The production of radioactive isotopes in scintillation detectors by muons and their secondary shower particles has been studied experimentally at the SPS muon beam at CERN. This paper shows the ...results obtained in cross-section measurements on liquid scintillator targets, especially on
12C which is the most relevant target in these organic materials. Their energy dependence has been deduced from the cross-sections determined at two muon energies 100 and 190 GeV. Based on the measured cross-sections the muon-induced background rates for the forthcoming solar neutrino experiments BOREXINO and KAMLAND have been calculated for different energy regions that are relevant for solar neutrino physics.
We report the direct measurement of the {sup 7}Be solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The interaction rate of the 0.862 MeV ...{sup 7}Be neutrinos is 49{+-}3{sub stat}{+-}4{sub syst} counts/(day{center_dot}100 ton). The hypothesis of no oscillation for {sup 7}Be solar neutrinos is inconsistent with our measurement at the 4{sigma} C.L. Our result is the first direct measurement of the survival probability for solar {nu}{sub e} in the transition region between matter-enhanced and vacuum-driven oscillations. The measurement improves the experimental determination of the flux of {sup 7}Be, pp, and CNO solar {nu}{sub e}, and the limit on the effective neutrino magnetic moment using solar neutrinos.
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, Letnik:
600, Številka:
3
Journal Article
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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).
A very sensitive NAA technique of liquid organic scintillators has been developed at the Technische Universität München focusing on quasistable radionuclides. Combining important input factors for ...sensitive NAA very low detection limits are obtained, e.g. 2 · 10
−16
g/g for
238
U. This article describes these input factors and how they have been realized for the NAA of liquid organic scintillators. The results are discussed in the context with the solar neutrino experiment BOREXINO, for which this work has been started. Possibilities for a further improvement of sensitivity are presented as an outlook.
The need to analyze small amounts of materials on surfaces, e.g. in semiconductor industry, drives the development of high resolution X-ray spectrometers based on superconducting detector technology. ...Since low excitation energies needed for high spatial resolution in Field Emission Scanning Electron Microscopes (FESEM) yield only X-ray lines in the lower part of the X-ray spectrum ( < 5 keV), line overlaps become a serious issue in the spectral analysis. This problem can be overcome with superconducting detector technology having better energy resolution and thus the ability to separate X-ray lines of important material combinations. For industrial applications, the cooling system for the superconducting sensor plays an important role, since liquid coolants are not desirable in clean room environments. This work covers the basic needs of the materials analyst as well as the practical implementation of superconducting X-ray spectrometers for industrial applications. (Author)
We report the direct measurement of the 7Be solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The interaction rate of the 0.862 MeV 7Be ...neutrinos is 49±3stat±4syst counts/(day·100 ton). The hypothesis of no oscillation for 7Be solar neutrinos is inconsistent with our measurement at the 4σ C.L. Our result is the first direct measurement of the survival probability for solar νe in the transition region between matter-enhanced and vacuum-driven oscillations. The measurement improves the experimental determination of the flux of 7Be, pp, and CNO solar νe, and the limit on the effective neutrino magnetic moment using solar neutrinos.
A large volume (4.8 m
3) liquid scintillator detector has been running in Hall C of the Gran Sasso Underground Laboratory since February 1995. This detector is called the “Counting Test Facility” ...(CTF). The main goal of the detector facility is the measurement of ultralow background levels in scintillators and the development of processes able to purify them at this level. The detector has been designed to have exceptional sensitivity using a variety of methods to identify backgrounds. With the CTF, records were achieved in the domain of low background large volume detectors. Limits of 3.5 ± 1.3 × 10
−16 g/g and 4.4
−1.2
+1.5 × 10
−16 g/g for the
238U and
232Th daughters, respectively, and 1.85 ± 0.13 ± 0.01 × 10
−18 for the isotopic abundance of
14C relative to
12C were obtained. These results are very encouraging and point towards the feasibility of low energy, real time scintillation detectors for solar neutrinos, such as Borexino.
High resolution, superconducting detectors allow energy dispersive X-ray spectrometry (EDX) with energy resolution and energy threshold far beyond the levels obtained with semiconductor detectors. ...These cryogenic detectors are run at temperatures of less than 100 mK and combine the excellent energy resolution of wavelength dispersive X-ray spectrometry (WDX) with the fast, energy dispersive analysis of EDX. CSP cryogenic spectrometer's microcalorimeter type EDX cryodetectors are equipped with a mechanical cooling system that runs vibration free and allows completely automated operations on scanning electron microscopes (SEMs), field emission guns (FEGs) and transmission electron microscopes (TEMs). This detector type offers new opportunities in material analysis, especially when low excitation energies are applied or light elements are to be determined. Materials include Au thin film on Ir substrate, and titanium nitride.
Neutron Activation Analysis has emerged to be an analytical method sensitive enough to detect fg/g traces of unstable primordial nuclides in complex matrices. Especially low count rate experiments in ...the field of solar neutrino physics and dark matter search can profit from the detection capabilities of this method which had been unattained so far. This gain in sensitivity has been achieved by combining neutron activation, radiochemical separation methods, and efficient low level counting systems at the new underground laboratory of the accelerator laboratory in Garching.
Recent improvements which have been made in the purification and analysis of the liquid scintillator, as foreseen for the solar neutrino experiment BOREXINO, are being presented as an example in this paper
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