the lifetime (3.2±_1.3^3..0)×10^?13 s.     

The Glimm-Jaffe-Spencer expansion for the classical boundary conditions and coexistence of phases in the λφ24 Euclidean (quantum) field theory

The λφ₂⁴ Euclidean (quantum) field theory is studied in the multiphase region, and the following results are proven: (1) The “low temperature” expansion converges for Dirichlet (D), free (F), Neumann (N), and periodic (P), boundary conditions, and the even-point Schwinger functions for these boundary conditions have a mass gap; (2) $\text{〈}\text{o}\text{〉}{}^{\mathrm{b}}\text{=}\text{1}\text{2}\text{〈o〉}{}^{\mathrm{+}}\text{+}\text{1}\text{2}\text{〈o〉}{}^{\mathrm{?}}$, where b = D, F, N, P, and 〈o〉^± are the pure states of Glimm, Jaffe, and Spencer; (3) 〈o〉^±ξ = 〈o〉^± for all ξ > 0, where ξ is the buondary field; (4) alternative characterizations of the pure states 〈·〉^± are given.     

激发态铯原子间的碰撞能量转移

用激光抽运基态Cs₂分子,通过预离解或碰撞转移,由一部分的激发态Cs₂产生Cs原子6P,5D激发态。测量了Cs(5D)+Cs(6P)→Cs(7D_J)+Cs(6S)碰撞激发能量转移截面σ_(7DJ),以及Cs(7D_J)+Cs(6S)→除Cs(7D)外的态的截面σ_tr。结果是,对于J=5/2,3/2,σ_(7DJ)(以 关键词：     

Determination of fine structure intervals in a series of excited sodium D states using doppler free two-photon spectroscopy

Using Doppler free two-photon spectroscopy technique, we have measured the absolute values of fine-structure (fs) intervals in a series of excited sodium n²D states (n = 3,6,7, and 8). We have shown the structures are inverted and our measured values for these states are: Δ_fs(3²D) = -1523 ± 8 MHz, Δ_fs(6²D) = -385 ± 5 MHz, Δ_fs(7²D) = -253 ± MHz, and Δ_fs(8²D) = -173 ± 10 MHz.     

Anregung gebundener Atomzustände durch die plötzliche Zentralfeldänderung beim β−-Zerfall des Kerns

By the sudden change of nuclear charge during β^?-decay the daughter-ion is ionized or excited with probabilities of the order of some percent; other processes in the electron shell may be neglected, therefore unperturbed excitations can be measured by detecting photons emitted from the decaying excited atomic states in delayed coincidence with β^?-particles as is shown in an earlier paper for the Kr 85-β^?-decay. More extensive measurements of the photonemission after this decay give results in good agreement with theoretical predictions. Mostly such photons are observed, which can be emitted after a monopol-excitation, for which the selectionrulesΔ J=0 andΔ l=0 are valid. The total excitationprobability into both 5p(J=0)-states of Rb II is found to be P(4p?5p)=5,6±1,0%. The lifetimes of these two states are measured (correspondingly) to be τ=7,6 ±0,5 nsec, from which the reduced matrixelements ¦〈5p∥D∥5s〉¦²=18,9±3,2 and ¦〈5p∥D∥4d〉¦²=10,4 ±1,8 a.u. are calculated.     

Laser Stark spectroscopy of FCN

Using a CO₂ laser, Stark shifted resonances have been measured for the CF stretching fundamental (ν₃) of FCN near 9.3 μm, and for two nearby “hot” bands. The band centers measured are 1076.492007 ± 0.000013 cm^?1 for 00⁰1-00⁰0, 1085.741046 ± 0.000050 cm^?1 for 01¹1-01¹0, and 1091.16222 ± 0.00015 cm^?1 for 02⁰1-02⁰0. The ground state dipole moment of FCN is found to be 2.1203 ± 0.0010 D and dipole moments are also given for the other states observed. Values are given for the rotational constant and l-doubling constant for the 01¹1 state.     

The Jπ = 3− doublet at Ex = 6241 keV in 18F: Isospin mixing

The resonance previously observed at E_x = 6241 keV in the reactions ¹⁷O(p, γ)¹⁸F and ¹⁴N(α, γ)¹⁸F has been found to be a closely separated doublet (ΔE_x = 2.09±0.04 keV). Resonance strengths in ¹⁷O(p, γ)¹⁸F, ¹⁷O(p, α)¹⁴N and ¹⁴N(α, γ)¹⁸ have been measured and partial widths for the resonance states have been obtained. The doublet was further investigated by means of the ⁴He(¹⁴N, α)¹⁴N reaction using the differentially pumped gas target at CRNL. Analysis of these data using R-matrix theory yielded J^π = 3^? for both states and more precise values of the α-particle widths (Γ_α(lower) = 133 ±4 eV; Γ_α(upper) = 137 ±4 eV). The reduced α-particle widths and the E1 and M1 transition strengths indicate that the doublet arises from the nearly complete mixing of T = 0 and T = 1 eigenstates which in the absence of an isospin breaking interaction would have been separated by less than 40 eV. The α-particle scattering experiments included the J^π = 1⁺ resonance at E_x = 6257 keV and yielded the new values of Γ_α = 580±12 eV and Γ_p = 25⁺³⁵_?25 eV.     

Determination of the 5d6p 3F4-5d2 3F transition probabilities of Ba I

Whether the transitions between 6s5d ³D and 5d6p ³F can be used for laser cooling of barium heavily depends upon the transition probabilities of 5d6p ³F-5d^{2 3}F. Taking the transition 6s5d ³D₃-5d6p ³F⁴ as a scale, the leakage rate of 5d6p ³F₄-5d^{2 3}F was used to evaluate the transition probabilities. 706 nm laser pulses with different durations were applied to a barium atomic beam for 6s5d ³D₃-5d^{2 3}F₄ optical pumping, and the remaining percentages in 6s5d ³D₃ were measured. After exponential fitting, the transition probability of 5d6p ³F₄-5d^{2 3}F_3,4 was determined to be 2.1(4)×10⁴ s^?1, which is in agreement with theoretical calculations using the scaled Thomas-Fermi-Dirac method.     

Investigation of the ν5 band of methylacetylene by infrared laser Stark and microwave spectroscopy

Microwave spectra have been studied in the ground and v₅ = 1 (CC stretching mode) states of methylacetylene. From these data, dipole moments and rotational and centrifugal distortion constants have been determined, as follows: μ_D⁽⁰⁾ = 0.7839 ± 0.0010 D, μ_D⁽⁵⁾ = 0.7954 ± 0.0010 D, B₅ = 8508.119 ± 0.003 MHz, D_J⁽⁵⁾ = 1.8 ± 0.2 kHz, and D_JK⁽⁵⁾ = 169 ± 1 kHz. Laser Stark spectra have been obtained for the ν₅ band of this molecule and from these spectra the following vibration-rotation parameters have been determined: ν₅⁰ = 93.27540 ± 0.00007 cm^?1, A₅ - A₀ = ?227.0 ± 2.3 MHz and D_K⁽⁵⁾ - D_K⁽⁰⁾ = ?0.05 ± 0.50 MHz. The higher-J and -K states of the v₅ = 1 state appear to be purturbed.     

7 MeV dipole ground state transitions in 207Pb, 208Pb and 209Bi

The Doppler-broadened 7.117 MeV line from the ¹⁹F(p, αγ)¹⁶O reaction has been used to resonantly excite levels in ²⁰⁸Pb at 7071±2 and 7091±2 keV, in ²⁰⁷Pb at 7186±5 and 7206±5 keV and in ²⁰⁹Bi at 7179±5 and 7202±5 keV. On the basis of angular distribution measurements the 7071 and 7091 keV levels of ²⁰⁸Pb are assigned spins of 1 and assuming 100% ground state branching the widths are calculated to be 31±3 and 17±2 eV respectively. It is suggested that the states in ²⁰⁷Pb and ²⁰⁹Bi arise from the weak coupling of a $\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ neutron hole and an $\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ proton respectively to one or the other of the ²⁰⁸Pb levels. The widths obtained in terms of _gΓ_o²/Γ are 15±4 and 25±5 eV for the 7186 and 7206 keV levels of ²⁰⁷Pb and 24±5 and 30±5 for the levels of ²⁰⁹Bi respectively. These values are consistent with the weak-coupling suggestion.     

Investigation of gamma ray transitions and lifetimes in35Cl

Fortyeight resonances of the³⁴S(p, γ)³⁵Cl reaction in the proton rangeE _p=1–2 MeV have been observed. Gamma decay of twentyeight of these was investigated by means of a 55 cm³ Ge(Li) detector, and the energies and branching ratios of several bound states have been determined. TheQ-value was found to be 6367.0 ± 1.5 keV. The lifetimes 150±20, 400±140, 19±4, 14±2, 145±50, 20±5, 20±4, 42±4 and 7±3 fs were determined with the DSA method for the states at 1219, 1763, 2694, 3003, 3944, 3967, 4059, 4178 and 4882 keV, respectively. The experimental transition strengths were found to be in agreement with those given by manyparticle shell-modell calculations.     

Investigation of states in17F by the15N(3He,n)17F reaction

The absolute differential cross sections for several levels in the¹⁵N(³He,n)¹⁷F reaction were measured at laboratory scattering angles from 0 to 140 degrees using neutron time-of-flight techniques. Angular distributions were obtained at effective helion bombarding energies of 3.8 and 4.8 MeV. A new state was identified at 5.18 ±0.02 MeV excitation energy which is probably the analogue of the 5.217 MeV state in¹⁷O. Spectroscopic factors were obtained for the low-lying states using distorted wave method calculations.     

Proton-Gamma-Winkelverteilungen an der Reaktion19F(p, α γ)16O

The angular distributions of the 6.13 MeV γ₁ transition in the reaction¹⁹F(p, α γ)¹⁶O have been measured with improved accuracy at proton energies of 873 keV and 1,374 keV using a Ge(Li) detector. The results can be fitted by Legendre polynom series witha ₂=?0,018±0.008;a ₄=0.000±0.008 atE _p =873 keV anda ₂=?0.130±0.005;a ₄=+0.004±0.004 atE _p =1,374 keV. From the measured Legendre coefficients α₁-angular momentum mixing ratios are extracted and compared with the results from (p, α₁) and (α₁, γ₁) correlations.     

Measurement of the lifetime of the first excited state in17O and17F

A new version of the “recoil distance method”, making use of a gas target, has been used to determine the lifetime of the 871 keV level in¹⁷O and of the 495 keV level in¹⁷F. The measured values of the lifetimes are (2.32±0.08) · 10^?10 sec and (3.96±0.10) · 10^?10 sec for¹⁷O and¹⁷F, respectively.     

Precise measurement of the magnetic moment of17F(I x =5/2+,T 1/2=64.5 s) and its hyperfine interactions in ionic crystals

Hyperfine interactions of β-emitting¹⁷F implanted in single crystals of NaF and CaF₂ were studied. The nuclear magnetic moment of theT ^π=5/2⁺ state was determined with an improved precision to be |μ(¹⁷F;π=5/2⁺,T _1/2=64.5s|=4.72130±0.00025. nm. Isoscalar magnetic moments of the doubly closed shell ±1 nucleon nuclei around mass number 16 were derived and the effective nucleon mass in the nucleus was discussed.     

Nuclear structure of 18F: (IV). Negative-parity states

Studies via the ¹⁶O(³He, pγ)¹⁸F, ¹⁴N(α,γ)¹⁸F and ¹⁷O(p, γ)¹⁸F reactions have resulted in new J^π assignments for 11 states or negative parity: E_x(keV) (J^π) = 3791(3^?), 4226(2^(?)), 4398(4^?), 4860(1^(?)), 5502(3^(?)), 5785(2^?), 6097(4^?), 6108(1^(?), 2^(?), 3^(?)), 6241(3^?, T = 1), 6643(2^?, T = 1) and 6878(3^(t-), 4^?). The 6241 keV state is probably isospin mixed. New information for 5 states of positive parity has also been obtained: E_x(keV) (J^π) = 3838(2⁺), 4115(3⁺), 4652(4⁺, T = 1), 4753((0⁺), T = 1) and 4964(2⁺, T = 1). Mean lives, branching and mixing ratios are reported for all states. The results for the negative-parity states are discussed in the framework of the various models available. The states at E_x = 1080(0^?), 2100(2^?) and 4398(4^?) keV are interpreted as the first three members of a K^π = 0^? rotational band.     

Vibronic and cation spectroscopy of selected rotamers of 4-chloro-3-fluorophenol

We applied the two-colour resonant two-photon ionisation and mass-analysed threshold ionisation techniques to record the vibrationally resolved spectra of the selected rotamers and ³⁵Cl and ³⁷Cl isotopologues of 4-chloro-3-fluorophenol in the electronically excited S₁ and cationic ground D₀ states. The band origins of the S₁ ← S₀ electronic transition and the adiabatic ionisation energies of the cis and trans rotamers of 4-chloro-3-fluorophenol are determined to be 35,233 ± 2 and 35,405 ± 2 cm^?1, and 69,334 ± 5 and 69,460 ± 5 cm^?1, respectively. The electronic transition energies and general spectral features of the two isotopologues are nearly identical. Most of the observed active vibrations result from the in-plane ring deformation and substituent-sensitive motions. The experimental data show that the frequency difference in the observed active vibrations of the rotamers and isotopologues depends on the nature, vibrational pattern, location, and relative orientation of the substituents.     

Anomalies in Elastic Scattering at Isobaric Analogue States

Excitation functions for proton elastic scattering on Mn⁵⁵ at proton energies from 1320 KeV to 1480 KeV have been measured at the angles 135° and 150°. Anomalies in the differential elastic scattering were observed at E_p = 1350 ± 4 KeV, 1385 ± 4 KeV and 1445 ± 4 KeV respectively. These resonance states are the isobaric analogues of the ground, first excited and second excited states in Mn⁵⁶ respectively. Analysis of the results showed that these resonance states are best fitted to a J^π = 3⁺, 2⁺ and 1⁺ which is in excellent agreement with the J^π values of the corresponding states in Mn⁵⁶. The total widths and proton widths of these states were determined.     

332—362nm范围内CF2Cl自由基的共振增强多光子电离研究

用CF₂Cl₂分子直流脉冲放电的方法产生CF₂Cl自由基，结合共振增强多光子电离(REMPI)技术，测量了332—362nm波长范围内CF₂Cl自由基的(2+1)REMPI光谱，分析并标识了4s Rydberg态带源位于(ν_0—0=55371cm^-1)，两个被激活振动模ω′₃(CF₂剪式振动模)和ω₄′(OPL 关键词：