Completion of ?-decay chains: The ?-decays of162Ta and163Ta

Abstract

Using the reactions 3~l(13~a;4.5n) and 3bAr(133Cs;6,7n), the hal=-lives of 160,161Ta were measured to be 1.2(3) and 2.7(2) s, respectively, and the ~-lines observed at 4.88(1) and 4.63(1) MeV were assigned to 162fa and 163Yia, respectively. 'lhe e-decay branch of 162Ta was determined to be 0.065(14)%. PACS:23.60.+e, 27.70.+q In the region of proton-ri~n heavy lanthanide nuclides a few key isotopes exist, which on the one hand represent the endpoints of long adecay chains and on the other hand are situated close enough to the line of stability to allow precise mass n~asurements by the study of S-decay properties.In consequence the masses of all eprecursors up to exotic nuclides near the proton drip line can be deduced. However, not ~ 88 dnair~ are complete: in the ones based on Tb and 150~io, the masses of which have recently been measured /1-3/, there were still missin~ links, the not observed e-decays of 16~a andl~a.The identification of these decay branches was the aim of the present study.

Revision of the decay data of166?170Re, including new isomers167m,169mRe

“…The trend of the production ratio is similar to that of 94keV or ll0keV v-rays, both belonging to t'6vW [4]. We note that the excitation function of 5.26 MeV e-rays of Cabot et al [1][2][3][4][5][6][7][8] is rather wide, a fact which might aggravate their assignment. Our inspection of the presented e-ray spectra of Schrewe et al (Fig.…”

“…These investigations were performed for the tantalum isotopes 16o-164Ta [1], for i64'16STa, 164'165Hf, 166W [2], 171Re [3], the tungsten isotopes 167-174W E4~6], and 176'177Ir E7]. In this paper we report on rhenium isotopes with mass numbers A = 166 to 170.…”

The decay of the new isotope171Re

“…Using the coincidence relations and the energy and intensity balances, we were able to construct the decay scheme of ~71Re (Fig. 4). ECK/fl + =NKo:/Ns11 9 1/2 * t51 ~/eK *f* 1/~or 9 IK~/(IK~ + IK,), (1) where N number of coincident K~ or 511 keV coincidences e detector efficiency: er~=9.0%, es~ = 1.6% oK -fluorescence yield for K X-rays I -relative intensity for K~ and K~ X-rays f -correction for extended source of annihilation quanta.…”

“…Under these circumstances, the helium jet technique, combined with a fast transport tape, turned out to be a suited tool for systematic spectroscopic investigations with the aim of yielding fundamental decay characteristics for nuclides in the specified area. The investigations were started for tantalum isotopes with A=160-164 [1] and continued for the tungsten isotopes with A = 167-171, which are subject to a forthcoming paper [2]. With the recent identification of 173Re [3], the unknown isotope aV~Re remained as last white spot in the inland region of the nuclear chart.…”

Collective excitations in the transitional nucleiRe163andRe165

“…The minimum time difference was selected to reduce background from escaping α particles from correlated short-lived parent activities. Figure 6 [32] arising from the decay of 166 Re is not observed. There are several α-decay emissions arising from spurious decay correlations due to the long correlation time between first-and second-generation α decays.…”