310 research outputs found
Gedanken zur Vollbeschäftigung
"Dieses Diskussionspapier entstand auf Aufforderung des schwedischen Sekretariats für Zukunftsstudien und entwickelt thesenartig zunächst überraschend wirkende praktisch-utopische Ideen zur politischen Umgestaltung unserer Arbeitsgesellschaft. Es versteht sich als Beitrag zur gegenwärtigen Bewußtseinsveränderung und -sensibilisierung in diesen Fragen, die in den Wirtschaftswissenschaften - von Ausnahmen wie Schumacher und Binswanger abgesehen - bisher kaum das ökonomische Denken beeinflußt hat. Gunnar Adler-Karlson mit seiner Kritik der Wachstumsgesinnung, die neuerdings immer stärker vom Vollbeschäftigungspostulat her begründet wird, strebt ein Umdenken an. "Homo oeconomicus erdrosselt homo ludens" sagt Adler-Karlson und denkt in Richtung auf eine 'lebenswerte' menschliche Ökonomie weiter, die es politisch zu gestalten gilt und die der einstellungsmäßigen und praktischen Umkehr im Leben der einzelnen bedarf. So bezweckt er einen Denkanstoß zur ökologisch orientierten Diskussion um eine mögliche Zukunft, die es heute zu beginnen gilt, wenn sie überhaupt noch eine Chance haben soll. Nicht als fertiges Konzept will er seine Vorschläge verstehen, sondern als Denkanstöße zur Verbindung von individueller und gruppenmäßiger - auch alternativer - Lebenspraxis und einer staatlichen Arbeits- und Wirtschaftspolitik, die sich neue Orientierungspunkte setzt. Gegenüber dem Vorrang der Ökonomie in allen real existierenden Ordnungen will er neue Akzente setzen."Vollbeschäftigung, Zukunft der Arbeit, Arbeitszeit, Lebensqualität, Ökologie
Near-threshold measurement of the 4He(g,n) reaction
A near-threshold 4He(g,n) cross-section measurement has been performed at
MAX-lab. Tagged photons from 23 < Eg < 42 MeV were directed toward a liquid 4He
target, and neutrons were detected by time-of-flight in two liquid-scintillator
arrays. Seven-point angular distributions were measured for eight photon
energies. The results are compared to experimental data measured at comparable
energies and Recoil-Corrected Continuum Shell Model, Resonating Group Method,
and recent Hyperspherical-Harmonic Expansion calculations. The angle-integrated
cross-section data is peaked at a photon energy of about 28 MeV, in
disagreement with the value recommended by Calarco, Berman, and Donnelly in
1983.Comment: 10 pages, 3 figures, some revisions, submitted to Physics Letters
A measurement of the 4He(g,n) reaction from 23 < Eg < 70 MeV
A comprehensive set of 4He(g,n) absolute cross-section measurements has been
performed at MAX-lab in Lund, Sweden. Tagged photons from 23 < Eg < 70 MeV were
directed toward a liquid 4He target, and neutrons were identified using
pulse-shape discrimination and the Time-of-flight Technique in two
liquid-scintillator detector arrays. Seven-point angular distributions have
been measured for fourteen photon energies. The results have been subjected to
complementary Transition-coefficient and Legendre-coefficient analyses. The
results are also compared to experimental data measured at comparable photon
energies as well as Recoil-Corrected Continuum Shell Model, Resonating Group
Method, and Effective Interaction Hyperspherical-Harmonic Expansion
calculations. For photon energies below 29 MeV, the angle-integrated data are
significantly larger than the values recommended by Calarco, Berman, and
Donnelly in 1983.Comment: 16 pages, 14 figures, some more revisions, submitted to Physical
Review
Pion emission in 2H, 12C, 27Al, gamma pi+ reactions at threshold
The first data from MAX-lab in Lund, Sweden on pion production in
photonuclear reactions at threshold energies, is presented. The decrease of the
total yield of pi+ in gamma + 12C, 27Al reactions below 200 MeV as well as
differential, dsigma/dOmega, cross sections follow essentially predictions from
an intranuclear cascade model with an attractive potential for pion-nucleus
interaction in its simplest form. Double differential, d2sigma/dOmegadT, cross
sections at 176 MeV show, however, deviations from the model, which call for
refinements of nuclear and Coulomb potentials and possibly also for coherent
pion production mechanisms.Comment: 19 pages, 7 figure
Excitations in the Halo Nucleus He-6 Following The Li-7(gamma,p)He-6 Reaction
A broad excited state was observed in 6-He with energy E_x = 5 +/- 1 MeV and
width Gamma = 3 +/- 1 MeV, following the reaction Li-7(gamma,p)He-6. The state
is consistent with a number of broad resonances predicted by recent cluster
model calculations. The well-established reaction mechanism, combined with a
simple and transparent analysis procedure confers considerable validity to this
observation.Comment: 3 pages of LaTeX, 3 figures in PostScript, approved for publication
in Phys. Rev. C, August, 200
A measurement of the differential cross section for the two-body photodisintegration of 3He at theta_LAB = 90deg using tagged photons in the energy range 14 -- 31 MeV
The two-body photodisintegration of 3He has been investigated using tagged
photons with energies from 14 -- 31 MeV at MAX-lab in Lund, Sweden. The
two-body breakup channel was unambiguously identified by the (nonsimultaneous)
detection of both protons and deuterons. This approach was made feasible by the
over-determined kinematic situation afforded by the tagged-photon technique.
Proton- and deuteron-energy spectra were measured using four silicon
surface-barrier detector telescopes located at a laboratory angle of 90deg with
respect to the incident photon-beam direction. Average statistical and
systematic uncertainties of 5.7% and 6.6% in the differential cross section
were obtained for 11 photon-energy bins with an average width of 1.2 MeV. The
results are compared to previous experimental data measured at comparable
photon energies as well as to the results of two recent Faddeev calculations
which employ realistic potential models and take into account three-nucleon
forces and final-state interactions. Both the accuracy and precision of the
present data are improved over the previous measurements. The data are in good
agreement with most of the previous results, and favor the inclusion of
three-nucleon forces in the calculations.Comment: 12 pages, 13 figures; further Referee comments addresse
A new state in 6He following the 7Li(γ,p)6He reaction
A broad excited state was observed in 6He with energy Ex=5+-1 MeV and width Gamma=3+-1 MeV, following the reaction 7Li(γ,p)6He. The state is consistent with a number of broad resonances predicted by recent cluster model calculations. The well-established reaction mechanism, combined with a simple and transparent analysis procedure confers considerable validity to this observation
Compton Scattering from the Deuteron and Extracted Neutron Polarizabilities
Differential cross sections for Compton scattering from the deuteron were
measured at MAX-lab for incident photon energies of 55 MeV and 66 MeV at
nominal laboratory angles of , , and . Tagged
photons were scattered from liquid deuterium and detected in three NaI
spectrometers. By comparing the data with theoretical calculations in the
framework of a one-boson-exchange potential model, the sum and difference of
the isospin-averaged nucleon polarizabilities, and (in units of fm),
have been determined. By combining the latter with the global-averaged value
for and using the predictions of the Baldin sum rule for
the sum of the nucleon polarizabilities, we have obtained values for the
neutron electric and magnetic polarizabilities of (total) (model) and (total) (model), respectively.Comment: 4 pages, 2 figures, revtex. The text is substantially revised. The
cross sections are slightly different due to improvements in the analysi
Measurement and simulation of the neutron response of the Nordball liquid scintillator array
The response of the liquid scintillator array Nordball to neutrons in the
energy range 1.5 < T_n < 10 MeV has been measured by time of flight using a
252Cf fission source. Fission fragments were detected by means of a thin-film
plastic scintillator. The measured differential and integral neutron detection
efficiencies agree well with predictions of a Monte Carlo simulation of the
detector which models geometry accurately and incorporates the measured,
non-linear proton light output as a function of energy. The ability of the
model to provide systematic corrections to photoneutron cross sections,
measured by Nordball at low energy, is tested in a measurement of the two-body
deuteron photodisintegration cross section in the range E_gamma=14-18 MeV.
After correction the present 2H(gamma,n)p measurements agree well with a
published evaluation of the large body of 2H(gamma,p)n data.Comment: 20 pages 10 figures, submitted Nucl. Instr. Meth.
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