1、Designation: E668 10E668 13Standard Practice forApplication of Thermoluminescence-Dosimetry (TLD)Systems for Determining Absorbed Dose in Radiation-Hardness Testing of Electronic Devices1This standard is issued under the fixed designation E668; the number immediately following the designation indica
2、tes the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of t
3、he Department of Defense.1. Scope1.1 This practice covers procedures for the use of thermoluminescence dosimeters (TLDs) to determine the absorbed dose ina material irradiated by ionizing radiation. Although some elements of the procedures have broader application, the specific areaof concern is rad
4、iation-hardness testing of electronic devices. This practice is applicable to the measurement of absorbed dose inmaterials irradiated by gamma rays, X rays, and electrons of energies from 12 to 60 MeV. Specific energy limits are covered inappropriate sections describing specific applications of the
5、procedures. The range of absorbed dose covered is approximately from102 to 104 Gy (1 to 106 rad), and the range of absorbed dose rates is approximately from 102 to 1010 Gy/s (1 to 1012 rad/s).Absorbed dose and absorbed dose-rate measurements in materials subjected to neutron irradiation are not cove
6、red in this practice.(See Practice E2450 for guidance in mixed fields.) Further, the portion of these procedures that deal with electron irradiation areprimarily intended for use in parts testing. Testing of devices as a part of more massive components such as electronics boards orboxes may require
7、techniques outside the scope of this practice.NOTE 1The purpose of the upper and lower limits on the energy for electron irradiation is to approach a limiting case where dosimetry is simplified.Specifically, the dosimetry methodology specified requires that the following three limiting conditions be
8、 approached: (a) energy loss of the primaryelectrons is small, (b) secondary electrons are largely stopped within the dosimeter, and (c) bremsstrahlung radiation generated by the primary electronsis largely lost.1.2 This standard dose not purport to address all of the safety concerns, if any, associ
9、ated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E170 Terminology Relating to Radiation Measurements and Dosime
10、tryE380 Practice for Use of the International System of Units (SI) (the Modernized Metric System) (Withdrawn 1997)3E666 Practice for Calculating Absorbed Dose From Gamma or X RadiationE2450 Practice for Application of CaF2(Mn) Thermoluminescence Dosimeters in Mixed Neutron-Photon Environments2.2 Int
11、ernational Commission on Radiation Units and Measurements (ICRU) Reports:4ICRU Report 14Radiation Dosimetry: X Rays and Gamma Rays with Maximum Photon Energies Between 0.6 and 50 MeVICRU Report 17Radiation Dosimetry: X Rays Generated at Potentials of 5 to 150 keVICRU Report 21Radiation Dosimetry: El
12、ectrons with Initial Energies Between 1 and 50 MeVICRU Report 31Average Energy Required to Produce an Ion PairICRU Report 33Radiation Quantities and UnitsICRU Report 34The Dosimetry of Pulsed Radiation1 This practice is under the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applicati
13、onsand is the direct responsibility of Subcommittee E10.07 onRadiation Dosimetry for Radiation Effects on Materials and Devices on Materials and Devices.Current edition approved June 1, 2010Jan. 1, 2013. Published August 2010January 2013. Originally approved in 1978. Last previous edition approved i
14、n 20052010 asE668 05.E668 10. DOI: 10.1520/E0668-10.10.1520/E0668-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM
15、website.3 The last approved version of this historical standard is referenced on www.astm.org.4 Available from International Commission on Radiation Units and Measurements, 7910, Woodmont Ave., Suite 800, Bethesda, MD 20814.This document is not an ASTM standard and is intended only to provide the us
16、er of an ASTM standard an indication of what changes have been made to the previous version. Becauseit 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 versionof the standard a
17、s published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1ICRU Report 37Stopping Powers for Electrons and Positrons3. Terminology3.1 Definitions:3.1.1 absorbed dose, Dthe quotient of
18、 d by dm, where d is the mean energy imparted by ionizing radiation to the matterin a volume element and dm is the mass of matter in that volume element.D 5 ddm (1)Previously, the special unit of absorbed dose was the rad; however, the gray (Gy) has been adopted as the official SI unit(see Practice
19、E380).1Gy51Jkg215102 rad (2)3.1.2 absorbed-dose ratethe absorbed dose per unit time interval.3.1.3 annealingthermal treatment of a TLD prior to irradiation or prior to readout.3.1.3.1 DiscussionPre-irradiation annealing of TLDs is usually done to erase the effects of previous irradiation and to read
20、just the sensitivity of thephosphor; pre-readout annealing usually is done to reduce low-temperature TLD response.3.1.4 calibration conditionsthe normal environmental conditions prevailing during routine calibration irradiations such as theambient temperature, humidity, and lighting.3.1.5 equilibriu
21、m absorbed dosethe absorbed dose at some incremental volume within the material which the condition ofelectron equilibrium (as many electrons of a given energy enter as leave the volume) exists (1)5 (see Appendix X1).3.1.6 exposure, Xthe quotient of dQ by dm, where dQ is the absolute value of the to
22、tal charge of the ions of one sign producedin air when all the electrons (negatrons and positrons) liberated by photons in a volume element of air having mass dm arecompletely stopped in air.X 5dQdm (3)Unit C kg13.1.6.1 DiscussionFormerly the special unit of exposure was the roentgen (R).1R 52.58310
23、21Ckg21 exactly! (4)1R 52.5831024Ckg21 exactly! (4)3.1.7 primary electronsfor the case of electron irradiation, the electrons introduced into the device under test by theirradiation source.3.1.8 secondary-electron equilibriumfor the case of electron irradiation, the condition where as many secondary
24、 electrons ofa given energy enter a given volume as leave it.3.1.9 secondary-electron equilibrium absorbed dosefor the case of electron irradiation, the absorbed dose at someincremental volume within the material in which the condition of secondary-electron equilibrium exists.3.1.9.1 DiscussionAddit
25、ional definitions can be found in ICRU Report 33.3.1.10 secondary electrons for the case of electron irradiation, electrons knocked out of the electron shells of the materialbeing irradiated by the primary electron. For the case of photon irradiation, energetic electrons (photoelectrons, Auger elect
26、rons,and Compton electrons) produced within the material being irradiated by the action of the incident photons.3.1.10.1 Discussion5 The boldface numbers in parentheses refer to the list of references at the end of this practice.E668 132Secondary electrons are produced by the interaction of the prim
27、ary electrons with the atoms of the material being irradiated. Thisinteraction is a principal means of energy loss for the primary electrons. The kinetic energy of a secondary electron is typicallymuch lower than that of the primary electron which creates it.3.1.11 test conditionsthe normal environm
28、ental conditions prevailing during routine hardness-test irradiations such as theambient temperature, humidity, and lighting.3.1.12 thermoluminescence dosimeter (TLD)a TL phosphor, alone, or incorporated in a material, used for determining theabsorbed dose in materials. For example, the TL phosphor
29、is sometimes incorporated in a TFE-fluorocarbon matrix.3.1.13 thermoluminescence dosimeter (TLD) batcha group of TLDs, generally originating from a single mix or lot of TLphosphor, having similar TL responses and similar thermal and irradiation histories.3.1.14 thermoluminescence dosimeter (TLD) rea
30、deran instrument used to measure the light emitted from a TLD consistingessentially of a heating element, a light-measuring device, and appropriate electronics.3.1.15 thermoluminescence dosimeter (TLD) responsethe measured light emitted by the TLD and read out during its heatingcycle consisting of o
31、ne of the following: (a) the total light output over the entire heating cycle, (b) a part of that total light output,or (c) the peak amplitude of the light output.3.1.16 thermoluminescence (TL) phosphora material that stores, upon irradiation, a fraction of its absorbed dose in variousexcited energy
32、 states. When thermally stimulated, the material emits this stored energy in the form of photons in the ultraviolet,visible, and infrared regions.3.1.17 TLD preparationthe procedure of cleaning, annealing, and encapsulating the TL phosphor prior to irradiation.3.2 For units and terminology in report
33、s of data, Terminology E170 may be used as a guide.4. Significance and Use4.1 Absorbed dose in a material is an important parameter that can be correlated with radiation effects produced in electroniccomponents and devices that are exposed to ionizing radiation. Reasonable estimates of this paramete
34、r can be calculated ifknowledge of the source radiation field (that is, energy spectrum and particle fluence) is available. Sufficiently detailed informationabout the radiation field is generally not available. However, measurements of absorbed dose with passive dosimeters in a radiationtest facilit
35、y can provide information from which the absorbed dose in a material of interest can be inferred. Under certainprescribed conditions, TLDs are quite suitable for performing such measurements.NOTE 2For comprehensive discussions of various dosimetry methods applicable to the radiation types and energy
36、 and absorbed dose-rate rangediscussed in this practice, see ICRU Reports 14, 17, 21, and 34.5. Apparatus5.1 The TLD System consists of the TLDs, the equipment used for preparation of the TLDs, and the TLD reader.5.2 Calibration Facility delivers a known quantity of radiation to materials under cert
37、ain prescribed environmental andgeometrical conditions. Its radiation source is usually a radioactive isotope, commonly either 60Co or 137Cs, whose radiation outputhas been calibrated by specific techniques to some specified uncertainty (usually to within 65 %) and is traceable to nationalstandards.
38、5.3 Storage Facility provides an environment for the TLDs before and after irradiation, that is light tight and that has anegligible background absorbed-dose rate. A TLD stored in the facility for the longest expected storage period should absorb nomore than 1 % of the lowest absorbed dose expected
39、to be measured in hardness-testing applications.5.4 Environmental Chamber is used in testing the effects of temperature and humidity on TLD response. The chamber shouldbe capable of controlling the temperature and humidity within 65 % over the range expected under both calibration and testconditions
40、.6. Handling and Readout Procedures6.1 Bare TLDs should not be handled with the bare fingers; dirt or grease on their surfaces can affect their response and cancontaminate the heating chamber of the TLD reader.Avacuum pen or tweezers coated with TFE-fluorocarbonPTFE should be usedin handling. If req
41、uired, the TLDs can be cleaned by using the procedures in accordance with Appendix X2.6.2 TLDs, especially those with high sensitivity, should be protected from light having an appreciable ultraviolet component,such as sunlight or fluorescent light. Prolonged exposure to ultraviolet light, either be
42、fore or after irradiation, can cause spuriousTLD response or enhanced post-irradiation fading. Incandescent lighting should be used for theTLD preparation and readout areas.However, brief exposures of a few minutes to normal room fluorescent lighting is not likely to significantly affect theTLD resp
43、onseexcept for low absorbed-dose measurements (102 Gy (104 rad). See, however, X2.2.2.8.2 Reproducibility of TLD Response of Individual Reusable DosimetersCertain types of TLDs may be utilized as individualreusable dosimeters. In this case, the identity of each individual dosimeter is maintained dur
44、ing repeated measurement cyclesthroughout its useful life. This is in contrast to utilization in the batch mode where individual dosimeters within the batch are notidentified. To test the reproducibility of the response of an individual reusable dosimeter, the following procedures should befollowed:
45、8.2.1 Select the individual TLD to be tested, prepare it, irradiate it in the calibration facility to a specific absorbed-dose level(for example, at the midpoint of the absorbed-dose range of interest), and read it out. In an identical manner, repeat this procedure30 times. Determine the variance, s
46、2, of the responses and estimate the standard deviation of the TLD response distribution 5=s2!. The standard deviation, , should not exceed 5 % of the mean response value, Y0, that is (0.05)Y0.8.2.2 Some types of TLDs may exhibit a change in sensitivity (that is, response per unit absorbed dose) wit
47、h repeatedanneal-irradiation-readout cycling. This effect is most pronounced if the TLD is not annealed thoroughly. The test results inaccordance with 8.2.1 may not show such a change in response sensitivity. However, if such a change is shown in that test or ifit appears after a larger number of cy
48、cles than specified in that test, then a different analysis of the data is required. In this case,a curve should be fitted to the data of response versus number of cycles by a least-squares method. A measure of reproducibilitywould then be given by the average standard deviation of the data points f
49、rom the least-squares curve. The performance criterionis the same as in 8.2.1.8.2.3 Since the identity of each TLD is maintained when it is utilized as an individual dosimeter, it is not necessary that groupsof such individual TLDs meet the batch requirements in accordance with 8.1. However, for the other performance tests andcorrection factors discussed in Section 8, it is assumed that such tests and factors are evaluated by utilizing TLDs in a batch mode.8.3 Dependence of TLD Response on Absorbed-Dose Rate:8.3.1 From a T
