We present an improved search for neutrinoless double-beta (0νββ) decay of ^{136}Xe in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a ...significant reduction of the ^{110m}Ag contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0νββ decay half-life of T_{1/2}^{0ν}>1.07×10^{26} yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.
We report on the measurement of the two-neutrino double-beta decay half-life of Formula omittedTe with the CUORE-0 detector. From an exposure of 33.4 kg year of TeO Formula omitted, the half-life is ...determined to be Formula omitted = 8.2 ± 0.2 (stat.) ± 0.6 (syst.) Formula omitted 10 Formula omitted year. This result is obtained after a detailed reconstruction of the sources responsible for the CUORE-0 counting rate, with a specific study of those contributing to the Formula omittedTe neutrinoless double-beta decay region of interest.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The projected background for the CUORE experiment Alduino, C.; Avignone, F. T.; Azzolini, O. ...
European physical journal. C, Particles and fields,
08/2017, Letnik:
77, Številka:
8
Journal Article
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The Cryogenic Underground Observatory for Rare Events (CUORE) is designed to search for neutrinoless double beta decay of
130
Te with an array of 988 TeO
2
bolometers operating at temperatures ...around 10 mK. The experiment is currently being commissioned in Hall A of Laboratori Nazionali del Gran Sasso, Italy. The goal of CUORE is to reach a 90% C.L. exclusion sensitivity on the
130
Te decay half-life of 9
×
10
25
years after 5 years of data taking. The main issue to be addressed to accomplish this aim is the rate of background events in the region of interest, which must not be higher than 10
-
2
counts/keV/kg/year. We developed a detailed Monte Carlo simulation, based on results from a campaign of material screening, radioassays, and bolometric measurements, to evaluate the expected background. This was used over the years to guide the construction strategies of the experiment and we use it here to project a background model for CUORE. In this paper we report the results of our study and our expectations for the background rate in the energy region where the peak signature of neutrinoless double beta decay of
130
Te is expected.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We describe in detail the methods used to obtain the lower bound on the lifetime of neutrinoless double-beta (0 nu beta beta) decay in Te-130 and the associated limit on the effective Majorana mass ...of the neutrino using the CUORE-0 detector. CUORE-0 is a bolometric detector array located at the Laboratori Nazionali del Gran Sasso that was designed to validate the background reduction techniques developed for CUORE, a next-generation experiment scheduled to come online in 2016. CUORE-0 is also a competitive 0 nu beta beta decay search in its own right and functions as a platform to further develop the analysis tools and procedures to be used in CUORE. These include data collection, event selection and processing, as well as an evaluation of signal efficiency. In particular, we describe the amplitude evaluation, thermal gain stabilization, energy calibration methods, and the analysis event selection used to create our final 0 nu beta beta search spectrum. We define our high level analysis procedures, with emphasis on the new insights gained and challenges encountered. We outline in detail our fitting methods near the hypothesized 0 nu beta beta decay peak and catalog the main sources of systematic uncertainty. Finally, we derive the 0 nu beta beta decay half-life limits previously reported for CUORE-0, T-1/2(0 nu) > 2.7 x 10(24) yr, and in combination with the Cuoricino limit, T-1/2(0 nu) > 4.0 x 10(24) yr.
ABSTRACT In the late stages of nuclear burning for massive stars (M > 8 M ), the production of neutrino-antineutrino pairs through various processes becomes the dominant stellar cooling mechanism. As ...the star evolves, the energy of these neutrinos increases and in the days preceding the supernova a significant fraction of emitted electron anti-neutrinos exceeds the energy threshold for inverse beta decay on free hydrogen. This is the golden channel for liquid scintillator detectors because the coincidence signature allows for significant reductions in background signals. We find that the kiloton-scale liquid scintillator detector KamLAND can detect these pre-supernova neutrinos from a star with a mass of 25 M at a distance less than 690 pc with 3 significance before the supernova. This limit is dependent on the neutrino mass ordering and background levels. KamLAND takes data continuously and can provide a supernova alert to the community.
The MuCap experiment at the Paul Scherrer Institute has measured the rate Λ(S) of muon capture from the singlet state of the muonic hydrogen atom to a precision of 1%. A muon beam was stopped in a ...time projection chamber filled with 10-bar, ultrapure hydrogen gas. Cylindrical wire chambers and a segmented scintillator barrel detected electrons from muon decay. Λ(S) is determined from the difference between the μ(-) disappearance rate in hydrogen and the free muon decay rate. The result is based on the analysis of 1.2 × 10(10) μ(-) decays, from which we extract the capture rate Λ(S) = (714.9 ± 5.4(stat) ± 5.1(syst)) s(-1) and derive the proton's pseudoscalar coupling g(P)(q(0)(2) = -0.88 m(μ)(2)) = 8.06 ± 0.55.
Radioactive isotopes produced through cosmic muon spallation are a background for rare-event detection in nu detectors, double-beta-decay experiments, and dark-matter searches. Understanding the ...nature of cosmogenic backgrounds is particularly important for future experiments aiming to determine the pep and CNO solar neutrino fluxes, for which the background is dominated by the spallation production of {sup 11}C. Data from the Kamioka liquid-scintillator antineutrino detector (KamLAND) provides valuable information for better understanding these backgrounds, especially in liquid scintillators, and for checking estimates from current simulations based upon MUSIC, FLUKA, and GEANT4. Using the time correlation between detected muons and neutron captures, the neutron production yield in the KamLAND liquid scintillator is measured to be Y{sub n}=(2.8+-0.3)x10{sup -4} mu{sup -1} g{sup -1} cm{sup 2}. For other isotopes, the production yield is determined from the observed time correlation related to known isotope lifetimes. We find some yields are inconsistent with extrapolations based on an accelerator muon beam experiment.
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•Preparation and optimization of MIPs for detection of noradrenaline.•Screen-printing MIPs onto different support surfaces (polyester, PVC and paper).•Thermal detection noradrenaline ...with HTM and TWTA.•Development paper-based MIP sensing platform, which is sustainable and flexible.
Molecularly Imprinted Polymers (MIPs) are synthesized for the neurotransmitter noradrenaline with the optimal composition and binding conditions being determined via optical batch rebinding experiments. Next, the obtained MIP polymer particles are mixed within screen-printed inks to produce mass-producible bulk modified MIPs screen-printed electrodes (MIP-SPEs). In this contribution, the supporting surface which the MIP-SPEs are screen-printed upon are explored to deviate from conventional polyester, to polyvinylchloride, tracing paper and household-printing paper. The performance of the MIP-SPEs are measured using the Heat-Transfer Method (HTM), a straightforward and low-cost detection technique based on thermal resistance. At first, the noise on the signal is minimized by adjusting the settings of the temperature feedback loop. Second, the response of the MIP-SPEs to noradrenaline is measured and compared for the different substrate materials. Sensors printed onto paper are considered in further experiments as their response to noradrenaline is the highest and advantageous material properties, including sustainability and flexibility of the material. Subsequently, dose-response curves are determined by simultaneously measuring HTM and Thermal Wave Transport Analysis (TWTA). The latter is a new thermal detection method that relies on the use of thermal waves and has the advantage of a short measurement time (2min). With these thermal methods, it is possible to specifically detect noradrenaline in aqueous solutions and quantify it at relevant concentrations. In summary, by combining synthetic receptors with thermal measurement techniques it is possible to develop a portable sensor platform that is capable of low-cost and straightforward detection of biomolecules. Through exploring novel SPE substrates, a system is designed that is flexible and holds potential for the use in commercial biomedical devices and complex sensor architectures.
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