The experimental findings reported in our original paper de Sangro et al. (Eur. Phys. J. C 75:137,
2015
) have been criticized in Shabad (Eur. Phys. J. C 76:508,
2016
). We believe that the arguments ...brought in Shabad (Eur. Phys. J. C 76:508,
2016
) are not correct and we show evidence for this.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Measuring propagation speed of Coulomb fields de Sangro, R.; Finocchiaro, G.; Patteri, P. ...
The European physical journal. C, Particles and fields,
03/2015, Letnik:
75, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The problem of gravity propagation has been subject of discussion for quite a long time: Newton, Laplace and, in relatively more modern times, Eddington pointed out that, if gravity propagated with ...finite velocity, planet motion around the sun would become unstable due to a torque originating from time lag of the gravitational interactions. Such an odd behavior can be found also in electromagnetism, when one computes the propagation of the electric fields generated by a set of uniformly moving charges. As a matter of fact the Liénard–Weichert retarded potential leads to the same formula as the one obtained assuming that the electric field propagate with infinite velocity. The Feynman explanation for this apparent paradox was based on the fact that uniform motions last indefinitely. To verify such an explanation, we performed an experiment to measure the time/space evolution of the electric field generated by an uniformly moving electron beam. The results we obtain, on a finite lifetime kinematical state, are compatible with an electric field rigidly carried by the beam itself.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recent astrophysical and terrestrial experiments have motivated the proposal of a dark sector with GeV-scale gauge boson force carriers and new Higgs bosons. We present a search for a dark Higgs ...boson using 516 fb(-1) of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the product of the standard model-dark-sector mixing angle and the dark-sector coupling constant.
A
bstract
Using a total of 5
.
25 fb
−
1
of
e
+
e
−
collision data with center-of-mass energies from 4.236 to 4.600 GeV, we report the first observation of the process
e
+
e
−
→ ηψ
(2
S
) with a ...statistical significance of 4.9 standard deviations. The data sets were collected by the BESIII detector operating at the BEPCII storage ring. We measure the yield of events integrated over center-of-mass energies and also present the energy dependence of the measured cross section.
A
bstract
Using 10
.
1
×
10
9
J/ψ
events produced by the Beijing Electron Positron Collider (BEPCII) at a center-of-mass energy
s
= 3
.
097 GeV and collected with the BESIII detector, we present a ...search for the rare semi-leptonic decay
J/ψ → D
−
e
+
ν
e
+ c.c. No excess of signal above background is observed, and an upper limit on the branching fraction ℬ(
J
/
ψ
→
D
−
e
+
ν
e
+
c
.
c
.) < 7.1 × 10
−8
is obtained at 90% confidence level. This is an improvement of more than two orders of magnitude over the previous best limit.
The CGEM-IT readout chain Amoroso, A.; Baldini Ferroli, R.; Balossino, I. ...
Journal of instrumentation,
08/2021, Letnik:
16, Številka:
8
Journal Article
Recenzirano
Odprti dostop
An innovative Cylindrical Gas Electron Multiplier (CGEM) detector is under construction for the upgrade of the inner tracker of the BESIII experiment. A novel system has been worked out for the ...readout of the CGEM detector, including a new ASIC, dubbed TIGER -Torino Integrated GEM Electronics for Readout, designed for the amplification and digitization of the CGEM output signals. The data output by TIGER are collected and processed by a first FPGA-based module, GEM Read Out Card, in charge of configuration and control of the front-end ASICs. A second FPGA-based module, named GEM Data Concentrator, builds the trigger selected event packets containing the data and stores them via the main BESIII data acquisition system. The design of the electronics chain, including the power and signal distribution, will be presented together with its performance.
In planetary systems the problem arises whether gravity attracting the planets towards the central star has an instantaneous action or propagates with finite velocity. Laplace noticed that, if ...gravity propagated with finite velocity, planets motion would become unstable due to a torque originating from time lag of the gravitational interactions. Given that actions describing gravitational interaction are formally the same as that describing electrostatic interactions, we have performed an experiment meant to measure the time/space evolution of the electric field generated by an uniformly moving set of electrons. The results we obtain seem compatible with an electric field rigidly carried by the beam itself.
BESIII is a multipurpose spectrometer optimized for physics in the tau-charm energy region. Both the detector and the accelerator are undergoing an upgrade program, that will allow BESIII to run for ...5 to 10 more years. A major upgrade is the replacement of the inner drift chamber with a new detector based on Cylindrical Gas Electron Multipliers to improve both the secondary vertex reconstruction and the radiation tolerance. The CGEM-IT will be composed of three coaxial layers of cylindrical triple GEMs, operating in an Ar+iC4H10(90:10) gas mixture with field and gain optimized to minimize the spatial resolution. The new detector is readout with innovative TIGER electronics produced in 110 nm CMOS technology. The front-end is a custom designed 64 channel ASIC featuring a fully digital output and operated in trigger-less mode. It can provide analog charge and time measurements with a TDC time resolution better than 100 ps, which will allow operating in μTPC mode. With planar prototypes, we measured an unprecedented spatial resolution below 150 μm in a 1 Tesla magnetic field in a wide range of incident angles of the incoming particle. Before the installation inside BESIII, foreseen in 2021, a long standalone data taking is ongoing at the Institute of High Energy Physics in Beijing; currently, the first two cylindrical chambers are available for the test, and are used to complete the integration between the detector and the electronics and to assess the required performance. In this proceeding, a description of the CGEM-IT project, the TIGER features and performance, and the results of the analysis of first cosmic ray data taking will be presented. Focus will be given on the strip analysis, from which it is possible to measure the basic properties of the detector, and the cluster analysis, where a comparison with the results with planar prototypes will be discussed. The first preliminary results on efficiency and spatial resolution will be also presented.
The J/ψ meson has negative G parity so that, in the limit of isospin conservation, its decay into π+π− should be purely electromagnetic. However, the measured branching fraction B(J/ψ→π+π−) exceeds ...by more than 4.5 standard deviations the expectation computed according to BABAR data on the e+e−→π+π− cross section. The possibility that the two-gluon plus one-photon decay mechanism is not suppressed by G-parity conservation is discussed, even by considering other multipion decay channels. As also obtained by phenomenological computation, such a decay mechanism could be responsible for the observed discrepancy. Finally, we notice that the BESIII experiment, having the potential to perform an accurate measurement of the e+e−→π+π− cross section in the J/ψ mass energy region, can definitely prove or disprove this strong G-parity-violating mechanism by confirming or confuting the BABAR data.
Micro Pattern Gas Detectors (MPGD) are the new frontier in gas trackers. Among this kind of devices, the Gas Electron Multiplier (GEM) chambers are widely used. The experimental signals acquired with ...the detector must obviously be reconstructed and analysed. In this contribution, a new offline software to perform reconstruction, alignment and analysis on the data collected with APV-25 and TIGER ASICs will be presented. GRAAL (Gem Reconstruction And Analysis Library) is able to measure the performance of a MPGD detector with a strip segmented anode (presently). The code is divided in three parts: reconstruction, where the hits are digitized and clusterized; tracking, where a procedure fits the points from the tracking system and uses that information to align the chamber with rotations and shifts; analysis, where the performance is evaluated (e.g. efficiency, spatial resolution,etc.). The user must set the geometry of the setup and then the program returns automatically the analysis results, taking care of different conditions of gas mixture, electric field, magnetic field, geometries, strip orientation, dead strip, misalignment and many others.
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