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Search for alpha and double alpha decays of natural Nd isotopes accompanied by gamma quanta
Ist Teil von
The European physical journal. A, Hadrons and nuclei, 2024-03, Vol.60 (3), Article 46
Ort / Verlag
Berlin/Heidelberg: Springer Berlin Heidelberg
Erscheinungsjahr
2024
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
From 7 naturally occurring Nd isotopes, 5 are unstable in relation to
α
decay. If an excited level of the daughter nucleus is populated, or the daughter nucleus is unstable,
γ
quanta can be emitted. We used an ultra-low background spectrometry system with 4 high purity germanium (HPGe) detectors (about 225 cm
3
volume each) to search for such decays using a highly purified Nd-containing sample with mass of 2.381 kg. Measurements were performed at the INFN Gran Sasso underground laboratory (with an overburden of about 3600 m w.e.) during 51,237 h. Half-life limits for
α
decays of
143
Nd and
145
Nd were determined to be
T
1/2
(
143
Nd) > 1.1 × 10
20
year and
T
1/2
(
145
Nd) > 2.7 × 10
19
year at 90% C.L. This is an increase of three and two orders of magnitude, respectively, compared with the most restrictive values currently given in literature. A limit for
α
decay of
144
Nd to the excited level of
140
Ce with
E
exc
= 1596.2 keV was determined for the first time as
T
1/2
(
144
Nd →
140
Ce
*
) > 9.3 × 10
20
year. Restriction for the
α
decay of
146
Nd to the excited level of
142
Ce with
E
exc
= 641.3 keV was increased by 3 orders of magnitude to
T
1/2
(
146
Nd →
142
Ce
*
) > 1.4 × 10
21
year. For
α
and 2
α
decays of
148
Nd, first
T
1/2
limits were set as 4.2 × 10
18
year and 2.1 × 10
20
year, respectively.