The K¯N system at threshold is a sensitive testing ground for low energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we have measured the K-series X-rays of kaonic hydrogen ...atoms at the DAΦNE electron–positron collider of Laboratori Nazionali di Frascati, and have determined the most precise values of the strong-interaction energy-level shift and width of the 1s atomic state. As X-ray detectors, we used large-area silicon drift detectors having excellent energy and timing resolution, which were developed especially for the SIDDHARTA experiment. The shift and width were determined to be ϵ1s=−283±36(stat)±6(syst) eV and Γ1s=541±89(stat)±22(syst) eV, respectively. The new values will provide vital constraints on the theoretical description of the low-energy K¯N interaction.
The VIolation of Pauli exclusion principle -2 experiment, or VIP-2 experiment, at the Laboratori Nazionali del Gran Sasso searches for X-rays from copper atomic transitions that are prohibited by the ...Pauli exclusion principle. Candidate direct violation events come from the transition of a 2p electron to the ground state that is already occupied by two electrons. From the first data taking campaign in 2016 of VIP-2 experiment, we determined a best upper limit of Formula omitted for the probability that such a violation exists. Significant improvement in the control of the experimental systematics was also achieved, although not explicitly reflected in the improved upper limit. By introducing a simultaneous spectral fit of the signal and background data in the analysis, we succeeded in taking into account systematic errors that could not be evaluated previously in this type of measurements.
The VIolation of Pauli exclusion principle -2 experiment, or VIP-2 experiment, at the Laboratori Nazionali del Gran Sasso searches for X-rays from copper atomic transitions that are prohibited by the ...Pauli exclusion principle. Candidate direct violation events come from the transition of a 2
p
electron to the ground state that is already occupied by two electrons. From the first data taking campaign in 2016 of VIP-2 experiment, we determined a best upper limit of
3.4
×
10
-
29
for the probability that such a violation exists. Significant improvement in the control of the experimental systematics was also achieved, although not explicitly reflected in the improved upper limit. By introducing a simultaneous spectral fit of the signal and background data in the analysis, we succeeded in taking into account systematic errors that could not be evaluated previously in this type of measurements.
The first observation of the kaonic 3He 3d→2p transition was made, using slow K− mesons stopped in a gaseous 3He target. The kaonic atom X-rays were detected with large-area silicon drift detectors ...using the timing information of the K+K− pairs of ϕ-meson decays produced by the DAΦNE e+e− collider. The strong interaction shift of the kaonic 3He 2p state was determined to be −2±2(stat)±4(syst) eV.
We present the tests performed by the SIDDHARTA-2 collaboration at the
DA
Φ
NE
collider with a quasi-hemispherical CdZnTe detector. The very good room-temperature energy resolution and efficiency in ...a wide energy range show that this detector technology is ideal for studying radiative transitions in intermediate and heavy mass kaonic atoms. The CdZnTe detector was installed for the first time in an accelerator environment to perform tests on the background rejection capabilities, which were achieved by exploiting the SIDDHARTA-2 Luminosity Monitor. A spectrum with an
241
Am
source has been acquired, with beams circulating in the main rings, and peak resolutions of 6% at 60 keV and of 2.2% at 511 keV have been achieved. The background suppression factor, which turned out to be of the order of
≃
10
5
-
6
, opens the possibility to plan for future kaonic atom measurements with CdZnTe detectors.
The study of the K¯N system at very low energies plays a key role for the understanding of the strong interaction between hadrons in the strangeness sector. At the DAΦNE electron–positron collider of ...Laboratori Nazionali di Frascati we studied kaonic atoms with Z=1 and Z=2, taking advantage of the low-energy charged kaons from Φ-mesons decaying nearly at rest. The SIDDHARTA experiment used X-ray spectroscopy of the kaonic atoms to determine the transition yields and the strong interaction induced shift and width of the lowest experimentally accessible level (1s for H and D and 2p for He). Shift and width are connected to the real and imaginary part of the scattering length. To disentangle the isospin dependent scattering lengths of the antikaon–nucleon interaction, measurements of K−p and of K−d are needed. We report here on an exploratory deuterium measurement, from which a limit for the yield of the K-series transitions was derived: Y(Ktot)<0.0143 and Y(Kα)<0.0039 (CL 90%). Also, the upcoming SIDDHARTA-2 kaonic deuterium experiment is introduced.
Abstract
The nuclear E2 resonance effect occurs when an atomic de-excitation energy is closely matched by a nuclear excitation energy. It produces an attenuation of some of the atomic X-ray lines in ...the resonant isotope target. Investigating the nuclear E2 resonance effect in kaonic atoms, important information about kaon-nucleus strong interaction can be provided. The only
K
−
−
42
98
Mo
nuclear resonance effect was measured by G. L. Goldfrey, G- K. Lum and C. E. Wiegand at Lawrence Berkeley Laboratory, in 1975. The nuclear E2 resonance effect was observed in 25 hours of data taking, not enough to provide a conclusive result. In four kaonic Molybdenum isotopes (
42
94
Mo
,
42
96
Mo
,
42
98
Mo
and
42
100
Mo
), the nuclear E2 resonance effect is expected at the same transition, with similar energy values. The KAMEO (Kaonic Atoms Measuring nuclear resonance Effects Observables) experiment plans to study the E2 nuclear resonance effect in kaonic Molybdenum isotopes at the DAΦNE e
+
e
−
collider, during the SIDDHARTA-2 experiment. The experimental strategy consists of exposing four solid strip targets, each enriched with one Molybdenum isotope, to negatively charged kaons, using a germanium detector for X-ray transition measurements. A further exposure of a non-resonant
42
92
Mo
isotope solid strip target will be used as reference for standard non-resonant transitions.
The dynamics of the strong interaction processes in the non-perturbative regime is currently approached by lattice calculations and effective field theories (ChPT), still lacking several experimental ...results, fundamental for a good understanding of the strangeness sector. Among these, the information provided by the low-energy kaon nucleon/nuclei interaction, accessible through the study of kaonic atoms and kaonic nuclear processes, plays a key-role. The lightest atomic systems, the kaonic hydrogen and the kaonic deuterium, deliver, in a model-independent way, the isospin-dependent kaon-nucleon scattering lengths, through the X- ray spectroscopy of the exotic atoms de-exciting to the fundamental level. The most precise kaonic hydrogen measurement to-date, together with an exploratory measurement of kaonic deuterium, were carried out in 2009 at the DAΦNE collider, by the SIDDHARTA collaboration. Nowadays, an upgraded setup was built, for a precise measurement of kaonic deuterium and, eventually, of heavier exotic atoms. A correlated study of the kaon-nuclei interaction at momenta below 130 MeV/c is carried out by the AMADEUS collaboration, using the KLOE detector and dedicated targets inserted near the collider interaction point. Preliminary results of the study of charged antikaons interacting with nuclei are shown, including a discussion of the still controversial Λ(1405).
PDF
