Scission neutrons and other scission properties as function of mass asymmetry in {sup 235}U(n{sub th},f)

Journal Article · Thu Jul 15 04:00:00 EDT 2010 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.82.014617· OSTI ID:21389210

Carjan, N ^[1]; Rizea, M ^[2]

---

1. Centre d'Etudes Nucleaires de Bordeaux-Gradignan, UMR 5797, CNRS/IN2P3-University Bordeaux I, BP 120, F-33175 Gradignan Cedex (France)
2. Horia Hulubei, National Institute for Nuclear Physics and Engineering, P.O. Box MG-6, RO-76900, Bucharest (Romania)

The emission of scission neutrons is studied in the frame of the sudden approximation, i.e., under the assumption that fission motion is adiabatic until the neck ruptures at finite radius and that this rupture is followed by a sudden absorbtion of the neck pieces by the fragments. We are therefore dealing with a transition between two different nuclear configurations (epsilon{sub i}->epsilon{sub f}) and we only need to know the corresponding two sets of neutron eigenstates. The accent in the present work is put on the dependence on the mass asymetry A{sub L}/A{sub H} of the primary fission fragments during the thermal neutron fission of {sup 235}U. At epsilon{sub i}, i.e., just before scission, the neutrons are considered both independent and pairing correlated. We estimate the scission neutron multiplicity nu{sub sc}, the spatial distribution of the emission points S{sub em}(rho,z) and the primary fragments' excitation energy E{sub sc}*. nu{sub sc} is found to depend only slightly on A{sub L}. The multiplicity has an average value of 0.76 (which represents one third of the prompt neutron multiplicity) with a maximum deviation from this value of less than 0.1. S{sub em}(rho,z) is mainly concentrated in the region between the fragments giving a useful detail of the emission mechanism. E{sub sc}* together with the extradeformation energy is used to evaporate neutrons and emit gamma rays from fully accelerated fragments.

• OSTI ID: 21389210
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 1 Vol. 82; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
APPROXIMATIONS
ASYMMETRY
BARYONS
CALCULATION METHODS
DISTRIBUTION
EIGENSTATES
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
EMISSION
ENERGY-LEVEL TRANSITIONS
EVEN-ODD NUCLEI
EXCITATION
FERMIONS
FISSION
FISSION FRAGMENTS
FISSION NEUTRONS
GAMMA RADIATION
HADRONS
HEAVY NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MASS
MINUTES LIVING RADIOISOTOPES
MULTIPLICITY
NEUTRONS
NUCLEAR FRAGMENTS
NUCLEAR REACTIONS
NUCLEI
NUCLEONS
PROMPT NEUTRONS
RADIATIONS
RADIOISOTOPES
SPATIAL DISTRIBUTION
SPONTANEOUS FISSION RADIOISOTOPES
SUDDEN APPROXIMATION
THERMAL NEUTRONS
URANIUM 235
URANIUM ISOTOPES
YEARS LIVING RADIOISOTOPES