A first search for rare decays of gadolinium isotopes was performed with an ultra-low background high-purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 198 g
Gd
2
O
3
powder ...sample was measured for 63.8 d with a total Gd exposure of 12.6 kg
×
d.
152
Gd is the most promising isotope for resonant enhanced neutrinoless double electron capture which could significantly increase the decay rate over other neutrinoless double beta decay processes. The half-life for this decay was constrained to
>
4.2
×
10
12
year (90% credibility). This limit is still orders of magnitude away from theoretical predictions but it is the first established limit on the transition paving the way for future experiments. In addition, other rare alpha and double beta decay modes were investigated in
152
Gd,
154
Gd, and
160
Gd with half-life limits in the range of
10
17
-
20
year.
A search for alpha and double beta decays of ytterbium isotopes was performed with an ultra low-background high purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 194.7 g Yb
2
...(C
2
O
4
)
3
powder sample was measured for 11.3 days with a total Yb exposure of 1.25 kg
×
day. Half-life limits for
α
-decay modes of
168
Y
b
,
170
Y
b
,
171
Y
b
,
172
Y
b
,
173
Y
b
,
174
Y
b
and
176
Y
b
into the first excited states have been obtained between
6
×
10
14
years and
2
×
10
16
years. These are the first experimental constraints of these decay modes. Double electron capture of
168
Y
b
and double beta decay of
176
Y
b
into the first excited 2
+
and 0
+
states could be excluded with limits between
1
×
10
14
years to
8
×
10
16
years. This improves the experimental information on some of the decay modes compared to previous constraints.
We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer VEto), recently built and now operated at the shallow underground laboratory ...of the Max-Planck-Institut für Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of
≤
100
μ
Bq kg
-
1
for primordial radionuclides from U and Th in typical
γ
ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites.
A 510 day long-term measurement of a 45.3 g platinum foil acting as the sample and high voltage contact in an ultra-low-background high purity germanium detector was performed at Laboratori Nazionali ...del Gran Sasso (Italy). The data was used for a detailed study of double beta decay modes in natural platinum isotopes. Limits are set in the range
O
(
10
14
-
10
19
)
years (90% C.L.) for several double beta decay transitions to excited states confirming, and partially extending existing limits. The highest sensitivity of the measurement, greater than
10
19
years, was achieved for the two neutrino and neutrinoless double beta decay modes of the isotope
198
Pt. Additionally, novel limits for inelastic dark matter scattering on
195
Pt are placed up to mass splittings of approximately 500 keV. We analyze several techniques to extend the sensitivity and propose a few approaches for future medium-scale experiments with platinum-group elements.
Radioactivity was recently discovered as a source of decoherence and correlated errors for the real-world implementation of superconducting quantum processors. In this work, we measure levels of ...radioactivity present in a typical laboratory environment (from muons, neutrons, and
γ
-rays emitted by naturally occurring radioactive isotopes) and in the most commonly used materials for the assembly and operation of state-of-the-art superconducting qubits. We present a GEANT-4 based simulation to predict the rate of impacts and the amount of energy released in a qubit chip from each of the mentioned sources. We finally propose mitigation strategies for the operation of next-generation qubits in a radio-pure environment.
First limits on double beta decays in 232Th Laubenstein, M.; Lehnert, B.; Nagorny, S. S.
The European physical journal. C, Particles and fields,
08/2020, Letnik:
80, Številka:
8
Journal Article
Recenzirano
Odprti dostop
As one of the primordial radioactive isotopes,
232
Th
mainly undergoes
α
-decay with a half-life of
1.402
·
10
10
years. However, it is also one of 35 double beta decay candidates in which the ...single
β
-decay is forbidden or strongly suppressed. 181 mg of thorium contained in a gas mantle were measured in a HPGe well-detector at the Gran Sasso Underground Laboratory with a total exposure of 3.25 g
×
d.
We obtain half-life limits on all double beta decay modes of
232
Th
to excited states of
232
U
on the order of
10
11
-
15
years. For the most likely transition into the 0
1
+
state we find a lower half-life limit of
6.7
·
10
14
years (90% C.I.). These are the first constraints on double beta decay excited state transition in
232
Th
.
As one of the primordial radioactive isotopes, Formula omitted mainly undergoes Formula omitted-decay with a half-life of Formula omitted years. However, it is also one of 35 double beta decay ...candidates in which the single Formula omitted-decay is forbidden or strongly suppressed. 181 mg of thorium contained in a gas mantle were measured in a HPGe well-detector at the Gran Sasso Underground Laboratory with a total exposure of 3.25 g Formula omittedd.
Upgrade for Phase II of the Gerda experiment Agostini, M.; Bakalyarov, A. M.; Balata, M. ...
European physical journal. C, Particles and fields,
05/2018, Letnik:
78, Številka:
5
Journal Article
Recenzirano
Odprti dostop
The
Gerda
collaboration is performing a sensitive search for neutrinoless double beta decay of
76
Ge
at the INFN Laboratori Nazionali del Gran Sasso, Italy. The upgrade of the
Gerda
experiment from ...Phase I to Phase II has been concluded in December 2015. The first Phase II data release shows that the goal to suppress the background by one order of magnitude compared to Phase I has been achieved.
Gerda
is thus the first experiment that will remain “background-free” up to its design exposure (
100 kg
year
). It will reach thereby a half-life sensitivity of more than
10
26
year within 3 years of data collection. This paper describes in detail the modifications and improvements of the experimental setup for Phase II and discusses the performance of individual detector components.
A new study of double beta decay processes in natural Zr isotopes using Zr metal samples and an ultra-low-background high-purity germanium detectors was performed at Laboratori Nazionali del Gran ...Sasso of INFN (Italy). Two data sets were collected with a 736.35 g and a 129.94 g Zr metal over 59.7 days and 37.3 days, respectively, and were used for a detailed analysis. A new limit on the double beta decay of
94
Zr to the 1st excited level of
94
Mo was set as
T
1
/
2
β
β
>
2.1
×
10
20
year
, which is a factor of three better than the previous result. It is shown that the current radiopurity of Zr metal (tens of Bq/kg), produced via two methods, do not comply with the radiopurity requirements for low-background experiments. Hence, we propose to use a purified ZrCl
4
powder in an optimized geometry as a new approach for future experiments with extended sensitivity focused on studies of rare nuclear processes in Zr isotopes.
Abstract
A new study of double beta decay processes in natural Zr isotopes using Zr metal samples and an ultra-low-background high-purity germanium detectors was performed at Laboratori Nazionali del ...Gran Sasso of INFN (Italy). Two data sets were collected with a 736.35 g and a 129.94 g Zr metal over 59.7 days and 37.3 days, respectively, and were used for a detailed analysis. A new limit on the double beta decay of
$$^{94}$$
94
Zr to the 1st excited level of
$$^{94}$$
94
Mo was set as
$$T_{1/2}^{\beta \beta } > 2.1\times 10^{20}~\text {year}$$
T
1
/
2
β
β
>
2.1
×
10
20
year
, which is a factor of three better than the previous result. It is shown that the current radiopurity of Zr metal (tens of Bq/kg), produced via two methods, do not comply with the radiopurity requirements for low-background experiments. Hence, we propose to use a purified ZrCl
$$_{4}$$
4
powder in an optimized geometry as a new approach for future experiments with extended sensitivity focused on studies of rare nuclear processes in Zr isotopes.
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