H. Oeschler
Technische Hochschule
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Featured researches published by H. Oeschler.
Physics Letters B | 1985
M. Conjeaud; S. Harar; M. Mostefai; E.C. Pollacco; C. Volant; Y. Cassagnou; R. Dayras; R. Legrain; H. Oeschler; F. Saint-Laurent
Abstract Angular correlations between fission fragments induced by an 40Ar bombardment of 232Th targets at four energies, 31, 35, 39 and 44 MeV/u, have been measured as well as the energies, velocities and masses of both fragments. The characteristics of peripheral collisions remain about constant in the range studied, whereas the component attributed to the central collisions which shows a saturation in linear momentum transfer at 180 MeV/c per incident nucleon, has a cross section decreasing with bombarding energy which is correlated to an increase of the excitation energy of the fissioning nuclei.
Physics Letters B | 1984
E.C. Pollacco; M. Conjeaud; S. Harar; C. Volant; Y. Cassagnou; R. Dayras; R. Legrain; M.S. Nguyen; H. Oeschler; F. Saint-Laurent
Abstract Angular correlations between fission fragments induced by 1760 MeV 40Ar bombarding 197Au and 232Th targets have been measured. Energies, velocities and masses have been obtained for both fragments. The momentum transfer and energy deposited were deduced from an event-by-event analysis. The recoil velocity and total mass spectra show that mass transfer is still a dominating process. Momentum transfer of at least 6.5 GeV/c and 900 MeV excitation energy are deduced.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1993
S.P. Avdeyev; V.A. Karnaukhov; W.D. Kuznetsov; L.A. Petrov; R. Barth; V. Lips; H. Oeschler; O.V. Bochkarev; L. V. Chulkov; E.A. Kuzmin; I.G. Mukha; V.A. Olkin; G.B. Yankov; W. Karcz; Y.T. Vidaj; W. Neubert; E. Norbeck
Abstract The FASA setup, installed at the JINR synchrophasotron providing light ion beams with energies up to 3.65 GeV/nucleon, is a fragment multiplicity detector, consisting of 55 scintillation counters made of thin CsI(TI) films, five time-of-flight telescopes and a large-area position-sensitive parallel-plate avalanche chamber. The basic aim of the device is to determine with high precision the energy, mass, and velocity of the fragments detected in the time-of-flight telescopes (TOF) while for the other fragments global multiplicity information is obtained. Therefore, the TOF telescopes serve as a trigger. In addition, angular correlations and distributions and relative velocity correlations for coincident fragments can be measured with the FASA setup.
Physics Letters B | 1994
V. Lips; R. Barth; H. Oeschler; S.P. Avdeyev; V.A. Karnaukhov; W.D. Kuznetsov; L.A. Petrov; O.V. Bochkarev; L. V. Chulkov; E. A. Kuzmin; W. Karcz; W. Neubert; E. Norbeck; D.H.E. Gross
Abstract The relative-angle distributions of IMFs, studied for the system α + 197 Au at 3.6 GeV/nucleon, show a strong suppression of small relative angles. By multi-body Coulomb trajectory calculations it is shown that the magnitude of this effect is very sensitive to the time scale of the IMF emission. The experimental angular distributions are well described assuming a fast breakup of the system with time less than 100 fm/c between IMF emissions.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1985
E. Kankeleit; U. Gollerthan; G. Klotz; M. Kollatz; M. Krämer; R. Krieg; U. Meyer; H. Oeschler; P. Senger
Abstract A new type of magnetic transport system, the Tori spectrometer, was constructed to measure positrons and electrons simultaneously. Via inhomogeneous toroidal magnetic fields the two charges are spatially separated and transported to different energy-analysing Si(Li) detectors. By means of a magnetic mirror a high positron transmission of about 70% is achieved while electrons are suppressed by about 10 4 . In the particular application for in-beam operation two gas counters for kinematical coincidences are included.
Physics Letters B | 1987
G. Klotz-Engmann; H. Oeschler; E. Kankeleit; Y. Cassagnou; M. Conjeaud; R. Dayras; S. Harar; M. Mostefai; R. Legrain; E.C. Pollacco; C. Volant
Abstract Fragment-fragment correlations have been studied in α -induced reactions at incident energies from 70 to 800 MeV/u on Ag, Ho and Au targets. Even at the highest energy binary thermal fission is observed with excitation energies up to 800–900 MeV. In addition, events with mass number around 30 and relative velocities up to twice the values expected for thermal fission occur and are attributed to multifragmentation. The energy deposit rather than the projectile velocity seems to be parameter governing the appearance of the multifragmentation process which competes strongly with fission for imparted energies beyond 800 MeV.
Physics Letters B | 1990
M. Krämer; B. Blank; E. Bożek; E. Ditzel; E. Kankeleit; G. Klotz-Engmann; G. Müntz; H. Oeschler; M. Rhein
Abstract The integral production probability of atomic positrons associated with elastic heavy ion collisions at beam energies from 5.9 to 10 MeV/u has been investigated as a function of the characteristic collision time t and with respect to its dependence on the combined nuclear charge Z united . Recent data from the systems Pb+Pb at 8.6 MeV/u and Pb+U at 8.4 MeV/u exhibit deviations from coupled-channels calculations: The experimental yield increases stronger towards shorter collision times than predicted.
Physical Review C | 1994
V. Lips; R. Barth; G. Klotz-Engmann; H. Oeschler; Y. Cassagnou; M. Conjeaud; R. Dayras; S. Harar; R. Legrain; E.C. Pollacco; C. Volant; SPhN, Ce Saclay, F Gif-sur-Yvette Cedex
The charge, velocity, and angular distributions of three coincident fragments measured for the system [sup 40]Ar on [sup 232]Th at an incident energy of 31 MeV/nucleon evidence a deep inleastic collision process followed by fission. The estimated total kinetic energy loss is about 600--800 MeV which represents roughly 60--80% damping of the initial kinetic energy.
Archive | 1987
H. Oeschler; B. Blank; E. Bożek; U. Gollerthan; H. Jäger; E. Kankeleit; G. Klotz-Engmann; M. Krämer; R. Krieg; U. Meyer; C. Müntz; M. Rhein; P. Senger
The main research line of the Tori group is the study of the reaction dynamics of dissipative collisions between heavy ions ia positron and electron spectroscopy. The last five years since the Lahnstein-Conference1 are marked for our group by the installation of a new experimental device for detecting positrons and electrons emitted in these collisions, the so-called Tori spectrometer2. The first part of this report is devoted therefore to describe the main characteristics of this apparatus.
Archive | 1987
M. Krämer; B. Blank; E. Bożek; H. Jäger; E. Kankeleit; G. Klotz-Engmann; R. Krieg; C. Müntz; H. Oeschler; M. Rhein; P. Senger
Recent measurements of positrons in coincidence with electrons emitted in U+Th collisions near the Coulomb barrier show sharp line structures in the sum and difference energy spectra of the two leptons (ref. 1). A possible method to clarify the origin of these lines is to study the angular correlation of the leptons. In this short contribution we want to report on a positron-electron coincidence test measurement performed with the TORI spectrometer. This apparatus offers the possibility to measure positrons in coincidence with electrons emitted into the same and opposite hemisphere as well.