Der mittlereg-Faktor der ersten angeregten Rotationszustände der geraden Wolframisotope in natürlichem Wolfram

The average gyromagnetic ratio of the first excited 2⁺ states of the Tungsten isotopes was measured using a target of natural Tungsten. An external magnetic field of 40950±200 Gauss was employed for observing the precession of the angular distribution of the 115 keV deexcitationγ-rays following Coulomb-excitation with an atomic hydrogen beam of 2·18 MeV. The measurement of the angular distribution was carried out with a proton beam at 6 different energies between 1·5 and 3·7 MeV, and was found to be slightly perturbed by internal fields. The measured attenuation coefficients areG ₂=0·966±0·049,G ₄=1·07±0·15. The gyromagnetic ratio was found be\(\bar g = 0 \cdot 264_{ - 0 \cdot 019}^{ + 0 \cdot 023}\), in agreement with the average value of the measurements ofGoldring andVager and the average theoretical value ofNilsson andPrior, but lower than the measurements ofBodenstedt et al.     

New emission spectrum of the TeO molecule

The spectrum of Tellurium monoxide as excited in a heavy current arc run by a 2000 volt D.C. generator was studied in the visible and ultraviolet regions. Photographs of the spectrum revealed many new bands in the regionλ 6200 toλ 3300, which are clearly degraded to longer wavelengths. Some of the bands in the regionλ 3800 toλ 3300 were identified with those of the system in the regionλ 3800 toλ 3060 (here designated as system,B-X) observed and analysed byChoong Shin Piaw. The analysis of theB-X system was extended to include some of the new bands uptoλ 4500. In addition to those assigned toB-X system, a number of new bands in the regionλ 5000 toλ 3500 constitute another system designated asA-X system. The analysis of this system has led to the following quantum formula for the band heads.v=27835+408 (v′+1/2)?4·0(v′+1/2)² ?796 (v″+1/2)+3·5 (v″+1/2)². The lower state of the two systems is common and is identified as the ground state of the TeO molecule. Bands in the regionλ 6200 to 5000 were analysed as belonging to another brief system. This system appears to arise from a transition between two escited states of the TeO molecule. The nature and properties of electronic terms responsible for the observed electronic states of the TeO molecule were discussed along with those of the related molecules O₂, SO, and SeO from considerations of electron configurations.     

Absorptive corrections to associated production of strange baryon and meson resonances in πp scattering

Absorptive corrections are calculated for the reactionsπ ⁺ p→K ^*+∑⁺(K ^*+ Y ₁ ^*+ ) mediated byK-exchange andπ ⁺p→K⁺ Y ₁ ^*+ withK ^*-exchange. The effect of the finite width of the resonances is included. Numerical results are given for 5 and 8 GeV/c.     

Einfluß der Pion-Pion-Wechselwirkung auf Pion-Nukleon-Streuphasen

The isospin dependent part of theS-wave pion-nucleon amplitude is calculated according to the CGLN approach, but recoil and projection on the partial waves are treated exactly. Then the difference against the experimental data is approximately a constant up to 100 MeV and amounts to 1/3 of the total value. It is shown, that at low energies the main corrections of the CGLN equations are taken into account by a subtraction of theπ+π→?+\(\overline \Re \),J=I=1 amplitudesf _± ¹ (t) as proposed byMandelstam andFrazer. Calculations have been done forS, P andD pion-nucleon amplitudes. The main result is a prediction of theS-wave amplitude obtained without adjusting free parameters up to 100 MeV. The relations of this method to the equations derived byBowcock, Cottingham andLurié according to the Cini-Fubini approach are discussed.     

Bestimmung der Kernmomente des Ho165 aus der Hyperfeinstruktur des Grundzustandes im Ho I-Spektrum

In an atomic beam magnetic resonance experiment, the hyperfine interaction constantsA andB of the⁴ I _2/15-groundstate of Ho¹⁶⁵ were found to beA=800,58389 (50) MHz,B=?1667,997 (50) MHz. Using an effective value for 〈r ^?3〉, the magnetic moment of the Ho¹⁶⁵ nucleus was calculated to beμ=4·1(4)μ _n . The quadrupolement was determined by use of the 〈r ^?3〉 given byWatson andFreeman. The result isQ=2·4·10^?24 cm².     

Emission und Schwingungsverteilung der 1. neg. Gruppe und der 2. pos. Gruppe in einem Stickstoffplasma

The intensity of the first negative system ofN ₂ ⁺ (B ² Σ _u ⁺ -X ² Σ _g ⁺ and of the second positive system ofN ₂(C ³ Π _u -B ³ Π _g ) was observed in the discharge and in the afterglow as function of discharge current. An a. c. discharge in pure nitrogen was used at pressures of about 5 torr. The intensity of the first negative system ofN ₂ ⁺ — in the discharge and in the afterglow — rises to a maximum and decreases with further increase of the discharge current. The afterglow intensity of the second positive system ofN ₂ shows a maximum too. In the discharge, however, the intensity of the second positive system ofN ₂ increases with increasing discharge current. The relative population of the vibrational levelsN _v′ =i/N _v′ =0 (i=1,2,3,4) of theB ² Σ _u ⁺ state ofN ₂ ⁺ , in the discharge and in the afterglow, increases with increasing discharge current, while the relative population of the vibrational levelsN _v′ =i/N _v′ =0 (i=1, 2, 3, 4) of theC ³ Π _u state ofN ₂ reaches a maximum in the discharge. There seems to be evidence that the first negative system ofN ₂ ⁺ is not excited by electron impact withN ₂ molecules in ground state under the discharge conditions in question.     

Vergleich der Photoerzeugung von π0 am Proton mit der Voraussage nach der Dispersionstheorie

The real parts of the photoamplitudesE 1S _1/2,M 1P _1/2,M 1P _3/2 have been calculated from the angular distribution of the reactionγ+p→p+π⁰ recently measured byGoldansky et al. at 160 to 240 MeV. One of the solutions fits pretty well to the theoretical prediction for theM 1P _3/2-amplitude according to the dispersion method ofChew, Goldberger, Low andNambu. There is a discrepancy forM 1P _1/2 ifα ₁₁ is taken from the effective range formula, but the positive values ofα ₁₁, necessary to give agreement, are not excluded by the results of the phase shift analysis, especially sincePontecorvo et al. have recently found positive values at higher energies. The prediction for the real part of theE 1 S_1/2-amplitude agrees with the experimental data, if pretty large recoil corrections are added which had been neglected byChew et al.     

Determination ofL subshell ratios of pureM1 transitions

L subshell ratios have been accurately measured for two pureM1 transitions, 82.5 keV in ₆₇ ¹⁶⁶ Ho and 238.6 keV in ₈₃ ²¹² Bi. The results for all ratios are in fairly good agreement with those obtained from the theoretical calculations bySliv andBand.     

Delbrück-Streuung von 17 MeV-Photonen

Differential cross sections have been measured for the small angle scattering ofγ-rays by iron, silver, tantalum, lead and uranium with 17 MeV photons from Li⁷ (p, γ) Be⁸ at mean four momentum transfersq of 0·5mc and 1·3mc and with 7 MeV photons from F¹⁹(p, αγ)O¹⁶ at mean four momentum transfer of 0·5mc. Under these experimental conditions only Compton, Rayleigh and possibly Delbrück scattering are of importance. Extrapolation of known theoretical results to higher energies shows, that Rayleigh and Compton scattering from bound electrons should depend only onq for small angles, smallq and fixedZ. Using this it follows, that at 17 MeV andq≈0·5mc an additional scattering process must be present, which increases with growingZ and which is negligible in the measurements at 17 MeV withq≈1·3mc and at 7 MeV withq≈0·5mc. These results are in qualitative agreement with the approximate theory for Delbrück scattering ofBethe andRohrlich, however experimental cross sections at 17 MeV andq≈0·5mc are about a factor of 1·6 lower than those predicted by this theory. This discrepancy is not unexpected, since exact calculations of Delbrück scattering amplitude fromKessler andZernik at 2·62 MeV and 6·14 MeV show even greater deviations in the same sense.     

Untersuchung des Iridium-191m-Zerfalls

Theγ-radiation of the nuclear isomer Ir^191m (T _1/2=4.5 sec) has been investigated with the aid of a scintillation fast-slow coincidence-spectrometer. Theγ-rays of the 42 keV-transition have been measured for the first time. The conversion coefficient α of this transition was found to be α = 13500 ₊₂₁₁₀₀ ^?5200 in acceptable agreement with the value taken from the tables ofRose under the assumption of anE3-transition. Thus this assignment proposed earlier by other authors has been confirmed. TheK-conversion coefficient of the 129 keV-transition has been remeasured yielding α _K =2.32±0.06.     

Contributions to the theory of alpha-decay

The theory of α-decay is reformulated in order to point out the necessary approximations in a rigorous way. The connection between the formulas given byThomas and byMang is easily established.Mang's explicit expressions of reduced widths, valid for shell model wave functions, are brought into a general form. The theory is applied to BCS wave functions and the decay constants of several Po-isotopes are calculated as an example. Furthermore results are presented which favour a spin assignmentI=18 and a predominating (h9/2) ₈ ² (i11/2) ₁₀ ² configuration for the Po²¹² isomeric state. The penetrabilities are calculated numerically, since the WKB-method is found to be unsatisfactory.     

Messung der 2P-1S-Übergangsenergie im Myon-Barium-Atom

As a means of studying the nuclear charge radius, the 2P-1S-transition energy of the muon-barium-atom (μ-mesonicK _α -line) was measured. A 3″×3″ NaJ-spectrometer was used at the muon channel of the CERN-synchrocyclotron. Since the muon intensity was high, measurements could be repeated under various conditions. Experiment, checks, and results are described. The 2P-1S-energy obtained, (3981±30) keV, agrees with the value calculated byFord andWills (3974 keV) for a “family II”-charge distribution fitted to the Stanford electron scattering data.     

Spin-lattice relaxation of protons and deuterons in NH4NO3 and ND4NO3

The spin-lattice relaxation timesT ₁ were measured for protons and deuterons in polycrystalline NH₄NO₃ and ND₄NO₃. The investigation was carried out at temperatures between about 80°K and 430°K using the NMR pulse method. From the measured values ofT ₁ the activation energies for the reorientation motions of NH ₄ ⁺ and ND ₄ ⁺ ions below 200°K were calculated to be 2.07±0.11 kcal/mole and 2.56±0.23 kcal/mole, respectively. The quadrupole coupling constante ² Qq/h of the deuteron in ND ₄ ⁺ ion was found to be 194±30 kc/s.     

Dasβ-Spektrum des Cs137

Theβ-ray spectrum of Cs¹³⁷ has been measured with an iron-free spectrometer. The energy of the soft component was found to beE ₀=514±2 keV. The parameterk of the hard-component shape factorC _2VA ⁽²⁾ (W)=q ²+kp ² was determined to bek=0.015±0.004. Theβ intensities amount to 6.5% (hard component) and 93.5% (soft component). TheK conversion coefficient of the isomeric transition was measured to beα _K=0.093±0.003, in excellent agreement withSliv's theoretical value.     

Zerfallsschema und Matrixelemente für denβ-Übergang Ag110m→Cd110

Theβ decay Ag^110m→Cd¹¹⁰ has been investigated with a double lens spectrometer and aβ-γ circular-polarization correlation setup. The shape of the 6⁺→6⁺ β spectrum withE ₀=529 keV was found to be allowed, in disagreement with earlier work. The constantA of theβ-γ circular-polarization correlation was measured to beA=0·07±0·02. This implies a ratioX of Fermi to Gamow-Teller contribution to the decay ofX ₁=?0·02±0·03 orX ₂=?10·3 _?4·1 ^+2·3 . Qualitative shell model considerations favor the valueX ₁. Additional information is given for the disintegration schemes of Ag^110m and Ag¹¹⁰.     

Concerning internal conversion coefficients in Hf180

The gamma-ray relative intensities from transitions in Hf¹⁸⁰ following the 5.5 hour Hf^180m decay have been measured using a bent-crystal gamma-ray diffraction monochromator and a least-squares fitting technique. From these measurements it was possible to deduce a value for the internal conversion coefficient for the 93.3-keV transition of α _T ⁹³ =4.91±0.23. From previous measurements of conversion electron intensities byEdwards andBoehm and our gamma-ray relative intensities, internal conversion coefficients for all transitions except the 57.5-keV transition were obtained. These coefficients agree well with the previous determinations byEdwards andBoehm, however, our measurements have improved precision, particularly in the case of 501.3-keV transition. The present measurements of α _K for the 215.3-, 332.5-and 443.8-keVE2 transitions are 11% lower than theoretical values while α_K for 93.3 keV E2 transition agrees closely with the theoretical value. These results are in close agreement with the previous measurements ofEdwards andBoehm. The present experimental α_K for the 501-keV transition agrees closely with the theoretical α_K for an E3 multipolarity.     

Comparison of theK ± p scattering data with the forward dispersion relations

The dispersion relations forK ^± p forward scattering were evaluated in order to test the compatibility with the experimental data and to obtain an estimation of the effective coupling constantG ^2/4π=(G _Λ ² +G _Σ ² )/4π.     

Konversion der 238,6 keV-γ-Linie des ThB und Vergleich mit den Tabellen von Sliv und von Rose

The conversion ratiosK/L _I andK/L _II of the 238.6 keVγ transition of ThB have been measured with the new Heidelbergπ/2 √13Β-ray spectrometer. For this transition there are great discrepancies between the values as given bySliv andBand, and byRose. The experimental resultsK/L _I=5.96±0.26 andK/L _II=60.3±7.1 are in excellent agreement with the values ofSliv andBand.     

Inelastische Positronenstreuung am Atomkern

The ratio of the total and differential cross section for the inelastic positron-nucleus scattering (ē, N)-process to the total (γ, N) -cross section is derived in Born approximation for electric and magnetic dipole transitions. The result agrees with that obtained for the (e, N)-processes. Using the relativistic Coulomb Eigenfunctions for the continuous spectrum of the positrons, the Coulomb correction, the effect of screening and that of finite nuclear size agree with the (e, N)-process, when the annihilation of positrons with atomic electrons is neglected, and for positron energiesE _1,2 ⁺ >10 MeV. The effect of finite nuclear size is only calculated in Born approximation. ForE _1,2 ⁺ ≦2 MeV only the Coulomb correction differs from that obtained for the (e, N)-process. In the angular distribution for the (ē, N)-process there should be no interference of positron waves scattered by different multipoles, where the inelastic scattered positrons are detected. Numerical calculations have been carried out for nuclei withZ=6.29 and 82 and scattering angles ?=1°, 132°, 160° and 180° of the positron. This theory can be compared with the experiments in progress by W.C.Barber et al. using positrons for the inelastic scattering process at nuclei. The two-and three-virtual quanta-exchange effect in the (ē, N)-cross section is below 1.3% for positron energies between 10≦E ₁ ⁺ ≦300 MeV, and decreases rapidly for higher energies. This theory is also valied for inelastic scattering processes with positiveμ-mesons at nuclei; one has only to change the mass in the following equations.     

Zur Chronologie des alten Ägypten

The velocityv of the propagation of discharge along the anode of a self-quenchingG—M-counter is a function of total pressureP, pressure of the quenching gasP _D, radius of the cathoder _a and of the anoder _i andV _ü the difference between working- and starting-potential. For the mixtures argon-methylal, argon-alcohol and helium-alcohol isv=v ₀·exp[k·(V _ü/V _e)^1/2] withv ₀ the velocity at the starting potentialV _e v ₀=(a+b·P _D/P)·V _n ^1/2 ·exp [(c?d·P_D/P·V _n ^?1/2 ] andV _n=V _e·(lnr _a/r _i)^?1.k, a, b, c andd are characteristical constants of the filling gas.