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  • 1
    Digitale Medien
    Digitale Medien
    The number of neurons, glial and perineurium cells in an insect ganglion (1965)
    Springer
    Cellular and molecular life sciences 21 (1965), S. 719-719 
    Details
    ISSN: 1420-9071
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Zusammenfassung Im zweiten Abdominalganglion der Indischen Stabheuschrecke (Carausius morosus Br.) wurden 600 ± 50 Neurone, 1000 ± 100 Gliazellen und 500 ± 30 Perineuriumzellen, zusammen etwa 2100 Zellen gezählt. Die Volumina des Ganglions, des Neuropilems und des Zellcortex betrugen etwa: 140 · 10−4 mm3, 75 · 10−4 mm3 und 65 · 10−4 mm3.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02138494
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  • 2
    Digitale Medien
    Digitale Medien
    Destruction of26Al in explosive nucleosynthesis (1986)
    Springer
    The European physical journal 323 (1986), S. 1-11 
    Details
    ISSN: 1434-601X
    Schlagwort(e): 25.90 ; 95.90
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The26Al(n, p)26Mg reaction has been studied using neutron spectra which closely resembled Maxwell-Boltzmann (M.-B.) distributions with thermal energies ofkT=40 ×10−6, 31 and 71 keV and also forE n =270–350 keV. These energies correspond to stellar temperaturesT 9=4.6×10−7, 0.36, 0.82 and 3.1–4.1, whereT 9 is in units of 109 K. The partial cross sections for thep 0-(p 1-)transition are found to equal 26±10(1,850 ±150), 13±6(124±17), 16±13(84±14) and 21±8(72±15) mb for the above neutron spectra, respectively. The astrophysical reaction rate is determined for the combinedp 0- andp 1-transitions to beN A 〈σν〉=(0.324±0.026, 20.5±2.7, 22.6±4.3 and 38.7±11.1) ×106 cm3 mole−1 s−1. The results are compared with previous investigations and with statistical model calculations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01294550
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  • 3
    Digitale Medien
    Digitale Medien
    Absolute cross section of the3He(α,γ)7Be reaction (1988)
    Springer
    The European physical journal 329 (1988), S. 243-254 
    Details
    ISSN: 1434-601X
    Schlagwort(e): 25.55.-e ; 27.10 ; 27.20
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The absolute cross section σ(E) of the3He(α, γ)7Be reaction has been measured fromE c.m. =195 to 686 keV. The studies employed both a supersonic jet gas target and an extended gas target, and were carried out by the observation of the prompt capture γ-ray transitions as well as the7Be residual nuclei. The absolute cross sections deduced from the capture γ-rays are in good agreement with most previous work and remove a discrepancy with other earlier work. In comparison, the σ(E) values obtained from the7Be residual nuclei are systematically higher, suggesting a small production of additional7Be by contaminant reactions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01283781
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  • 4
    Digitale Medien
    Digitale Medien
    The cross section of14N(n, p)14C at stellar energies and its role as a neutron poison forS-process nucleosynthesis (1988)
    Springer
    The European physical journal 330 (1988), S. 167-172 
    Details
    ISSN: 1434-601X
    Schlagwort(e): 95.30.C ; 97.10.C ; 25.70
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The absolute average cross section 〈σ〉 of the14N(n, p)14C reaction has been measured using neutron spectra that closely resemble Maxwell-Boltzmann distributions with thermal energies of kT=25.0 and 52.4 keV: 〈σ〉=0.81±0.05 and 0.52±0.06 mb, respectively. The resulting reaction rates are nearly the same at T9=0.29 and 0.61, and their average, NA〈συ〉=(1.3±0.1)×105 cm3 s−1 mol−1, is about a factor of three smaller than the previously adopted values obtained by extrapolation between thermal and higher-energy data. Thus, the14N(n, p)14C reaction plays a correspondingly smaller role as a neutron poison fors-process nucleosynthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01293392
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  • 5
    Digitale Medien
    Digitale Medien
    Stellar reaction rate of26Mg(p, γ)27Al (1980)
    Springer
    The European physical journal 296 (1980), S. 273-280 
    Details
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The reaction26Mg(p, γ)27Al has been investigated atE p (lab)=80–355 keV. The existence of the resonances atE p =292 and 338 keV has been verified and new resonances were found atE p =227 and 275 keV. Information on branching and mixing ratios,ωγ values, total widths, andJ π assignments for the observed resonances is given. Upper limits on theωγ strengths for expected resonances in the energy range covered are presented. The astrophysical aspects of the data are discussed in the light of the26Mg(26Al) isotopic anomaly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01415841
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  • 6
    Digitale Medien
    Digitale Medien
    The15N(p,α 0)12C reaction at stellar energies (1982)
    Springer
    The European physical journal 305 (1982), S. 325-333 
    Details
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The15N(ρ, α0)12C reaction has been investigated in the energy range ofE p (lab)=78-810keV. The measurement of the excitation functions and α-particle angular distributions involved solid targets as well as a quasi-point supersonic jet gas target. The determination of absolute cross sections has been carried out with the gas target. The observed energy dependence of the total cross sections can be described in terms of two-level Breit-Wigner shapes including the resonances atE p (J π)=335(1−) and 1,028(1−)keV. The data lead to a zero-energy intercept of the astrophysicalS(E) factor ofS(0)= 65±4MeV-b. The angular distributions are asymmetric around 90° and require an additional amplitude in the reaction mechanism, which interferes predominantly with the 335 keV resonance. The origin of this background amplitude is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01419081
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  • 7
    Digitale Medien
    Digitale Medien
    The4He(12C, γ)16O reaction at stellar energies (1982)
    Springer
    The European physical journal 308 (1982), S. 73-94 
    Details
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The capture reaction4He(12C, γ)16O (E c.m.= 1.34–3.38 MeV) as well as the elastic scattering process4He(12C,12C)4He (E c.m.=1.44–3.38 MeV) have been investigated with the use of an intense12C beam and a windowless and4He recirculating gas target system. The measurements involved two large NaI(T1) crystals in close geometry to an extended gas target, whereby angle-integrated γ-ray yields were obtained. A large area plastic detector was used for the suppression of time-independent background. A search for cascade γ-ray transitions was carried out by coincidence techniques. The measurement of absolute cross sections is also reported. Theoretical fits of the excitation function for the groundstate γ-ray transition requireE1 as well asE2 capture amplitudes, which are of equal importance at stellar energies. This result increases significantly the stellar burning rate of4He(12C, γ)16O and leads to16O as the dominant product at the end of helium burning in massive stars. The observed capture yield to the 6.92 MeV state is dominated by the direct capture mechanism and plays a small role at stellar energies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01415851
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  • 8
    Digitale Medien
    Digitale Medien
    Helium burning of22Ne (1989)
    Springer
    The European physical journal 334 (1989), S. 491-510 
    Details
    ISSN: 1434-601X
    Schlagwort(e): 25.55 ; 97.10
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The22Ne(α, γ)26Mg and22Ne(α, n)25Mg reactions were investigated forE α(lab) from 0.71 to 2.25 MeV. Neon gas enriched to 99% in22Ne was recirculated in a differentially pumped gas target system of the extended type. Theγ-ray transitions were observed with Ge(Li) detectors and the neutrons with3He ionization chambers. A previously known resonance at ER(lab)=2.05 MeV was verified and 15 new resonances were found in the energy range covered, with the lowest at ER(lab)=0.83 MeV. Information on resonance energies, widths, strengths,γ-ray branching ratios, as well asJ π assignments, is reported. The energy range investigated corresponds to the important temperature range ofT 9 from 0.3 to 1.4 (109 K), for which the astrophysical rates were determined for both reactions. The results show that the ratios of the rates for22Ne(α, n)25Mg and22Ne(α, γ)26Mg are significantly smaller than the previously adopted values, e.g., by at least a factor of 60 nearT 9=0.65. Thus, the22Ne(α, n)25Mg reaction will likely play a smaller role as a neutron source fors-process nucleosynthesis, than has frequently been assumed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01294757
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  • 9
    Digitale Medien
    Digitale Medien
    Electron screening in thed+3He fusion reaction (1994)
    Springer
    The European physical journal 350 (1994), S. 171-176 
    Details
    ISSN: 1434-601X
    Schlagwort(e): 25.55.−e
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Cross section measurements of thed(3He,p)4He reaction have been extended to an energy as low asE cm =5.4 keV. The data have an improved accuracy compared with previous work and confirm the existence of electron screening. The combined analysis of the present and previous data leads to an electron screening potential ofU e =123 ± 9 eV. A similar analysis of previous data for3He(d, p)4He leads toU e =186 ± 9 eV. Both screening potentials differ due to the molecular and atomic aggregate state of the targets involved in these investigations and are significantly larger than expected from available atomic physics models, supporting the general trend in studies of electron screening.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01290685
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  • 10
    Digitale Medien
    Digitale Medien
    The3He(α,γ)7Be reaction and the solar neutrino problem (1982)
    Springer
    The European physical journal 304 (1982), S. 307-332 
    Details
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The capture reaction3He(α,γ)7Be has been investigated in the energy range ofE c.m. =107 to 1,266 keV. The4He or3He beams of up to 300 μA particle current were incident on3He or4He gas targets, respectively. The gas target systems were all of the windowless and recirculating type. Excitation functions have been obtained with the use of an extended-static gas target, while the measurements ofγ-ray angular distributions involved a quasi-point supersonic jet system. The determination of absolute cross sections has been carried out with both types of gas target systems. Theγ-ray yields in the3He(α,γ)7Be reaction were detected using 80 cm3 Ge(Li) detectors. The data lead to a zero-energy intercept of the astrophysicalS(E) factor ofS(0)=0.30±0.03 keV-b. This result reduces the calculated solar neutrino rate by a factor of 1.76.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01421513
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