UCRL,_.1---,--'_ ~ /t>/,.f oW c-, ( UNIVERSITY OF CALIFORNIA FOR REFERENCE NOT TO BE TAKEN FROM THIS ROOM BERKELEY, CALIFORNIA , • ENG-48 INDEX ITO. ~e:~ -.;;:y ~ This document contains ? pgs, and . plates of figures .-- I: i:BJ·~-;:'--CQPY_.&t.. of' // • Series~ '. e~j" .~ DO NOT RET'40VE LlIS PAGE ----------.._- ~r['N'" '?~,." 1'HIS IS A CLA':'" '-'~~'::::::"".'STF I','P ':i}P~.\'rl.RI=~i1i.3i6TED,.;"-;,- . , ~~~~~-0" .:~.. ",.~. ~~ ---'-clas S":r.iI; ~ i~·nt::6otte'oe;l;"J.m.D.. edhEJre \\ --&~t:' ~l :..'J' ". e}- /; .~ ,s,sWIC-'\l' ti-I'{.t},l J.: li!/er ,.. 'l'bis document contains restrj.cted data within the meaning of ~Rt! ~~ic~rll!¥GY Act of 1946 and/or information affecting the national defense of the :ut~d States within the meaning of the Espionage Act U. S. C. 31 & 32, as amended. Its transmission or the revelation of its contents in an'! manner to an unauthor- ized person is prohibited''';;:na may' r.esult in' severe crimi;,al penalti. 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NEurRON DEFICIENT ISOTO~E~i%1i1~I~~II.t:Jw1.~CltYP~lANT IM:)NY --o~\,< -, '('r:, :Lrt.'t'W~_ M. Lindner and I. Perlman: ':" Radiation Laboratory and Department of Chemistry University of California, Berkeley, California While investigatinf. the relative yields for the many reactions resulting from the irradiation of antimony with 200-Mev deuterons in the Berkeley 184-inch cyclotron- several previously unreported isotopes of tellurium and antimony were encountered~ The tellurium fraction when followed on a thin mica window counter could be resolved into half-life periods of 2.5 hrs, 6.0 days and a small amount of a long-lived component. The 2.5 hour period has not been further characterized with respect to mass number or'mode of decay other than to note that the radiation is predominantly electrons. The 6.0-day period is accompanied by positrons which were shown to be due to a 3.5 minute antimony dau~hter which is undoubtedly the same activity 1l8 assip-ned to Sb by Risser, Lark... Horowitz and Smithl • The positron energy was found to be 3.1 ~ O~ 2 .lVlev by absorption in berylllum and from the and point of the energy distribution curve taken with a low-resolution beta-ray spectrometer. C~mma activity is also present with this period. The 6~0-day tellurium showed a high abundance of x-rays, little or no conversion electrons and some gamma-ray activity which could be due to the 3.5 minute antimony daughter. The tellurium fraction contained another component of 4.5-d13.y half-life which could not be observed in the decay curve because of' its low abundance but which was detected by means of its 39-hour antimony daughter. The 39-hour antimony showed x-rays of tin (critical absorption with cadmi~mi.:·;~i1"Ver and palladium), no detectable hard radiation or electrons and i~8i'~~p~:txnt1Y identioal,with an activity 1l9 recently assip~ned to Sb by Coleman and P0012 <' • "d cl.t~'~~.;;:'Qf,~,ift~ • corM;"s {e~t~ct - ',:'";'@;';'p;.2"",.,_ 'T' .~ t4 .........'\"'~f1. f l. / • J '~;.~~,~:'i.~~ .•. :1~r'7!"1 ~ l)\li~ej ':.Jl.~lfJS ·O>·1-'.6"!~i)\<:: "". ; AC; .1 "" I. t _.__" ... " - t ,. ':'2 as ame"-- -~~'.:::,~'; ~~n'1 tho!!, j. J:,,;;., ,< \0-; ! 0"", , ' _' the £,sp . "r",' 1 j ,. __ ' "'l_\, ~n !:I~."(;,~.'" \;6 reve\t1t\o. .. d oJ m..-j (~;;'.'oi.' ,'- _ ' ... if~!l:'l:'> or ~ \. ptohib\\.b Q . ,I'_'~!I ""'4.-.!..~ \:z;eOI'el~on IS ~'i~:~~';{~_>:._!", QJ;'~:. ':.;:--::~_- g--,,_P'~: :<~- ~~'~~~~"'>' ments was predicted to produce the d,4n reaction in'gb6d yield and the d,5n reaction in poorer yield. If the 4.5-day tellurium is Te l19 and the B.O-day period is ll8 Te the desired result should be achieved. The counting rates for the x-rays of the ~!o activities were found to be in the ratio of 40:1 in the direction anticipated. Since the rlctivity of' several days half-life is larp-ely that of the 1l8 4.5-day tellurium (except for the positrons of the 3~5"minute Sb ), the negative particles and electromagnetic radiation may be assumed to belong to this isotope. Conversion eleetrons of 0.2 Mev ahd 0.5 .L1!ev were measured with the iow resolution beta-r~y spectrometer and a hard gamma-ray of about 1.5 Mev was detected through a lead absorption curve. Softer gamma radiation could have been present. All tellurium decay curve s ta iled out into a longer period) probably Te 121 • The antimony fraction from bombardments of antimony with 200-~1ev deuterons showed a number of periods which could be resolved by selectively counting the x-reys through beryllium and the electrons without- absorber. There was x-ray activity of a. fe''! hours half-life which could be a mixture of the 2.8 hour and 5.1 hour periods reported by Coleman and Pool. The 2.8-day Sb122 showed up well in the curve taken without absorbers and the 39-hour antimony was prominent in the decay curve taken throu~h beryllium. The yield of the 39-hour antimon~ was much greater than that which could have grown from its 4.5-day tellurium parent, indi- eating direct formation. Another antimony isotope of 6.0-day half-life was also observed. This activity is characterized by a preponderance of x-ray and gamma-ray activity with electrons in low abundance. Since the 6.0-day antimony did not appear in antimony removed from tellurium, the tellurium isobar is either stable or of half-life less than 10 minutes. Although the half-iliife is the same as that of the tellurium mentioned above, it could be separated chemically with antimony from -.- <,,~~--:,;_:,._-.-- .. UCRL-39 Page 3 ) tellurium and there was no positron activity accompanying it. It is not possible to me,ke an isotopic ass io-nment of this activity. After the decay of the 6. O-day antimony, the curve turned into the 60-day period of Sb124 wh'1.0h was 1.'dent'f'1 led 124 } also by its radiation characteristics. The formation of Sb presents tle unans- wered question as to whether this isotope is formed by the hi~h ener~y deuterons or by secondary low enerry neutrons. Table 't: lists the isotopes of antimony and tellurium found in the bombardment of antimony with ZOO-Mev deuterons. The cross sections for their formation will be I"iven in a later publication in which the yields fo r the large number of products of 200-Mev deuterons on antimony will .be discussed. The ass ip'nment of the 4.