The first model independent results obtained by the DAMA/LIBRA-phase2 experiment are presented. The data have been collected over 6 annual cycles corresponding to a total exposure of 1.13 t yr, ...deep underground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N. The DAMA/LIBRA-phase2 apparatus, ≃ 250 kg highly radio-pure NaI(Tl), profits from a second generation high quantum efficiency photomultipliers and of new electronics with respect to DAMA/LIBRA-phase1. The improved experimental configuration has also allowed to lower the software energy threshold. New data analysis strategies are presented. The DAMA/LIBRA-phase2 data confirm the evidence of a signal that meets all the requirements of the model independent Dark Matter (DM) annual modulation signature, at 9.5 C.L. in the energy region (1 - 6) keV. In the energy region between 2 and 6 keV, where data are also available from DAMA/NaI and DAMA/LIBRA-phase1 (exposure 1.33 t yr, collected over 14 annual cycles), the achieved C.L. for the full exposure (2.46 t yr) is 12.9 ; the modulation amplitude of the single-hit scintillation events is: (0.0103 ± ± 0.0008) cpd/kg/keV, the measured phase is (145 ± 5) d and the measured period is (0.999 ± 0.001) yr, all these values are well in agreement with those expected for DM particles. No systematics or side reaction able to mimic the exploited DM signature (i.e. to account for the whole measured modulation amplitude and to simultaneously satisfy all the requirements of the signature), has been found or suggested by anyone throughout some decades thus far.
Profiting of the favourable conditions offered by the Gran Sasso underground laboratory and of the several low-background DAMA set-ups, many and competitive results have been obtained for rare ...processes. Here the main results will be briefly resumed and some more details about the latest activities will be given. In particular, the searches on ββdecays of
106
Cd and
116
Cd and the perspectives of a complementary investigation on those Dark Matter (DM) candidates inducing just nuclear recoils, by exploiting the directionality approach with the anisotropic ZnWO
4
scintillators, will be underlined.
Over the last decade, a lot of research has been directed toward integrating performance analysis into the software development process. Traditional software development methods focus on software ...correctness, introducing performance issues later in the development process. This approach does not take into account the fact that performance problems may require considerable changes in design, for example, at the software architecture level, or even worse at the requirement analysis level. Several approaches were proposed in order to address early software performance analysis. Although some of them have been successfully applied, we are still far from seeing performance analysis integrated into ordinary software development. In this paper, we present a comprehensive review of recent research in the field of model-based performance prediction at software development time in order to assess the maturity of the field and point out promising research directions.
Many experimental observations and theoretical arguments have pointed out that a large fraction of the Universe is composed by Dark Matter particles. Many possibilities are open on the nature and ...interaction types of such relic particles. In particular, this paper summarizes the main results obtained by exploiting the model independent Dark Matter annual modulation signature for the presence of Dark Matter particles in the galactic halo by DAMA experiment.
The results obtained with the total exposure of 1.04 ton × yr collected by DAMA/LIBRA–phase1 deep underground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N. during 7 annual cycles are ...summarized. The DAMA/LIBRA–phase1 and the former DAMA/NaI data (cumulative exposure 1.33 ton × yr, corresponding to 14 annual cycles) give evidence at 9.3 σ C.L. for the presence of Dark Matter (DM) particles in the galactic halo, on the basis of the exploited model independent DM annual modulation signature by using highly radio-pure NaI(Tl) target. No systematic or side reaction able to mimic the exploited DM signature has been found or suggested by anyone over more than a decade. The same data of DAMA/LIBRA–phase1 have also been analyzed searching for possible DM second-order diurnal effect; at present, the DM diurnal modulation amplitude – expected because of the Earth diurnal motion – evaluated on the basis of the DAMA Dark Matter annual modulation results is below the reached experimental sensitivity. Some of the perspectives of the presently running DAMA/LIBRA–phase2 are outlined.
The DAMA/LIBRA experiment (∼ 250 kg of highly radio-pure NaI(Tl)) is running deep underground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N. Here we briefly recall the results obtained ...in its first phase of measurements (DAMA/LIBRA–phase1; total exposure: 1.04 ton × yr). DAMA/LIBRA–phase1 and the former DAMA/NaI (cumulative exposure: 1.33 ton × yr) give evidence at 9.3 σ C.L. for the presence of DM particles in the galactic halo by exploiting the model-independent DM annual modulation signature. No systematic or side reaction able to mimic the exploited DM signature has been found or suggested by anyone over more than a decade. At present DAMA/LIBRA–phase2 is running with increased sensitivity.
The DAMA/LIBRA experiment, running at the Gran Sasso National Laboratory of the I.N.F.N. in Italy, has a sensitive mass of about 250 kg highly radiopure NaI(Tl). It is mainly devoted to the ...investigation of Dark Matter (DM) particles in the Galactic halo by exploiting the model independent DM annual modulation signature. The present DAMA/LIBRA experiment and the former DAMA/NaI one (the first generation experiment having an exposed mass of about 100 kg) have released so far results corresponding to a total exposure of 1.17 ton x yr over 13 annual cycles. They provide a model independent evidence of the presence of DM particles in the galactic halo at 8.9 sigma C.L. on the basis of the investigated DM signature. The data of another annual cycle in the same DAMA/LIBRA running conditions are at hand. After the replacement at the end of 2012 of all the photomultipliers (PMTs) with new ones, having higher quantum efficiency, DAMA/LIBRA has entered to its phase 2; such a replacements allowed the lowering of the software energy threshold of the experiment in the present data taking. A short summary of the obtained results is presented and future perspectives of the experiment mentioned.
We consider the dynamics of a quantum phase-slip junction (QPSJ), a dual Josephson junction, connected to a microwave source with frequency omega sub(mw). With respect to an ordinary Josephson ...junction, a QPSJ can sustain dual Shapiro steps, consisting of well-defined current plateaus at multiple integers of e omega sub(mw)/pir in the current-voltage (I-V) characteristic. The experimental observation of these plateaus has been elusive up to now. We argue that thermal as well as quantum fluctuations can smear the I-V characteristic considerably. In order to understand these effects, we study a current-biased QPSJ under microwave irradiation and connected to an inductive and resistive environment. We find that the effect of the fluctuations is governed by the resistance of the environment and by the ratio of the phase-slip energy and the inductive energy. Our results are of interest for experiments aiming at the observation of dual Shapiro steps in QPSJ devices for the definition of a new quantum current standard.
Highlights of DAMA/LIBRA Bernabei, R.; Belli, P.; d’Angelo, A. ...
EPJ Web of Conferences,
01/2016, Letnik:
126
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The DAMA project develops and uses new/improved low background scintillation detectors to investigate the Dark Matter (DM) particle component(s) in the galactic halo and rare processes deep ...underground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N.. Here some highlights of DAMA/LIBRA (Large sodium Iodide Bulk for Rare processes) as a unique apparatus in direct DM investigation for its full sensitive mass, target material, intrinsic radio-purity, methodological approach and all the controls performed on the experimental parameters are outlined. The DAMA/LIBRA–phase1 and the former DAMA/NaI data (cumulative exposure 1.33 ton × yr, corresponding to 14 annual cycles) have reached a model-independent evidence at 9.3 σ C.L. for the presence of DM particles in the galactic halo exploiting the DM annual modulation signature with highly radio-pure NaI(Tl) target. Some of the perspectives of the presently running DAMA/LIBRA–phase2 are summarised and the powerful tools offered by a model independent strategy of DM investigation are pointed out.
DAMA/LIBRA results and perspectives Bernabei, R; Belli, P; Cappella, F ...
Journal of physics. Conference series,
01/2012, Letnik:
375, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The DAMA project operates as an observatory for rare processes, located deep underground at the Gran Sasso National Laboratory of the I.N.F.N. The main apparatus, DAMA/LIBRA, is investigating the ...presence of Dark Matter particles in the galactic halo by exploiting the model independent DM annual modulation signature. The present DAMA/LIBRA and the former DAMA/NaI (exposed masses: ≃ 250 kg and ≃ 100 kg of highly radiopure NaI(Tl), respectively) experiments have released so far a total exposure of 1.17 ton × yr, collected over 13 annual cycles. They have obtained a positive model independent result for the presence of DM particles in the galactic halo at 8.9 σ C.L. The main results are here briefly summarised and the future perspectives are considered.
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