ASTM_F_526_-_11.pdf

Designation:F52611Standard Test Method forUsing Calorimeters for Total Dose Measurements in PulsedLinear Accelerator or Flash X-ray Machines1This standard is issued under the fixed designation F526;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers a calorimetric measurement ofthe total dose delivered in a single pulse of electrons from anelectron linear accelerator or a flash X-ray machine(FXR,e-beam mode)used as an ionizing source in radiation-effectstesting.The test method is designed for use with pulses ofelectrons in the energy range from 10 to 50 MeV and is onlyvalid for cases in which both the calorimeter and the testspecimen to be irradiated are“thin”compared to the range ofthese electrons in the materials of which they are constructed.1.2 The procedure described can be used in those cases inwhich(1)the dose delivered in a single pulse is 5 Gy(matl)2(500 rd(matl)or greater,or(2)multiple pulses of a lower dosecan be delivered in a short time compared to the thermal timeconstant of the calorimeter.Matl refers to the material of thecalorimeter.The minimum dose per pulse that can be accept-ably monitored depends on the variables of the particular test,including pulse rate,pulse uniformity,and the thermal timeconstant of the calorimeter.1.3 Adetermination of the total dose is made directly for thematerial of which the calorimeter block is made.The total dosein other materials can be calculated from this measured valueby formulas presented in this test method.The need for suchcalculations and the choice of materials for which calculationsare to be made shall be subject to agreement by the parties tothe test.1.4 The values stated in SI units are to be regarded as thestandard.The values in parenthesis are provided for informa-tion only.1.5 This standard does not purport to address the safetyconcerns,if any,associated with its use.It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2.Referenced Documents2.1 ASTM Standards:3E230 Specification and Temperature-Electromotive Force(EMF)Tables for Standardized ThermocouplesE1894 Guide for Selecting Dosimetry Systems for Applica-tion in Pulsed X-Ray Sources3.Terminology3.1 Definitions:3.1.1 device under test(DUT)the device that is under thecurrent test.3.1.2 thermal time constant of a calorimeterthe time forthe temperature excursion of the calorimeter resulting from aradiation pulse to drop to 1/e of its initial maximum value.4.Summary of Test Method4.1 Single-Pulse MethodThis method consists of(1)irradiating,with a single pulse of high-energy electrons froman electron linear accelerator(linac)or flash X-ray machine(FXR),a small block of material to which either a thermistor ora thermocouple made from small-diameter wire is attached;(2)recording and measuring the resulting signal from a bridgecircuit or directly from the thermocouple;(3)calculating thetotal dose deposited in the block based on the temperature riseand the specific heat of the material;and(4)if required,calculating the equivalent dose in other specified materials.4.2 Multiple-Pulse MethodIf the dose available in a singlepulse is not large enough to give measurable results,the linacis pulsed repeatedly within a time short compared to thethermal time constant of the calorimeter.This method is similarto the single-pulse method except that the average dosedelivered in each pulse is calculated from the measuredcumulative dose of all the pulses.1This test method is under the jurisdiction of ASTM Committee E10 on NuclearTechnology and Applications and is the direct responsibility of SubcommitteeE10.07 on Radiation Dosimetry for Radiation Effects on Materials and Devices.Current edition approved Jan.1,2011.Published February 2011.Originallypublished as F526 77 T.Last previous edition approved in 2003 asF526 97(2003).DOI:10.1520/F0526-11.2In 1975 the General Conference on Weights and Measures adopted the unit gray(symbolGy)for absorbed dose;1 Gy=100 rad.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Significance and Use5.1 An accurate measure of the dose is necessary to ensurethe validity of the data taken,to enable comparison to be madeof data taken at different facilities,and to verify that compo-nents or circuits are tested to the radiatio