Deformed states of high spin in42Ca

The⁴²Ca levels at 4,715 and 6,633 keV excitation energy have been investigated using the³⁹ K(α,pγ reaction atE _α=14 and 15 MeV. From particle-γ-ray angular correlations the spin assignmentsJ(4,715)=6, 4 andJ(6,633)=8, 6, 4 have been obtained. Lifetime measurements using the Doppler-shift attenuation method yieldedτ (4,715)=120±46 fs andτ(6,633)=52±21 fs. Both levels have positive parity and decay by enhancedE2 transitions. They are interpreted as theJ ^π=6⁺ and 8⁺ members, respectively, of theK ^π=0⁺ rotational band which has theE _x =1,837, 2,423 and 3,250 keV states as further members. The enhancement of inbandE2 transitions is 50 _?16 ⁺³⁵ W.u. (6→4) and 63 W.u. (8→6) respectively. The intrinsic quadrupole moments which have been derived on the basis of the coexistence model, areQ ₀=1.13?0.16/+0.37b(8→6) andQ ₀=1.36±0.25b(6→4), respectively. TheJ ^π=10⁺ member of the rotational band has possibly been observed as a level at 8,856±5 keV excitation energy.     

Electric quadrupole and magnetic dipole moments of the first excited 2+ states of186Os and188Os

The spectroscopic quadrupole moments and the magnetic dipole moments of the lowest 2⁺ states in¹⁸⁶Os (137 keV) and¹⁸⁸Os (155 keV) have been determined by Mößbauer transmission experiments. The electric quadrupole momentsQ ₂₊(Os 186)=? (1.80±0.22) b andQ ₂₊(Os 188)=?(1.81±0.24) b as well as their ratioQ ₂₊(Os 188)/Q ₂₊(Os 186)=1.00±0.07 within the limits of error agree withB(E2) data, if a comparison on the basis of the rotational model is made. For the g-factors and their ratio g₂₊(Os 186)=0.281±0.008, g₂₊(Os 188)=0.305±0.015 andg ₂₊(Os 188)/g ₂₊(Os 186)=1.08±0.05 was obtained. All results are compared with recent model calculations.     

Study of the ηπ+π− system centrally producedin the reactionpp→p f (ηπ+π−)p s at 300 GeV/c

The reactionpp→p _f (ηπ⁺π^?)p _s where the ηπ⁺π^? system is centrally produced has been studied at 300 GeV/c incident momentum at the CERN Ω spectrometer. The ηπ^± mass spectrum shows a strong δ/a ₀(980) signal having a mass of 984±4 and Γ=95±14 MeV. The ηπ⁺π^? mass spectrum shows η′ andf ₁(1285) signals over little background. A spin-parity analysis of the ηπ⁺π^? system shows evidence for aJ ^PC =1⁺⁺ peak at thef ₁(1285) mass but no evidence for the pseudoscalar states η(1270) andl/η(1440). No evidence is found for the ηππ decay of theE/f ₁(1420) meson for which we set an upper limit BR(E/f ₁(1420)→ηππ)<0.1 at 95% cl.     

Hyperfeinstrukturuntersuchung des 6p 2 P 3/2-Terms im Au I-Spektrum durch Resonanzstreuung von Licht

From about 6×10⁶ stoppingK ^?-meson reactions in the Saclay 80 cm hydrogen bubble chamber 70Σ ^?→Λe^?¯ν and 11Σ⁺→Λe⁺ν decays have been identified. The ratio of the vector to axial vector coupling constant has been determined,f ₁/g ₁=?0.22±0.28, consistent with the predictionf ₁=0 of the CVC-theory. The branching ratios for the two decay modes are,Γ(Σ ^?→Λe^?ν)/Γ(Σ^?→ all modes)=(0.69±0.12). 10^?4,Γ(Σ⁺→Λe⁺ν)/Γ(Σ⁺→ all modes)=(0.29±0.10). 10^?4. The ratio, Γ(Σ⁺→Λe⁺)/Γ(Σ^?→Λe^?v)=0.69±0.18, agrees with the phase space ratio, 0.61, therefore a theory that includes no second class currents is consistent with the data.     

Measurement of the f0(1270) polarization in the J/ψ → f0γ decay

The polarization of the f⁰(1270) and ?⁰(770) produced in the J/ψ decays into f⁰γ and ?⁰π⁰ are measured in e⁺e^? collisions at 3.1 GeV. A fit to the f⁰ production and decay angular distributions yields the values A₁/A₀ = 0.6 ± 0.3 and A₂/A₀ = 0.3 _?1.6^+0.6, where A_λ are the f⁰ helicity amplitudes. These results are in good agreement with the values predicted from a QCD two-gluon-exchange model. In addition an upper limit of 2.3 × 10^?4 is obtained for the J/ψ → f′⁰(1514) γ decay branching ratio which implies Γ(J/ψ → f′γ)/Γ(J/ψ → f⁰γ) ? 0.12 ± 0.05.     

An interpretation of the energy-momentum tensor of the dirac field with anomalous magnetic moment

The ground state radiative widths of the 1.56 MeV (3/2⁺) and the 1.35 MeV (5/2^?) levels in¹⁹F were determined by inelastic electron scattering. The measured cross sections have been analysed using DWBA calculations. The resultsΓ _y ⁰ (5/2^?→1/2^?,E3)=(8.1±1.7)·10^?10eV andΓ _y ⁰ (3/2⁺→1/2⁺,E2=(1.76±0.15)·10^?4eV are in agreement with, but more accurate than, former measurements.     

Measurement of radiative Σ±→nπ±γ decay

The radiativeΣ ⁺ → nπ⁺ γ decay mode was analysed in the 81 cm SACLAY hydrogen bubble chamber exposed to a stoppingK ^? beam at the CERN PS. The pion spectrum was measured up to momenta of 150 MeV/c in theΣ rest frame. We obtain the following branching ratios based on 180 Σ⁺→nπ⁺γ and 292Σ ^?→ nπ^?γ events:Γ(Σ⁺ → nπ⁺ γ)/Γ(Σ⁺→nπ⁺)=(0.93±0.10)×10^?3 Γ(Σ^?→nπ^? γ)/Γ(Σ^?→nπ^?)=(0.46±0.06)×10^?3. An unambiguous assignment ofS-wave to the Σ^?→nπ^? andP-wave toΣ ⁺→nπ⁺ was obtained. The absolute and differential decay rates as well as the parity assignments are in good agreement with theoretical predictions.     

The e + e −→π0π0γ process below 1.0 GeV

The e ⁺ e ^?→π⁰π⁰ γreaction was studied in the energy range 0.36–0.97 GeV on a VEPP-2M e ⁺ e ^? collider with an SND detector. The decay probabilities were found to be B(ω→ π⁰π⁰γ)= (7.8 ±2.7±2.0)×10^?5 and B(π→ π⁰π⁰γ)= (4.8 _?1.8 ^+3.4 ±0.2)×10^?5.     

Measurement of the KS0 → π+π−γ decay rate

From a study of 70 000 K° decays in the CERN 2m hydrogen bubble chamber, we have estimated the rate for K_S⁰ → π⁺π^?γ for different cuts in the γ momentum. The results are in good agreement with inner bremsstrahlung on K_S⁰ → π⁺π^?. For γ momentum in the K° c.m. greater than 50 MeV/c, we obtain the branching ratio: Γ(K_S → π⁺π^?γ, k>50 MeV/c)/Γ(K_S→π⁺π^?)=(2.8. ± 0.6)×10^?3. This leads to an estimate for the direct γ emission process: Γ(K_S→π⁺π^?γ direct)/Γ(K_S → π⁺π^?)=(0.3 ± 0.6) × 10^?3.     

Measurement of the branching ratio and π° energy spectrum for K°L → π+π−π°

The K°_L → π⁺π^?π° decay was studied in a bubble chamber experiment at an average momentum of 1.3 GeV/c. We measure the branching ration Γ(K°_L → π⁺π^?π°)/Γ(K°_L → charged) to be 0.1605 ± 0.0038. The data are well fitted with a linear matrix element in the π° kinetic energy with a slope g = 0.612 ± 0.032.     

A study of the centrally produced π+π−π0 system formed in the reactionpp→p f (π+π−π0)p s at 300 GeV/c

The reactionpp→p _f (π⁺π^?π⁰)p _s , where the π⁺π^?π⁰ system is centrally produced, has been studied at 300 GeV/c. The π⁺π^?π⁰ mass spectrum shows evidence for the η, ω anda ₂ (1320) as well as an enhancement in thea ₁ (1260) region. A Dalitz plot analysis of the π⁺π^?π⁰ system has been performed. Thea ₁ (1260) parameters coming from the fit of the 1⁺ S wave arem=1208±15 MeV and Γ=430±50 MeV. No evidence is found for theh ₁(1170) orh ₁(1380).     

Determination of the radiative widths of the η′ and A2 from two-photon exchange production

From the two-photon exchange processes e⁺e^? → e⁺e^?η' (958) → e⁺e^??⁰γ and e⁺e^? → e⁺e^?A₂ (1310) → e⁺e^?π⁺π^?π⁰ observed using the CELLO detector at PETRA the radiative widths of the η' and A₂ have been determined with the results: Γ_γγ(η') = 5.4 ± 1.0[stat.] ± 0.7[syst.] keV; Γ_γγ(A₂) = 0.59 ± 0.14[stat.] _?0.08^+0.31[syst.] keV.     

Interactions of slow neutrons with the chromium isotopes

Neutron transmission experiments and determinations of coherent scattering lengths were performed on natural chromium and enriched samples of⁵⁰Cr,⁵²Cr,⁵³Cr and⁵⁴Cr. By means of the Christiansen-filter-technique we obtained new values for the scattering lengths of the bound atoms:b(^natCr)=3.635±0.007 fm,b(⁵⁰Cr)=?4.50±0.05 fm,b(⁵²Cr)=4.914±0.015 fm,b(53Cr)=?4.20±0.03 fm, andb(⁵⁴Cr)=4.55±0.10 fm. The transmission experiments with neutrons of 510 ΜeV, 1.26 eV and 5.19 eV energy resulted in data for the absorption cross sectionσ _a (^natCr) =3.05±0.08 b and for the scattering cross section at “zero energy”:σ ₀ (^natCr)=3.381±0.010 b. Data for incoherent and spin-state scattering and for the potential-scattering radius of the nuclei could be deduced from these results.     

Spectroscopic quadrupole moment of holmium from pionic X-ray measurement

From the observed quadrupole splitting of the 5g-4f X-ray transition in π-¹⁶⁵Ho we determine the spectroscopic quadrupole moment of ¹⁶⁵Ho to be Q = 3.47±0.11 b. The strong interaction shift and the width of the 4f level are found to be ?₀ = 0.35±0.08 keV and Γ₀ = 0.21±0.04 keV, respectively.     

Inclusive production of non-strange resonances inK − p interactions at 32 GeV/c

New data on the inclusive production of the non-strange resonances ?⁰(770), ω(783), ?(1020) andf(1270) inK ^? p interactions at 32 GeV/c are presented. The inclusive production cross sections are equal to (4.32±0.72) mb, (3.7±1.4) mb, (0.65±0.10) mb and (0.91±0.35) mb respectively. Estimates of the topological cross sections are also obtained. The invariant and non-invariantx-distributions for the vector mesons ?⁰ and ? indicate the prevalence of forward resonance production in the c.m. system. For the tensorf-meson the rapidity andx-distributions are presented. Thet′-distributions for ?⁰, ?, andf have exponential slopes of 0.6±0.1 GeV^?2, 1.2±0.2 GeV^?2, and 0.8±0.5 GeV^?2 respectively. The exponential slope ofp _T ² -distribution of thef-meson is equal to (2.3±0.5) GeV^?2.     

The hadronic cross section of electron-positron annihilation at 9.5 GeV and the ϒ and ϒ′ resonance parameters

The reaction e⁺e^?→ hadrons has been measured in the ? and ?′ region using the DASP detector at the DESY storage ring DORIS. The following final results are obtained: R_had(9.5 GeV)=3.73±0.16±0.28, Γ_ee(?)=(1.23 ± 0.08 ± 0.12) keV, B_μμ(?)=(3.2±1.3±0.3)%, $\text{Γ}{}_{\mathrm{<mtext>ee</mtext>}}\text{Γ}{}_{\mathrm{<mtext>had</mtext>}}\text{Γ}{}_{\mathrm{<mtext>tot</mtext>}}\text{(?′)=(0.55±0.11 ±0.06)}\text{keV}$, and M(?′)?M(?)=(556 ±10) MeV.     

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.