Fission probabilities across the π-nucleon delta resonance

Peterson, R.J.; Barros, S. de; Schechter, H.; Mashnik, S. G.; daSilva, A.G.; Suita, Julio Cezar

doi:10.1007/s100500170145

Cited by 13 publications

(14 citation statements)

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“…One can see that we globally reproduce the trend, except for U above 150 MeV. However, one has to realize these experimental points, when compared with a reasonable value of the reaction cross section yield a fission probability larger than 1 [33]. Our modified version slightly improves on the standard INCL4 results and gives similar results to the CEM model of Ref.…”

Section: Residue Production In Pion-induced Reactionssupporting

confidence: 66%

Pion physics in the Liège intranuclear cascade model

Aoust

2006

Phys. Rev. C

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The implementation of π production in the Liège intranuclear cascade model (INCL4) for spallation reactions is revisited to alleviate the overestimate of the π yield. Three modifications are proposed for this purpose: a better πN cross section at high energy, the introduction of a π average potential, and the modification of the average mass of the resonance. The π potential is determined from a global fit of a set of data bearing on π production in proton-induced reactions, on π -nucleus and absorption cross sections, and on proton production in π -induced reactions. The resulting π potential is poorly determined in the nuclear interior and agrees with the phenomenological optical-model potentials in the surface region. With these modifications, the predictions of the INCL4 model concerning π production cross sections in proton-induced reactions are considerably improved. Predictions of the improved version for π -nucleus reaction and absorption cross sections and for proton, residue, and fission cross sections in π -induced reactions are also presented and shown to give reasonably good agreement. Neutron production and some aspects of fission in π -induced reactions are also investigated and reasonably well predicted. Effects on the modifications on observables, which are not directly linked with π 's, such as the neutron yield and the residue mass and charge spectra in proton-induced reactions are also investigated and shown to improve the description of these observable quantities. Several results on π production and the relative insentivity to the π potential in the nuclear interior are shown to be consistent with the fact that most π 's are not produced in early collisions. Importance of rescattering in π absorption on nuclei is also pointed out. A comparison is made with the so-called -hole model. Residual discrepancies are identified and are interpreted as due to the lack of π interaction with two nucleons at low energy, to the neglect of quantum motion effects, and to a possible underestimate of rescattering.

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Section: Residue Production In Pion-induced Reactionssupporting

confidence: 66%

Pion physics in the Liège intranuclear cascade model

Aoust

2006

Phys. Rev. C

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“…As can be seen from Figs. 28,29,49,50, and from results presented in Refs. [97,196,212], the "G" Pb(1GeV/A) + p, LAQGSM + GEMINI Figure 50: Comparison of all measured [213] cross sections of fission products from the reaction 1 GeV/nucleon 208 Pb on p (filled circles) with LAQGSM+GEMINI (LAQGSM03.G1) results (open circles).…”

Section: Reactions Involving Pions and Photons; Excitation Functionsmentioning

confidence: 95%

“…Fig. 13 presents part of the recent extensive experimental data on fragmentation cross sections of 28 Si on H, C, Al, Cu, Sn, and Pb at energies from 290 to 1200 MeV/nucleon [100]. Such measurements are of interest for NASA to plan long-duration space-flights and to test the models used to evaluate radiation exposure in flight, and were performed at many incident energies in this energy range at the Heavy Ion Medical Accelerator in Chiba (HIMAC) and at Brookhaven National Laboratory (see details in [100] and references therein).…”

Section: The Inc Of Laqgsm0303mentioning

confidence: 99%

“…Fig. 27 shows an example of an excitation function of interest to space applications used to estimate the risk assessment for electronic devices (SEUs and MBUs), namely 28 Si(p,x) 7 Be, calculated with an already quite old version of CEM, CEM2k [17], and with our recent versions CEM03.01 [23] and CEM03.02 [63] compared with experimental data from our T-16 compilation [164]. CEM2k, which does not consider evaporation of up to 66 types of particles and the Fermi breakup of light excited nuclei, underestimates these data by two orders of magnitude, providing only a tiny production of 7 Be, only at high incident energies as final residual nuclei produced at the end of the reaction after INC, preequilibrium, and evaporation.…”

Section: Evaporationmentioning

confidence: 99%

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CTOF measurements and Monte Carlo analyses of neutron spectra for the backward direction from a lead target irradiated with 200–1000 MeV protons

Azhgirey¹,

Belyakov-Bodin²,

Degtyarev³

et al. 2010

Nuclear Instruments and Methods in Physics Research Section B:

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A description of the IntraNuclear Cascade (INC), preequilibrium, evaporation, fission, coalescence, and Fermi breakup models used by the latest versions of our CEM03.03 and LAQGSM03.03 event generators is presented, with a focus on our most recent developments of these models. The recently developed "S" and "G" versions of our codes, that consider multifragmentation of nuclei formed after the preequilibrium stage of reactions when their excitation energy is above 2A MeV using the Statistical Multifragmentation Model (SMM) code by Botvina et al. ("S" stands for SMM) and the fission-like binary-decay model GEMINI by Charity ("G" stands for GEMINI), respectively, are briefly described as well. Examples of benchmarking our models against a large variety of experimental data on particle-particle, particle-nucleus, and nucleus-nucleus reactions are presented. Open questions on reaction mechanisms and future necessary work are outlined.

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“…Recently [2,19] fission cross sections and fission probabilities have been calculated for positive and negative pion induced fission of different heavy nuclei in small steps across the (3,3) resonance to observe any possible resonant effects in complex nuclei across this sensitive region. The lack of any pronounced resonant peak indicates that there is no significant change in the reaction mechanism in this important energy range.…”

mentioning

confidence: 99%

Comparison of fission induced by nucleons and pions

Yasin

Peterson

Shahzad

et al. 2007

Nd2007

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Abstract. The goal of the present work is to compare properties of fission induced by nucleons and pions. Three different methodologies are used to make this comparison. Firstly, it is shown that pion-induced fission cross sections are not much different in magnitude from proton induced fission cross sections at the same kinetic energy. Secondly, across the pion-nucleon (3,3) resonance so prominent with free nucleons, it is observed that there is no significant change in the reaction mechanism in the case of pions. Thirdly, it is noted that an empirical expression used for evaluations of proton induced fission cross sections is also valid for positive pion-induced fission cross sections, at least for actinide nuclei.Nuclear fission is an important, interesting and complex nuclear reaction, with relevance in areas ranging from nuclear structure models to accelerator-driven systems (ADS). There is need in basic and applied nuclear physics to understand the properties of fission induced by nucleons and pions, and cross sections for fission induced by nucleons and pions have applications in advanced nuclear reactor technologies, in medicine, for effects on electronics, etc. In ADS using high energy protons, pions are created from the primary proton reactions, and are then part of complex cascades of reactions. Hence, fission induced by nucleons and pions are both important, and fission reactions may have a significant effect on spallation target performance and may contribute to the production of radioactive or chemically hazardous materials in targets [1].Fission induced by pions is not as much studied as fission induced by nucleons. Hence, the goal of the present work is to compare properties of fission induced by nucleons and pions. Three different methodologies are used to make this comparison. Firstly, it is shown that pion-induced fission cross sections are not much different in magnitude from proton induced fission cross sections at the same beam kinetic energy. Secondly, across the pion-nucleon (3,3) resonance so prominent with free nucleons, it is observed that there is no significant change in the reaction mechanism in the case of pions. Thirdly, it is noted that an empirical expression used for evaluations of proton induced fission cross sections is also valid for positive pion-induced fission cross sections, at least for actinide nuclei. Fission cross sections computed using a cascade-exciton model code for 209 Bi and 238 U are also compared with available experimental data.Proton and pion induced fission cross sections are computed using the cascade-exciton model code CEM95. Three stages are incorporated in CEM95; cascade, preequilibrim and compound nucleus stages. A change in the ratio of the level density parameter for fission and neutron emission channels (a f /a n ) is taken into account with change in the incident energy of the projectile to account for the change in the excitation energy of the compound nucleus. Other parameters are the same as are used in our paper [2]. A statistical weight metho...

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Fission probabilities across the π-nucleon delta resonance

Cited by 13 publications

References 0 publications

Pion physics in the Liège intranuclear cascade model

Pion physics in the Liège intranuclear cascade model

CTOF measurements and Monte Carlo analyses of neutron spectra for the backward direction from a lead target irradiated with 200–1000 MeV protons

Comparison of fission induced by nucleons and pions

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