A detailed investigation of the thermal neutron induced ternary fission of 235U

doi:10.1016/0375-9474(79)90551-7

Nuclear Physics A

Volume 314, Issue 1, 29 January 1979, Pages 1-26

https://doi.org/10.1016/0375-9474(79)90551-7 Get rights and content

Abstract

The energy and angular distributions of the long-range α-particles released in the thermal neutron induced fission of ²³⁵U have been measured as a function of the mass and kinetic energy of the fission fragments. Only one of the fission fragments was detected, its mass being determined by kinetic energy and time-of-flight measurements. The dependence of the light particle kinetic energy spectra on its final direction is examined as a function of mass and kinetic energy of the fission fragments. The angular distribution of all α-particles with respect to the light fragment direction has a most probable value of 81.3°±0.5° with a dispersion (FWHM) of 18.5°±0.8° which compares very well to the angular spread measured in the spontaneous fission of ²⁵²Cf. Other striking similarities between the ternary fission of ²³⁶U and ²⁵²Cf are pointed out. A positive correlation between the mean emission angle and the mass of the light fragment resolves the controversy which remained on this point up to now. The influence of the total fragment kinetic energy on the width of the angular distribution is investigated in detail. A preliminary interpretation of our data shows that α-accompanied fission should no longer be considered as contradictory to the semi-statistical models of fission.

References (48)

Y. Boneh et al.
Phys. Lett.
(1976)
J. Randrup
Nucl. Instr.
(1977)
M. Asghar et al.
Nucl. Phys.
(1970)
H.W. Schmitt et al.
Nucl. Instr.
(1966)
R. Vandenbosch
Nucl. Phys.
(1963)
E. Piasecki et al.
Nucl. Phys.
(1973)
J.R. Nix
Nucl. Phys.
(1969)
K.T.R. Davies et al.
Phys. Rev.
(1976)
W.J. Swiatecki
J. Blocki et al.
Preprint LBL, 6536
(1977)

L.W. Alvarez

Phys. Rev.

(1947)

Tsien San-Tsiang et al.

Nature

(1947)

H.W. Schmitt et al.

Phys. Rev. Lett.

(1962)

Z. Fraenkel

Phys. Rev.

(1967)

G.K. Mehta et al.

Phys. Rev.

(1973)

Y. Gazit et al.

Phys. Rev.

(1971)

M.J. Fluss et al.

Phys. Rev.

(1973)

C. Carles et al.

Y. Boneh et al.

Phys. Rev.

(1967)

K. Tsuji et al.

M. Rajagopalan et al.

Phys. Rev.

(1972)

V. T. Grachov, D. M. Seliverstov and N. N. Smirnov,...

A. Mougin et al.

Internal Report, DRF/CPN, CEN/Grenoble

(1975)

C.F. Williamson et al.

Rapport CEA-R3042, CEN/Saclay

(1966)

Cited by (29)

Excitation energy dependence of charge odd-even effects in the fission of <sup>238</sup>U close to the fission barrier
1993, Nuclear Physics, Section A
Independent yields of the heavy fragments have been determined for the photofission of ²³⁸U at excitation energies in the barrier region. Bremsstrahlung with six different endpoint energies between 6.1 and 11 MeV was used. The independent and cumulative yields of the fragments were measured using γ-spectrometry techniques. Fragment charge, isotopic mass, elemental yield distributions and proton and neutron odd-even effects are deduced from these independent yields.
The experiments revealed a sizeable odd-even effect [δ_p = (29±2)%] in the element distributions, but on the other hand a small effect [δ_n = (3±2)%] in the isotonic distributions. The proton odd-even effect in the photofission of ²³⁸U remains fairly constant for excitation energies up to about 7.85 MeV. When the excitation energy of the fissioning nucleus is raised slightly higher, the proton odd-even effect drops off quickly.
Low-energy ternary fission
1989, Nuclear Physics, Section A
The double-torus ionization chamber diogenes for the investigation of charged particle associated nuclear fission
1989, Nuclear Inst. and Methods in Physics Research, A
Angular distributions of light charged particles from <sup>252</sup>Cf fission in the ranges 0-46° and 134-180°
1985, Nuclear Physics, Section A
Alpha particles, tritons, deuterons and protons accompanying ²⁵²Cf fission were registered in coincidence with both fission fragments by means of a system containing two-dimensional position-sensitive silicon detectors. Angular distributions, kinetic energy spectra of light charged particles as well as mass distributions of fission fragments in coincidence with light charged particles were measured. The experimental results are compared with some theoretical models.
Microscopic analysis of collective dynamics in low energy fission
1984, Nuclear Physics, Section A
A microscopic description based on the density-dependent Hartree-Fock-Bogolyubov approach with several kinds of constraints is used to extract the characteristic features of the collective dynamics of the fission process at low energy. The dynamical behaviour of the nucleus beyond the second saddle point and a mechanism for scission are deduced. They are analyzed in the framework of a quantum-mechanical treatment of collective dynamics taking into account the variations of the collective inertia.
The double-torus ionization chamber "diogenes" for multiparameter experiments on light charged particle accompanied fission
1983, Nuclear Physics, Section A

View all citing articles on Scopus

^☆: This work constitutes a part of a doctorate thesis undertaken by C. Guet (Grenoble University).

^††: This work constitutes a part of a doctrate thesis undertaken by C. Guet (Grenoble University).

^†††: DPhN/MF, CEN-Saclay, BP no. 2,91190 Gif-sur-Yvette,France.

^†††: DRF-CPN, CEN-Grenoble,85X, 38041 Grenoble Cedex, France.

^‡: CEN Bordeaux, Le Haut-Vigneau, 33 Gradignan, France.

View full text

A detailed investigation of the thermal neutron induced ternary fission of 235U☆

Abstract

Phys. Lett.

Nucl. Instr.

Nucl. Phys.

Nucl. Instr.

Nucl. Phys.

Nucl. Phys.

Nucl. Phys.

Phys. Rev.

Preprint LBL, 6536

Phys. Rev.

Nature

Phys. Rev. Lett.

Phys. Rev.

Phys. Rev.

Phys. Rev.

Phys. Rev.

Phys. Rev.

Phys. Rev.

Internal Report, DRF/CPN, CEN/Grenoble

Rapport CEA-R3042, CEN/Saclay

A detailed investigation of the thermal neutron induced ternary fission of ²³⁵U☆