Experimental detection of α-particles from the radioactive decay of natural bismuth

Abstract

The only naturally occurring isotope of bismuth, 209Bi, is commonly regarded as the heaviest stable isotope. But like most other heavy nuclei abundant in nature and characterized by an exceptionally long lifetime, it is metastable with respect to alpha-decay. However, the decay usually evades observation because the nuclear structure of 209Bi gives rise to an extremely low decay probability and, moreover, generates low-energy alpha-particles difficult to detect. Indeed, dedicated experiments attempting to record the alpha-decay of 209Bi in nuclear emulsions failed. However, scintillating bolometers operated at temperatures below 100 mK offer improved detection efficiency and sensitivity, whereas a broad palette of targets could be available. Here we report the successful use of this method for the unambiguous detection of 209Bi alpha-decay in bismuth germanate detectors cooled to 20 mK. We measure an energy release of 3,137 +/- 1 (statistical) +/- 2 (systematic) keV and a half-life of (1.9 +/- 0.2) x 10(19) yr, which are in agreement with expected values.

YAG:Nd crystals as possible detector to search for and decay of neodymium

“…This result was confirmed in the measurements with CaWO 4 crystal as scintillator [22] and bolometer [34]. It should be also referred the excellent result on the detection of alpha decay of 209 Bi with the half-life T 1/2 = (1.9 ± 0.2) × 10 19 y [35]. In both the experiments [34] and [35] the cryogenic technique, which uses simultaneous registration of heat and light signals, have been applied.…”

“…It should be also referred the excellent result on the detection of alpha decay of 209 Bi with the half-life T 1/2 = (1.9 ± 0.2) × 10 19 y [35]. In both the experiments [34] and [35] the cryogenic technique, which uses simultaneous registration of heat and light signals, have been applied. This method provides perfect selection of α events on the background caused by γ rays (electrons).…”

Highly sensitive bolometers for rare alpha decay studies

“…Taking into accounts for both the trigger e ciency and the pulse-shape cuts e ciency, the detection e ciency was (87±2)%. The half-life for the GS-GS transition results ⌧ GS GS 1/2 =(2.04±0.08)·10 19 years in good agreement with the previously reported one [8].…”

“…2 Rare ↵ decay of 209 Bi 209 Bi was thought to be the heaviest stable isotope, until the first evidence of its decay was obtained by means of a BGO scintillating crystal [8]. This measurement provided the half-life of the ground state (GS) decay.…”

Bismuth‐based candidates for topological insulators: Chemistry beyond Bi2Te3

“…On top of that, bismuth is plentiful and can be easily produced in economically exploitable forms, it is a nontoxic and a practically non-radioactive [11] element -this all making it an appealing candidate for industrious applications. Other neighbours of bismuth in the Periodic Table that also possess strong spin-orbit interaction are either costly (iridium, platinum, gold) or hazardous (thallium, lead).…”