Abstract
The MoCRiL (Measurements of Cosmic Rays in Lake) project has re-proposed, in an educational way and using modern measuring instruments, Domenico Pacini’s experiment for determining the ...origin of the natural ionizing radiation that surrounds us in any instant. The students of 4 different schools from Calabria Region with the collaboration of the INFN researchers (OCRA collaboration of Cosenza 1) and of the Physics department of UNICAL, performed the measurement of the ionizing particle rate at different depths in the waters of the Arvo Lake in the Sila plateau (1300 m asl). The aim of this project is to let students know and understand the often very difficult way that leads to scientific discovery, sharing ideas and results with other students, from different years and schools, and with teachers and researchers.
A
bstract
The ratio
R
= Γ(
K
S
→ πeν
)
/
Γ(
K
S
→ π
+
π
−
) has been measured with a sample of 300 million
K
S
mesons produced in
ϕ → K
L
K
S
decays recorded by the KLOE experiment at the DAΦNE
e
+
e
...−
collider.
K
S
→ πeν
events are selected by a boosted decision tree built with kinematic variables and time-of-flight measurements. Data control samples of
K
L
→ πeν
decays are used to evaluate signal selection efficiencies. With 49647
±
316 signal events we measure
R
= (1
.
0421
±
0
.
0066
stat
±
0
.
0075
syst
)
×
10
−
3
. The combination with our previous measurement gives
R
= (1
.
0338
±
0
.
0054
stat
±
0
.
0064
syst
)
×
10
−
3
. From this value we derive the branching fraction
B
(
K
S
→ πeν
) = (7
.
153
±
0
.
037
stat
±
0
.
044
syst
)
×
10
−
4
and
f
+
(0)
|V
us
|
= 0
.
2170
±
0
.
009.
Ceramic thermal barrier coatings (TBCs) are advanced systems for more efficient turbine engines. In this work, thick lanthanum zirconate TBCs were fabricated by Air Plasma Spraying (APS). The ...coatings showed a lamellar microstructure containing splat boundaries, pores and microcracks. After thermal exposure at 1200 and 1350°C the partial sintering of the porous microstructure occurred.
High-temperature evolution of the mechanical properties was investigated by arranging specific bending tests up to 1500°C using SiC testing assembly which allowed to calculate the strain by means of curvature measurement. The mechanical properties improved with increasing the testing temperature, due to the inelastic deformation and stress relaxation which counteracted the sintering effects.
The elastic modulus increased after thermal aging, but decreased for the aged coatings tested at higher temperature.
The thermal expansion coefficient of as-sprayed coatings slightly increased after thermal aging, while a reduction of specific heat capacity was noticed.
•Thick lanthanum zirconate TBCs were deposited by APS.•Thermal aging of as-sprayed samples promoted partial sintering of microstructure.•The TBCs were characterized by four-point bending tests from RT to 1500°C.•High-temperature microcracking and stress relaxation enhanced mechanical properties.•The Cp decreased after thermal aging at 1350°C, while the CTE slightly changed.
A
bstract
Using 1.63 fb
−1
of integrated luminosity collected by the KLOE experiment about 7 × 10
4
K
S
→
π
±
e
∓
ν
decays have been reconstructed. The measured value of the charge asymmetry for this ...decay is
A
S
= (−4.9 ± 5.7
stat
± 2.6
syst
) × 10
−3
, which is almost twice more precise than the previous KLOE result. The combination of these two measurements gives
A
S
= (−3.8 ± 5.0
stat
± 2.6
syst
) × 10
−3
and, together with the asymmetry of the
K
L
semileptonic decay, provides significant tests of the
CPT
symmetry. The obtained results are in agreement with
CPT
invariance.
The existence of a light dark force mediator has been tested with the KLOE detector at DAΦNE. This particle, called U, is searched for using the decay chain ϕ→ηU, η→π+π−π0, U→e+e−. No evidence is ...found in 1.5 fb−1 of data. The resulting exclusion plot covers the mass range 5<MU<470 MeV, setting an upper limit on the ratio between the U boson coupling constant and the fine structure constant, α′/α, of ⩽2×10−5 at 90% C.L. for 50<MU<420 MeV.
The existence of a new force beyond the Standard Model is compelling because it could explain several striking astrophysical observations which fail standard interpretations. We searched for the ...light vector mediator of this dark force, the U boson, with the KLOE detector at the DAΦNE e+e− collider. Using an integrated luminosity of 1.54 fb−1, we studied the process e+e−→Uγ, with U→e+e−, using radiative return to search for a resonant peak in the dielectron invariant-mass distribution. We did not find evidence for a signal, and set a 90% CL upper limit on the mixing strength between the Standard Model photon and the dark photon, ε2, at 10−6–10−4 in the 5–520 MeV/c2 mass range.
•The possibility to recognize composition and structure of end-of-life PV modules by optical methods is investigated.•The usefulness of recognizing the original PV panel structure in order to assess ...next recycle steps is highlighted.•A procedure based on mechanical delamination and vibrational spectroscopy analysis of the separated layers is proposed to assess the PV panel structure.•Advantages and drawbacks of the proposed recognition solutions are discussed.•The importance of labelling PV panels put on the market with information on their composition is highlighted.
The aim of this work is to investigate the possibility of applying optical spectroscopy methods for the recognition and sorting of end-of life (EoL) photovoltaic panels (PVs) collected at WEEE pre-treatment plants, where they arrive, nowadays, without any label containing information about their composition and structure. EoL PVs belong to the category of layered waste containing hazardous materials, like fluorine in the backsheet, therefore implicating a proper treatment based on their composition, in order to reduce the environmental impact. The identification of the PV panel structure is fundamental to assess the next steps of the recycling process, which is strongly dependent on the constituent materials. Vibrational spectroscopy, commonly used to identify the materials composing waste products, is certainly capable of giving the compositional structure of EoL PVs. However, the identified procedure to recognize the multilayer structure requires a mechanical or chemical delamination of a representative piece of the EoL PV and the following optical spectroscopy analysis of each face of the delaminated layers. Despite this procedure employs cheap and easy to handle equipment, like portable spectrometers, it appears time consuming and not easy to be automatized in a WEEE pre-treatment plant. Therefore, we define more rapid methodologies suitable to be adopted in pre-treatments plants. We discuss the drawbacks of the proposed methodologies and we suggest, as a more efficient solution for the future, the labelling of the PVs put on the market (for example inserting RFID or QR Code tags) containing information on their structure and composition.
Display omitted
A
bstract
The quantum interference between the decays of entangled neutral kaons is studied in the process
ϕ
→ K
S
K
L
→
π
+
π
−
π
+
π
−
, which exhibits the characteristic Einstein-Podolsky-Rosen ...correlations that prevent both kaons to decay into
π
+
π
−
at the same time. This constitutes a very powerful tool for testing at the utmost precision the quantum coherence of the entangled kaon pair state, and to search for tiny decoherence and
CPT
violation effects, which may be justified in a quantum gravity framework.
The analysed data sample was collected with the KLOE detector at DAΦNE, the Frascati
ϕ
-factory, and corresponds to an integrated luminosity of about 1.7 fb
−
1
, i.e. to about 1
.
7 × 10
9
ϕ
→ K
S
K
L
decays produced. From the fit of the observed ∆
t
distribution, being ∆
t
the difference of the kaon decay times, the decoherence and
CPT
violation parameters of various phenomenological models are measured with a largely improved accuracy with respect to previous analyses.
The results are consistent with no deviation from quantum mechanics and
CPT
symmetry, while for some parameters the precision reaches the interesting level at which — in the most optimistic scenarios — quantum gravity effects might show up. They provide the most stringent limits up to date on the considered models.
Ceramic thermal barrier coatings (TBCs) are potential tools to increase the durability of metal parts operating in turbine engines. In this work, partially yttria stabilized zirconia (YSZ) and ...lanthanum zirconate (LZ) coatings were deposited by plasma spraying on stainless steel substrates. X-Ray Diffraction (XRD) analysis revealed that plasma spraying promoted the formation of metastable phases in both the cases. Both YSZ and LZ coatings exhibited porous microstructure with a network of embedded pores and microcracks, that resulted in similar porosity values. The average microhardness of LZ coating was about 92% of that of YSZ one (5.4 against 5.9GPa), whereas the thermal expansion coefficient (CTE) of LZ coating was about 86% of that of YSZ one. Based on the results herein discussed the development of multilayered microstructures represents a promising solution in order to develop TBCs with enhanced performance.
We have searched for a light vector boson U, the possible carrier of a “dark force”, with the KLOE detector at the DAΦNE e+e− collider, motivated by astrophysical evidence for the presence of dark ...matter in the Universe. Using e+e− collisions collected with an integrated luminosity of 239.3 pb−1, we look for a dimuon mass peak in the reaction e+e−→μ+μ−γ, corresponding to the decay U→μ+μ−. We find no evidence for a U vector boson signal. We set a 90% CL upper limit for the mixing parameter squared between the photon and the U boson of 1.6×10−5 to 8.6×10−7 for the mass region 520<mU<980 MeV.
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