A model for continuous particle spectra from light and heavy ion induced reactions

Machner, H.

doi:10.1007/bf01290622

Cited by 4 publications

(9 citation statements)

References 25 publications

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“…Analysis of the present data in terms of a generalized moving-source model [15] yields a common behavior of all fragments and at all energies, irrespective of whether the energy range under consideration is dominated by the intermediate component or the projectilelike component.…”

Section: Discussionmentioning

confidence: 83%

“…The moving-source prescription was recently generalized to lightand heavy-ion reactions [15]. In the moving-source parametrization, one assumes a small for the initial-state occupation probability.…”

Section: A Energy Spectra and Distributions Of Cross Sectionsmentioning

confidence: 99%

“…mon to all these approaches is the treatment of nucleonnucleon interactions in a potential well. Our objective is to make a relative assessment of the two theoretical points of view and also to examine whether a "generalized moving source model, " proposed by one of the authors [15], would provide a comprehensive basis for the description of both light charged particles as well as intermediate-mass fragments (IMF's) emitted in heavyion reaction at the Fermi velocity.…”

Section: Introductionmentioning

confidence: 99%

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Particle emission fromAs71produced via
Buhr
¹
,
Machner
²
,
Nolte
³

et al. 1992
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Charged particles from protons up to projectile particles were measured from the systems Ne+ 'V and ' N+ Fe at 530 MeV bombarding energy forming the same composite "As . The data show entrance channel effects with respect to spectral distributions and fragment abundances. The data analysis in terms of different models indicates a common reaction mechanism for all particles produced.PACS number(s): 23.70. +j, 25.70.z

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Section: Discussionmentioning

confidence: 83%

Section: A Energy Spectra and Distributions Of Cross Sectionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Particle emission fromAs71produced via
Buhr
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Machner
²
,
Nolte
³

et al. 1992
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“…For completeness the content of the model [22] is briefly repeated here. Suppose an IMF is emitted statistically from a source.…”

Section: Discussionmentioning

confidence: 99%

Isotopic production cross sections in proton-nucleus collisions at 200 MeV

et al. 2006

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Intermediate mass fragments (IMF) from the interaction of 27 Al, 59 Co and 197 Au with 200 MeV protons were measured in an angular range from 20 degree to 120 degree in the laboratory system. The fragments, ranging from isotopes of helium up to isotopes of carbon, were isotopically resolved. Double differential cross sections, energy differential cross sections and total cross sections were extracted.

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“…We can show that (19) (after substitution into the expression for the double differential cross-section and summation over angular momenta) formally results in the hot spot model [10] with a time and angle-dependent nuclear "temperature" which relaxes from its maximal E/n o value for the forward scattering angles in the initial reaction stage towards the compound nucleus angle-independent temperature E/~. A connection between the exciton model and the hot spot model has been discussed in [11].…”

Section: (H/q) This Requirement Ensuresmentioning

confidence: 98%

Novel approach to angular distributions in precompound reactions Does the Bohr hypothesis always work?

Kun¹

1994

Z. Physik A - Hadrons and Nuclei

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Abstraet. We modify the standard statistical model for precompound reactions (exciton model) by taking into account the correlations between fluctuating S-matrix elements with different J (total spin) values. This is done in the framework of the statistical approach to nuclear reactions. While angle-integrated cross-sections are not affected by our modification, differential cross-sections become asymmetric about 90 ~ c.m. This asymmetry weakens with time and with increasing complexity of the decaying nuclear system, but need not disappear even for the compound (thermalized) system. We present a comparison with data showing such an asymmetry. PACS: 24.10.Cn; 24.60.Dr In the modern approach to precompound reaction theory, it is customary to distinguish the multistep-direct and the multistep-compound processes [1]. The former yields forward-peaked angular distributions, and the latter cross-sections which are symmetric about 90 ~ c.m. The distinction is based on the difference between a continuum and a bound-state shell-model wave function for the nucleon in intermediate states of the collision process [1][2][3]. While intuitively appealing and quite successful in general, this approach suffers from two shortcomings. First, the transition from one type of reaction to the other is abrupt: Entirely different statistical assumptions are used in the theory [1][2][3] for nucleons in continuum and in bound-state orbitals. In the first case, direct amplitudes dominate the process; in a statistical description [4], such direct reactions imply strong correlations between reaction amplitudes carrying different total spins J and, hence, give asymmetric angular distributions. In the second case, such correlations are from the outset assumed to be absent; this implies symmetry about 90 ~ c.m. A second shortcoming becomes apparent upon inspection of a number of experimental angular distributions of neutrons of low energy < 1-2 MeV (see Figs. 1 and 2 as examples) and sub Coulomb charged particles emitted in nucleoninduced precompound reactions with a few to several tens of MeV incident energy. Although the above-mentioned theories predict these low-energy particles to originate overwhelmingly from the multistep-compound process, a considerable fraction of them (up to 20-30%) displays forward peaking outside of experimental errors reported. This is not consistent with present-day theory.It is the purpose of this work to overcome these difficulties by a suitable modification of the statistical model. Here we briefly present the main sheme of our formulation, the results and simple applications to the analysis of data. The detailed derivations and discussion will be given elsewhere.The main idea is this. We relinquish distinguishing continuum and bound-state orbitals and classify intermediate configurations by their particle-hole numbers (m) only. (In this respect, our approach is a kin to the exciton model [5]). For each class of states with fixed m and J, we introduce the usual statistical assumptions. Spin correlations of S-ma...

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A model for continuous particle spectra from light and heavy ion induced reactions

Cited by 4 publications

References 25 publications

Particle emission fromAs71produced via
Buhr
¹
,
Machner
²
,
Nolte
³

et al. 1992
Phys. Rev. C*
Self Cite
9
1
7
1
View full text Add to dashboard Cite

Particle emission fromAs71produced via
Buhr
¹
,
Machner
²
,
Nolte
³

et al. 1992
Phys. Rev. C*
Self Cite
9
1
7
1
View full text Add to dashboard Cite

Isotopic production cross sections in proton-nucleus collisions at 200 MeV

Novel approach to angular distributions in precompound reactions Does the Bohr hypothesis always work?

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A model for continuous particle spectra from light and heavy ion induced reactions

Cited by 4 publications

References 25 publications

Particle emission fromAs*71produced viaBuhr1, Machner2, Nolte3 et al. 1992Phys. Rev. CSelf Cite9171View full textAdd to dashboardCite

Particle emission fromAs*71produced viaBuhr1, Machner2, Nolte3 et al. 1992Phys. Rev. CSelf Cite9171View full textAdd to dashboardCite

Isotopic production cross sections in proton-nucleus collisions at 200 MeV

Novel approach to angular distributions in precompound reactions Does the Bohr hypothesis always work?

Contact Info

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Particle emission fromAs71produced via
Buhr
¹
,
Machner
²
,
Nolte
³

et al. 1992
Phys. Rev. C*
Self Cite
9
1
7
1
View full text Add to dashboard Cite

Particle emission fromAs71produced via
Buhr
¹
,
Machner
²
,
Nolte
³

et al. 1992
Phys. Rev. C*
Self Cite
9
1
7
1
View full text Add to dashboard Cite