Discovery ofXe109andTe105: Superallowedα

Abstract

Two new alpha emitters 109Xe and 105Te were identified through the observation of the 109Xe --> 105Te --> 101Sn alpha-decay chain. The 109Xe nuclei were produced in the fusion-evaporation reaction 54Fe(58Ni,3n)109Xe and studied using the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. Two transitions at Ealpha = 4062 +/- 7 keV and Ealpha = 3918 +/- 9 keV were interpreted as the l = 2 and l = 0 transitions from the 7/2+ ground state in 109Xe (T1/2 = 13 +/- 2 ms) to the 5/2+ ground state and a 7/2+ excited state, located at 150 +/- 13 keV in 105Te. The observation of the subsequent decay of 105Te marks the discovery of the lightest known alpha-decaying nucleus. The measured transition energy Ealpha = 4703 +/- 5 keV and half-life T1/2 = 620 +/- 70 ns were used to determine the reduced alpha-decay width delta2. The ratio delta105Te(2)/delta213Po(2) of approximately 3 indicates a superallowed character of the alpha emission from 105Te.

Direct observation of theBa114→Xe110→Te106→Sn

“…Another interesting aspect in this region is the prediction of cluster radioactivity [7]. It has been widely reported that the most promising candidate for this type of decay in the region is the 12 C decay 114 Ba→ 102 Sn [8][9][10], and that the theoretical predictions of the partial half-life depend very sensitively on the Q value for 12 C emission (Q12 C ) [8]. The value of Q12 C is therefore an important quantity in the design of experiments to search for this novel decay mode.…”

“…For example, the 109 Xe→ 105 Te→ 101 Sn decay chain has recently been studied despite the very short half-life of 620(70) ns for 105 Te [12]. Further study of this decay chain in Ref.…”

N=Znuclei: a laboratory for neutron–proton collective mode

“…Refs. [115] compared the α-decay reduced widths for Xe and Te nuclei with that of 212 Po and neighboring Po isotopes and an enhancement by a factor of 2-3 is seen. We also noticed that the |RF (R)| 2 value of 194 Rn is larger by a similar factor compared to the |RF (R)| 2 of the textbook α-decay isotope 212 Po [117,118].…”

“…If it is indeed correct, that would mean that the cluster formation increases when protons and neutrons occupy the same shells [115,116]. Refs.…”

Nucleon pair approximation description of the low-lying structure of108,109Te and109I

“…Towards the proton drip line, these nuclei become unstable against particle emissions [13][14][15][16]. α decays have been observed in nuclei 105−110 Te and 108−113 I [1, 13], and the nucleus 109 I is known as a proton emitter [14,16].…”