Decay of 1221n

fro,,, nucleal. I-eaction The measurements usually began 15 s after the prest~~dies and little is derived from ~.uclioactive decay. paration of soul.ces. The clecay of 1??ln was repol-ted by ~~~~~l~ The y-ray measurements were carried out using :\,,d K~~-~~~ (2) to have a half-life of7,5 and later, two Ge(Li) detectors of efficiencies 8 and 18%, and a decay scheme (3) was proposed, I,, 1971, energy I-esolutions of 2.0 and 2.5 keV (FWHM), ~~k~h~~hi rr (4) I-epol-ted the existence of two respectively, for the 1333 keV y-I-ny from a Vo isonlers in 1x1~ with J" = (4+, 5') (T,,, = los) and SOLIIC~. For low energy y-rays and X-rays. a low J": = (1') (T,,, = 1.5 s). proposed decay energy photon spectrometer having a resolution of schemes involved five levels in 'xsn. ~~~h groups 450eV for 87 keV y-rays was used. Energy calib1.aLlsed 1x1~ sources pl-oduced via I~~S,,(~,~) tion was carried out using IX'Ta, 133Ba, and jhCo tion. More recently. preliminary reports (5,6) using sttlndard sources from QSIRIS filcility suggested that the The two Ge(Li) detectors were also used for y-y 10s isomer of '"In should have .ln = (8--). coincidence measurement. They were placed facwe have stlldied the decay of~??ln LIsinga soLII-ce ing each other with a 1 cm thick Pb plate placed produced by 2x3~(~,0 i-e:,ction followed by isotope between them. The time resolution used was 80ns. sep;lri,tion. our prelin,jnury I.epol-t (7) suggested Digital energy gates were selected on the y-ray that the los consisted of the decay of two peaks and theit- adjacent backgl-ound from one cleisomel-s with sinlilur half-lives. subsequently, ad- tector and the cot-responding coincidence y-ray ditionaj stlldies using a source produced via spectra were stored. These two detectors were also I?IS~(~~,~)I'~~,