The results of measurements of natural radioactive isotopes content in different source materials of natural and enriched composition used for CaMoO4 scintillation crystal growing are presented. The ...crystals are to be used in the experiment to search for neutrinoless double beta decay of 100Mo.
The GERDA experiment searches for the lepton-number-violating neutrinoless double-β decay of ^{76}Ge (^{76}Ge→^{76}Se+2e^{-}) operating bare Ge diodes with an enriched ^{76}Ge fraction in liquid ...argon. The exposure for broad-energy germanium type (BEGe) detectors is increased threefold with respect to our previous data release. The BEGe detectors feature an excellent background suppression from the analysis of the time profile of the detector signals. In the analysis window a background level of 1.0_{-0.4}^{+0.6}×10^{-3} counts/(keV kg yr) has been achieved; if normalized to the energy resolution this is the lowest ever achieved in any 0νββ experiment. No signal is observed and a new 90% C.L. lower limit for the half-life of 8.0×10^{25} yr is placed when combining with our previous data. The expected median sensitivity assuming no signal is 5.8×10^{25} yr.
The results of measurements of natural radioactive isotopes content in different source materials of natural and enriched composition used for CaMoO sub(4) scintillation crystal growing are ...presented. The crystals are to be used in the experiment to search for neutrinoless double beta decay of super(100)Mo.
The results of measurements of natural radioactive isotopes content in different source materials of natural and enriched composition used for CaMoO4 scintillation crystal growing are presented. The ...crystals are to be used in the experiment to search for double neutrinoless betas-decay of Mo-100.
Eur. Phys. J. C 81, 505 (2021) Neutrinoless double-$\beta$ decay of $^{76}$Ge is searched for with germanium
detectors where source and detector of the decay are identical. For the success
of future ...experiments it is important to increase the mass of the detectors. We
report here on the characterization and testing of five prototype detectors
manufactured in inverted coaxial (IC) geometry from material enriched to 88% in
$^{76}$Ge. IC detectors combine the large mass of the traditional semi-coaxial
Ge detectors with the superior resolution and pulse shape discrimination power
of point contact detectors which exhibited so far much lower mass. Their
performance has been found to be satisfactory both when operated in vacuum
cryostat and bare in liquid argon within the GERDA setup. The measured
resolutions at the Q-value for double-$\beta$ decay of $^{76}$Ge
(Q$_{\beta\beta}$ = 2039 keV) are about 2.1 keV full width at half maximum in
vacuum cryostat. After 18 months of operation within the ultra-low background
environment of the GERmanium Detector Array (GERDA) experiment and an
accumulated exposure of 8.5 kg$\cdot$yr, the background index after analysis
cuts is measured to be $4.9^{+7.3}_{-3.4}\times 10^{-4}$ counts
/(keV$\cdot$kg$\cdot$yr) around Q$_{\beta\beta}$. This work confirms the
feasibility of IC detectors for the next-generation experiment LEGEND.
The GERmanium Detector Array (GERDA) collaboration searched for neutrinoless double-\(\beta\) decay in \(^{76}\)Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. The ...experimental signature of the decay is a monoenergetic signal at Q\(_{\beta\beta}\) = 2039.061(7)keV in the measured summed energy spectrum of the two emitted electrons. Both the energy reconstruction and resolution of the germanium detectors are crucial to separate a potential signal from various backgrounds, such as neutrino-accompanied double-\(\beta\) decays allowed by the Standard Model. The energy resolution and stability were determined and monitored as a function of time using data from regular \(^{228}\)Th calibrations. In this work, we describe the calibration process and associated data analysis of the full GERDA dataset, tailored to preserve the excellent resolution of the individual germanium detectors when combining data over several years.
Phys. Rev. Lett. 125, 252502 (2020) The GERmanium Detector Array (GERDA) experiment searched for the
lepton-number-violating neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay of
$^{76}$Ge, whose ...discovery would have far-reaching implications in cosmology
and particle physics. By operating bare germanium diodes, enriched in
$^{76}$Ge, in an active liquid argon shield, GERDA achieved an unprecedently
low background index of $5.2\times10^{-4}$ counts/(keV$\cdot$kg$\cdot$yr) in
the signal region and met the design goal to collect an exposure of 100
kg$\cdot$yr in a background-free regime. When combined with the result of Phase
I, no signal is observed after 127.2 kg$\cdot$yr of total exposure. A limit on
the half-life of $0\nu\beta\beta$ decay in $^{76}$Ge is set at
$T_{1/2}>1.8\times10^{26}$ yr at 90% C.L., which coincides with the sensitivity
assuming no signal.
Phys. Rev. Lett. 125, 011801 (2020) We present the first search for bosonic super-WIMPs as keV-scale dark matter
candidates performed with the GERDA experiment. GERDA is a neutrinoless
double-beta ...decay experiment which operates high-purity germanium detectors
enriched in $^{76}$Ge in an ultra-low background environment at the Laboratori
Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for
pseudoscalar and vector particles in the mass region from 60 keV/c$^2$ to 1
MeV/c$^2$. No evidence for a dark matter signal was observed, and the most
stringent constraints on the couplings of super-WIMPs with masses above 120
keV/c$^2$ have been set. As an example, at a mass of 150 keV/c$^2$ the most
stringent direct limits on the dimensionless couplings of axion-like particles
and dark photons to electrons of $g_{ae} < 3 \cdot 10^{-12}$ and
${\alpha'}/{\alpha} < 6.5 \cdot 10^{-24}$ at 90% credible interval,
respectively, were obtained.
Science 365, 1445 (2019); published online 05 Sep 2019 A discovery that neutrinos are not the usual Dirac but Majorana fermions,
i.e. identical to their antiparticles, would be a manifestation of new ...physics
with profound implications for particle physics and cosmology. Majorana
neutrinos would generate neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay,
a matter-creating process without the balancing emission of antimatter. So far,
0$\nu\beta\beta$ decay has eluded detection. The GERDA collaboration searches
for the $0\nu\beta\beta$ decay of $^{76}$Ge by operating bare germanium
detectors in an active liquid argon shield. With a total exposure of 82.4
kg$\cdot$yr, we observe no signal and derive a lower half-life limit of
T$_{1/2}$ > 0.9$\cdot$10$^{26}$ yr (90% C.L.). Our T$_{1/2}$ sensitivity
assuming no signal is 1.1$\cdot$10$^{26}$ yr. Combining the latter with those
from other $0{\nu}\beta\beta$ decay searches yields a sensitivity to the
effective Majorana neutrino mass of 0.07 - 0.16 eV, with corresponding
sensitivities to the absolute mass scale in $\beta$ decay of 0.15 - 0.44 eV,
and to the cosmological relevant sum of neutrino masses of 0.46 - 1.3 eV.
The GERmanium Detector Array (GERDA) is a low background experiment located at the Laboratori Nazionali del Gran Sasso in Italy, which searches for neutrinoless double beta decay of \(^{76}\)Ge into ...\(^{76}\)Se+2e\(^-\). GERDA has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new Ge detectors. These were manufactured according to the Broad Energy Germanium (BEGe) detector design that has a better background discrimination capability and energy resolution compared to formerly widely-used types. Prior to their installation, the new BEGe detectors were mounted in vacuum cryostats and characterized in detail in the HADES underground laboratory in Belgium. This paper describes the properties and the overall performance of these detectors during operation in vacuum. The characterization campaign provided not only direct input for GERDA Phase II data collection and analyses, but also allowed to study detector phenomena, detector correlations as well as to test the strength of pulse shape simulation codes.
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