<2^ M)Pß )0. WT-12(i8 (EX) EXTRACTED VERSION. October i^ ^^Nevada^ Tfst^Site rt^febmmf-may «55. - PDF

M)Pß )0 / W\ OPERATON TEAPOT. Gamma Radiatin as a Functin f Distance i Prject 13.3a«^ tf

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M)Pß )0 / W\ OPERATON TEAPOT. Gamma Radiatin as a Functin f Distance i Prject 13.3a«^ tf 2^ WT-12(i (EX) EXTRACTED VERSON Octber 1955 / 0 i^ ^^Nevada^ Tfst^Site rt^febmmf-may «55.!. '? J /^ NOTCE 1) A//5 J This is an extract f WT-120, Operatin TEAPOT, Prject 13.3a, which remains classified SECRET/ RESTRCTED DATA as f this date. Extract versin prepared fr: ^ Directr 3 DEFENSE NUCLEAR AG ^j Washingtn, D. C 1 Sep 10 A Apprved fr public release; distributin unlimited bj » ^. F ~ Best Available Cpy KmMwi j' i -.n Unclassified «CUTT CLAiunCATiON r THS PACE (in,,* OM*. «trout HUMCH WT-120 (EX) 4. TTLE r««sukuiitj REPORT DOCUMENTATON PAGE. COVT ACCCttlON NO. Operatin TEAPOT, Gamma Radiatin as a Functin f Distance, Prject 13.3a T. AUTHONfs; E. Strm E. Bemis READ NSTRUCTONS BEFORE COMPLETNG FORM. NECPlEHft CATALOG HUHE i TYPE OF NEPONT * PEROOCOVEED 1. PERFORMNG ORG. RENORT NUMRER WT-120 (EX). CONTRACT OR GRANT NUMERfi) t. PEirORMNCONCkNATON NAME ANO ADDXEtt. Ls Alams Scientific Labratry Ls Alams, New Mexic CONTttOLLHC OFFCE NAME ANO AOOnEtS U. MONTORNG AGENCY NAME 1 AODNESSril dilltnttl tm CMitlllitt Ollirm) 10. PROGRAM ELEMENT. PROJECT, TASK AREA t WORK UNT NUMER li. REPORT DATE Octber 1955 t. NUMRER OF PACES 3 S. SECURTY CLASS. f«( Mil«nflt) S«. mumm DECLASSFCATON/OORNCRAONO SCHEDULE *. DSTRBUTON STATEMENT (l hlm R«parl) Apprved fr public release; unlimited distributin. T. DSTRBUTON STATEMENT (l hr mbmlitrl tnltitd n Bluet 0, älllmif» hmm R«prl) «. SUPPLEMENTARY NOTES This reprt has had the classified infrmatin remved and has been republished in unclassified frm fr public release. This wrk was perfrmed by the General Electric Cmpany-TEMPO under cntract DNA C-0455 with the clse cperatin f the Classificatin Management DivisinTJT the Defense Nuclear Agency. '» KCV «OROt fc»nfmu«n fvmrm* tiä* tl n«r*i*ary mn4 dtnttly by ktcft number«operatin TEAPOT Gamma Radiatin Film Calibratin Film Badges 20. ABSTRACT fcantlnu«wl f«v«rclam n«r*«a«ry «nd ld*ni ty fcy fclcfc numt»t) _i OD JACT 1473 EDTON OF NOVSS S OBSOLETE MUli Unclassified WWc r»ccurty CLASSFCATON OF THS PACE (»li««0«ta tnl«.»«) FOREWORD This reprt has had classified material remved in rder t make the infrmatin available n an unclassified, pen publicatin basis, t any interested parties. This effrt t declassify this reprt has been accmplished specifically t supprt he Department f. Defense Nuclear Test Persnnel Review (NFPR) Prgram. The bjective is t facilitate studies f the lw levels f radiatin received by sme individuals during the almspheric nuclear test prgram by making as much infrmatin as pssible available t all interested parties. The material which has been deleted is all currently classified as Restricted Data r Frmerly Restricted Data under the prvisin f the Atmic Energy Act f 1954, (as amended) r is Natinal Security nfrmatin. This reprt has been reprduced directly frm available cpies f the riginal material. The lcatins frm which material has been deleted is generally bvius by the spacings and hles in the text. Thus the cntext f the material deleted is identified t assist the reader in the determinatin f whether the deleted infrmatin is germane t his study. t is the belief f the individuals wh have participated in preparing this reprt by deleting the classified material and f the Defense Nuclear Agency that the reprt accurately prtrays the cuntents f the riginal and that the deleted material is f little r n significance t studies int the amunts r types f radiatin received by any individuals during the atmspheric nuclear test prgram. Accessin Fr NTS QRAfcl DT1C TAB Unannuned Justtf lcatln_ ^j^ G D By- Distributin/ Availability Cdes Avail and/r Dibt Special B i %\ DT1C ELECTHpm JAN ' D UNANNOUNCED mumm ABSTHACT G.TTjrn r.ndi.'.tin expsure measurenents were made as a functin f disianctä n the c ee., Apple, ',\'asp Prime, Apple, and Zucchini shts f Dpprs.tin Teapt. The Apple T, Wasp Prime, and Zucchini gamma measnrements scaled with yield, the Bee results were high by abut 50^, and the Apcle measurements were affected by the cluds passing ver the nstrument line. The measurements made with the LASL aluminum-wd and the NBS lead-tin-pajcelite film badges are cmpared with the energy-independent Victreen thimble chamber readings. The apprximate film values relative t thimble chamber values are the fllwing; in the aluminum badge, film types 502 and 510 were 10^ high, and types 606 and 1290 were 20^ high; in the NBS badge, 502 was 7% lw, 510 was 19% lw, 606 was 10? lw, and 1290 was essentially crrect. ACKNGV/LEDÜÖ'ENTS The authrs gratefully acknwledge the assistance f Gerge Littlejhn and James Lawrence n the film calibratin and prcessing, the assistance f Maurice Janc in the field wrk, and the many useful suggestins f Simn Shlaer and Thmas White f LASL and Margarete Ehrlich f NBS. -3- Tim - - CONTENTS Page Abstract Acknwledgments 1. ntrductin 2. Methds and Prcedures U 2. 3. Results Film Types Film Badges lu Discussin f Results 1,1 Yield lj,2 Cmparisn f Chambers and Film Badges h,3 nterpretatin in Te^-ms f Energy Dependence h.h The LASL and ESL Discrepancy n Previus TesV n «MHMiMlMlilltHMH-Mil 1. ntrductin During Nevada peratins prir t Te.ipt, bth the Evans Signal Labratry (ESL) and the Ls Alams Scientific Labratry (LASL) measured gamma radiatin as a functin f distance n many f the shts, using film badges. The measurements f the tw labratries have nt been in agreement, the LASL values being generally higher than the ESL values. n 1953 an intercalibratln between LASL and the Natinal Bureau f Standards (NBS) revealed an errr f l}% in the LASL measurements, but the majr prtin f the discrepancy has remained unreslved. Since the primary purpse f the LASL measurements was t determine whether the gamma radiatin frm the varius devices tested n these peratins scaled with yield, which is a relative determinatin, n crrectin fr this calibratin errr was made nr were further attempts made at finding additinal errrs. Hwever, prir t the Teapt pera- tin it became apparent that there was a need fr a clarificatin f the results, including a determinatin f abslute expsure values. The widely differing respnse f the ESL and LASL badges t lw energy gamma radiatin appeared t be a likely surce f errr n bth ESL and LASL measurements. t was therefre decided t cmpare film badge measure- ments with thse btained with Vlctreen thimble chambers, which are essentially ndependent f energy abve 30 kev. ' - ' - i - _ i 2. Methds and Prcedures 2.1 Film Types The film types emplyed n previus tests by the tw grups and their apprximate expsure ranges are as fllws: Expsure range, r LASL film type ESL film type Du Pnt 502 Du Pnt Du Pnt 510 Du Pnt 510 1? Du Pnt 606 Du Pnt Du Pnt 1290 (Adlux) Du Pnt 1290 (Adlux) ,000 Eastman 5h-0 Eastman t shuld be nted that the film types are identical with the exceptin f the lwest expsure range, where LASL used type 502 and ESL used type 50. Of the six film types listed abve, nly Du Pnt 502, 510, 606, and 1290 were used n Operatin Teapt. An attempt was made by LASL t btain sme Du Pnt 50 film frm the ESL grup in Nevada during the peratin, but ESL had discntinued using this film type after Operatin Upsht-Knthle and was using Du Pnt 502. The high-range Eastman 54-O had been used nly t a limited extent by LAüL n previus tests - id cnsequently was nt included in the Teapt measurements. «H M^jt^ ^^^ ^^^^^^ 2.2 Fi', m Ba-i^es The film badge used by LASL cnsists f a sltted wden cylinder 2-5/ in. in diqneter and 6 in. in length enclsed in a l/l6 in. thick alunintm can munted n an angle-irn stake. This badge will be referred t as the aluminum-wd r AW badge. The film badge used by ESL cnsists f a Bakelite cntainer having an.25 mm wall thickness cvered with layers f 1.07 mm f tin and 0.3 mm f lead. A 0.7 mm thick lead strip is wrapped arund the uter edge f the badge and the entire assembly is placed in a plastic cigarette case and munted n a metal stake. This badge, designed by Ehrlich f the Natinal Bureau f Standards, is usually referred t as the NBS badge. Three ther badges were used t sme extent n Teapt. One f these, which will be called the B-C badge, cnsisted f tw separate filters, each filter cntaining varying amunts f six elements. Althugh this badge is still in the design stage, the decisin was made t use it because f its smewhat unique respnse in the very lw energy regin. At the request f Je Deal f the AEC, a film badge cnstructed by Edgertn, Gemeshausen, and Grier (EG&G), and a film badge used by the British n their test peratins were als used. The EG&O badge is similar n design t the UBS badge except that the Bakelite cntainer has been replaced with a plyethylene cntainer. The British badge cnsists f a 1.0 mm tin filter and a thin plastic jacket; lfrd film type ftl 3 was used with this badge. The five film badges used n Teapt are shwn in Fig, 1, 2.3 Film Calibratin The films used by LASL in the AW badge have been calibrated in the past with radiatin frm a 22 Mev betatrn. n 1953, an intercalibratin was perfrmed in which film types 1290 and 606 were expsed in the NBS and AW badges t radiatin frn NBS and LASL betatrns perating at peak energies f 10 and 22 Mev, respectively. T eliminate pssible incnsistencies in develping, tw sets f expsures were made and each labratry prcessed a cmplete set f 10 and 22 Mev film calibratins vith essentially identical results. The results, reprted in NBS Reprt 6A-121, shwed that the films in the NBS and AW badge have the sane respnse t 10 Mev radiatin. The film respnse f the NBS badge at 22 Mev was smewhat high, but this effect des nt influence the field discrepancy since ESL did nt calibrate at this high energy. The film respnse in the AW badge was fund t be 13% lwer at 22 Mev than at 10 Mev, and subsequent measurements at LASL demnstrated that the thickness f aluminum and wd in the badge was nt sufficient t prvide inic equilibrium at the higher energies. This 13% lwer respnse at the 22 Mev calibratin energy means that the interpreted field measurements were high by this amunt, because distances frm the surce were great enugh t prvide inic equilibrium. Tw different radium surces were used fr calibrating the film badges fr Operatin Teapt, ne apprximately 0,2 curies and the ther apprximately 2,3 curies. The rhm (rentgens per hur at 1 meter) f the 0.2 curie surce had been measured by NBS t within +1%, The 2.3 curie -- LlMi *.M, M. ^-.. - ^, -- surce was Calibrated by crr.parir.; th current it prduced in a Vic- treen thimble chamber attached t a vibrating-reed electrmeter t the current prduced under identical cnditins by the knwn 0.2 curie surce. After the peratin, bth surces were again measured using Victreen thimble chambers which had Just been calibrated by Frank Day f NBS t energies ranging frm 0,0$ t 1,3 Mev and fund t be independent f energy within +5'^. The surce utput f the tw radium surces as measured with the thimble chambers agreed t within +3^ f the previus calibratins. Typical calibratin curves fr Du Pnt 502, 510, 606, and 1290 are shwn in Fig. 2, Althugh nly the pints btained with the films in the NBS and AW badges are shwn, the curves we-e cnstructed with the data frm the NBS, AW, B-C, and EG&G badges. There is a small but cnsistent trend fr the NBS badge pints t lie belw thse f the AV badge, but the presumably similar BG4G badge gave pints which tended t be slightly higher than the NBS pints. Hwever, 90^ f the pints fr all badges were, in terms f expsure, within S% i the cmpsite curves shwn. 2.1i Energy Dependence f the Film Badges The energy dependence f the varius film types used n these tests in the AW and NBS badges is shwn in Fig. 3. The AW badge 606 and 1290 curves and all fur NBS badge curves are based n measurements made by Ehrlich, The AW badge 502 and 510 curves were cnstructed using unfil- tered film measurements made by Ehrlich and the true absrptin cef- ficients given by White in NBS Reprt As may be seen, the AW badge ^MM^,^ : mmmmmmmmmm has a large verrespnse fr energies belw 250 kev and the NBS badge has a large underrespnse belw 100 kev. f the spectrum f the measured gamma radiatin cntains cmpnents in the lw energy regin, resulting frm the surce spectrum r frm multiple scattering n air, the AW badge wuld verevaluate and the NBS badge wuld underevaluate the expsure. This pssible difference is in the directin f the gen- erally bserved discrepancy n previus peratins. The calculated respnse f filter B in the B-C badge t mnchr- matic radiatin is shwn in Fig. }. Between $0 and 90 kev the area under this curve is equal t the area under a curve f unit sensitivity. The respnse fr filter C is nly slightly different frm B, because f small differences in the relative amunts f the same elements. The discntinuities in the curve ccur at the K-edges f the six elements making up the filter. As indicated in Fig, 3, measurements made with h0 t 75 kev mnchrmatic radiatin gave excellent agreement with the calculated respnse; hwever, abut 90 kev hard-filtered x-rays gave a much higher respnse than calculated. t was this latter feature width resulted in the use f thimble chambers in the field, rather than the B-C badge, as standards with which t cmpare the AW and NBS badges. nitial results frm Bee j shwed the B-C badge t have a greater respnse than the AW badge, indicating the need fr air-equilibrium material between the filters and the film. Subsequent use f such material resulted in btaining the same respnse with the B-C badge as with the AV badge. Trcidentally, measurements made by Ehrlich LL l-l.^-ot. after the peratin demnstrated that the verrespnse f the B-C badge abve 90 kev was due t flurescent radiatin frm the elements in the filter, 2.5 Victreen Thimbl Chambers Victreen thimble chambers have lng been used in the labratry as secndary standards fr measuring expsures. The respnse f these instruments, as determined by Day f NBS, is essentially independent f energy abve 30 kev. Bth befre and after the peratin the chambers were calibrated t better than S% accuracy with the 2,3 curie radium surce. Tests fr charge-leak were made in the labratry and in the field ver perids f 1 t 15 days. Table 1 lists the calibratin and charge-leak crrectin factrs fr each chamber. Table 2 gives air densities, pressures, and temperatures and the applied pressure-temperature crrectin factrs fr the five tests n which measurements were made. Only six chambers, varying in full scale sensitivity frm 2.5 t 2^0 r, were available fr the Bee, Apple, and Wasp Prime tests. Fifteen chambers were used n the Apple sht and 13 n the Zucchini sht. Fr mechanical prtectin in the field, a cylindrical Lucite cap with a l/l6 in. wall and lined with aluminum fil, was placed ver each chamber. This assembly was held apprximately 10 in. abve grui.d by a 2 in, square wd stake. The additinal Lucite did nt affect the respnse f the chambers, because it added an amunt f air-like material wliich waa insignificant cmpared with the amunt f air already existing between -11- the surce and the chambers. Nne f the chanbers was da.tia?ed by the detnatins, althugh tw chambers lcated 2900 yd frm grund zer n Apple were accidently destryed by an Army tank shrtly befre recvery, 3, Results The expsures as a functin f distanca measured with chambers and film badges n the Bee, Apple, Wasp Prime, Apple, and Zucchini shts are given in Table 3, The calculated rd^ (expsure times distance squared) values are given in Table U as a functin f distance. The rd 2 V3 d curves fr the chambers, the AW badge, and the M3S badge are shwn in Figs, U, 5, and 6, respectively; als shwn are the curves nrmalized t an air density f 1,0$5 g/l. Table 5 gives the rd' values btained frm the nrmalized curves fr each instrument at 3000 yd. The ratis f these rd^ values measured n the Bee, Apple, Wasp Prime, and Apple tests t the rd' value measured n the Zucchini test are als given in the table, tgether with the yields btained frm these ratis by assuming a yield f 2 kt fr Zucchini' i The radichemistry yields are given in the sane table fr purpses f cmparisn. The fllwing sets f expsure ratis are given in Table 6 fr each film type, test, and each distance at which measurements were made: AW badge t chamber, NBS badge t chamber, and AW badge t NBS badge .^» ^^ Results bt.nined with the B-C, British, and EG&G badges are fiven in Table 3. j. Discussin f Results h.l Yield The yield calculatins in Table 5 shw that the ganma radiatin expsure n the Apple, Wasp Prime, and Zucchini tests varied prprtinately with yield, and that the chambers, AW badges, and NBS badges scaled equally well. Since there is n reasn cnnected with the Apple device itself that shuld prevent scaling, the apparent increase f expsure per kiltn is prbably due t the fissin clud, which was bserved t pass ver the instrument line. The resultant grund pattern f the cntaminatin strengthens this cnclusin. Once befre, n the li.2 Cmparisn f Chambers and Kilm Badges The varius ratis fr each instrument appearing in Table 6 were averaged fr all distances and the results are given n Table 7, Thus there are averages f AW t chamber, NBS t chamber, and AW t NP3 fr - ach film type and fr each test. Shwn in Table are the ratis fr -13- the varius film, film badge, and chamber cmbinatins averaged ver all distances and tests, these being called pled averages. N pled averages with Apple measurements are given because f the previusly mentined incnsistency due t the fissin clud; had these data been included the AW t chamber and the NBS t chamber ratis wuld have been anewhat lwer. Althugh there is cnsiderable scatter in the data, there appear t be trends frm which certain cnclusins may be drawn«with the exceptin f the Apple measurements, the AW badge gave cnsistently higher values than the chambers. The 502 and $10 films were abut 10^ higher, and the 606 and 1290 abut 20^ higher than the chambers. n the NBS badge the $02 films averaged abut 7% lwer than the chambers, the 510 abut 19% lwer, the 606 abut 10^ lwer, and the 1290 essentially the same as the chambers. Because f a lack f thimble chambers there were mre AW/NBS values than ratis invlving thimble chambers. n every case, the expsures measured in the AW badge were higher than thse measured in the NBS badge, the average difference varying with film types as fllws: the $02 film, 16% higher; 510, 36%; 606, 3Wj and 1290, 21^, The Apple data are nt ncluded in the weighted averages used t btain these differences. The few measurements made with the three ther badges indicate that the B-C and British badges gave essentially the same results as the AW hedge, and the EG&G badge gave abut the same results as the NBS badge. -lli-.*_~ ' - Lt. 3 nterpretatin in Termr. f Energy Dependence Figure 3 shws that between ho and 100 kev the AW badge is much mre sensitive than the NBS badge, mre than 100 t 1 at 4O kev. Since the largest difference fund between the tw badges was 36^, the spectrum seen by the badge cntains very little energy in this range. This same cnclusin is btained by cnsidering that the B-C and AW badges gave the same measured values even thugh the AW badge is as much as 20 times mre sensitive than the B-C badge in the ho t 100 kev regin. n the 100 t 250 kev range the AW and B-C badges have an verrespnse. A significant amunt f energy n this regin might accunt fr the 10 t 20^ greater respnse relative t the thimble chambers which these badges exhibited. f significant energy cmpnents exist in this range, the NBS badge wuld give lwer expsures than the AW and B-C badges, a result actually btained. Hwever, the ratis btained with the varius film types n the NBS badge are nt cnsistent with their energy dependence curves. Frm these curves ne wuld have expected the 510 film t read higher than the 606 film, and the 606 film t read higher than the 502 and 1290 films, but precisely the ppsite trend was fund. Thus, if the differences fund between the varius film types in the MBS badge are due t radiat
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