Papers by Hartmut Machner
Nuclear Instruments and Methods, 1978
... (ll) Because P~., is a probability, it is obvious that the equation : ~_, Pj.(E) = 1 (12) j=l... more ... (ll) Because P~., is a probability, it is obvious that the equation : ~_, Pj.(E) = 1 (12) j=l is valid as long as emission of the (x + 1)th neu-tron is impossible at the energy E. Then the P~,(E) are calculated starting at x-1 and using eq. ... Rev. 165 (1968) 1166. 5) M. Blann, Phys. Rev. ...
Zeitschrift f�r Physik A Atoms and Nuclei, 1982
Excitation functions of (α,xn yp) reactions on93Nb withy≦6 andx≦10 have been measured in four dif... more Excitation functions of (α,xn yp) reactions on93Nb withy≦6 andx≦10 have been measured in four different irradiations from 16 to 171 MeV bombarding energy by Ge(Li) spectroscopy of the residual activity of stacked foils. Similarly, previous measurements of181Ta(α,x n y p) reactions from 15 to 103 MeV were extended up to 170 MeVα-energy for residual nuclei withy≦4 andx≦12. Including isomeric states a total number of 37 residual activities could be identified in93Nb+α. From the rather complexγ-decay spectra altogether 28 different excitation functions of sizable length could be established. For181Ta+α 10 different residual activities were analyzed so that together with the former data a set of 15 excitation functions is available. The whole set of excitation functions provides a large data basis for probing the validity of combined equilibrium and preequilibrium reaction models in a wide energy range.
The European Physical Journal A - Hadrons and Nuclei, 2003
A stack of annular detectors made of high-purity germanium was used to measure $p + d\to\noindent... more A stack of annular detectors made of high-purity germanium was used to measure $p + d\to\noindent {^3{\rm He}} + \pi^0$ and $p + d\to{^3{\rm H}} + \pi^ + $ differential and total cross-sections at beam momenta from 900 MeV/ c to 1050 MeV/ c. The total cross-sections are consistent with $\Delta$ -excitation. The differential data consist of two components. One
Physical Review C, 1984
The exciton coalescence model is extended to include second chance emission during the pre-equili... more The exciton coalescence model is extended to include second chance emission during the pre-equilibrium phase. The extended model allows the calculation of the parts of the cross sections associated with large linear momentum transfer. Under the assumption that the linear momentum dissipation is independent of the linear momentum carried away by the first emitted particle, coincident spectra may be calculated. The model predictions are compared to data.
Physics Letters B, 2003
A stack of annular detectors made of high purity germanium was used to measure p + d → 3 He + π 0... more A stack of annular detectors made of high purity germanium was used to measure p + d → 3 He + π 0 and p + d → 3 H + π + differential and total cross sections at beam momenta from 900 to 1050 MeV/c. The total cross sections are consistent with ∆-excitation. The differential data consist of two components. One corresponds to large momentum transfer from the projectile to the pion, the other to small momentum transfer. The former shows an independence of the slope as function of the momentum transfer t (scaling). The scale parameter is different for π + and π 0 emission which violates isospin symmetry. The second component which is almost isotropic is in agreement with isospin symmetry. It is approximately a quarter of the total yield in the ∆ resonance region.
nouh 1 e different i a 1 crass sect i ans and different i a 1 crass sect i ans are tabulated far ... more nouh 1 e different i a 1 crass sect i ans and different i a 1 crass sect i ans are tabulated far charged particle spectra fram nuclear reactians af 100 MeV a-particles with 24 , 25 , 26 Mg, 27 Al, and 28 s; target nuclei. The energy spectrascapied particles are pratans, deuterans, tritans, 3 He and a-particles. The detectian angles caver the range fram 20a ta 110a in the reactian plane. Particle identifiaction was performed by feeding the analog ßE and (6E+E) signals into analog to digital converters (ADC's) of the on-line data acquisition system ND 6660 and employing its on-line sorting possibilities. In this method curved two-dimensional gates had to be set araund the event islands corresponding to different ejectiles on a ßE-{ßE+E)-map. Particle-analyzed energy spectra were recorded on magnetic tape after the end of each run.
Physik Journal, 1984
~ 285 felt. Es ist daher angebracht, auf die Gefahren von Uberreaktionen bei der Drosselung der L... more ~ 285 felt. Es ist daher angebracht, auf die Gefahren von Uberreaktionen bei der Drosselung der Lehrerausbildungskapazitaten hinzuweisen. So ist ganz unverstandlich, da13 gut ausgestattete und seit Jahrzehnten bewahrte Institutionen der akademischen Lehrerausbildung geschlossen werden. Dabei werden groBe Regionen einer regional verankerten Lehrerausbildung vor allem fur Grundschulen, Hauptschulen und Realschulen beraubt.
Journal of Computational and Applied Mathematics
... ITEM METADATA RECORD. Title: Special issue: Proceedings of the 11th International Congress on... more ... ITEM METADATA RECORD. Title: Special issue: Proceedings of the 11th International Congress on Computational and Applied Mathematics (ICCAM-2004) - Preface. Authors: Goovaerts, Marc × Vandewalle, Stefan Wuytack, L. Issue Date: May-2006. Publisher: Elsevier. ...
Le Journal de Physique Colloques, 1987
The e x c i t o n model f o r nuclear reactions i s reformulated t o includeenergy-momentum coupl... more The e x c i t o n model f o r nuclear reactions i s reformulated t o includeenergy-momentum coupling. A new d e f i n i t i o n f o r the cross s e c t i o n i s given s i m i l a r t o t h e Glauber model. The model p r e d i c t i o n s are compared w i t h medium energy data.
Chinese Physics C, 2010
The η meson can be bound to atomic nuclei. Experimental search is discussed in the form of final ... more The η meson can be bound to atomic nuclei. Experimental search is discussed in the form of final state interaction for the reactions dp → 3Heη and dd → 4Heη. For the latter case tensor polarized deuterons were used in order to extract the s-wave strength. For both reactions complex scattering lengths are deduced: a3Heη = [± (10.7 ± 0.8+0.1−0.5) + i. (1.5 ± 2.6 +1.0−0.9)] fm and a4Heη = [±(3.1 ±0.5) + i. (0 ±0.5)] fm. In a two-nucleon transfer reaction under quasi-free conditions, p27 Al → 3HeX, was investigated. The system X can be the bound 25Mg⊗η at rest. When a possible decay of an intermediate N* (1535) is required, a highly significant bump shows up in the missing mass spectrum. The data give for a bound state a binding energy of 13.3 ±1.6 MeV and a width of σ = 4.4±1.3 MeV.
Physical Review C, 1983
We measured neutron time-of-flight spectra from 90 MeV protons and 140 MeV alpha particles bombar... more We measured neutron time-of-flight spectra from 90 MeV protons and 140 MeV alpha particles bombarding thin targets of Al, Ni, Zr, and Bi at laboratory angles between 20 and 135. The lowenergy (5 to 45 MeV) portions of the spectra were measured with 5 cm diameter by 5 cm deep NE-213 counters at 1 m flight paths with n-y pulse-shape discrimination. The high-energy (35 to 150 MeV) portions of the spectra were measured with 12.7 cm diameter by 10.2 cm deep NE-102 counters at flight paths of 2.0 to 5.0 m. The proton-induced measured neutron spectra reveal three distinct energy regions: a low-energy evaporation region, a high-energy region dominated by the quasifree scattering process, and an intermediate-energy region dominated by multistep, preequilibrium processes. In the latter two regions, the spectra show strong angular dependence. The alphaparticle induced neutron spectra show these same distinct energy regions plus an exponential falloff above the beam energy per nucleon. The neutron spectra are compared with earlier proton spectra produced also by 90 MeV protons and 140 MeV alpha particles. It is observed that the high-energy portions of the forward-angle neutron and proton cross sections are in ratios consistent with the idea that single nucleon-nucleon scattering dominates. For the heavy-mass targets, the low-energy evaporation regions show neutron yields larger than proton yields. The proton-to-neutron ratios observed in the high-energy continua are interpreted with a quasifree calculation fitted simultaneously to the proton and the neutron spectra. Preequilibrium calculations with the exciton model and the hybrid model reproduce the shape of the experimental angle-integrated energy spectra down to lower energies than the quasifree calculations. The exciton model calculations underestimate the magnitudes of the cross sections, while the hybrid model provides better absolute agreement. One of the preequilibrium calculations uses the method of Mantzouranis and Weidenmuller to predict angular distributions; we find that the predicted angular distributions overestimate the neutron yields at forward angles. The intranuclear-cascade model predicts proton-to-neutron ratios much smaller than experimentally observed in the high-energy forward-angle continua.
Einführung in die Kern‐ und Elementarteilchenphysik, 2005
Einführung in die Kern‐ und Elementarteilchenphysik, 2005
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Papers by Hartmut Machner