- -a Hilrf' ddl rww v II I I - mil---I- -andY1 - ill I I- EIPresident's Secretary s File 11 3 anm to'tho l I believe that an j'mic lamb 'haa been demoed oven the I Asiatic land me during the period 26 August 1914 9 29 August 19149 I I bfaew im omatim that has been obtained ban the i I ayeten establisbedhby the U 5 Air Force for the long range detection a of foreia atomic energy activities I 2 Fission products have been collected since 3 Se qu 19159 I Although the system Is only partially developed hove been fort I not in securing eifficien y large and fresh who tor effective I scientific analysis The cloud containing fission producte to tacked 1 3 Conclusions our scientists band 1 physical and radio- chemical analyses or collected data have been count-nod by scientists I I or the A38 United Kingdom and Office Research If h it my request Dr Vannem Rub Dr J Robert Oppenheimer Ii Dr Robert Backer and Admiral William S 2 5 me Joint Chiefs of Staff have been interned a the contents of i this letter and the attached report 19 mo 0' mm mmnon 'm an oocunm comm so am on on tom nmuom_ - fix 7 H - a I i V 1 masons it i UNITED AIR FORCE - 1 WASHINGTON as me - General Hoyt S Vandenberg Chief of Staff -'United States Air Force Washington Dear General 'Vandenberg rou which _met-' at 1712 Street at 1000 l9 Segtemger 1949 to renew certain significant scientific data reported it i by your atomic detection system and to examine the ijia - techni cal analysis of these data At'your request I convened an advisory The group cons isted of Dr Robert Openheimer Robert bacher Rear Admiral Parsons and myself After careful consideration of the facts presented by 'your_ technical staff we unanimously agree with their conclusmns as presented in Te ch Memo No 37 copy attached hereto m self-BULB 0 Sincerely V BUS a Tech Memo Sep 1 #967 ROBERT i I jjl b EfRTf- iQHER hrii IHim-ll - a-I- Inn-ll- Iii- I'll I- r I 'zitvi Iu 110 Ail-berm and grand level sampling-ZapatatMP ewetdgeur the 1 5 tum itapitie from Japan teuilaeke out-tho Romantic continent and Ith Luann from Canadauto Honey reveal the presence I 1 351 hum abnormal radioactivity in air masses which emanated from - Jri'ROE I-u I 7 --I I II t_ - 35 E jiize detegijnatioq correlated iith Firm 3 999m9dnl Isia establishes the fact that tiaaimbliiuterial i fiseioned B - locations - the Lame - land mm IF In-nil II i I bitumiheISSth mt meridian and the meta egg mum 3 41 43004901rate at the first filter ample byiair- '13 532m nned tha pree nce of radioactivity iithI a mamas-11 at man-e which strongly indicated the presence of fission in premiumall mam measurements indicated that a innit-511950 this Io riapien preduqtaanalyaiu 'of aamp1eq papery-Md points in I the cloud resulted in tho pame 9 I 1 a 33 9 and the humus Isaiah P uetu atLIII llII413M - 11 11 5 2373 a 319'11- I'Isih 11- 1 Ill mm i an Inuit-rm 1111 ir rh' at I I- i Inuitr'L-i- '1 J Ii i- I Irv if a t-I a u rovided I petitiye Kantian with promo I F IpGut I Ifir I - II I iI i you 2 and 29 - -- It Gnu-v --wvu - fir-t mu warn - 1' 'a r - ass-I 41liter Jamplp increasing Iwith time as mould be expected I in Ithe ease 9 decaf ea I u II 3 312 um 1 warm-r i II i ll 1- Ili rj'I'--'lri ti ill r' I i l Ir ir'kl rill 'lI-Iql abborption curve or graf ti-nation of age Inch_have show that the r311 cafe mite th 1 i2 in nature 3 1 nt perucl eaLhuabqemuolated and a to be much miller and chemically different those obtained from Bikini or Shinto teats See Incl k D - Z Bug-Tho fission prodqot ratios consiatan xiindriutm rhioniu i antics qt Eithenivil'iuwpea he observed 7 1 11 31 product and fission ratios are hith' the fission 1 121 - 01 Uminn 235 either by thermal neutrons by norm 318 103 spectral biw- 0130 not canaiatent with ma experienced tron any device uranium The pram of Nepmninm agrmteiy indi- 393 233s See Incls 1 39 mlyai aii-bog i tuter f utted 34 to i ho 1 03 name Scientific Laboratory marinara ftha present of Ag and the absence of lead-carried radioactivityE'Iji 1 i a 1r it ll-l 1' in independent collection Ot-mtOM1Mih dB British '1 13- 3 1 31- with lauque filtara tron northemT SootJm to the north and northwest wading 3 972 malted 1n the positive identificatgion products 61' i 1- 1 mbmumof emu decay mu-ndlabadrption- neu- 3 1513313 Emu 9 uhu d the date or betum 30 mmg EJh -btriu nd iodine decay curves agregd 1m Eht otlmm i - W'rlv'theamzhti approxmtaly Grl rhaurn-dmu aus 40 35 du- per minute per cubic-1t the at so mOIh mourn duration - on 11 5epten oer an 0 25 uni cation per dininute' par 91bit 1 Successful auto-radiograth faults ith 9 gm days Ono lust disintegration per minute and have 'b can 10 l' 36 Bull particles i i - heiparticlea lawn- 11 noi utrenelrtino and 1 5 51 11 but a 61 percent _or the activity mtpmuum a - xi-hi i a 31 - Further rdmwetliu h 1- in - cm 301 and Iowa 3 J iris 2'47 a 225ais'ntfnitcrm -- t 'gnn'l ing mgmhonoitnter J 9 lm wtted 1h momma-9t - tiu1m products tho dram thiah mad ur- Ham Incl E 4 101 42kl itIt win-'IqIl i inl' - s - 1949 1 - on th o tshtio land I use 5 1 products resulted than 91 from the fission 3 Hamil Uranium or Uranium 238 was present in close prom i to tho i uim ble material at it the time of ee reactionphenomena are all the View that 3 tag-origin of the ssion predicts tea the explosion of an a th bomb gthou melee - cmpoaition was similar to the M9160 bomb I i 5 1 misty of alternetivo explanations have been ipropoeed gig Whoa examination none of urns out to be those which unliker are yet consiatent u1th the data all J a call for the use of enough Plutonium to have Mae an ate-1e bomb- i 6 We believe that at atomic bomb has been detonated Hammer i a 1 Technical Director - 51am not attached g - A Incl - Tracerlab Technical Report i i 1 ch - Lon Alanna Raport - - i 1 Incl United Kingdom Scientific Reports - 1931 3 - Beport of Office a nal unmet t -ifl1'35rlii lul Hm -- IJE II Ill-4' I w Jid- This document is from the holdings of The National Security Archive Suite 701 Gelman Library The George Washington University 2130 H Street NW Washington D C 20037 Phone 202 994-7000 Fax 202 994-7005 nsarchiv@gwu edu