Usually a thunderstorm region with lightning activity is necessary for the formation of known types of upper atmospheric transient luminous events (TLEs: sprites, emission of light and very low ...frequency perturbation, blue jets, etc.) with well-recognizable visible emissions. However, some "far-from-thunderstorm" transient events have been detected in some experiments. Measurements of transient atmospheric events (TAEs) were made on board the Vernov satellite by the sensitive UV and IR detector. Remote observation from the satellite's orbit provided measurements all over the globe and allowed us to study events associated with thunderstorms (lightning, TLEs) and unusual UV flashes (UV TAEs) far from thunderstorm regions. More than 8500 UV TAEs were measured by the Vernov satellite over the globe. Forty seven far-from-thunderstorm TAEs were selected having no lightning discharges during 1 h in a radius of 1000 km around the location of the event according to the Worldwide Lightning Location Network (WWLLN) and Vaisala Global Lightning Data Set (GLD360) data. Special attention was given to six events with complicated temporal structure and low luminosity in the IR channel. Their properties and atmospheric conditions were studied in detail. The analysis of cloud cover in addition to the lightning location networks data demonstrated the low probability of any lightning in the region of measurements.
Abstract
The development of low-threshold detectors for the study of
coherent elastic neutrino-nucleus scattering and for the search for
light dark matter necessitates methods of low-energy ...calibration. We
suggest this can be provided by the nuclear recoils resulting from
the γ emission following thermal neutron capture. In
particular, several MeV-scale single-γ transitions induce
well-defined nuclear recoil peaks in the 100 eV range. Using the
FIFRELIN code, complete schemes of γ-cascades for various
isotopes can be predicted with high accuracy to determine the
continuous background of nuclear recoils below the calibration
peaks. We present a comprehensive experimental concept for the
calibration of CaWO
4
and Ge cryogenic detectors at a research
reactor. For CaWO
4
the simulations show that two nuclear recoil
peaks at 112.5 eV and 160.3 eV should be visible above background
simply in the spectrum of the cryogenic detector. Then we discuss
how the additional tagging for the associated γ increases the
sensitivity of the method and extends its application to a wider
energy range and to Ge cryogenic detectors.
TUS (Tracking Ultraviolet Set-up) is the world's first orbital detector of ultra-high-energy cosmic rays (UHECRs). It was launched into orbit on 28th April 2016 as a part of the scientific payload of ...the Lomonosov satellite. The main aim of the mission was to test the technique of measuring the ultraviolet fluorescence and Cherenkov radiation of extensive air showers generated by primary cosmic rays with energies above ∼100 EeV in the Earth atmosphere from space. During its operation for 1.5 years, TUS registered almost 80,000 events with a few of them satisfying conditions anticipated for extensive air showers (EASs) initiated by UHECRs. Here we discuss an event registered on 3rd October 2016. The event was measured in perfect observation conditions as an ultraviolet track in the nocturnal atmosphere of the Earth, with the kinematics and the light curve similar to those expected from an EAS. A reconstruction of parameters of a primary particle gave the zenith angle around 44ˆ but an extreme energy not compatible with the cosmic ray energy spectrum obtained with ground-based experiments. We discuss in details all conditions of registering the event, explain the reconstruction procedure and its limitations and comment on possible sources of the signal, both of anthropogenic and astrophysical origin. We believe this detection represents a significant milestone in the space-based observation of UHECRs because it proves the capability of an orbital telescope to detect light signals with the apparent motion and light shape similar to what are expected from EASs. This is important for the on-going development of the future missions KLYPVE-EUSO and POEMMA, aimed for studying UHECRs from space.
The TUS detector is the first orbital telescope designed to test techniques for measuring ultraviolet fluorescence and Cherenkov radiation of extensive air showers (EASes). The detector was launched ...aboard the Lomonosov satellite on April 28, 2016. A two-level event selection system (trigger) was developed and implemented in the digital electronics of the photodetector. This trigger was optimized for the search for EASes, but at the same time operated under conditions of variable atmospheric luminescence of both natural (aurora light, diffused moonlight, thunderstorm phenomena) and anthropogenic origin (city lights, flashes at airports). The frequency of the trigger also depends on that of transient atmospheric phenomena of different origin. Examples of events recorded by the TUS detector and selected welve by the EAS trigger are given.
Coherent neutrino-nucleus scattering is a promising new tool in the toolbox of electroweak precision measurements at low
q
-transfer. It will enable precise measurements of standard model (SM) ...physics like the running of the Weinberg angle but also the search for new physics beyond the SM like sterile neutrinos. The
Nucleus
experiment aims at the first detection of fully coherent neutrino-nucleus scattering at the Chooz power plant in France, using its two 4GW
th
reactor cores as high-intensity source for anti-neutrinos. For this endeavour a new experimental site, the Very Near Site (VNS), with a shallow rock overburden of
≈
3
m w.e. is under development. To be competitive in this challenging environment,
Nucleus
developed the novel concept of fiducialised cryogenic bolometers based on CaWO
4
monocrystals operated at
O
(10 mK). The signature of a coherent neutrino-nucleus scattering is a nuclear recoil at the 10 eV-scale. Currently,
Nucleus
is preparing its first phase with 10 g of target mass at the VNS. In this contribution, we will first introduce
Nucleus
, report its current state and give an outlook to its future.
Abstract
The
Nucleus
experiment aims to measure coherent elastic neutrino nucleus scattering of reactor anti-neutrinos using cryogenic calorimeters. Operating at an overburden of 3 meters of water ...equivalent, muon-induced backgrounds are expected to be one of the dominant background contributions. Besides a high efficiency to identify muon events passing the experimental setup, the
Nucleus
muon veto has to fulfill tight spatial requirements to fit the constraints given by the experimental site and to minimize the induced detector dead-time. We developed highly efficient and compact muon veto modules based on plastic scintillators equipped with wavelength shifting fibers and silicon photo multipliers to collect and detect the scintillation light. In this paper, we present the full characterization of a prototype module with different light read-out configurations. We conclude that an efficient and compact muon veto system can be built for the
Nucleus
experiment from a cube assembly of the developed modules. Simulations show that an efficiency for muon identification of >99 % and an associated rate of 325 Hz is achievable, matching the requirements of the
Nucleus
experiment.
Abstract
Coherent elastic neutrino-nucleus scattering (CE
ν
NS) offers a unique way to study neutrino properties and to search for new physics beyond the Standard Model. The NUCLEUS experiment aims ...to measure CEνNS of reactor anti-neutrinos down to unprecedented low nuclear recoil energies. The novel gram-scale cryogenic detectors feature an ultra-low energy threshold of ≤20eV
nr
and a rise time of a few 100
μ
s which allows the operation above ground. The fiducialization of the detectors provides an effective discrimination of ambient
γ
- and surface backgrounds. Furthermore, the use of multiple targets promises a high physics potential. The NUCLEUS experiment will be located at a new experimental site at the Chooz nuclear power plant in France, providing a high anti-neutrino flux of
1.7
⋅
10
12
ν
¯
e
/
(
s
⋅
cm
2
)
. The commissioning of the experimental setup with a comprehensive background measurement is planned for 2022.
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