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
$$ \mathcal{CPT} $$
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
$$ \mathcal{CPT} $$
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
$$ \mathcal{CPT} $$
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.
LIDAL (Light Ion Detector for ALTEA system) is a compact detector designed to upgrade ALTEA (Anomalous Long Term Effects on Astronauts) silicon detector apparatus, in order to study in detail the ...low-Z part of ions spectrum inside the International Space Station (ISS) and to enhance the Particle Identification (PID) capability of the system.
The new detector is designed to trigger ALTEA and to perform Time-Of-Flight measurements. It is based on plastic scintillators for fast timing applications read by Photo-Multiplier-Tubes (PMTs). A custom Front End Electronics (FEE) has been designed to reach time resolutions less than 100 ps (σ) for protons.
A LIDAL prototype has been developed at the University of Rome Tor Vergata to test the timing performance of the scintillators, the PMTs and of the custom FEE using the proton beam line at the TIFPA (Trento Institute for Fundamentals Physics Applications) center in Trento, Italy. The results of these tests are reported and discussed. They have also been used for a preliminary evaluation of the Particle Identification (PID) capability of the final LIDAL-ALTEA detector system in response to the ions spectra expected on-board the ISS.
LIDAL–ALTEA is a detector designed to study the radiation flux and energy spectra in the International Space Station (ISS). Its mission is manifested by NASA in 2019. The ALTEA subsystem, which took ...data on the ISS in the past Zaconte et al. (2010), is based on Silicon Strip detectors and will measure the released energy of the traversing particles, while the LIDAL subdetector is based on fast plastic scintillators, read by PMTs, will measure the particle Time Of Flight. A custom Front End electronics has been designed to reach a time resolution better than 120ps. LIDAL is under construction while a prototype has been already tested with a proton beam. The measured time resolution fulfills the design expectation and is compatible with FLUKA simulations. The Monte Carlo results have also been validated by the comparison with a test measure where the ALTEA detector was exposed to proton beams.
We have searched for the C-violating decay η→γγγ in a sample of ∼18 million η mesons produced in φ→ηγ decays, collected with the KLOE detector at the Frascati φ-factory DAΦNE. No signal is observed ...and we obtain the upper limit BR(η→γγγ)⩽1.6×10−5 at 90% CL.
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.
We performed a direct measurement of the avalanche charge with a 10×10cm2 prototype resistive plate chambers with a 0.2cm gas gap. We studied its behaviour with respect to the high voltage and its ...dependence on the presence of the SF6 in the gas mixture (C2H2F4/i-C4H10/SF6 in the ratio 95/4/1 and 96/4/0). The measurements showed a double exponential behaviour of the average avalanche charge with respect to the high voltage. A comparison with other results has been discussed.
Based on a sample of 300 million K-S mesons produced in phi -> KLKS decays recorded by the KLOE experiment at the DA Phi NE e(+)e(-) collider we have measured the branching fraction for the decay ...K-S -> pi mu nu. The K-S mesons are identified by the interaction of K-L mesons in the detector. The K-S -> pi mu nu decays are selected by a boosted decision tree built with kinematic variables and by a time-of-flight measurement. Signal efficiencies are evaluated with data control samples of K-L -> pi mu nu decays. A fit to the reconstructed muon mass distribution finds 7223 +/- 180 signal events. Normalising to the K-S -> pi(+)pi(-) decay events the result for the branching fraction is B(K-S -> pi mu nu) = (4.56 +/- 0.11(stat) +/- 0.17(syst)) x 10(-4). It is the first measurement of this decay mode and the result allows an independent determination of vertical bar V-us vertical bar and a test of the lepton-flavour universality. (c) 2020 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
An extensive aging study of bakelite Resistive Plate Chambers Carboni, G.; De Capua, S.; Domenici, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We present recent results of an extensive aging test, performed at the CERN Gamma Irradiation Facility, on two bakelite Resistive Plate Chambers (RPC) detectors. With a method based on a model ...describing the behavior of an RPC exposed to a large particle flux, we have periodically measured the electrode resistivity
ρ of the two detectors over 3 years. We observed a large increase of
ρ with time, from initial values of about
10
10
Ω
cm
to more than
200×10
10
Ω
cm
. A corresponding degradation of the RPC rate capability, from about
3
kHz/cm
2
to less than
200
Hz/cm
2
, was observed. The reversibility of the process, using a humid gas mixture, has also been studied.
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