ASTM E496-14
(Test Method)Standard Test Method for Measuring Neutron Fluence and Average Energy from 3H(d,n) 4He Neutron Generators by Radioactivation Techniques
Standard Test Method for Measuring Neutron Fluence and Average Energy from <sup>3</sup >H(d,n)<sup> 4</sup>He Neutron Generators by Radioactivation Techniques
SIGNIFICANCE AND USE
5.1 Refer to Practice E261 for a general discussion of the measurement of fast-neutron fluence rates with threshold detectors.
5.2 Refer to Test Method E265 for a general discussion of the measurement of fast-neutron fluence rates by radioactivation of sulfur-32.
5.3 Reactions used for the activity measurements can be chosen to provide a convenient means for determining the absolute fluence rates of 14-MeV neutrons obtained with 3H(d,n)4He neutron generators over a range of irradiation times from seconds to approximately 100 days. High purity threshold sensors referenced in this test method are readily available.
5.4 The neutron-energy spectrum must be known in order to measure fast-neutron fluence using a single threshold detector. Neutrons produced by bombarding a tritiated target with deuterons are commonly referred to as 14-MeV neutrons; however, they can have a range of energies depending on: (1) the angle of neutron emission with respect to the deuteron beam, (2) the kinetic energy of the deuterons, and (3) the target thickness. In most available neutron generators of the Cockroft-Walton type, a thick target is used to obtain high-neutron yields. As deuterons penetrate through the surface and move into the bulk of the thick target, they lose energy, and interactions occurring deeper within the target produce neutrons with correspondingly lower energy.
5.5 Wide variations in neutron energy are not generally encountered in commercially available neutron generators of the Cockroft-Walton type. Figs. 1 and 2 (1)6 show the variation of the zero degree 3H(d,n)4He neutron production cross section with energy, and clearly indicate that maximum neutron yield is obtained with deuterons having energies near the 107 keV resonance. Since most generators are designed for high yield, the deuteron energy is typically about 200 keV, giving a range of neutron energies from approximately 14 to 15 MeV. The differential center-of-mass cross section is typically paramet...
SCOPE
1.1 This test method covers a general procedure for the measurement of the fast-neutron fluence rate produced by neutron generators utilizing the 3H(d,n) 4He reaction. Neutrons so produced are usually referred to as 14-MeV neutrons, but range in energy depending on a number of factors. This test method does not adequately cover fusion sources where the velocity of the plasma may be an important consideration.
1.2 This test method uses threshold activation reactions to determine the average energy of the neutrons and the neutron fluence at that energy. At least three activities, chosen from an appropriate set of dosimetry reactions, are required to characterize the average energy and fluence. The required activities are typically measured by gamma ray spectroscopy.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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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Designation: E496 − 14
StandardTest Method for
Measuring Neutron Fluence and Average Energy
3 4
from H(d,n) He Neutron Generators by Radioactivation
1
Techniques
This standard is issued under the fixed designation E496; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope Rate, and Spectra by Radioactivation Techniques
E265Test Method for Measuring Reaction Rates and Fast-
1.1 This test method covers a general procedure for the
Neutron Fluences by Radioactivation of Sulfur-32
measurement of the fast-neutron fluence rate produced by
3 4 E720Guide for Selection and Use of Neutron Sensors for
neutron generators utilizing the H(d,n) He reaction. Neutrons
Determining Neutron Spectra Employed in Radiation-
so produced are usually referred to as 14-MeV neutrons, but
Hardness Testing of Electronics
range in energy depending on a number of factors. This test
2.2 International Commission on Radiation Units and Mea-
method does not adequately cover fusion sources where the
3
surements (ICRU) Reports:
velocity of the plasma may be an important consideration.
ICRU Report 13Neutron Fluence, Neutron Spectra and
1.2 This test method uses threshold activation reactions to
Kerma
determine the average energy of the neutrons and the neutron
ICRU Report 26 Neutron Dosimetry for Biology and
fluence at that energy.At least three activities, chosen from an
Medicine
appropriate set of dosimetry reactions, are required to charac- 4
2.3 ISO Standard:
terize the average energy and fluence. The required activities
Guide to the Expression of Uncertainty in Measurement
are typically measured by gamma ray spectroscopy. 5
2.4 NIST Document:
1.3 The values stated in SI units are to be regarded as TechnicalNote1297GuidelinesforEvaluatingandExpress-
standard. No other units of measurement are included in this ing the Uncertainty of NIST Measurement Results
standard.
3. Terminology
1.4 This standard does not purport to address all of the
3.1 Definitions—Refer to Terminology E170.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety and health practices and determine the applica-
4.1 This test method describes the determination of the
bility of regulatory limitations prior to use.
average neutron energy and fluence by use of three activities
2. Referenced Documents from a select list of dosimetry reactions. Three dosimetry
2 reactionsarechosenbasedonanumberoffactorsincludingthe
2.1 ASTM Standards:
intensity of the neutron field, the reaction half-lives, the slope
E170Terminology Relating to Radiation Measurements and
of the dosimetry reaction cross section near 14-MeV, and the
Dosimetry
minimum time between sensor irradiation and the gamma
E181Test Methods for Detector Calibration andAnalysis of
counting. The activities from these selected reactions are
Radionuclides
measured. Two of the activities are used, in conjunction with
E261Practice for Determining Neutron Fluence, Fluence
the nuclear data for the dosimetry reactions, to determine the
average neutron energy. The third activity is used, along with
theneutronenergyandnucleardatafortheselectedreaction,to
1
ThistestmethodisunderthejurisdictionofASTMCommitteeE10onNuclear
determine the neutron fluence. The uncertainty of the neutron
Technology and Applications and is the direct responsibility of Subcommittee
E10.07 on Radiation Dosimetry for Radiation Effects on Materials and Devices.
Current edition approved Jan. 1, 2014. Published February 2014. Originally
3
approved in 1973. Last previous edition approved in 2009 as E496–09. DOI: Available from the International Commission on Radiation Units, 7910
10.1520/E0496-14. Woodmont Ave., Washington, DC 20014.
2 4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM 4th Floor, New York, NY 10036, http://www.ansi.org.
5
Standards volume information, refer to the standard’s Document Summary page on Available from National Institute of Standards and Technology (NIST), 100
the ASTM website. Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E496 − 14
energy and the neutron fluence is determined from the activity
measurement uncertainty and from the nuclear data.
5. Significance and
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E496 − 09 E496 − 14
Standard Test Method for
Measuring Neutron Fluence and Average Energy
3 4
from H(d,n) He Neutron Generators by Radioactivation
1
Techniques
This standard is issued under the fixed designation E496; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers a general procedure for the measurement of the fast-neutron fluence rate produced by neutron
3 4
generators utilizing the H(d,n) He reaction. Neutrons so produced are usually referred to as 14-MeV neutrons, but range in energy
depending on a number of factors. This test method does not adequately cover fusion sources where the velocity of the plasma
may be an important consideration.
1.2 This test method uses threshold activation reactions to determine the average energy of the neutrons and the neutron fluence
at that energy. At least three activities, chosen from an appropriate set of dosimetry reactions, are required to characterize the
average energy and fluence. The required activities are typically measured by gamma ray spectroscopy.
1.3 The measurement of reaction products in their metastable states is not covered. If the metastable state decays to the ground
state, the ground state reaction may be used.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
2. Referenced Documents
2
2.1 ASTM Standards:
E170 Terminology Relating to Radiation Measurements and Dosimetry
E181 Test Methods for Detector Calibration and Analysis of Radionuclides
E261 Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation Techniques
E265 Test Method for Measuring Reaction Rates and Fast-Neutron Fluences by Radioactivation of Sulfur-32
E720 Guide for Selection and Use of Neutron Sensors for Determining Neutron Spectra Employed in Radiation-Hardness
Testing of Electronics
3
2.2 International Commission on Radiation Units and Measurements (ICRU) Reports:
ICRU Report 13—Neutron13 Neutron Fluence, Neutron Spectra and Kerma
ICRU Report 26—Neutron26 Neutron Dosimetry for Biology and Medicine
4
2.3 ISO Standard:
Guide to the Expression of Uncertainty in Measurement
5
2.4 NIST Document:
Technical Note 1297—Guidelines1297 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results
1
This test method is under the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applications and is the direct responsibility of Subcommittee E10.07
on Radiation Dosimetry for Radiation Effects on Materials and Devices.
Current edition approved June 15, 2009Jan. 1, 2014. Published August 2009February 2014. Originally approved in 1973. Last previous edition approved in 20022009 as
E496 – 02.E496 – 09. DOI: 10.1520/E0496-09.10.1520/E0496-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from the International Commission on Radiation Units, 7910 Woodmont Ave., Washington, DC 20014.
4
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
5
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E496 − 14
3. Terminology
3.1 Definitions—Refer to Terminology E170.
4. Summary of Test Method
4.1 This test method describes the determination of the average neutron energy and fluence by use of three activities from a
select list of dosimetry reactions. Three dosimetry reactions are chosen based on a number of factors including the intensity of the
neutron field, the reaction half-lives, the slope of the dosimetry reactio
...
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