Photoprotonen aus Kohlenstoff,Stickstoff, Sauerstoff und Neon

The energy spectra of photoprotons from carbon, nitrogen, oxygen and neon were investigated with 30·5 MeV bremsstrahlung of the Heidelberg betatron using a CsI(Tl)-spectrometer. The known resonances could be confirmed, new resonances are found in nitrogen. Yields and cross sections relative to those of the reaction C¹²(γ, n)C¹¹ are given.     

Chemische Zusammensetzung der kosmischen Strahlung niederenergetischer Teilchen vonZ=12 bisZ=28, gemessen in Plastikdetektoren

Results of a balloon flight experiment flown from Fort Churchill, Canada, at 1.8 g/cm² for about 10 hours in 1968 are presented. The study was made using Lexan polycarbonate plastic sheets as a particle detector. The analysis of the flux and the charge composition is based on the measurement of 313 stopping particles from Mg to Ni with energies between 150 and 400 MeV/Nucl. The identification of the tracks of the particles is achieved using the restricted energy loss criterion. The flux is corrected for scanning and detector efficiency corresponding to their charge. We are able to measure the charge of a particle with an accuracy of ±0.3 charge units in the region of the iron peak. This accuracy depends on the detailed study of the cone length versus residual range. The evenZ to oddZ ratio for chargesZ≧20 is 3. We have measured the ratios of Mn/Fe=0.34, Cr/Fe=0.42 and Ca+Sc+Ti/Fe=1.05. From these measured charge ratios a thickness of (3±1) g/cm² interstellar matter can be deduced.     

Messung der Photoprotonen aus Argon und Sauerstoff

A thin Cs I(Tl) crystal was used to measure the yield of photoprotous for a 34·5 MeV bremsstrahlung spectrum. The following values relative to the yield of the C¹²(γ, n) reaction were obtained: 2·45±0·35 for argon and 2·06±0·28 for oxygen. An upper limit of the integrated cross section for the (γ, n)- and (γ, p)-reaction in oxygen is given.     

Die Feinstruktur desL-MM-Auger-Elektronenspektrums von Argon und derK-LL-Spektren von Stickstoff,Sauerstoff und Methan

The fine structure ofL-MM Auger electron spectrum of argon andK-LL spectra of the gases N₂, O₂ and CH₄ was investigated with an electrostatical spectrometer. The ionisation was caused by the continuous X-radiation from a tungsten target. From the results of Auger electron energies measured, the binding energies of the electrons of the inner shells were calculated. The results obtained with argon agreed exactly with the known values. Further it could be shown, that the value of 400 eV for the binding energy of a 1s-electron in the N₂-molecule, so far obtained, must be replaced by the value (409,4±1,0) eV. A comparison between the relative intensities of fine structure lines and the theory of the Auger process given byAsaad andBurhop could not be carried out, because the Auger electrons, having in our experiment an angular distribution relativ to the incident X-ray beam, could only be measured between an angular range of 49,3° and 61,0°.     

Erzeugung von Be7 durch Kernphotoeffekt am Beryllium,Bor und Kohlenstoff

Beryllium, natural boron, boron enriched with B¹⁰, and graphite were irradiated with 44 and 56,5 MeV bremsstrahlung. The yields of Be⁷ from each of these targets were measured by comparison with the C¹²(γ, n) C¹¹ reaction.     

Zur Tiefenverteilung der durch Elektronenstoß angeregten charakteristischen Röntgenstrahlung von Bor,Kohlenstoff, Aluminium und Silber

The peak intensity of the X-ray emission bands of boron (BK; 67 Å), carbon (CK; 44 Å), aluminium (AlL _2,3; 171 Å), and silver (AgMζ; 40 Å) excited by electron bombardment of evaporated targets has been measured as a function of the thickness of the target and at several accelerating voltages in the range 1 to 4 kV. The electron beam was inclined at an angle of 50° to the surface of the target; the take-off angle for the radiation was about 20°. From these measurements one obtaines the thickness of layers effective in producing X-rays. The influence of surface contamination and oxide layers on the intensity distribution of emission bands is discussed. It is then shown that the effect of anode self-absorption can be evaluated, if the absorption coefficientμ(λ) is available. As an example theL ₃/L ₂ intensity ratio of aluminium, and an averaged depth of X-ray production are calculated; moreover data for the electron range are given and compared with earlier results. Finally the BK-emission band of evaporated boron is presented.     

Schwingungsrelaxation und Gasaufheizung bei periodischem Betrieb der Impulslaser-Gasentladung in Stickstoff

For a typical pulse laser gas discharge in nitrogen without gas streaming, the time variation of the vibration temperature between two pulses is calculated based on a generalized Treanor distribution of the vibration term population. As processes destroying vibration energy, the wall desactivation, VV- and VT-processes are considered. As results, values of the vibration temperature at the beginning of the pulse discharge and data for the gas temperature difference between tube wall and axis are presented in dependence on the repetition frequency. Finally is discussed, in which scale the elevated vibration temperature and the gas temperature may influence the power of the nitrogen pulse laser.     

Kernphotoprozesse im Sauerstoff und ihre Bedeutung für die Kontrolle der Energie und des Photonenspektrums an Elektronenbeschleunigern

The yields of the photonuclear reactions¹⁶O(γ,n) and¹⁶O(γ, 2n) are measured with a newly constructed device for fluid samples. The well known structures of the (γ,n) cross section are used for the energy calibration of our accelerator. Though the yield should be strongly dependent on small changes of the bremsspectrum no difference was found, using a thin or a thick target. The conclusion is, that also the thick target is in its effect a thin target under the accelerator conditions. The (γ, 2n) cross section is measured for the first time between threshold and 120 MeV. It is unusually small compared to the (γ,n) cross section.     

Bestimmung der Driftgeschwindigkeit von Elektronen in Wasserstoff und Stickstoff bei hohem Druck

By means of a time of flight method the electron drift velocity in hydrogen and nitrogen was determined for high pressure, at which no measurements were as yet available. The values are obtained in the range fromE/p=12 toE/p=0,03 V/cm Torr with an accuracy from 1% to 1,5%. The pressure range available (up to 31000 Torr) enabled an examination of the similarity rule. The measurements show that for constantE/p, in the rangeE/p<1, the drift velocities decrease with increasing pressure.     

Onsager-Zerlegung und Entropieproduktion für ein Brownsches Teilchen in der harmonischen Kette

The momentum autocorrelation function of a heavy particle in an infinite harmonic chain in thermal equilibrium is shown to be an example of “Onsager separation”. This separability ensures that thestatistical entropy production associated with the momentum relaxation of the particle contains aphenomenological part which proves to be always positive.     

Onsager-Zerlegung und generalisierte Langevin-Theorie für ein Brownsches Teilchen in der harmonischen Kette

To illustrate the so-called Onsager separability of dynamic correlation functions (which is fundamental to the Statistical Mechanics of phenomenological processes) we consider the exact generalized Langevin equation for the momentum of a Brownian particle in a harmonic chain. The time dependence of the Langevin force and its dynamic autocorrelation (the after effect kernel) are calculated and shown to have no hydrodynamic part—in contrast to the particle's momentum correlation.