The neutron detection efficiency of a sampling calorimeter made of 1
mm diameter scintillating fibers embedded in a lead/bismuth structure has been measured at the neutron beam of The Svedberg ...Laboratory at Uppsala. A significant enhancement of the detection efficiency with respect to a bulk organic scintillator detector with the same thickness is observed.
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.
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 cylindrical-GEM inner tracker detector of the KLOE-2 experiment Bencivenni, G.; Branchini, P.; Ciambrone, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Volume:
958
Journal Article
Peer reviewed
The KLOE-2 experiment represents the continuation of KLOE. It acquired 5.5 fb−1 data from November 2014 to March 2018 with the aim of collecting the largest sample of ϕ mesons at the DAΦNE e+e− ...collider at Frascati National Laboratory of INFN.
A new tracking device, the Inner Tracker, was installed at the interaction region of KLOE-2 and it was operated together with the Drift Chamber to improve track and vertex reconstruction capabilities of the new experimental apparatus. The Inner Tracker is a four-layer cylindrical triple-GEM detector with each layer equipped with an X-V strips-pads stereo readout. Although GEM detectors have been extensively used in high energy physics experiments, the IT, with its fully-cylindrical geometry is a frontier detector and KLOE-2 is the first experiment which benefited of this novel detector technology operated at a collider.
The operation of the Inner Tracker will be presented, together with the results of the alignment and calibration and tracking–vertexing performance of such a unique detector.
The VME64x standard defines a double edge source synchronous block transfer (2eSST) capable to sustain a data transfer rate up to 320 MByte/s on the VMEbus. This level of performance is achieved by ...double edge clocking a 64-bit bus with bursts of data strobe pulses. The switching activity of such a wide bus on a shared backplane challenges the signal integrity and the data transfer reliability. The Bus-invert is a well known coding technique developed to lower the peak power dissipation in I/O busses by decreasing their switching activity. It has been originally proposed for lowering the power consumption of CMOS VLSI devices and so reducing the on-chip line coupling and noise. In this paper we discuss how the Bus-Invert coding can be applied to improve the 2eSST performance. A custom designed board-set has been used to characterize jitter, noise and power consumption with different data patterns, coding schemes and bus loading conditions. The hardware overheads introduced by the encoding algorithm is discussed in the view of deployments in low-latency, real-time applications.
The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in ...e+e−→Uγ, U→π+π− based on 28 million e+e−→π+π−γ events collected at DAΦNE by the KLOE experiment. The π+π− production by initial-state radiation compensates for a loss of sensitivity of previous KLOE U→e+e−, μ+μ− searches due to the small branching ratios in the ρ–ω resonance region. We found no evidence for a signal and set a limit at 90% CL on the mixing strength between the photon and the dark photon, ε2, in the U mass range between 527 and 987MeV. Above 700 MeV this new limit is more stringent than previous ones.
Since its introduction in the early 1980s, the VMEbus plays a leading role in the embedded computing, real-time control and data acquisition systems for high energy physics experiments. In more than ...20 years, the original standard has undergone major improvements and new features have been added to physical and logical layers, yet retaining a backward compatibility to protect investments and products life. High-speed data transactions are one of the most important features of the protocol in many applications. In this paper, we focus on the performances of the multiplexed block transfer cycle, a 64-bit data burst transaction fully supported by well-established VME64 silicon interfaces and the majority of high-end modules on the market. We confronted VME with VME64x backplane behaviors in light-to-moderate bus loading scenarios. Test results obtained with a blend of VME64 and VME64x-compliant boards are presented and discussed together with the backplanes' impedance analysis carried out with time domain reflectometry techniques. The impact on the transfer bandwidth of different load topologies is also reviewed.
The Astrophysical Radiation with Ground-based Observatory at Yang Ba Jing (ARGO-YBJ) detector is an extensive air shower array that has been used to monitor the northern gamma -ray sky at energies ...above 0.3 TeV from 2007 November to 2013 January. In this paper, we present the results of a sky survey in the declination band from -10degrees to 70degrees, using data recorded over the past five years. With an integrated sensitivity ranging from 0.24 to ~1 Crab units depending on the declination, six sources have been detected with a statistical significance greater than five standard deviations. Several excesses are also reported as potential gamma -ray emitters. The features of each source are presented and discussed. Additionally, 95% confidence level upper limits of the flux from the investigated sky region are shown. Specific upper limits for 663 GeV gamma -ray active galactic nuclei inside the ARGO-YBJ field of view are reported. The effect of the absorption of gamma -rays due to the interaction with extragalactic background light is estimated.
The Double-Edge Source Synchronous Block Transfer (2eSST) is the latest performance update to the VME64 protocol, approved as an ANSI standard in 2003. This extension has taken the VMEs data transfer ...rate from the original 40 MByte/s to 320 MByte/s. The architectural change at the base of such an impressive step forward is twofold. Different from all the previous cycles, data transfers are driven synchronously by the producer, without handshaking, and data is latched on both the rising and falling edges of the strobe signal. The double edge clocking effectively doubles the bandwidth and it is normally present on PC motherboards equipped with double data rate RAM chips and high-performance graphic adapters. In these applications, a careful approach to signal integrity has shown to be critical in order to avoid timing violations. In parallel, multidrop bus architecture with long lines and up to 21 slots, these concerns become imperative for successful operations. In this paper we present the tests performed on 2eSST. The Motorola MVME6100 and a custom designed board have been used to characterize the timing with different bus loading conditions and to evaluate the impact of different layout choices. Driving capability and crosstalk immunity of enhanced transceivers specifically developed for 2eSST and traditional components are compared.
Measurement of the K-S ? Babusci, D.; Berlowski, M.; Bloise, C. ...
The journal of high energy physics,
02/2023
2
Journal Article
Peer reviewed
Open access
The ratio R = gamma(K-S -> pi e nu)/gamma(KS -> pi(+)pi(-)) has been measured with a sample of 300 million KS mesons produced in phi -KLKS decays recorded by the KLOE experiment at the DA Phi ...NE e(+)e(-) collider. K-S -> pi e nu events are selected by a boosted decision tree built with kinematic variables and time-of-flight measurements. Data control samples of K-L -> pi e nu decays are used to evaluate signal selection efficiencies. With 49647 +/- 316 signal events we measure R = (1.0421 +/- 0.0066(stat) +/- 0.0075(syst)) x 10(-3). The combination with our previous measurement gives R = (1.0338 +/- 0.0054(stat) +/- 0.0064(syst)) x 10(-3). From this value we derive the branching fraction B(K-S -> pi e nu) = (7.153 +/- 0.037(stat)+/- 0.044(syst)) x 10(-4) and f(+)(0)|V-us| = 0.2170 +/- 0.009.
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