Quantum Chromodynamics (QCD) is the theory of the strong interaction, but the properties of the hadrons cannot be directly calculated from the QCD Lagrangian and alternative approaches are then used. ...In order to test the different models, precise measurements of hadron properties are of extreme importance. This is the main motivation for the hadron spectroscopy experimental program carried out since many years with different probes and different detectors. A survey of some recent results in the field is here presented and commented, together with the opportunities offered by the forthcoming experimental programs.
The PADME beam line Monte Carlo simulation Bossi, F.; Branchini, P.; Buonomo, B. ...
The journal of high energy physics,
09/2022, Letnik:
2022, Številka:
9
Journal Article
Recenzirano
Odprti dostop
A
bstract
The PADME experiment at the DAΦNE Beam-Test Facility (BTF) of the INFN Laboratory of Frascati is designed to search for invisible decays of dark sector particles produced in ...electron-positron annihilation events with a positron beam and a thin fixed target, by measuring the missing mass of single-photon final states. The presence of backgrounds originating from beam halo particles can significantly reduce the sensitivity of the experiment. To thoroughly understand the origin of the beam background contribution, a detailed G
eant
4-based Monte Carlo simulation has been developed, containing a full description of the detector together with the beam line and its optical elements. This simulation allows the full interactions of each particle to be described, both during beam line transport and during detection, a possibility which represents an innovative way to obtain reliable background predictions.
The P̅ANDA physics program Gianotti, P.
EPJ Web of Conferences,
01/2016, Letnik:
130
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The understanding of the QCD in the non-perturbative regime, is one of the key issues to have a complete picture of strong interactions. Recent findings of new and unexpected resonances, with ...unresolved properties, show that the hadron spectrum is not yet completely understood. This is also underlined by the ongoing discussion on multiquark states, and on other exotic states with gluonic degrees of freedom. The P̅ANDA experiment, one of the biggest enterprises at the FAIR facility, aims at exploring this field thanks to the gluon rich environment offered by the annihilation of antiprotons. A general overview of the P̅ANDA physics program is given in this paper.
The PADME experiment will search for the <inline-formula> <tex-math notation="LaTeX">e^{+} e^{-} \rightarrow \gamma A^{\prime } </tex-math></inline-formula> process in a positron-on-target ...experiment, assuming a decay of the <inline-formula> <tex-math notation="LaTeX">A^{\prime } </tex-math></inline-formula> into invisible particles of the hidden sector. The 550-MeV positron beam of the DA<inline-formula> <tex-math notation="LaTeX">\Phi </tex-math></inline-formula>NE beam-test facility (BTF), at Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, will be used. The suppression of the background, due to bremsstrahlung emission from the beam positrons, requires highly efficient charged-particle detectors with optimized geometry. A fine-grained plastic scintillator veto composed of three stations operating in vacuum is proposed. Two stations, placed inside a dipole magnet with 0.6-T magnetic field, will also provide momentum measurement at the percent level. Different prototypes for the design of the detector elements, the photosensor, and the front-end electronics were studied with single electron beam at the DA<inline-formula> <tex-math notation="LaTeX">\Phi </tex-math></inline-formula>NE BTF to choose the optimal technologies and construction solutions. PADME is currently under construction, and it is planned to begin data collection in 2018. The design of the charged-particle vetoes and the test beam performance of the prototypes are reviewed.
The slow high-efficiency extraction from a ring positron accelerator (SHERPA) project’s aim is to develop an efficient technique to extract a positron beam from one of the accelerator rings composing ...theDAΦNEcomplex at the Frascati National Laboratory of INFN, setting up a new beam line able to deliver positron spills of O(ms) length, excellent beam energy spread and emittance. The most common approach to slowly extract from a ring is to increase betatron oscillations approaching the third order tune resonance to gradually eject particles from the circulating beam. SHERPA proposes a paradigm change for lepton machines using coherent processes in bent crystals to kick out positrons from the ring, a cheaper and less complex alternative. A description of this innovative nonresonant extraction technique is reported in this manuscript, including its performance preliminary estimation.
We have searched for a deeply bound kaonic state by using the FINUDA spectrometer installed at the e(+)e(-) collider DAPhiNE. Almost monochromatic K(-)'s produced through the decay of phi(1020) ...mesons are used to observe K(-) absorption reactions stopped on very thin nuclear targets. Taking this unique advantage, we have succeeded to detect a kaon-bound state K(-)pp through its two-body decay into a Lambda hyperon and a proton. The binding energy and the decay width are determined from the invariant-mass distribution as 115(+6)(-5)(stat)(+3)(-4)(syst) MeV and 67(+14)(-11)(stat)(+2)(-3)(syst) MeV, respectively.
Previous studies of proton and neutron spectra from Non-Mesonic Weak Decay of eight Λ-Hypernuclei (A=5–16) have been revisited. New values of the ratio of the two-nucleon and the one-proton induced ...decay widths, Γ2N/Γp, are obtained from single proton spectra, Γ2N/Γp=0.50±0.24, and from neutron and proton coincidence spectra, Γ2N/Γp=0.36±0.14stat−0.04sys+0.05sys, in full agreement with previously published ones. With these values, a method is developed to extract the one-proton induced decay width in units of the free Λ decay width, Γp/ΓΛ, without resorting to Intra Nuclear Cascade models but by exploiting only experimental data, under the assumption of a linear dependence on A of the Final State Interaction contribution. This is the first systematic determination ever done and it agrees within the errors with recent theoretical calculations.
PDF
