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. Moreover, the poor knowledge of many fundamental astrophysical, nuclear and particle Physics aspects and of some experimental and theoretical parameters, the different used approaches and target materials, etc. make challenging the comparisons and the implications of the different experimental efforts. Some general arguments are addressed here and future perspectives are mentioned. A particular care will be given to the 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. Results from the other experiments using different procedures, different techniques and different target-materials will be shortly addressed as well as implications and experimental perspectives.
An overview of the latest results of Dark Matter direct detection obtained by experiments using crystals will be summarized. A particular care will be given to the results obtained by exploiting the ...model independent Dark Matter annual modulation signature for the presence of Dark Matter particles in the galactic halo. Results from the other experiments using different procedures, different techniques and different target-materials will be shortly addressed as well as implications and experimental perspectives.
The long-standing model-independent annual modulation effect measured by DAMA Collaboration is examined in the context of asymmetric mirror dark matter, assuming that dark atoms interact with target ...nuclei in the detector via kinetic mixing between mirror and ordinary photons, both being massless. The relevant ranges for the kinetic mixing parameter are obtained taking into account various existing uncertainties in nuclear and particle physics quantities as well as characteristic density and velocity distributions of dark matter in different halo models.
A multiphase study was proposed to examine microbial communities linked to the nitrogen cycle in the first stage of four full-scale French vertical flow treatment systems. To this end, denaturing ...gradient gel electrophoresis (DGGE) was performed for structural assessment and quantitative PCR (qPCR) to enumerate the abundance of ammonia-oxidizing (AOB). 16S rRNA sequencing was used to assess the taxonomic profile followed by putative assessment of functional genes. The samples were collected under different conditions, such as operational time (presence/absence of sludge layer on the surface of the filters), season (winter and summer), sampling depth (0, 15 and 30 cm) and operation cycle (rest and feed periods). A structural disparity was noted in the upper layers, whereas higher similarity at 30 cm was observed highlighting the effect of organic matter on bacterial diversity. The 7th rest day was highlighted by an apparent decline in the microbial community abundance. Additionally, qPCR indicated that the largest amount of AOB was found at 30 cm depth and during the feeding period. From the taxonomic profile, Mycobacterium, Acinetobacter, Flavobacterium, and Nitrospira were the most abundant genre found in all systems. The functional prediction results showed predicted genes linked to the denitrification process. The results suggested that operating time and season were responsible for the pattern of the microbial community behavior. This study allowed us to further understand the bacterial dynamics and to advance the idea of design modifications made in the first stage of the classical French system to improve nitrogen removal are promising.
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 ...(i.e. adding a further 0.17 ton × yr exposure) are presented. The DAMA/LIBRA–phase1 data give evidence 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, at 7.5
σ
C.L. Including also the first generation DAMA/NaI experiment (cumulative exposure 1.33 ton × yr, corresponding to 14 annual cycles), the C.L. is 9.3
σ
and the modulation amplitude of the
single-hit
events in the (2–6) keV energy interval is: (0.0112±0.0012) cpd/kg/keV; the measured phase is (144±7) days and the measured period is (0.998±0.002) yr, values well in agreement with those expected for DM particles. No systematic or side reaction able to mimic the exploited DM signature has been found or suggested by anyone over more than a decade.
DAMA annual modulation and mirror Dark Matter Cerulli, R.; Villar, P.; Cappella, F. ...
The European physical journal. C, Particles and fields,
02/2017, Letnik:
77, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The DAMA experiment using ultra low background NaI(Tl) crystal scintillators has measured an annual modulation effect in the keV region which satisfies all the peculiarities of an effect induced by ...Dark Matter particles. In this paper we analyze this annual modulation effect in terms of mirror Dark Matter, an exact duplicate of ordinary matter from parallel hidden sector, which chemical composition is dominated by mirror helium while it can also contain significant fractions of heavier elements as Carbon and Oxygen. Dark mirror atoms are considered to interact with the target nuclei in the detector via Rutherford-like scattering induced by kinetic mixing between mirror and ordinary photons, both being massless. In the present analysis we consider various possible scenarios for the mirror matter chemical composition. For all the scenarios, the relevant ranges for the kinetic mixing parameter have been obtained taking also into account various existing uncertainties in nuclear and particle physics quantities.
The highly radiopure ≃ 250 kg NaI(Tl) DAMA/LIBRA set-up is running at the Gran Sasso National Laboratory of the INFN. In this paper the first result obtained by exploiting the model independent ...annual modulation signature for Dark Matter (DM) particles is presented. It refers to an exposure of 0.53 ton×yr. The collected DAMA/LIBRA data satisfy all the many peculiarities of the DM annual modulation signature. Neither systematic effects nor side reactions able to account for the observed modulation amplitude and to contemporaneously satisfy all the several requirements of this DM signature are available. Considering the former DAMA/NaI and the present DAMA/LIBRA data all together (total exposure 0.82 ton×yr), the presence of Dark Matter particles in the galactic halo is supported, on the basis of the DM annual modulation signature, at 8.2
σ
C.L.; in particular, in the energy interval (2–6) keV, the modulation amplitude is (0.0131±0.0016) cpd/kg/keV and the phase and the period are well compatible with June 2
nd
and one year, respectively.
The microorganism community that grows under duckweed shelter can play an important role on treatment processes. Therefore, the present study aimed to assess the zooplankton dynamic and microbial ...community in duckweed ponds (DPs) applied for domestic wastewater treatment under open field conditions. A pilot system comprised of two DPs in series (DP1 and DP2), with 10 m
each, received domestic wastewater through a flow rate of 200 L·day
. Thus, the system was monitored during 314 days through samples collected and analysed weekly. Also, the zooplankton organisms were identified and quantified. DNA sequencing was performed in order to identify the bacterial populations. The findings showed a high efficiency of nutrient removal with 93% and 91% of total phosphorus and total nitrogen, respectively. A high density of microcrustaceans was observed in DP1 reaching 4,700 org.100 mL
and rotifers (over than 32,000 org.100 mL
) in DP2, that could be related to the low suspended solids concentration (<30 mg·L
) and turbidity (<10 NTU). The bacterial community showed a strong heterogeneity between samples collected along the seasons. Through these findings, it is possible to realise that the understanding of ecology could help to enhance the operation and designs of DPs.
New results from DAMA/LIBRA Bernabei, R.; Belli, P.; Cappella, F. ...
The European physical journal. C, Particles and fields,
05/2010, Letnik:
67, Številka:
1-2
Journal Article
Recenzirano
Odprti dostop
DAMA/LIBRA is running at the Gran Sasso National Laboratory of the I.N.F.N. Here the results obtained with a further exposure of 0.34 ton × yr are presented. They refer to two further annual cycles ...collected one before and one after the first DAMA/LIBRA upgrade occurred on September/October 2008. The cumulative exposure with those previously released by the former DAMA/NaI and by DAMA/LIBRA is now 1.17 ton × yr, corresponding to 13 annual cycles. The data further confirm the previous positive results obtained investigating the presence of Dark Matter (DM) particles in the galactic halo by means of the model independent Dark Matter annual modulation signature; the confidence level is now 8.9
σ
for the cumulative exposure. In particular, with the cumulative exposure the modulation amplitude of the
single-hit
events in the (2–6) keV energy interval measured in NaI(Tl) target is (0.0116±0.0013) cpd/kg/keV; the measured phase is (146±7) days and the measured period is (0.999±0.002) yr, values well in agreement with those expected for the DM particles.
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.
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