Any considerations on propagation of particles through the Universe must involve particle interactions: processes leading to production of particle cascades. While one expects existence of such ...cascades, the state of the art cosmic-ray research is oriented purely on a detection of single particles, gamma rays or associated extensive air showers. The natural extension of the cosmic-ray research with the studies on ensembles of particles and air showers is being proposed by the CREDO Collaboration. Within the CREDO strategy the focus is put on generalized super-preshowers (SPS): spatially and/or temporally extended cascades of particles originated above the Earth atmosphere, possibly even at astrophysical distances. With CREDO we want to find out whether SPS can be at least partially observed by a network of terrestrial and/or satellite detectors receiving primary or secondary cosmic-ray signal. This paper addresses electromagnetic SPS, e.g. initiated by VHE photons interacting with the cosmic microwave background, and the SPS signatures that can be seen by gamma-ray telescopes, exploring the exampleof Cherenkov Telescope Array. The energy spectrum of secondary electrons and photons in an electromagnetic super-preshower might be extended over awide range of energy, down to TeV or even lower, as it is evident from the simulation results. This means that electromagnetic showers induced by such particles in the Earth atmosphere could be observed by imaging atmospheric Cherenkov telescopes. We present preliminary results from the study of response of the Cherenkov Telescope Array to SPS events, including the analysis of the simulated shower images on the camera focal plane and implementedgeneric reconstruction chains based on the Hillas parameters.
The main objective of the Cosmic-Ray Extremely Distributed Observatory (CREDO) is the detection and analysis of extended cosmic ray phenomena, so-called super-preshowers (SPS), using existing as well ...as new infrastructure (cosmic-ray observatories, educational detectors, single detectors etc.). The search for ensembles of cosmic ray events initiated by SPS is yet an untouched ground, in contrast to the current state-of-the-art analysis, which is focused on the detection of single cosmic ray events. Theoretical explanation of SPS could be given either within classical (e.g., photon-photon interaction) or exotic (e.g., Super Heavy Dark Matter decay or annihilation) scenarios, thus detection of SPS would provide a better understanding of particle physics, high energy astrophysics and cosmology. The ensembles of cosmic rays can be classified based on the spatial and temporal extent of particles constituting the ensemble. Some classes of SPS are predicted to have huge spatial distribution, a unique signature detectable only with a facility of the global size. Since development and commissioning of a completely new facility with such requirements is economically unwarranted and time-consuming, the global analysis goals are achievable when all types of existing detectors are merged into a worldwide network. The idea to use the instruments in operation is based on a novel trigger algorithm: in parallel to looking for neighbour surface detectors receiving the signal simultaneously, one should also look for spatially isolated stations clustered in a small time window.
The Cosmic-Ray Extremely Distributed Observatory (CREDO) is an infrastructure for global analysis of extremely extended cosmic-ray phenomena, so-called super-preshowers, beyond the capabilities of ...existing, discrete, detectors and observatories. To date cosmic-ray research has been focused on detecting single air showers, while the search for ensembles of cosmic-ray events induced by super-preshowers is a scientific terra incognita - CREDO explores this uncharted realm. Positive detection of super-preshowers would have an impact on ultra-high energy astrophysics, cosmology and the physics of fundamental particle interactions as they can theoretically be formed within both classical (photon-photon interactions) and exotic (Super Heavy Dark Matter particle decay and interaction) scenarios. Some super-preshowers are predicted to have a significant spatial extent - a unique signature only detectable with the existing cosmic-ray infrastructure taken as a global network. An obvious, although yet unprobed, super-preshower 'detection limit' would be located somewhere between an air shower, induced by a super-preshower composed of tightly collimated particles, and a super-preshower composed of particles spread so widely that only few of them can reach the Earth. CREDO will probe this detection limit, leading to either an observation of an as yet unseen physical phenomenon, or the setting upper limits to the existence of large extraterrestrial cascades which would constrain fundamental physics models. While CREDO's focus is on testing physics at energies close to the Grand Unified Theories range, the broader phenomena are expected to be composed of particles with energies ranging from GeV to ZeV. This motivates our advertising of this concept across the astroparticle physics community.
The double-beta decay of 82Se to the 0+1 excited state of 82Kr has been studied with the NEMO-3 detector using 0.93 kg of enriched 82Se measured for 4.75 y, corresponding to an exposure of 4.42 kg y. ...A dedicated analysis to reconstruct the gamma-rays has been performed to search for events in the 2e2g channel. No evidence of a 2nbb decay to the 0+1 state has been observed and a limit of T2n 1/2(82Se; 0+gs -> 0+1) > 1.3 1021 y at 90% CL has been set. Concerning the 0nbb decay to the 0+1 state, a limit for this decay has been obtained with T0n 1/2(82Se; 0+g s -> 0+1) > 2.3 1022 y at 90% CL, independently from the 2nbb decay process. These results are obtained for the first time with a tracko-calo detector, reconstructing every particle in the final state.
We compared the average force required to separate normal corneas at a 50% stromal depth, with the force required to separate corneas stored for 2, 5, 7, 10, and 14 days in either McCarey-Kaufman or ...Dexsol corneal storage medium. The required interlamellar separation force was calculated by standardizing the width of the test strips. The average required force for 35 fresh rabbit corneas (no storage) was 9.1 +/- 1.5 g/mm. There was no significant change in the required separation force after storage in either medium for up to 14 days.
The full data set of the NEMO-3 experiment has been used to measure the half-life of the two-neutrino double beta decay of \(^{100}\)Mo to the ground state of \(^{100}\)Ru, \(T_{1/2} = \left 6.81 \pm ...0.01\,\left(\mbox{stat}\right) ^{+0.38}_{-0.40}\,\left(\mbox{syst}\right) \right \times10^{18}\) y. The two-electron energy sum, single electron energy spectra and distribution of the angle between the electrons are presented with an unprecedented statistics of \(5\times10^5\) events and a signal-to-background ratio of ~80. Clear evidence for the Single State Dominance model is found for this nuclear transition. Limits on Majoron emitting neutrinoless double beta decay modes with spectral indices of n=2,3,7, as well as constraints on Lorentz invariance violation and on the bosonic neutrino contribution to the two-neutrino double beta decay mode are obtained.
Using data from the NEMO-3 experiment, we have measured the two-neutrino
double beta decay ($2\nu\beta\beta$) half-life of $^{82}$Se as $T_{1/2}^{2\nu}
= \left 9.39 \pm 0.17\,\left(\mbox{stat}\right) ...\pm
0.58\,\left(\mbox{syst}\right)\right \times 10^{19}$ y under the single-state
dominance hypothesis for this nuclear transition. The corresponding nuclear
matrix element is $\left|M^{2\nu}\right| = 0.0498 \pm 0.0016$. In addition, a
search for neutrinoless double beta decay ($0\nu\beta\beta$) using 0.93 kg of
$^{82}$Se observed for a total of 5.25 y has been conducted and no evidence for
a signal has been found. The resulting half-life limit of $T_{1/2}^{0\nu} > 2.5
\times 10^{23} \,\mbox{y} \,(90\%\,\mbox{C.L.})$ for the light neutrino
exchange mechanism leads to a constraint on the effective Majorana neutrino
mass of $\langle m_{\nu} \rangle < \left(1.2 - 3.0\right) \,\mbox{eV}$, where
the range reflects $0\nu\beta\beta$ nuclear matrix element values from
different calculations. Furthermore, constraints on lepton number violating
parameters for other $0\nu\beta\beta$ mechanisms, such as right-handed
currents, majoron emission and R-parity violating supersymmetry modes have been
set.
