ASTM E720-04e1
(Guide)Standard Guide for Selection and Use of Neutron Sensors for Determining Neutron Spectra Employed in Radiation-Hardness Testing of Electronics
Standard Guide for Selection and Use of Neutron Sensors for Determining Neutron Spectra Employed in Radiation-Hardness Testing of Electronics
SIGNIFICANCE AND USE
Because of the wide variety of materials being used in neutron-activation measurements, this guide is presented with the objective of bringing improved uniformity to the specific field of interest here: hardness testing of electronics primarily in critical assembly reactor environments.
Note 2—Some of the techniques discussed are useful for 14-MeV dosimetry. See Test Method E 496 for activation detector materials suitable for 14-MeV neutron effects testing.
Note 3—The materials recommended in this guide are suitable for 252Cf or other weak source effects testing provided the fluence is sufficient to generate countable activities.
This guide is organized into two overlapping subjects; the criteria used for sensor selection, and the procedures used to ensure the proper determination of activities for determination of neutron spectra. See Terminology E 170 and General Methods E 181. Determination of neutron spectra with activation sensor data is discussed in Guides E 721 and E 944.
SCOPE
1.1 This guide covers the selection and use of neutron-activation detector materials to be employed in neutron spectra adjustment techniques used for radiation-hardness testing of electronic semiconductor devices. Sensors are described that have been used at many radiation hardness-testing facilities, and comments are offered in table footnotes concerning the appropriateness of each reaction as judged by its cross-section accuracy, ease of use as a sensor, and by past successful application. This guide also discusses the fluence-uniformity, neutron self-shielding, and fluence-depression corrections that need to be considered in choosing the sensor thickness, the sensor covers, and the sensor locations. These considerations are relevant for the determination of neutron spectra from assemblies such as TRIGA- and Godiva-type reactors and from Californium irradiators. This guide may also be applicable to other broad energy distribution sources up to 20 MeV.
Note 1—For definitions on terminology used in this guide, see Terminology E 170.
1.2 This guide also covers the measurement of the gamma-ray or beta-ray emission rates from the activation foils and other sensors as well as the calculation of the absolute specific activities of these foils. The principal measurement technique is high-resolution gamma-ray spectrometry. The activities are used in the determination of the energy-fluence spectrum of the neutron source. See Guide E 721.
1.3 Details of measurement and analysis are covered as follows:
1.3.1 Corrections involved in measuring the sensor activities include those for finite sensor size and thickness in the calibration of the gamma-ray detector, for pulse-height analyzer deadtime and pulse-pileup losses, and for background radioactivity.
1.3.2 The primary method for detector calibration that uses secondary standard gamma-ray emitting sources is considered in this guide and in General Methods E 181. In addition, an alternative method in which the sensors are activated in the known spectrum of a benchmark neutron field is discussed in Guide E 1018.
1.3.3 A data analysis method is presented which accounts for the following: detector efficiency; background subtraction; irradiation, waiting, and counting times; fission yields and gamma-ray branching ratios; and self-absorption of gamma rays and neutrons in the sensors.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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e1
Designation:E720–04
Standard Guide for
Selection and Use of Neutron Sensors for Determining
Neutron Spectra Employed in Radiation-Hardness Testing of
1
Electronics
This standard is issued under the fixed designation E720; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1
e NOTE—Editorial corrections were made throughout in April 2007.
1. Scope calibration of the gamma-ray detector, for pulse-height ana-
lyzer deadtime and pulse-pileup losses, and for background
1.1 This guide covers the selection and use of neutron-
radioactivity.
activationdetectormaterialstobeemployedinneutronspectra
1.3.2 The primary method for detector calibration that uses
adjustment techniques used for radiation-hardness testing of
secondary standard gamma-ray emitting sources is considered
electronic semiconductor devices. Sensors are described that
in this guide and in General Methods E181. In addition, an
have been used at many radiation hardness-testing facilities,
alternative method in which the sensors are activated in the
and comments are offered in table footnotes concerning the
known spectrum of a benchmark neutron field is discussed in
appropriateness of each reaction as judged by its cross-section
Guide E1018.
accuracy, ease of use as a sensor, and by past successful
1.3.3 A data analysis method is presented which accounts
application. This guide also discusses the fluence-uniformity,
for the following: detector efficiency; background subtraction;
neutron self-shielding, and fluence-depression corrections that
irradiation, waiting, and counting times; fission yields and
need to be considered in choosing the sensor thickness, the
gamma-ray branching ratios; and self-absorption of gamma
sensor covers, and the sensor locations. These considerations
rays and neutrons in the sensors.
are relevant for the determination of neutron spectra from
1.4 The values stated in SI units are to be regarded as the
assembliessuchasTRIGA-andGodiva-typereactorsandfrom
standard.
Californium irradiators. This guide may also be applicable to
1.5 This standard does not purport to address all of the
other broad energy distribution sources up to 20 MeV.
safety concerns, if any, associated with its use. It is the
NOTE 1—For definitions on terminology used in this guide, see Termi-
responsibility of the user of this standard to establish appro-
nology E170.
priate safety and health practices and determine the applica-
1.2 This guide also covers the measurement of the gamma-
bility of regulatory limitations prior to use.
ray or beta-ray emission rates from the activation foils and
2. Referenced Documents
other sensors as well as the calculation of the absolute specific
activities of these foils. The principal measurement technique
2.1 General considerations of neutron-activation detectors
is high-resolution gamma-ray spectrometry. The activities are
discussed in Practice E261, Test Method E262, and Guides
usedinthedeterminationoftheenergy-fluencespectrumofthe
E721 and E844 are applicable to this guide. Background
neutron source. See Guide E721.
informationforapplyingthisguidearegivenintheseandother
1.3 Details of measurement and analysis are covered as
relevant standards as follows:
2
follows:
2.2 ASTM Standards:
1.3.1 Corrections involved in measuring the sensor activi-
E170 Terminology Relating to Radiation Measurements
ties include those for finite sensor size and thickness in the
and Dosimetry
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This guide is under the jurisdiction of ASTM Committee E10 on Nuclear
2
Technology and Applications and is the direct responsibility of Subcommittee For referenced ASTM standards, visit the ASTM website, www.astm.org, or
E10.07 on Radiation Dosimetry for Radiation Effects on Materials and Devices. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
CurrenteditionapprovedJune1,2004.PublishedJuly2004.Originallyapproved Standards volume information, refer to the standard’s Document Summary page on
in 1980. Last previous edition approved in 2002 as E720–02. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E720–04
E181 Test Methods for Detector Calibration and Analysis recommended because of their demonstrated compatibility
of Radionuclides with other reactions used in spectrum adjustment determina-
E261 Practice for Determining Neutron Fluence, Fluence tions.This compatibility is primarily based on experience wit
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