ASTM E265-98

Standard Test Method for Measuring Reaction Rates and Fast-Neutron Fluences by Radioactivation of Sulfur-32

SCOPE
1.1 This test method describes procedures for measuring reaction rates and fast-neutron fluences by the activation reaction  32 S(n,p) 32 P.
1.2 This activation reaction is useful for measuring neutrons with energies above approximately 3 MeV.
1.3 With suitable techniques, fission-neutron fluences from about 5 X 10  to 10 16  n/cm  can be measured.
1.4 Detailed procedures for other fast-neutron detectors are described in Practice E261.
1.5 This standard does not purport to address all of the safety problems, 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.

General Information

• Status: Historical
• Publication Date: 09-Jun-1998
• Technical Committee: E10 - Nuclear Technology and Applications
• Drafting Committee: E10.07 - Radiation Dosimetry for Radiation Effects on Materials and Devices

Relations

• Replaced By: ASTM E265-98(2002) - Standard Test Method for Measuring Reaction Rates and Fast-Neutron Fluences by Radioactivation of Sulfur-32
• Effective Date: 10-Jun-1998
• Referred By: ASTM E798-16 - Standard Practice for Conducting Irradiations at Accelerator-Based Neutron Sources
• Effective Date: 10-Jun-1998
• Referred By: ASTM F980-16 - Standard Guide for Measurement of Rapid Annealing of Neutron-Induced Displacement Damage in Silicon Semiconductor Devices
• Effective Date: 10-Jun-1998
• Referred By: ASTM E720-23 - Standard Guide for Selection and Use of Neutron Sensors for Determining Neutron Spectra Employed in Radiation-Hardness Testing of Electronics
• Effective Date: 10-Jun-1998
• Referred By: ASTM E1854-19 - Standard Practice for Ensuring Test Consistency in Neutron-Induced Displacement Damage of Electronic Parts
• Effective Date: 10-Jun-1998
• Referred By: ASTM E496-14(2022) - Standard Test Method for Measuring Neutron Fluence and Average Energy from <sup >3</sup>H(d,n)⁴He Neutron Generators by Radioactivation Techniques
• Effective Date: 10-Jun-1998
• Referred By: ASTM E1855-20 - Standard Test Method for Use of 2N2222A Silicon Bipolar Transistors as Neutron Spectrum Sensors and Displacement Damage Monitors
• Effective Date: 10-Jun-1998
• Referred By: ASTM E1005-21 - Standard Test Method for Application and Analysis of Radiometric Monitors for Reactor Vessel Surveillance
• Effective Date: 10-Jun-1998
• Referred By: ASTM E722-19 - Standard Practice for Characterizing Neutron Fluence Spectra in Terms of an Equivalent Monoenergetic Neutron Fluence for Radiation-Hardness Testing of Electronics
• Effective Date: 10-Jun-1998
• Referred By: ASTM E944-19 - Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance
• Effective Date: 10-Jun-1998
• Referred By: ASTM E261-16(2021) - Standard Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation Techniques
• Effective Date: 10-Jun-1998
• Referred By: ASTM E721-22 - Standard Guide for Determining Neutron Energy Spectra from Neutron Sensors for Radiation-Hardness Testing of Electronics
• Effective Date: 10-Jun-1998
• Referred By: ASTM E2005-21 - Standard Guide for Benchmark Testing of Reactor Dosimetry in Standard and Reference Neutron Fields
• Effective Date: 10-Jun-1998
• Referred By: ASTM F1190-18 - Standard Guide for Neutron Irradiation of Unbiased Electronic Components
• Effective Date: 10-Jun-1998

Standards Content (Sample)

Designation:E265–98
Standard Test Method for
Measuring Reaction Rates and Fast-Neutron Fluences by
Radioactivation of Sulfur-32
This standard is issued under the fixed designation E265; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 4. Summary of Test Method
1.1 This test method describes procedures for measuring 4.1 Elemental sulfur or a sulfur-bearing compound is irra-
reaction rates and fast-neutron fluences by the activation diatedinaneutronfield,producingradioactive Pbymeansof
32 32 32 32
reaction S(n,p) P. the S(n,p) P activation reaction.
1.2 Thisactivationreactionisusefulformeasuringneutrons 4.2 The beta particles emitted by the radioactive decay of
with energies above approximately 3 MeV. Pare counted by techniques described in Methods E181 and
1.3 With suitable techniques, fission-neutron fluences from the reaction rate, as defined in Practice E261, is calculated
8 16 2
about 5 310 to 10 n/cm can be measured. from the decay rate and irradiation conditions.
1.4 Detailed procedures for other fast-neutron detectors are 4.3 The neutron fluence above 3 MeV can then be calcu-
described in Practice E261. lated from the spectral-averaged neutron activation cross
1.5 This standard does not purport to address all of the section, s¯, as defined in Practice E261.
safety problems, if any, associated with its use. It is the
5. Significance and Use
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 5.1 Refer to Guide E844 for the selection, irradiation, and
quality control of neutron dosimeters.
bility of regulatory limitations prior to use.
5.2 Refer to Practice E261 for a general discussion of the
2. Referenced Documents
determination of fast-neutron fluence and fluence rate with
2.1 ASTM Standards: threshold detectors.
E170 Terminology Relating to Radiation Measurements 5.3 The activation reaction produces P, which decays by
and Dosimetry the emission of a single beta particle in 100% of the decays,
E181 Test Methods for Detector Calibration and Analysis and which emits no gamma rays. The half life of Pis 14.262
2 3 4
of Radionuclides (14) days (1) andthemaximumbetaenergyis1710keV(2).
E261 Practice for Determining Neutron Fluence Rate, Flu- 5.4 Elemental sulfur is readily available in pure form and
ence, and Spectra by Radioactivation Techniques any trace contaminants present do not produce significant
E844 Guide for Sensor Set Design and Irradiation for amounts of radioactivity. Natural sulfur, however, is composed
32 34
Reactor Surveillance, E706(IIC) of S (95.02% (9)), S (4.21% (8)) 1, and trace amounts of
E944 Guide for Application of Neutron Spectrum Adjust- othersulfurisotopes.Thepresenceoftheseotherisotopesleads
ment Methods in Reactor Surveillance, (IIA) to several competing reactions that can interfere with the
E1018 Guide for Application of ASTM Evaluated Cross counting of the 1710-keV beta particle. This interference can
Section Data File, Matrix E706(IIB) usually be eliminated by the use of appropriate techniques, as
discussed in Section 8.
3. Terminology
6. Apparatus
3.1 Definitions:
3.1.1 Refer to Terminology E170. 6.1 Sinceonlybetaparticlesof Parecounted,proportional
counters or scintillation detectors can be used. Because of the
ThistestmethodisunderthejurisdictionofASTMCommitteeE-10onNuclear
Technology and Applications and is the direct responsibility of Subcommittee The non-bolface number in parentheses after the nuclear data indicates the
E10.07 on Radiation Dosimetry for Radiation Effects on Materials and Devices. uncertainty in the last significant digit of the preceeding number. For example, 8.1
Current edition approved June 10, 1998. Published January 1999. Originally s (5) means 8.1 6 0.5 seconds.
published as E265–70. Last previous edition E265–93. The boldface numbers in parentheses refer to the list of references at the end
Annual Book of ASTM Standards, Vol 12.02. of this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E265–98
high resolving time associated with Geiger-Mueller counters, irradiation of the sulfur inside 1 mm-thick cadmium shields.
their use is not recommended. They can be used only with This should be done whenever possible in thermal-neutron
relatively low counting rates, and then only if reliable correc- environments. Those reaction products having relatively short
31 34 31 37
tions for coincidence losses are applied. half-lives, that is, S, P, Si, and S, can be eliminated by
6.2 RefertoMethodsE181forpreparationofapparatusand
a waiting period before the counting is started.Adelay of 24 h
counting procedures. is sufficient for the longest lived of these, although shorter
delays are possible depending on the degree of thermalization
7. Materials and Manufacture
of the neutron field. Finally, those with relatively low beta
33 35
7.1 Commercially available sublimed flowers of sulfur are particle energies, that is, Pand S, can be eliminated by the
inexpensive and sufficiently pure for normal usage. Sulfur can inclusion of a 70-mg/cm aluminum absorber in front of the
be used directly as a powder or pressed into pellets. Sulfur detector.Forparticularlylongdecaytimes,anabsorbermustbe
pelletsarenormallymadeatleast3mmthickinordertoobtain
used because the S becomes dominant. Note that the use of
maximum counting sensitivity independent of small variations an internal (windowless) detector maximizes the interference
in pellet mass. A0.8 g/cm pellet can be considered infinitely
in counting from S.
thickforthemostenergeticbetaparticlefrom P(seeTable1).
8.3 Irradiated sulfur can be counted directly, or may be
Due to the relatively long half-life of P, it may not be
burned to increase the efficiency of the counting system.
practicaltouseapelletmorethanonce.Aperiodofatleastone
Dilution may be used to reduce counting system efficiency for
year is recommended between uses. However, see 8.2 regard-
measurements of high neutron fluences.
ing long-lived interfering reaction products. 32
8.4 Burning the sulfur leaves a residue of P that can be
7.2 Where temperatures approaching the melting point of
counted without absorption of the beta particles in the sulfur
sulfur are encountered (113°C), sulfur-bearing compounds
pellet. Place the sulfur in an aluminum planchet on a hot plate
suchasammoniumsulfate(NH ) SO ,lithiumsulfateLi SO ,
4 2 4 2 4
until the sulfur melts and turns to a dark amber color. At this
or magnesium sulfate MgSO can be used. These are suitable
point the liquid gives off sulfur fumes. Ignite the fumes by
fortemperaturesupto250,850,and1000°C,respectively.The
bringing a flame close to the dish, and allow the sulfur to burn
reduced sensitivity of these compounds offers no disadvantage
out completely. In order to reduce the sputtering that can lead
since high temperatures are usually associated with a high-
to variations in the amount of P remaining on the planchet,
neutron fluence rate. The sulfur content by weight of
thehotplatemustbeonlyashotasnecessarytomeltthesulfur.
(NH) SO is 24%, of Li SO is 29.2%, and of MgSO is
2 4 2 4 4
In addition, air flow to the burning sulfur must be controlled,
26.6%.
suchasbytheplacementofachimneyaroundthesulfur.Count
7.3 The isotopic abundance of S in natural sulfur is 95.02
the residue remaining on the dish for beta activity.
6 0.09 atom% (1) .
NOTE 1—The fumes given off by the burning sulfur are toxic. Burning
8. Sample Preparation and Irradiation
should be done under a ventilating hood.
8.1 Place sulfur in pellet or powdered form in a uniform
8.5 An alternative to burning is sublimation of the sulfur
fast-neutron flux for a predetermined period of time. Record
under a heat lamp. Removal of the sulfur is very gradual, and
the beginning and end of the irradiation period.
there is no loss of P from sputtering.
8.2 Table 2 lists competing reaction products that must be
8.6 Counting of dilute samples is useful for measuring high
eliminated from the counting. Those resulting from thermal-
33 35 37 neutron fluences, although it is applicable to virtually all
neutroncapture,thatis, P, S,and S,canbereducedbythe
irradiation conditions. Use lithium sulfate, reagent grade or
better, as the target material because of its high melting point
TABLE 1 Sulfur Counting Rate Versus Mass for a Pellet of
(860°C), good solubility in water, and minimum production of
25.4-mm Diameter
undesirable activation products. Prepare a dry powder by
Sample Mass, g Relative Counting Rate
spreading about 10 g of Li SO in a weighing bottle and place
2 4
0.4 0.46
in a drying oven for 24 h at 150°C. Place the dried Li SO in
2 4
0.6 0.58
a dessicator for cooling and storage. Prepare a phosphorus
0.8 0.66
carrier solution by dissolving 21.3 g of (NH ) HPO in water
1.0 0.73
4 2 4
1.2 0.78
to make 1 L of solution. Prepare a Li SO sample for
2 4
1.4 0.82
irradiation by placing about 150 mg of material in an air-tight
1.6 0.86
1.8 0.89 aluminum capsule or other suitable container. Following the
2.0 0.91
irradiation, accurately weigh a sample of about 100 mg and
2.2 0.93
dissolve in 5 mL of phosphorus carrier solution to minimize
2.4 0.94
2.6 0.95 adsorptionof Pontheglasscontainer.Adropofconcentrated
2.8 0.96
HCl may be used to speed solution of the sample. Place the
3.0 0.97
solution in a volumetric flask and add additional phosphorus
3.2 0.98
3.4 0.99 carrier solution to bring the total volume to 100 mL. Prepare a
3.6 0.99
sample for counting by pipetting 0.050 mL of the P solution
3.8 1.0
onto a standard planchet and evaporating in air to dryness.
4.0 1.0
Counting procedures and calculations are the same as in other
E265–98
TABLE 2 Neutron-induced Reactions in Sulfur Giving Radioactive Products
Maximum Average Isotopic
Cross Section Cross Section (mb)
Product Energy of Energy of Abundance
235 B
U Fast
Reaction Halflife Product Product of
A 252
Library Material ID Thermal Thermal Cf
(1) Beta (MeV) Beta Target (%)
Fission Fission
(2) (MeV) (2) (1)
32 32 C
1. S(n,p) P GLUCS-93 1625 . 64.69 70.44 14.262 1.7104 0.6949 95.02 (9)
d (14)
32 31 D −6 −5
2. S(n,2n) S JENDL-3 3161 . 7.742 3 10 2.5 3 10 2.572 s 5.3956 1.9975 95.02 (9)
(13) (b+) (b+)
33 33 D
3. S(n,p) P JENDL-3 3162 1.6 57.46 58.77 25.34 d 0.2485 0.0764 0.75 (1)
(12)
34 34 D
4. S(n,P) P JENDL-3 3163 . 0.8001 1.079 12.43 s 5.3743 2.3108 4.21 (8)
(8)
34 31 D
5. S(n,a) Si JENDL-3 3163 . 3.281 4.064 157.3 m 1.4908 0.59523 4.21 (8)
(3)
34 35 D
6. S(n,g) S JENDL-3 3163 226 0.2749 0.2705 87.51 d 0.16684 0.04863 4.21 (8)
(12)
36 37 D
7. S(n,g) S JENDL-3 3164 151 0.2511 0.2509 5.05 m 4.86516 0.800418 0.02 (1)
(2)
A
The thermal cross section corresponds to neutrons with a velocity of 2200 m/s or an energy of 0.0253 eV.
B 235
The fast cross section corresponds to the spectrum-averaged cross section from the ENDF/B-VI (MAT=9228, MF=5, MT=18) U thermal fission spectrum (5,6) and
the ENDF/B-VI (MAT=9861, MF=5, MT=18) Cf spontaneous fission spectrum (4-6).
C
Cross section produced for the 1993 GLUCS library (7) and is similar to that in the IRDF-90 library (8).
D
The JENDL-3 (9) sulfur isotopes were adopted in the latest JEF 2.2 cross section (10) compilations. The ENDF/B-VI library (5) does not include the individual sulfur
isotopic cross sections.
methods with the exception that an aliquot factor of 2000 must
where:
be introduced for the 0.050-mL sample removed from the
C = counts recorded in detector, less background,
100-mL flask.
f = correction for coincidence losses, if needed,
t
32 −7 −1
l = P decay constant,=5.625 310 s ,
9. Calibration t = decay time, s,
d
t = count time, s,
c
9.1 Calibration is achieved by irradiation of sulfur in a
t = duration of irradiation, s,
i
fast-neutron field of known spectrum and intensity, and mea-
N = number of S atoms in pellet,
suringtheresulting Pactivitytodetermineacountingsystem
s¯ = spectrum-averaged cross section for S in the calibra-
s
efficiency. This calibration is specific for a given detector
2 24
tion neutron field, cm =10 b, and
system, counting geometry, and sulfur pellet size and mass or
F = neutron fluence, n/cm .
sample preparation. It is, however, valid for subsequent use in
10.1.1 Fig. 1 shows a plot of sulfur cross section as a
measuring activities in any arbitrary spectrum, and therefore,
functionofenergy.Fig.2showsaplotoftheuncertaintyinthe
may be used with activation data from other foils in determin-
sulfur cross section as a function of energy. (See also Guide
ing neutron energy spectra as described in Practice E944.
E1018.)The spectrum-averaged cross section for Cf fission
235 252
9.2 U fission and Cf spontaneous fission neutron
neutrons is about 70 mb, and for U fission is about 63 mb.
sources of known source strength are available for direct
(See Table 2.)
free-field calibrations (3).
10.1.2 Thecorrectionforcoincidencelosses,f ,isafunction
t
9.3 Once a sulfur counting system is calibrated, it must be
of the particular counting system, and may be already ac-
monitored to ensure that the calibration remains valid. There
countedforbythesystemelectronicsif“livetime”isused(see
are several isotopes that can be used as reference standards for
234 Methods E181). Coincidence loss corrections can be large,
this monitoring. One is Pa, having a maximum beta energy
32 especially when Geiger-Mueller counters are used.
of about 2000 keV, comparable to the 1710-keVbeta from P.
It is obtained as a daughter of U, that can be dispersed as a
NOTE 2—Because of b self-absorption in counting thick pellets intact,
powder in plastic granules and formed to the shape of a detection efficiency is not sensitive to small variations in pellet mass but
is rather a function of the pellet dimensions. The detection efficiency
standard pellet. The concentration of U can be varied to
should be determined for each different pellet size that is to be used. The
obtain the desired counting rate. Uranium alpha particles can
value of N in Eq 1 can be taken to be the arithmetic mean over a number
be prevented from reaching the detector by use of a 7-mg/cm
ofpellets.Whetherornotthisisadequatedependsontheuniformityofthe
2 absorber. Another useful isotope is Bi, that produces beta
pellets and the desired measurement uncertainties.
particles having a maximum energy of 1161 keV. It is obtained
NOTE 3—When the calibration is performed using a point source such
asadaughterof Pb,andsourcesarecommerciallyavailable. 252
as Cf, a correction shou
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