The GIOVE (Germanium Inner Outer VEto) detector setup is a low level Germanium spectrometer for material screening with elaborated shield located at the shallow depth underground laboratory of the ...Max-Planck-Institut für Kernphysik in Heidelberg. It is equipped with a double active muon veto with a total muon rejection efficiency of ~99% and there are also passive layers to moderate and capture neutrons. With this setup an integral count rate is achieved comparable to detectors far deeper underground. The detector and shield geometry has been implemented into a Monte Carlo simulation, using the simulation framework MaGe based on Geant4. The Monte Carlo simulation is employed to determine sample efficiencies for γ ray screening measurements as well as to reproduce the remaining detector background from cosmic ray muon-induced secondaries. In terms of the background modeling of the unvetoed γ ray spectrum an excellent agreement better than 10% in the integral count rate in (40, 2700) keV as well as for the 511 keV line has been found. However, concerning the expected number of neutrons at the diode, the simulation outcome lays 40-80% below the measurement results. Being able to reproduce the detector background in the simulation, the simulation can be used to further optimize the shield design.
We consider the potential for a 10 kg undoped cryogenic CsI detector operating at the Spallation Neutron Source to measure coherent elastic neutrino-nucleus scattering and its sensitivity to discover ...new physics beyond the standard model (BSM). Through a combination of increased event rate, lower threshold, and good timing resolution, such a detector would significantly improve on past measurements. We considered tests of several BSM scenarios such as neutrino nonstandard interactions and accelerator-produced dark matter. This detector’s performance was also studied for relevant questions in nuclear physics and neutrino astronomy, namely the weak charge distribution of Cs and I nuclei and detection of neutrinos from a core-collapse supernova. Published by the American Physical Society 2024
Using an 185-kg NaITl array, COHERENT has measured the inclusive electron-neutrino chargedcurrent cross section on 127I with pion decay-at-rest neutrinos produced by the Spallation Neutron Source at ...Oak Ridge National Laboratory. Iodine is one the heaviest targets for which low-energy (≤ 50 MeV) inelastic neutrino-nucleus processes have been measured, and this is the first measurement of its inclusive cross section. After a five-year detector exposure, COHERENT reports a flux-averaged cross section for electron neutrinos of ${9.2}_{—1.8}^{+2.1}$ × 10—40 cm2. This corresponds to a value that is ~41% lower than predicted using the MARLEY event generator with a measured Gamow-Teller strength distribution. In addition, the observed visible spectrum from charged-current scattering on 127I has been measured between 10 and 55 MeV, and the exclusive zero-neutron and one-or-more-neutron emission cross sections are measured to be ${5.2}_{—3.1}^{+3.4}$ × 10—40 and ${2.2}_{—2.2}^{+3.5}$ × 10—40 cm2, respectively.
Abstract
Neutrinoless double-
$$\beta $$
β
decay of
$$^{76}$$
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
$$^{76}$$
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-
$$\beta $$
β
decay of
$$^{76}$$
76
Ge (
$$Q_{\beta \beta }$$
Q
β
β
= 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
$$\cdot $$
·
year, the background index after analysis cuts is measured to be
$$4.9^{+7.3}_{-3.4}\times 10^{-4} \ \text {counts}/(\text {keV} \cdot \text {kg} \cdot \text {year})$$
4
.
9
-
3.4
+
7.3
×
10
-
4
counts
/
(
keV
·
kg
·
year
)
around
$$Q_{\beta \beta }$$
Q
β
β
. This work confirms the feasibility of IC detectors for the next-generation experiment
Legend
.
Abstract
We search for tri-nucleon decays of
$$^{76}$$
76
Ge in the dataset from the GERmanium Detector Array (GERDA) experiment. Decays that populate excited levels of the daughter nucleus above the ...threshold for particle emission lead to disintegration and are not considered. The ppp-, ppn-, and pnn-decays lead to
$$^{73}$$
73
Cu,
$$^{73}$$
73
Zn, and
$$^{73}$$
73
Ga nuclei, respectively. These nuclei are unstable and eventually proceed by the beta decay of
$$^{73}$$
73
Ga to
$$^{73}$$
73
Ge (stable). We search for the
$$^{73}$$
73
Ga decay exploiting the fact that it dominantly populates the 66.7 keV
$$^{73m}$$
73
m
Ga state with half-life of 0.5 s. The nnn-decays of
$$^{76}$$
76
Ge that proceed via
$$^{73m}$$
73
m
Ge are also included in our analysis. We find no signal candidate and place a limit on the sum of the decay widths of the inclusive tri-nucleon decays that corresponds to a lower lifetime limit of 1.2
$$\times $$
×
10
$$^{26}$$
26
yr (90% credible interval). This result improves previous limits for tri-nucleon decays by one to three orders of magnitude.
Abstract The GERmanium Detector Array ( Gerda ) experiment operated enriched high-purity germanium detectors in a liquid argon cryostat, which contains 0.33% of $$^{36}$$ 36 Ar, a candidate isotope ...for the two-neutrino double-electron capture (2 $$\nu $$ ν ECEC) and therefore for the neutrinoless double-electron capture (0 $$\nu $$ ν ECEC). If detected, this process would give evidence of lepton number violation and the Majorana nature of neutrinos. In the radiative 0 $$\nu $$ ν ECEC of $$^{36}$$ 36 Ar, a monochromatic photon is emitted with an energy of 429.88 keV, which may be detected by the Gerda germanium detectors. We searched for the $$^{36}$$ 36 Ar 0 $$\nu $$ ν ECEC with Gerda data, with a total live time of 4.34 year (3.08 year accumulated during Gerda Phase II and 1.26 year during Gerda Phase I). No signal was found and a 90% CL lower limit on the half-life of this process was established $$T_{1/2} >1.5\cdot 10^{22} $$ T 1 / 2 > 1.5 · 10 22 year.
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