Measurements of the Spectra of Uncollided Fission Neutrons Transmitted Through Thick Samples of Nitrogen, Oxygen, Carbon, and Lead: Investigation of the Minima in Total Cross Sections

Clifford, C.E.; Straker, E.A.; Muckenthaler, F.J.; Verbinski, V.V.; Freestone, R.M.; Henry, K.M.; Burrus, W.R.

doi:10.13182/nse67-a18269

Cited by 10 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Doppler broadening is assumed to follow a G-aussian function which neglects the effects of the crystal lattice on the motion of the atoms (63) and may have to be taken into account in very accurate measurements.…”

Section: The Effects Of Doppler and Resolution Broadeningmentioning

confidence: 99%

“…From the Euratom request of EANDC list of June 1967 (63) (64), the requests of J. Ravier, based on a common work with J.Y. Barr4 (64) on the influence of nuclear data inaccuracies on some characteristic parameters of fast reactors, are not all satisfied in the actual status of the data.…”

Section: Fast Reactor Needsmentioning

confidence: 99%

“…(62) Transmission measurements through thick samples of several materials have been performed at Oak Ridge. (63) The goal here has been to determine the accuracy of the total cross section, particularly in the valleys that are important for solving deep-penetration problems. [2] to determine the leakage spectrum from 235jj and Tungsten.…”

Section: Purpose Of Integral Experimentsmentioning

confidence: 99%

See 2 more Smart Citations

Neutron cross sections and technology :

Goldman¹

1968

View full text Add to dashboard Cite

Continuous SourcesThese sources can again be divided up into groups (a) nuclear reactors with their wide energy spectrum of neutrons, (b) crystal monochromators giving nearly mono-energetic neutrons and (c) charged particle reactions producing nearly mono-energetic neutrons in the energy region above about 20 keV.The resonance integral (1 ,2) has been measured for many nuclei in the well moderated neutron flux of a nuclear reactor where the intensity of the neutron flux in the resonance region is assumed to be inversely proportional to the neutron energy. The data are often difficult to interpret, involving corrections both for finite size of the samples and departures from the 1/E law of the neutron spectrum.More detailed data on neutron cross-sections have been obtained from narrow beams of reactor neutrons incident on a single crystal (3 5 4) (e.g. beryllium) which can produce nearly mono-energetic neutrons with an energy spread^S(eV)~5 x 10"^E^/ 2(eV). The crystal spectrometer has been used to measure all types of neutron cross-sections and many accurate resonance parameters below about 20 eV have been obtained from the data (6,7,0,9).Charged particle reactions with light elements can give intense 6^2 sources of nearly mono-energetic neutrons above neutron energies of about a few keV.A general discussion of these types of neutron sources will be found in references 10 and 11. The neutron energy resolution using continuous beams of particles has been pushed close to its limit by Mewson who achieved a resolution of < 1 keV. These continuous sources have been used mainly to measure average cross-sections for medium and heavy nuclei and only in the light nuclei are they the main source of the resonance data. Pulsed Sources of NeutronsIn the neutron energy range 1 0 eV to 1 00 keV time of flight techniques using intense pulsed neutron sources are superior to any other method of carrying out neutron cross-section measurements.Fast choppers (12) with a burst width of~1 us are used with neutron beams emerging from nuclear reactors to measure neutron crosssections, but are being superseded by pulsed accelerator sources.These pulsed accelerator sources can be divided into two main groups: firstly those giving a white neutron spectrum and secondly those using charged^article reactions to give neutrons with a finite energy band.Electron linear accelerators (13) and proton cyclotrons (14) with pulse lengths less than 100 nS are used to produce intense pulsed white sources of neutrons for use in time of flight measurements and are superior to choppers for all neutron measurements in excess of 100 eV.The Van de G-raaff accelerator used with top terminal pulsing and pulse compression magnets, can be used to produce pulses of 10 niA of protons of duration 1 nsec. They have been used to measure neutron cross-sections in the neutron energy region above a few kilovolts. Time of flight is used to determine both the neutron energy and the background.The background can be measured at times when no neutrons coming directly f...

show abstract

Section: The Effects Of Doppler and Resolution Broadeningmentioning

confidence: 99%

Section: Fast Reactor Needsmentioning

confidence: 99%

Section: Purpose Of Integral Experimentsmentioning

confidence: 99%

See 1 more Smart Citation