79-Au-197(n,tot)

ID 10
Type G - General request
Target 79-Au-197
Reaction (n,tot)
Quantity SIG - Cross section
Incident energy 5 keV - 200 keV
Accuracy 5 %
Field(s) Fusion, Science
Subfield Dosimetry
Accepted date 06-Jun-2007
Status Archived
Latest review date 16-May-2018

Requester

Dr Roberto CAPOTE NOY at IAEA, AUT

Project (context)

Dosimetry

Impact

INDC(NDS)-0507 Summary Report of Consultants’ Meeting Review the Requirements to Improve and Extend the IRDF library (International Reactor Dosimetry File (IRDF-2002)), IAEA Headquarters, Vienna, Austria 20-21 April 2006, prepared by L.R. Greenwood and Alan L. Nichols (IAEA, Vienna, January 2007)

Accuracy

5%

Justification document

Gold is an extremely important material in nuclear applications: the capture on gold is a standard neutron cross-section, gold has been proposed as a high energy neutron dosimeter (see below), Au-197(n,2n) is a reactor dosimetry reaction considered in all recent IRDF files, etc. Reactions on gold are also of interest for nuclear model code testing as gold is a mono-isotopic element being amenable to detailed calculations.
Taken from INDC(NDS)-0507 "... proposed high energy dosimetry reactions 197Au(n,2n)196Au, 197Au(n,3n)195Au, and 197Au(n,4n)194Au require the extension of the gold evaluation up to 60 MeV"
To our surprise we found large discrepancies in the measured total cross section data of gold in the 5-200 keV energy range (URR) as can be seen from the attached plots. The only existing evaluation (Young et al in red in the figures) has been carried out in the early nineties and has been adopted for all subsequent libraries with minor modifications. This evaluation follows the Seth et al. data measured in 1965, which is in contradiction with several new measurements (for example Purtov 1994 and Wishak 1995-2006). The spread of the Wishak measurements is puzzling.

Comment from requester

A new dispersive coupled-channel optical model potential (5 keV - 200 MeV) derived using the requested data (plus the existing database above 200 keV) will have a direct impact on future evaluations of neutron induced reactions on gold.

Review comment

While considerable data exist for the 5-200 keV total cross section, there is considerable scatter in these data. The measurement range is well suited for time-of-flight facilities and may also be accessed with quasi-monoenergetic beams using the Li(p,n) neutron source reactions. For a transmission measurement optimal conditions are obtained with a transmission factor close to 0.5, which implies that getting a sample might be costly, but purity and chemical issues should not be concerns. A measurement which overlaps with the region of the Au capture standard (200 keV to 2.5 MeV) would be of interest to allow a consistency check.

Entry status

Completed (as of SG-C review of May 2018) - The JEFF-3.2 evaluation [Sirakov:2013] based on new JRC-Geel measurements [Sirakov:2014;Massimi:2014] is significantly below the target accuracy. The evaluation has been validated against the Grenoble LSDS integral experiment [Zerovnik:2013].

Main recent references

Please report any missing information to hprlinfo@oecd-nea.org

Experiments

  • R. Hannaske, et al., Neutron total cross section measurements of gold and tantalum at the nELBE photoneutron source, EPJA 49 (2013) 137, EXFOR 23199
  • I. Sirakov, et al., Results of total cross section measurements for 197Au in the neutron energy region from 4 to 108 keV at GELINA, EPJA 49 (2014) 144, EXFOR 23222
  • C. Massimi et al., Neutron capture cross section measurements for 197Au from 3.5 to 84 keV at GELINA, EPJA 50 (2014) 124, EXFOR 23253

Theory/Evaluation

  • A.B. Smith, Neutron Scattering from the Standard 197Au, ANL/NDM-161, 2005
  • I. Sirakov et al., Evaluation of neutron induced reaction cross sections on gold, Report JRC 78690, EUR 25803, 2013
  • B. Becker, et al., Evaluation of the Covariance Matrix of Estimated Resonance Parameters, NDS 118 (2014) 381
  • A.D. Carlson et al., Evaluation of the Neutron Data Standards, NDS 148 (2018) 143

Validation

Additional file(s)

  1. AU197 NTOT RECENT - 13.63 KB PDF
  2. AU197 WISHAK - 13.92 KB PDF