This final article about the CHOOZ experiment presents a complete description of the \(\bar{\nu}_e\) source and detector, the calibration methods and stability checks, the event reconstruction ...procedures and the Monte Carlo simulation. The data analysis, systematic effects and the methods used to reach our conclusions are fully discussed. Some new remarks are presented on the deduction of the confidence limits and on the correct treatment of systematic errors.
Initial results are presented from CHOOZ
1
The CHOOZ experiment is named after the new nuclear power station operated by Électricité de France (EdF) near the village of Chooz in the Ardennes region ...of France.
1
, a long-baseline reactor-neutrino vacuum-oscillation experiment. The data reported here were taken during the period March to October 1997, when the two reactors ran at combined power levels varying from zero to values approaching their full rated power of 8.5
GW
(thermal). Electron antineutrinos from the reactors were detected by a liquid scintillation calorimeter located at a distance of about 1
km
. The detector was constructed in a tunnel protected from cosmic rays by a 300
MWE
rock overburden. This massive shielding strongly reduced potentially troublesome backgrounds due to cosmic-ray muons, leading to a background rate of about one event per day, more than an order of magnitude smaller than the observed neutrino signal. From the statistical agreement between detected and expected neutrino event rates, we find (at 90% confidence level) no evidence for neutrino oscillations in the
ν
e
disappearance mode for the parameter region given approximately by
Δm
2>0.9
10
−3
eV
2
for maximum mixing and sin
22
θ>0.18 for large
Δm
2.
It is shown in this article that, when bees used plant flowers from a site that was moderately polluted by heavy metals (HMs), the smallest quantity of these metals was accumulated in honey, while ...the largest quantity was in propolis. The coefficient of biological accumulation of lead and cadmium in honey was at the level of 0.43 and 0.12, respectively. The largest quantity of HMs in the bee body is accumulated in the abdominal regions, while the smallest quantity is accumulated in the head region.
The Borexino detector at the Laboratori Nazionali del Gran Sasso Back, H.; Balata, M.; de Bellefon, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2009, Volume:
600, Issue:
3
Journal Article
Peer reviewed
Open access
Borexino, a large volume detector for low energy neutrino spectroscopy, is currently running underground at the Laboratori Nazionali del Gran Sasso, Italy. The main goal of the experiment is the ...real-time measurement of sub-MeV solar neutrinos, and particularly of the monoenergetic (862
keV)
7Be electron capture neutrinos, via neutrino–electron scattering in an ultra-pure liquid scintillator. This paper is mostly devoted to the description of the detector structure, the photomultipliers, the electronics, and the trigger and calibration systems. The real performance of the detector, which always meets, and sometimes exceeds, design expectations, is also shown. Some important aspects of the Borexino project, i.e. the fluid handling plants, the purification techniques and the filling procedures, are not covered in this paper and are, or will be, published elsewhere (see Introduction and Bibliography).
We present new results based on the entire CHOOZ (The CHOOZ experiment is named after the new nuclear power station operated by Électricité de France (EdF) near the village of Chooz in the Ardennes ...region of France) data sample. We find (at 90% confidence level) no evidence for neutrino oscillations in the
ν
̄
e
disappearance mode, for the parameter region given by approximately
δm
2>7·10
−4
eV
2
for maximum mixing, and sin
22
θ=0.10 for large
δm
2. Lower sensitivity results, based only on the comparison of the positron spectra from the two different-distance nuclear reactors, are also presented; these are independent of the absolute normalization of the
ν
̄
e
flux, the cross section, the number of target protons and the detector efficiencies.
The Pauli exclusion principle (PEP) has been tested for nucleons (n,p) in \({}^{12}{\rm C}\) and \({}^{16}{\rm O}\) nuclei, using the results of background measurements with the prototype of the ...Borexino detector, the Counting Test Facility (CTF). The approach consisted of a search for \(\gamma\), n, p and/or \(\alpha\)’s emitted in a non-Paulian transition of 1P- shell nucleons to the filled 1S1/2 shell in nuclei. Similarly, the Pauli-forbidden \(\beta^{\pm}\) decay processes were searched for. Due to the extremely low background and the large mass (4.2 tons) of the CTF detector, the following most stringent up-to-date experimental bounds on PEP violating transitions of nucleons have been established: \(\tau({}^{12}{\rm C} \rightarrow {}^{12}{\rm\widetilde C} + \gamma) > 2.1\cdot10^{27} \mathrm y\), \(\tau({}^{12}{\rm C} \rightarrow {}^{11}{\rm\widetilde B} + p) > 5.0\cdot10^{26} {\mathrm{y}}\), \(\tau({}^{12}{\rm C} ({}^{16}{\rm O}) \rightarrow {}^{11}{\rm\widetilde C} ({}^{15}{\rm\widetilde O} ) + n) > 3.7 \cdot 10^{26} {\mathrm{y}}\), \(\tau({}^{12}{\rm C} \rightarrow {}^{8}{\rm\widetilde{Be}} + \alpha) > 6.1 \cdot 10^{23} \mathrm y\), \(\tau({}^{12}{\rm C} \rightarrow {}^{12}{\rm\widetilde N} + e^- + \widetilde{\nu_e}) > 7.6 \cdot 10^{27} \mathrm y\) and \(\tau({}^{12}{\rm C} \rightarrow {}^{12}{\rm\widetilde B} + e^ + + \nu_e) > 7.7 \cdot 10^{27} \mathrm y\), all at \(90 \%\) C.L.
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