Delayed neutron energy spectra following fast fission of [sup 238]U

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7295978

Villani, M F

Delayed neutron energy spectra have been measured for six delay-time intervals following the fast fission of [sup 238]U nuclei. The delay-time intervals span the range 0.17 to 10.2 seconds following initial fission while the measured spectra span neutron energies from 10 keV to 4 MeV. The experiment was performed utilizing the UMass/Lowell 5.5 MV Van de Graff accelerator to produce fast neutrons for inducing fission in a [sup 238]U lined fission chamber. The fission fragments were flushed via a helium jet stream to a well-shielded counting room where they were deposited onto a moving tape (magnetic audio tape) and transferred to a beta-neutron time-of-flight spectrometer. By adjusting the tape speed, composite delayed neutron time-of-flight spectra were measured for several different delay-time intervals. These measurements involved beta-neutron coincidences with [sup 6]Li-loaded glass scintillators for neutron energies from 10 keV to 450 keV and Bicron BC 501 liquid scintillators for the neutron energy range 200 keV-4 MeV. The measured composite delayed neutron energy spectra for [sup 238]U are compared to the composite spectra for [sup 235]U and [sup 239]Pu, and also to composite spectra derived for [sup 238]U from the ENDF/B-VI database, which is based on summation calculations of individual precursor data supplemented by theoretical estimates. The composite spectra of [sup 235]U and [sup 239]Pu were obtained from previous measurements of delayed neutron spectra at this laboratory. The composite spectra are also decomposed into Keepin six-group spectra and compared with those for [sup 239]Pu and [sup 235]U. In addition, an equilibrium spectrum has been calculated from the measured composite spectra using several different analytical techniques and is also compared with the equilibrium spectrum of [sup 238]U measured in an earlier study at this lab.

• Research Organization: Massachusetts Univ., Lowell, MA (United States)
• OSTI ID: 7295978
• Country of Publication: United States
• Language: English

Related Subjects

663470* -- Fission-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
BARYON REACTIONS
BARYONS
DELAYED NEUTRONS
ELEMENTARY PARTICLES
EVEN-EVEN NUCLEI
FAST FISSION
FERMIONS
FISSION
FISSION NEUTRONS
HADRON REACTIONS
HADRONS
HEAVY NUCLEI
ISOTOPES
NEUTRON REACTIONS
NEUTRON SPECTRA
NEUTRONS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEONS
RADIOISOTOPES
SPECTRA
SPONTANEOUS FISSION RADIOISOTOPES
TIME-OF-FLIGHT METHOD
URANIUM 238
URANIUM ISOTOPES
YEARS LIVING RADIOISOTOPES