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Title: Study of {sup 27}Al(n,x{gamma}) reactions up to a neutron energy of 400 MeV

Abstract

The prompt {gamma}-radiation from the interaction of fast neutrons with Al was measured using the white neutron beam of the WNR facility at the Los Alamos National Laboratory. Partial production cross sections for residual nuclei in the range from F to Al were measured from threshold up to 400 MeV by observing the most intense {gamma}-transitions between low lying levels of these nuclei. Two-dimensional neutron time-of-flight versus gamma pulse height spectra from the interaction of the neutrons with Al were observed after flight-paths of about 20 and 40 m with a high-purity Ge-detector. The neutron cross sections for prominent {gamma}-transitions in a large number of residual nuclei could be derived with typical uncertainties of 10--20% up to a neutron energy of 400 MeV. The energy resolution varies from {approx}0.2 MeV at 10 MeV to {approx}50 MeV at 400 MeV. In the low energy range (up to 60 MeV) the results are compared with nuclear model calculations using the code GNASH. A very good overall agreement is obtained without special adjustment of parameters.

Authors:
; ;  [1]; ; ; ;  [2]
  1. Wien Univ. (Austria). Inst., fuer Radiumforschung und Kernphysik
  2. Los Alamos National Lab., NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab., NM (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10156284
Report Number(s):
LA-UR-94-1582; CONF-940507-13
ON: DE94012893; TRN: 94:012103
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: International conference on nuclear data for science and technology: nuclear data for the twenty-first century,Gatlinburg, TN (United States),9-13 May 1994; Other Information: PBD: [1994]
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ALUMINIUM 27 TARGET; NEUTRON REACTIONS; PROMPT GAMMA RADIATION; PHOTOPRODUCTION; CROSS SECTIONS; ENERGY DEPENDENCE; 663430; 663530; 663220; NUCLEON-INDUCED REACTIONS AND SCATTERING; A = 20-38; ELECTROMAGNETIC TRANSITIONS

Citation Formats

Hitzenberger, H., Pavlik, A., Vonach, H., Chadwick, M.B., Haight, R.C., Nelson, R.O., and Young, P.G.. Study of {sup 27}Al(n,x{gamma}) reactions up to a neutron energy of 400 MeV. United States: N. p., 1994. Web.
Hitzenberger, H., Pavlik, A., Vonach, H., Chadwick, M.B., Haight, R.C., Nelson, R.O., & Young, P.G.. Study of {sup 27}Al(n,x{gamma}) reactions up to a neutron energy of 400 MeV. United States.
Hitzenberger, H., Pavlik, A., Vonach, H., Chadwick, M.B., Haight, R.C., Nelson, R.O., and Young, P.G.. Wed . "Study of {sup 27}Al(n,x{gamma}) reactions up to a neutron energy of 400 MeV". United States. doi:. https://www.osti.gov/servlets/purl/10156284.
@article{osti_10156284,
title = {Study of {sup 27}Al(n,x{gamma}) reactions up to a neutron energy of 400 MeV},
author = {Hitzenberger, H. and Pavlik, A. and Vonach, H. and Chadwick, M.B. and Haight, R.C. and Nelson, R.O. and Young, P.G.},
abstractNote = {The prompt {gamma}-radiation from the interaction of fast neutrons with Al was measured using the white neutron beam of the WNR facility at the Los Alamos National Laboratory. Partial production cross sections for residual nuclei in the range from F to Al were measured from threshold up to 400 MeV by observing the most intense {gamma}-transitions between low lying levels of these nuclei. Two-dimensional neutron time-of-flight versus gamma pulse height spectra from the interaction of the neutrons with Al were observed after flight-paths of about 20 and 40 m with a high-purity Ge-detector. The neutron cross sections for prominent {gamma}-transitions in a large number of residual nuclei could be derived with typical uncertainties of 10--20% up to a neutron energy of 400 MeV. The energy resolution varies from {approx}0.2 MeV at 10 MeV to {approx}50 MeV at 400 MeV. In the low energy range (up to 60 MeV) the results are compared with nuclear model calculations using the code GNASH. A very good overall agreement is obtained without special adjustment of parameters.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jun 01 00:00:00 EDT 1994},
month = {Wed Jun 01 00:00:00 EDT 1994}
}

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  • The spectra of neutrons with initial energy 14.6 MeV inelastically scattered by the nuclei /sup 23/Na, /sup 27/Al, and /sup 32/S have been measured in coincidence with energetic prompt ..gamma.. rays. Differential cross sections for inelastic scattering are obtained, and also the differential cross sections for the neutron yield. Radiative decay of states with an unbound proton is responsible for 300 mb in the inelastic scattering cross section for /sup 23/Na, 400 mb for /sup 27/Al, and 110 mb for /sup 32/S with a total (n,n'..gamma..) cross section respectively 560, 580, and 270 mb. Cross sections are given for themore » reactions (n,np) and (n,pn). A calculation of the cross sections according to a statistical model systematically taking into account angular momentum does not give complete agreement with experiment. The observed deviations can be explained by the dominance of certain single-particle configurations in the highly excited nucleus immediately before nucleon emission.« less
  • Double differential (n,xp) and (n,x{alpha}) cross section ratio measurements are performed at the 7 MV Van de Graaff for neutron energies between 2.0 and 15.5 MeV. The following reaction rate ratios are measured: {sup 63}Cu(n,xp) to {sup 58}Ni(n,xp), {sup 63}Cu(n,xp) to {sup 27}Al(n,x{alpha}) and {sup 58}Ni(n,x{alpha}) to {sup 27}Al(n,x{alpha}). The measurement procedure with the five angle {Delta}E-{Delta}E-E telescope was checked by measuring the known reaction rate ratio of {sup 58}Ni(n,p) to {sup 27}Al(n,{alpha}). Cross section data of {sup 63}Cu(n,xp) and {sup 58}Ni(n,x{alpha}) are compared with evaluated data and with cross sections obtained by calculation with the STAPRE-H code.
  • A neutron detector has been constructed and calibrated for the accurate measurement of total neutron-production cross sections. The detector consists of a polyethylene sphere of 24'' diameter in which 8-/sup 10/BF/sub 3/ counters have been installed radially. The relative efficiency of this detector has been determined for average neutron energies, from 30 keV to 1.5 MeV by counting neutrons from /sup 7/Li(p,n)/sup 7/Be. By adjusting the radial positions of the BF/sub 3/ counters in the polyethylene sphere the efficiency for neutron detection was made nearly constant for this energy range. Measurement of absolute efficiency for the same neutron energy rangemore » has been done by counting the neutrons from /sup 51/V(p,n)/sup 51/Cr and /sup 57/Fe(p,n)/sup 57/Co reactions and determining the absolute number of residual nuclei produced during the measurement of neutron yield. Details of absolute efficiency measurements and the use of the detector for measurement of total neutron yields from neutron producing reactions such as /sup 23/Na(p,n)/sup 23/Mg are given.« less
  • Cross sections for neutron threshold reactions (n,p) with Mg/sup 24/, Al/ sup 27/, Pa/sup 31/, S/sup 32/, Fe/sup 54/, Fe/sup 56/, and Ni/sup 58/ and for the (n, alpha ) reaction with Al/sup 27/ are presented. The cross-section values are printed on several sheets of transparent paper enabling a survey of a given series of measurements separately as well as permitting the intercomparison of different measuring series. Uncertainties of cross section values and neutron energies are indicated. The figures of merit for the reactions are also included. (C.E.S.)