As part of the R2D2 (Rare Decays with Radial Detector) R &D, the use of a gas detector with a spherical or cylindrical cathode, equipped with a single anode and operating at high pressure, was ...studied for the search of rare phenomena such as neutrinoless double-beta decay. The presented measurements were obtained with a cylindrical detector, covering gas pressures ranging from 1 to 10 bar in argon and 1 to 6 bar in xenon, using both a point-like source of
210
Po (5.3 MeV
α
) and a diffuse source of
222
Rn (5.5 MeV
α
). Analysis and interpretation of the data were developed using the anodic current waveform. Similar detection performances were achieved with both gases, and comparable energy resolutions were measured with both sources. As long as the purity of the gas was sufficient, no significant degradation of the measured energy was observed by increasing the pressure. At the highest operating pressure, an energy resolution better than 1.5% full-width at half-maximum (FWHM) was obtained for both gaseous media, although optimal noise conditions were not reached.
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The CODALEMA experiment aims to study the radio-detection of Ultra High Energy Cosmic Rays in the energy range of 1017eV. Spread over an area of 0.25km2, the original device hosted at Nançay (France) ...has mainly benefited of an array of short dipoles, connected by cables up to a centralized acquisition room. Since 2010, a major evolution has been initiated to add 60 autonomous radio-detection stations, covering a surface of 1.5km2. This enlarged configuration should help refine the studies and serve as a bench test for the mastery of autonomous detection. The main characteristics of this new mode of operation is presented in the light of recent results obtained by the original CODALEMA setup.
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New Experiments with Spheres-Gas (NEWS-G) is a dark matter direct detection experiment that will operate at SNOLAB (Canada). Similar to other rare-event searches, the materials used in the detector ...construction are subject to stringent radiopurity requirements. The detector features a 140-cm diameter proportional counter comprising two hemispheres made from commercially sourced 99.99% pure copper. Such copper is widely used in rare-event searches because it is readily available, there are no long-lived Cu radioisotopes, and levels of non-Cu radiocontaminants are generally low. However, measurements performed with a dedicated 210Po alpha counting method using an XIA detector confirmed a problematic concentration of 210Pb in bulk of the copper. To shield the proportional counter’s active volume, a low-background electroforming method was adapted to the hemispherical shape to grow a 500-µm thick layer of ultra-radiopure copper to the detector’s inner surface. In this paper the process is described, which was prototyped at Pacific Northwest National Laboratory (PNNL), USA, and then conducted at full scale in the Laboratoire Souterrain de Modane in France. The radiopurity of the electroplated copper was assessed through Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Measurements of samples from the first (second) hemisphere give 68% confidence upper limits of <0.58µBq/kg (<0.24µBq/kg) and <0.26µBq/kg (<0.11µBq/kg) on the 232Th and 238U contamination levels, respectively. These results are comparable to previously reported measurements of electroformed copper produced for other rare-event searches, which were also found to have low concentration of 210Pb consistent with the background goals of the NEWS-G experiment.
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Spherical time projection chambers (TPC), also known as spherical proportional counters, are employed in the search for rare phenomena, such as light Dark Matter candidates. The spherical TPC ...exhibits a number of essential features, making it a promising candidate for the search of neutrinoless double beta decay (ββ0ν). A tonne-scale spherical TPC experiment could cover a region of parameter space relevant for the inverted mass hierarchy with a few years of data taking. In this direction, the major R&D goal of the R2D2 effort is the demonstration of the required energy resolution. First results from an argon-filled prototype detector are reported, demonstrating an energy resolution of 1.1% FWHM for 5.3 MeV α tracks in the 0.2 to 1.1 bar pressure range. This is a major milestone in terms of energy resolution, paving the way for further studies with xenon gas, and the possible use of this technology for ββ0ν searches.
Several efforts are ongoing for the development of spherical gaseous time projection chamber detectors for the observation of rare phenomena such as weakly interacting massive particles or neutrino ...interactions. The proposed detector, thanks to its simplicity, low energy threshold and energy resolution, could be used to observe the ββ0ν process i.e. the neutrinoless double beta decay. In this work, a specific setup is presented for the measurement of ββ0ν on 50 kg of 136Xe. The different backgrounds are studied, demonstrating the possibility to reach a total background per year in the detector mass at the level of 2 events per year. The obtained results are competitive with the present generation of experiments and could represent the first step of a more ambitious roadmap including the ββ0ν search with different gases with the same detector and therefore the same background sources. The constraints in terms of detector constructions and material purity are also addressed, showing that none of them represents a show stopper for the proposed experimental setup.
An antenna array devoted to the autonomous radio-detection of high energy cosmic rays is being deployed on the site of the 21
cm array radio telescope in XinJiang, China. Thanks in particular to the ...very good electromagnetic environment of this remote experimental site, self-triggering on extensive air showers induced by cosmic rays has been achieved with a small scale prototype of the foreseen antenna array. We give here a detailed description of the detector and present the first detection of extensive air showers with this prototype.
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Abstract
The measurement of neutrino magnetic moment larger than
10
-19
μ
B
would be a clear signature of physics beyond the
standard model other than the existence of massive Dirac
neutrinos. The ...use of a spherical proportional counter detector
filled with gas at 40 bar located near a nuclear reactor would be a
simple way to perform such a measurement exploiting the developments
made on such a technology for the search of dark matter and
neutrinoless double beta decay. Different targets can be used just
by replacing the gas: xenon, CF
4
and argon were compared and the
sensitivity in one year of data taking could reach the level of
4.3 × 10
-12
μ
B
, 6.5 × 10
-12
μ
B
, and
8.5 × 10
-12
μ
B
, respectively.
The amount of energy released by a nuclear recoil ionizing the atoms of the active volume of detection appears “quenched” compared to an electron of the same kinetic energy. This different behavior ...in ionization between electrons and nuclei is described by the Ionization Quenching Factor (IQF) and it plays a crucial role in direct dark matter searches. For low kinetic energies (below
50
keV
), IQF measurements deviate significantly from common models used for theoretical predictions and simulations. We report measurements of the IQF for proton, an appropriate target for searches of Dark Matter candidates with a mass of approximately
1
GeV
, with kinetic energies in between
2
keV
and
13
keV
in
100
mbar
of methane. We used the Comimac facility in order to produce the motion of nuclei and electrons of controlled kinetic energy in the active volume, and a NEWS-G SPC to measure the deposited energy. The Comimac electrons are used as a reference to calibrate the detector with 7 energy points. A detailed study of systematic effects led to the final results well fitted by
IQF
(
E
K
)
=
E
K
α
/
(
β
+
E
K
α
)
with
α
=
0.70
±
0.08
and
β
=
1.32
±
0.17
. In agreement with some previous works in other gas mixtures, we measured less ionization energy than predicted from SRIM simulations, the difference reaching
33
%
at
2
keV
.
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9.
R2D2 TPC: first Xenon results Bouet, R.; Busto, J.; Cecchini, V. ...
Journal of instrumentation,
10/2023, Volume:
18, Issue:
10
Journal Article
Peer reviewed
Abstract
Radial time projection chambers (TPC), already employed in
the search for rare phenomena such as light Dark Matter candidate,
could provide a new detection approach for the search of
...neutrinoless double beta decay (
ββ
0
ν
). The assessment of
the performances of such a detector for
ββ
0
ν
search is
indeed the goal of the Rare Decays with Radial Detector (R2D2)
R&D. Promising results operating a spherical TPC with argon up to
1 bar have been published in 2021. Supplementary measurements were
recently taken extending the gas pressure range up to 3 bar. In
addition, a comparison between two detector geometries, namely
spherical (SPC for spherical proportional counter) and cylindrical
(CPC for cylindrical proportional counter), was performed. Using a
relatively simple gas purification system the CPC detector was also
operated with xenon at 1 bar: an energy resolution of 1.4%
full-width at half-maximum was achieved for drift distances up to
17 cm. Much lower resolution was observed with the SPC. These
results are presented in this article.
The new setup of the CODALEMA experiment installed at the Radio Observatory in Nançay, France, is described. It includes broadband active dipole antennas and an extended and upgraded particle ...detector array. The latter gives access to the air shower energy, allowing us to compute the efficiency of the radio array as a function of energy. We also observe a large asymmetry in counting rates between showers coming from the North and the South in spite of the symmetry of the detector. The observed asymmetry can be interpreted as a signature of the geomagnetic origin of the air shower radio emission. A simple linear dependence of the electric field with respect to
v
∧
B is used which reproduces the angular dependencies of the number of radio events and their electric polarity.
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