Forbidden lines in the hyperfine spectrum of the electron paramagnetic resonance of Mn++ in BaTiO3

The hyperfine spectrum of Mn⁺⁺ in powder BaTiO₃ was studied at 8740 MHz andT=80°K. The measured lines appearing as doublets between the hyperfine lines of Mn⁺⁺ are explained as forbidden transitions of the typeM=±1,m=±1. A theoretical expression for the position of these doublets is given and some of the constants of the spin Hamiltonian are determined:g=2.001±0.001, ¦A¦=86 Oe,D 40 Oe.     

Study of the centrally producer ππ andK \bar K systems at 85 and 300 GeV/c

We have studied the andK systems centrally produced in proton proton collisions at 300 GeV/c and ⁺/p proton collisions at 85 GeV/c using the CERN spectrometer. Clear evidence forS ^*/f _o(975) production is observed. An analysis performed on the ^{+ –} mass spectrum in the 1.0 GeV region, using a coupled channel formalism, shows that it is possible to describe theS ^*/f _o(975) effect with one single resonance once interference of theS ^*/f _o(975) with theS-wave background is introduced. The resultingS ^*/f _o(975) parameters arem _o =979±4MeV,g =0.28±0.04,g _K =0.56±0.18 corresponding to a pole position on sheet II at (1001±2)–i(36±4) MeV. Evidence is also found for a structure having a mass of 1472±12 MeV and a width of 195±33 MeV.     

Spectroscopy of excited state positronium

Electric dipole transitions in the microwave range have been induced between the fine-structure levels of positronium in the excited staten=2. As an indication of the transitions, we used the increase in Lyman- radiation when the metastable 2³S₁-level is depopulated. The results for the transitions 2³S₁2³P_0,1,2 are ₀=18499.65±1.20±4.00 MHz, ₁=13012.42 ±0.65±1.54 MHz and ₂=8624.38±0.54±1.40 MHz. The first error is statistical and the second systematic. The precision of the present measurement has improved by a factor of 3, compared to previous data. Recent bound state QED-calculations have been extended to the orderR _t8 ⁴ln ^–1. The not yet completely calculated orderR _t8 ⁴ is estimated to contribute less than 1 MHz. Our experimental results are in good agreement with theory. By applying a weak magnetic field, we were able to observe the transition 2³S₁2¹P₁ which is strictly forbidden byC-invariance in zero field. Our result, corrected for Zeeman- and motional Starkeffect, is ₃=11180.0±5.0±4.0 MHz. An upper limit for theC-violating matrix element of MHz could be deduced. Our experiment used moderated slow positrons from the bremsstrahlung and pair production of a pulsed electron linear accelerator (TEPOS facility at the university of Giessen).     

Measurements of theP 3/2-S 1/2-intervals in then=4,n=5 andn=6 states of ionized helium

TheP _3/2-S _1/2-intervals in then=4,n=5 andn=6 states of ionized helium have been measured by a radio frequency method, which permits to determine the disturbing electric fields in the interaction region and to correct their influences. The experimental results for theP _3/2-S _1/2 intervals in then=4,n=5 andn=6 states were (20,180.6±0.8) MHz, (10,332.9±1.4) MHz and (5,979.1±1.2) MHz respectively. From these intervals, the following indirect values for theS _1/2-P _1/2-Lambshifts can be deduced: (1,768.5±0.8) MHz in then=4 state, (905.0±1.4) MHz in then=5 state and (524.3±1.2) MHz in then=6 state. The results agree with the theoretical predictions. The static electric fields in the interaction region, ranging from 2 to 6 V/cm, increased with increasing electron excitation current, but were independent of the helium pressure within the range of 10 to 26 mTorr. All uncertainties are expressed as 68% confidence values.     

Production rate and decay lifetime measurements ofBs0 mesons at LEP usingDs and? mesons

The study of the properties of inclusive production ofD _s mesons and of events in which a and a muon are present in the same jet provides two independent measurements of the probability,f _s ^w , for a heavy quark to hadronize into a strangeB orD meson. The data sample analysed corresponds to 243,000 hadronicZ ⁰ decays. The combined value of these measurements isf _s ^w =0.19±0.06±0.08. From the flight distance distributions ofD _s and of (-lepton) secondary vertices, with the lepton emitted at high transverse momentum relative to the jet axis, two values are obtained for theB _s ⁰ meson lifetime. Combining these measurements with a previous result based on the study ofD _s- events, theB _s ⁰ meson lifetime is measured to be: 0.96±0.37 ps.     

Lamb shifts for hydrogen,using the sachs elementary interaction theory

The Lamb shifts of theS _1/2 andP _1/2 states of hydrogen atoms are calculated using the Sachs elementary interaction theory. BothS _1/2 andP _1/2 levels are shifted with respect to the Dirac levels by energies of the same order of magnitude. Agreement with experiment is obtained for the² S _1/2 –² P _1/2 and³ S _1/2 –³ P _1/2 Lamb shifts, but the predicted¹ S _1/2 –² P _1/2 Lamb shift term of 12,164 MHz is in disagreement with the experimental value of 7860 ± 1140 MHz.     

Local31P and distant31P and195Pt ENDOR studies of powdered samples of Bis(O,O′-disubstituted-dithiophosphato)copper(II) complexes magnetically diluted in the corresponding Pd(II) and Pt(II) host lattices

ENDOR studies on bis(dithiophosphato)copper(II) complexes magnetically diluted in the corresponding Pd(II) and Pt(II) host lattices performed with the use of the method of “polycrystalline ENDOR crystallography” are reported. In these samples well resolved local³¹P (A_iso ca. 29 MHz and A_aniso ca. 0.9 MHz) as wel1 as distant³¹P (A _iso ca. 1.3 and 5.5 MHz and A_aniso ca. 0.2 and 0.4 MHz) and¹⁹⁵Pt (A_iso ca. 3.1 MHz and A_aniso ca. 0.2 MHz) ENDOR transitions are recorded. It is shown that the directions of the main values of A_aniso for all local³¹P and distant³¹P and¹⁹⁵Pt ENDOR transitions are parallel. Comparison of these results with those reported about the same complexes but diluted in other host lattices shows that there is no difference in the EPR and local³¹P ENDOR parameters thus suggesting that the structure of the paramagnetic complex remains unchanged. It is found that distant ENDOR transitions appear only in the case when the host lattice contains one molecule in the unit cell, i.e., when all molecules are parallel to each other. Using the obtained data from local and distant³¹P ENDOR transitions some structural features of Cu(dtp)₂ as well as Pd(dtp)₂ and Pt(dtp)₂ complexes are found for the first time.     

Quality of the three-nucleon bound-state wave function from a two-nucleon separable expansion method

The numerical quality of the³H wave function obtained by the separable expansion method of Ernst, Shakin, and Thaler is examined. Separable approximations to the Paris potential with increasing accuracy are used in the¹ S ₀ and³ S ₁-³ D ₁ partial waves to calculate the binding energy, wave function, wave-function component percentages, and theS- andD-wave asymptotic normalization constants of³H. The results are compared with existing five-channel calculations obtained directly (without expansion) from the Paris potential to determine convergence. It is found that the results converge rapidly to the right values, indicating that the³H wave function thus obtained is of high quality and essentially indistinguishable from that obtained directly from the Paris interaction.Dedicated to Profs. Erich Schmid and Ivo laus on the occasion of their 60th birthdays     

Investigation by EPR and ENDOR spectroscopy of the novel 4Fe ferredoxin fromPyrococcus furiosus

The hyperthermophilic archaeonPyrococcus furiosus contains a four-Fe ferredoxin (Pf- Fd) that differs from most other 4Fe-Fd’s in that its [Fe₄S₄] cluster is anchored to protein by only three cysteinyl residues.Pf- Fd also is of interest because in its reduced form, [Fe₄S₄]⁺, the cluster exhibits bothS = 1/2 andS = 3/2 spin states. Addition of excess cyanide ion converts the cluster exclusively to anS = 1/2 state (g₁ = 2.09, g₂ = 1.95, g₃ = 1.92), however dialysis restores the EPR signal of native reduced protein indicating that the cluster is not irreversibly altered by cyanide. Both the native protein and protein in the presence of excess cyanide ion (Pf- Fd 4Fe-CN) were investigated here using the techniques of electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) spectroscopy. In particular,Pf- Fd 4Fe-CN was investigated using¹³CN^? and C¹⁵N^? ligands.¹³C and¹⁵N ENDOR indicated that a single cyanide ion bound directly, with the cluster showing an unusually small contact interaction (a_iso(¹³C)～ ?3 MHz, a_iso(¹⁵N) ～ 0). This is in contrast to cyanide bound to monomeric low-spin Fe(III)-containing proteins such as transferrin and myoglobin, for which the¹³C hyperfine coupling has a large isotropic component (a_iso(¹³C) ≈ ?30 MHz). This small contact interaction is not due to low spin density of Fe, as⁵⁷Fe ENDOR of the singly and triply labeledPf- Fd 4FeCN isotopologs, [⁵⁷FeFe₃S₄]⁺ and [Fe⁵⁷Fe₃S₄]⁺, show hyperfine coupling characteristic for [Fe₄S₄]⁺ clusters, particularly for the Fe to which cyanide binds. Thus, the low spin density on¹³C is not due to low spin density on the Fe ion to which it binds. Further theoretical work is needed to explain the contrast between the strong electronic effect of cyanide ion binding with the low spin density on the ligand.     

Inclusive production of charged pions, kaons and protons in υ(4S) decays

Using the detector ARGUS at thee ⁺ e ^– storage ring DORIS II, we have investigated inclusive momentum spectra of charged pions, kaons, and protons from decays of the (4S) meson. The kaon spectra have been measured in two independent ways, by coherently exploiting the detector's particle identification capabilities, and by detecting decays in-flight. The extracted mean multiplicities for charged hadrons are 7.17±0.05±0.14 pions, 1.56±0.03±0.05 kaons and 0.110±0.010±0.007 protons per (4S) decay, where pions and protons fromK _s ^o and decays have been subtracted.Supported in part by the Institute of Physics, University of Lund, Sweden     

Measurement ofR and determination of the charged-particle multiplicity ine+e? annihilation at 13-113-113-1around 10 GeV

We have measured theR value in non-resonante ⁺ e ^– annihilation using the ARGUS detector at the storage ring DORIS II. At a centre-of-mass energy GeV the ratio of the hadronic cross-section to the -pair cross section in lowest order QED has been determined to beR=3.46±0.03±0.13. In addition, we have measured the charged-particle multiplicities in non-resonant hadron production at GeV just below theB threshold and in (4S) resonance decays. For the average charged-particle multiplicities in continuum events and (4S)B decays we obtain n>_cont=8.35±0.02±0.20 and n>_(4s)=10.81±0.05±0.23.Supported by the German Bundesministerium für Forschung und Technologie, Contract no. 054DO51P     

Diffusion of selenium and tellurium in silicon

Diffusion of selenium and tellurium in silicon has been investigated in the temperature range 1000°C to 1310°C by sheet conductivity. For SiSeD ₀= 0.3±0.1 cm²/s andh=2.6±0.1 eV, and for SiTeD ₀=0.9±0.3 cm²/s and h=3.3±0.1eV have been obtained. The surface concentrations for both dopants were of the order of 5 × 10¹³ to 6×10¹⁶cm^–3. The Hall coefficient leads to an energy level of 300±15meV for selenium and 200±20meV for tellurium.     

2H-NMR study of ammonium ion rotational tunneling and reorientation in (ND4)2SnCl6 single crystal: I. Tunneling frequency measurements

Theory of²H-NMR spectra is developed for a ND ₄ ⁺ ion. Quadrupole and dipole-dipole interactions for four deuterons of the tetrahedral ion as well as the rotational tunneling are taken into account. Features in the single crystal spectra at the high magnetic field of 6.7 T are analyzed. Their central doublets (±5 kHz range around the Larmor frequency) are attributed to theA symmetry species and exhibit sensitivity to theA–T tunneling frequencyv _t . This allows the measurement ofv _t in a wide rangev _t <10 MHz. The shape of sidebands (±140 kHz range) is related to the T levels structure. Theoretical predictions are verified on a (ND₄)₂SnCl₆ single crystal at 44 MHz. The tunneling frequency at temperatures below 10 K equals 7.5 MHz, which is about 100 times smaller than for (NH₄)₂SnCl₆.v _t was measured up to 40 K. At still higher temperatures motional narrowing effects were observed for theA spectral components preventing the determination ofv _t .     

Double N-N scattering on polarized proton target

The triple scattering depolarization transfer parameterD _t in elastic p-p scattering was measured at an energy of 660 MeV using a polarzied proton target. All measurements have been carried out with the help of an optical spark chamber.The following results have been obtained:D _t (90)=D(90)=0·54±0·10.D _t (130)=D(130)=0·72±0·11.Devoted to Professor V. Petrílka on his sixty-fifth birthday.On leave of absence from theInstitute for Computing Technique of the Czechoslovak Academy of Sciences, Prague.On leave of absence from theNuclear Research Institute of the Czechoslovak Academy of Sciences, e.On leave of absence from theFaculty of Nuclear Science and Physical Engineering of the Technical University, Prague.In conclusion the authors express their deep gratitude to S. M. Bilenky, G. Gozzika, M. Hansroul, L. Lapidus, M. Odehnal, M. Maly, B. S. Neganov, R. M. Ryndin and P. Winternitz for helpful discussions and J. Cechová, E. Dudová and H. Sternová for help in the work.     

A study of double pomeron exchange inπ + p andK + p interactions at 250 GeV/c

Using the ARGUS detector at thee ⁺ e ^– storage ring DORIS II at DESY, we have measured the inclusive production ofD ⁰,D ⁺ andD ^*(2010)⁺ mesons inB decays and in nonresonante ⁺ e ^– annihilation around 10.6 GeV. The inclusive branching ratios forB decays toD ⁰,D ⁺ andD ^*+ mesons are found to be (52.2±8.2±3.5)%, (27.2±6.3±3.5)% and (34.8±6.0±3.5)% respectively. Thus,D ⁰ andD ⁺ production account for about 70% of the charm produced inB decays, neglectingbu contributions to the total width. The production cross sections and momentum spectra for continuume ⁺ e ^– annihilation are also presented.Supported by the German Bundesministerium für Forschung und Technologie, under contract number 054DO51P     

A measurement ofB meson production and lifetime usingDl? events inZ0 decays

A study ofB meson decays intoDl X final states is presented. In these events, neutral and chargedD mesons originate predominantly fromB ⁺ andB ⁰ decays, respectively. The dilution of this correlation due toD ^** production has been taken into account. From 263 700 hadronicZ ⁰ decays collected in 1991 with the DELPHI detector at the LEP collider, 92D ⁰K ^-+, 35D ⁺K ^-++ and 61D ^*0D ⁰⁺ followed byD ⁰K ^-+ orD ⁰K ^-++-, are found with an associated lepton of the same charge as the kaon. From theD ⁰ l ^- andD ^*+ l ^-, the probabilityf _d that ab quark hadronizes into aB ^– (or ) meson is found to be 0.44 ±0.08±0.09, corresponding to a total (B _s+ _b ) hadronization fraction of 0.12 _–0.12 ^+0.24 . By reconstructing the energy of eachB meson, theb quark fragmentation is directly measured for the first time. The mean value of theB meson energy fraction is:

Simultaneous phase-lock of five CO2 lasers to a primary Cs frequency standard

The output of a CO₂ laser, operating on theP _I(18) transition of¹³C¹⁶O₂ at 26941 GHz (11.128 m) was phase-locked to a 5 MHz signal from a primary Cs frequency standard by means of a frequency chain having only CO₂ lasers as infrared sources. Simultaneously, four other CO₂ lasers in the chain were phase-locked to the 26941 GHz output. This provided CO₂ laser frequencies at 26 450 305, 26 940 815, 28 694 625, 29 442 480, and 33 185 715 MHz having zero long-term-average frequency error relative to the Cs standard, and the ±10^–13 (3 Hz) long-term absolute uncertainty of the standard.     

The fine structure levels and spin-singlet contributions to zero-field-splitting parameters of Cr2+ ion in CdGa2S4

A theoretical investigation is reported of the fine structure levels and the spin-singlet contributions to zero-field-splitting (ZFS) parameters for Cr²⁺ ion in CdGa₂S₄ crystals. Firstly, the complete energy matrix including all spin states for a 3d ⁴ ion in tetrahedral D _2d symmetry is constructed according the double-group chain in the strong-field scheme. Then, by diagonalizing the complete energy of electron–electron interactions, the crystal field and the spin–orbit coupling for the Cr²⁺ (3d ⁴) ion in CdGa₂S₄ crystal, the fine structure levels and the spin-singlet contributions to ZFS parameters a, D and F are calculated. The results show that the spin-singlet contribution to D is negligible, but the contributions to a and F are very important. So, to obtain more accurate ZFS parameters for 3d ⁴ ions in the tetrahedral crystals, all spin states should be considered.     

B* production in Z decays

The decayB ^*B has been observed with the DELPHI detector at LEP, where theB ^* meson is produced inZ boson decays. The combination of inclusively reconstructedB mesons with well-measured converted photons yields a measurement of the flavour-averagedB ^*-B mass difference of 45.5±0.3 (stat.) ±0.8 (syst.) MeV/c². 95% confidence level upper limits at 6 MeV/c² are placed on both the isospin (i.e.B ⁺-B ⁰) and theB _s -B _ud splitting of the mass difference. The production ratio ofB ^* toB mesons inZ decays is measured to be 0.72±0.03 (stat.) ±0.06 (syst.). Limits on the production cross-section of other hypothetical excitedB hadron states decaying radiatively are established. The differentialB ^* cross section has been measured to be in good agreement with the averageb fragmentation, yielding an average fractionalB ^* energy of x _E =0.695±0.009 (stat.) ±0.013 (syst.). From the decay angular distribution the relative contribution of longitudinalB ^* polarisation states is measured to be _L/(_L + _T) = 0.32 ± 0.04 (stat.) ±0.03 (syst.).CICYT_AEN93-0832