Photofission cross section and fissility of pre-actinide and intermediate-mass nuclei by 120 and 145 MeV Compton backscattered photons

Terranova, Maria Letizia; Kezerashvili, G.Ya.; Milov, A.; Mishnev, S. I.; Muchnoi, N. Yu.; Naumenkov, A. I.; Protopopov, I.Ya.; Симонов, Е. А.; Shatilov, D.; Tavares, O. A. P.; Paiva, Eduardo De; Moreira, Elizabeth L.

doi:10.1088/0954-3899/24/1/023

Cited by 14 publications

(8 citation statements)

References 26 publications

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“…The results of the PICA3/GEM calculations [46] are smaller than the experimental ones for both 209 Bi and 197 Au, especially at lower E 0 . In recent years, total fission cross sections have been intensively measured by quasi-monochromatic photon beams of energies up to 300 MeV [25][26][27][28][29][30][31][32][33], and the detailed structure of the excitation function of the photofission of 209 Bi has become clear. The cross sections in the energy region for the giant dipole resonance and the quasi-deuteron mechanism were found to be negligibly small compared with those in the ∆ resonance.…”

Section: Mass Yield Distributionmentioning

confidence: 99%

“…The total photofission yields and/or cross sections on 209 Bi have been extensively measured with ionization chambers and solid-state track detectors so far [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. However, a few works measuring charge distribution and/or mass yield distribution, which are further essential for understanding of fission mechanisms, were performed in the past [34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

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Photofission of²⁰⁹Bi at intermediate energies

Haba¹,

Kasaoka²,

Igarashi³

et al. 2002

Radiochimica Acta

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Photofission / 209 Bi / Bremsstrahlung / Intermediate energies / Thick-target thick-catcher method / Charge and mass yield distributionsSummary. The reaction yields of 63 radionuclides with the mass number A = 56 − 135 produced in the photofission of 209 Bi by bremsstrahlung of end-point energies (E 0 ) from 450 to 1100 MeV have been measured using a catcher foil technique with the aid of intensive chemical separation. The charge distribution was well reproduced by a Gaussian function with the most probable charge (Z p ) expressed by a linear function of A, i.e., Z p = RA + S, and with the A-independent full width at half maximum (FWHM CD ). The charge distribution parameters R, S and FWHM CD were independent of E 0 above 600 MeV, reflecting the resonance nature in photonuclear reactions at intermediate energies. The weighted mean values at E 0 ≥ 600 MeV were R = 0.421 ± 0.001, S = 0.6 ± 0.1 and FWHM CD = 2.1 ± 0.1 charge unit (c.u.). The numbers of pre-and post-fission neutrons were deduced to be ν pre = 12 ± 1 and ν post = 1.4 ± 0.3, respectively, assuming the Unchanged Charge Distribution (UCD). Based on the charge distribution parameters, the symmetric mass yield distributions with the most probable mass A p of 96 ± 1 mass unit (m.u.) and the width FWHM MD of 33 ± 1 m.u. were also obtained. The characteristics of the charge and mass yield distributions are discussed by referring to those for 197 Au based on the results of calculations using the Photon-induced Intranuclear Cascade Analysis code combined with the Generalized Evaporation Model (PICA3/GEM).

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Section: Mass Yield Distributionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photofission of²⁰⁹Bi at intermediate energies

Haba¹,

Kasaoka²,

Igarashi³

et al. 2002

Radiochimica Acta

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“…The availability of high-quality monochromatic (or quasimonochromatic) photon beams generated by different techniques (tagged photons [1,6], and Compton backscattered photons [7,8]) has opened new possibilities for experimental investigation of photonuclear reactions in the energy range 0.02 E γ 4.0 GeV. In particular, the development of highperformance parallel-plate avalanche detectors ( PPAD ) for fission fragments [2,5,9,10] has allowed researchers to obtain photofission cross section data for actinide target nuclei (Th, U, Np) within ∼ 5% of uncertainty, and for pre-actinide (Pb, Bi) within ∼ 12%, covering a large incident photon energy-range from about ∼30 MeV on.…”

Section: Introductionmentioning

confidence: 99%

Fissility of actinide nuclei by 60-130 MeV photons

Morcelle¹,

Tavares²

2006

Braz. J. Phys.

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Nuclear fissilities obtained from recent photofission reaction cross section measurements carried out at Saskatchewan Accelerator Laboratory (Saskatoon, Canada) in the energy range 60-130 MeV for 232 Th, 233 U, 235 U, 238 U, and 237 Np nuclei have been analysed in a systematic way. To this aim, a semiempirical approach has been developed based on the quasi-deuteron nuclear photoabsorption model followed by the process of competition between neutron evaporation and fission for the excited nucleus. The study reproduces satisfactorily well the increasing trend of nuclear fissility with parameter Z 2 /A.

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“…The dotted line is the result using the RELDIS code (variant B) as reported in [3]. Experimental fissility data at lower energies are taken from [11,12] (squares), [13] (triangle), and [14,15] (diamonds), and the dashed line is a trend drawn by eye through these points. In the inset, points represent the semiempiricals-values obtained from the average experimental fissilities (fe-values); the full line is a least-squares fit to these points, and the dotted line is the trend ofs when only the relative fissilities are considered.…”

mentioning

confidence: 99%

“…Fig. 2 also shows a few experimental points obtained at different laboratories in the quasi-deuteron region of photoabsorption [11][12][13][14][15]. A free, dashed line shows the trend of fissility in this low energy region.…”

mentioning

confidence: 99%

New approach to nuclear photofission reactions above 0.15 GeV

Tavares¹,

Duarte²,

Deppman

et al. 2004

Braz. J. Phys.

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A simple approach to evaluate nuclear photofissilities at energies above the pion photoproduction threshold has been developed. It is based on the current, two-step model for intermediate-energy photonuclear reactions, i.e. a photon-induced intranuclear cascade followed by a fission-evaporation competition process for the excited, post-cascade residual nucleus. The calculation method (semiempirical by nature) shows that fissility (i.e., total fission probability) is governed by two basic quantities, namely, the first-chance fission probability for the average cascade residual, and a parameter which defines an evaporative sequence of residuals in which the average, equivalent chance-fission probabilities of nuclides belonging to the same generation are located. The nat Pb photofissility data measured recently in the range ∼ 0.2 − 3.8 GeV at the Thomas Jefferson Laboratory could be explained very satisfactorily by the present approach.The simultaneous photofission cross section measurements carried out very recently at the Thomas Jefferson Laboratory on a number of actinide target nuclei and natural lead using tagged photons in the range ∼0.2-3.8 GeV and PPAD-detectors for detection of fission fragments [1,2] made possible to extract important conclusions about the nuclear photoabsorption and fissility of these nuclei. Among others, i) the 237 Np photofissility is very close to unity in the whole energy interval, thus indicating that its photofission cross section is almost completely equal to the total photoabsorption cross section, and ii) the photofissility for all other actinide nuclei (uranium isotopes and thorium) is less than unity, therefore their photofission cross section does not represent the photoabsorption cross section for these nuclei. Very recently, results of a detailed and refined description of photofission reactions in heavy nuclei covering a large photon energy range ( ∼0.07−4.0 GeV) became also available [3]. Since photofissility data for actinide targets have been already analysed to some detail [2-4], we decided in the present work to focus attention on the newest photofissility data of nat Pb reported in [1,2]. Photofissility data will be here analysed in the framework of a phenomenological, semi-empirical way, aiming to obtain average calculated fissility values from an approach which has been developed for the first time in describing intermediate-energy photofission reactions in the entire energy range of ∼0.2−3.8 GeV covered by the measured photofission cross section data. Monte Carlo calculations are, at present, the main tool to describe quantitatively both the cascade and fission-evaporation competition processes, as well as to obtain the total fission probabilities (i.e., fissility values) for a number of photofission reaction cases. However, for cases where the target nucleus is expected to have very low fissility-values (pre-actinide, intermediate-mass, and less massive nuclei), the available codes may reveal themselves very time-consuming in obtaining a calculated fissility-cur...

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Photofission cross section and fissility of pre-actinide and intermediate-mass nuclei by 120 and 145 MeV Compton backscattered photons

Cited by 14 publications

References 26 publications

Photofission of²⁰⁹Bi at intermediate energies

Photofission of²⁰⁹Bi at intermediate energies

Fissility of actinide nuclei by 60-130 MeV photons

New approach to nuclear photofission reactions above 0.15 GeV

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Photofission cross section and fissility of pre-actinide and intermediate-mass nuclei by 120 and 145 MeV Compton backscattered photons

Cited by 14 publications

References 26 publications

Photofission of209Bi at intermediate energies

Photofission of209Bi at intermediate energies

Fissility of actinide nuclei by 60-130 MeV photons

New approach to nuclear photofission reactions above 0.15 GeV

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Photofission of²⁰⁹Bi at intermediate energies

Photofission of²⁰⁹Bi at intermediate energies