Kaonic Hydrogen X-ray Research Articles

The yield of kaonic hydrogen X-rays in the SIDDHARTA experiment

We measured K -series kaonic hydrogen X-rays in the SIDDHARTA experiment performed at the DAΦNE electron-positron collider of Laboratori Nazionali di Frascati. With a gaseous hydrogen target of density 15 ρ STP , preliminary values of the absolute yields, defined as the number of atomic X-rays emitted per kaon stopped inside the target, were determined to be 0.012 −0.004 +0.003 for K α transition and 0.045 −0.012 +0.009 for K tot , the summation of all the emitted K -series transitions.

Precision Spectroscopy of Kaonic Hydrogen X-rays Leading to a New Development in Low Energy QCD (Current Topics)

Precision Spectroscopy of Kaonic Hydrogen X-rays Leading to a New Development in Low Energy QCD (Current Topics)

Kaonic hydrogen X-ray measurement in SIDDHARTA

Kaonic hydrogen atoms provide a unique laboratory to probe the kaon-nucleon strong interaction at the energy threshold, allowing an investigation of the interplay between spontaneous and explicit chiral symmetry breaking in low-energy QCD. The SIDDHARTA Collaboration has measured the $K$-series X rays of kaonic hydrogen atoms at the DA$\Phi$NE electron-positron collider of Laboratori Nazionali di Frascati, and has determined the most precise values of the strong-interaction induced shift and width of the $1s$ atomic energy level. This result provides vital constraints on the theoretical description of the low-energy $\bar{K}N$ interaction.

Results from the kaonic hydrogen X-ray measurement at DAFNE and outlook to future experiments

The \(\overline{K}N\) system at rest plays a key role for the understanding of strong interaction of hadrons with strangeness involved. The experiment SIDDHARTA used X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. It was the first experiment on kaonic He3 and deuterium ever, kaonic hydrogen was measured with improved precision resulting in \(\epsilon_{1s} = -283 \pm 36 \mbox{(stat)} \pm 6 \mbox{(syst)}\) eV and \(\Gamma_{1s} = 541 \pm 89 \mbox{(stat)} \pm 22 \mbox{(syst)}\) eV. Additionally a scheme for an improved future experiment on kaonic deuterium is introduced in this contribution.

Kaonic Helium X-rays

The long-standing "Kaonic-helium puzzle", i.e., the discrepancy between the measured and calculated 2p-level strong-interaction shift of kaonic helium 4, has been solved by the KEK E570 experiment; the measured 2p-level shift was 2 ± 2(stat) ± 2(syst) eV, thus agreeing with a majority of the theoretical calculations in contradiction to the previous average of 3 experiments of −43 ± 8eV. The smallness of the kaonic helium-4 2p-level shift has recently been confirmed by the SIDDHARTA collaboration at DAΦNE. Both of these experiments used silicon drift X-ray detectors (SDDs), and have used elaborate in-situ calibration methods. In order to further study the low-energy kaon-nucleus interaction, the J-PARC E17 experiment will soon measure the kaonic helium-3 2p-level shift to high precision. I also briefly discuss the status of kaonic hydrogen x-ray spectroscopy.

A new measurement of kaonic hydrogen X-rays

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.

X-RAY SPECTROSCOPY OF KAONIC ATOMS AT DAΦNE

The SIDDHARTA experiment aims a precise measurement of K -series kaonic hydrogen x-rays and the first-ever measurement of the kaonic deuterium x-rays to determine the strong-interaction energy-level shifts and widths of the lowest lying atomic states. These measurements offer a unique possibility to precisely determine the isospin-dependent kaon-nucleon ( KN ) scattering lengths [1] which are directly connected with the physics of the KN interaction. Kaonic Helium transitions to the 2p level ( L -lines) were as well measured. The experiment has been performed at the DAΦNE e+e- collider which produces the Φ-resonance. The resulting low energy negative charged kaons, coming from the Φ decay, are well suited to be stopped efficiently in a high density gas target for producing such kind of atoms. As x-ray detectors, we employed 144 Silicon Drift Detectors developed especially for this experiment, having good energy resolution of 140 eV FWHM at 6keV and time resolution of sub-micro seconds. The data taking was completed in November 2009. In this paper, an overview of this experiment and preliminary results are presented, together with future plans.

Kaon-nucleon/nuclei interaction studies by kaonic atoms measurements: the SIDDHARTA experiment at DAΦNE

The SIDDHARTA experiment (SIlicon Drift Detector for Hadronic Atom Research by Timing Application) had the aim to perform a precise measurement of K-series kaonic hydrogen x-rays and the first-ever measurement of the kaonic deuterium x-rays to determine the strong-interaction energy-level shifts and widths of the lowest lying atomic states. These measurements offer a unique possibility to precisely determine the isospin-dependent kaon-nucleon(KN) scattering lengths which are directly connected with the physics of the KN interaction. The experiment combined the excellent low-energy kaon beam generated at DAΦNE, allowing to use gaseous targets, with excellent fast X-rays detectors: Silicon Drift Detectors. SIDDHARTA was installed on DAΦNE in autumn 2008 and took data till late 2009. Apart of the kaonic hydrogen and kaonic deuterium measurements, we have performed the kaonic helium transitions to the 2 p level (L-lines) measurements: for the first time in a gaseous target for kaonic helium 4 and for the first time ever for kaonic helium 3. In this paper, an overview of this experiment and preliminary results are presented, together with future plans.

Precision Spectroscopy of Kaonic Atoms at DAΦNE

The SIDDHARTA experiment aims at a precise measurement of K-series kaonic hydrogen x-rays and the first-ever measurement of the kaonic deuterium x-rays to determine the strong-interaction energy-level shift and width of the lowest lying atomic states. These measurements offer a unique possibility to precisely determine the isospin-dependent ¯ K-nucleon scattering lengths.

Kaonic hydrogen X-rays — experiments at DAFNE

At the DAΦNE electron–positron collider of Laboratori Nazionali di Frascati we study kaonic atoms, taking advantage of the low-energy kaons produced in the Φ-meson decay. The low-energy kaon–nucleon interaction in kaonic hydrogen and kaonic deuterium can be investigated under favorable conditions. The DEAR (DAΦNE Exotic Atom Research) experiment at LNF delivered the most precise data on kaonic hydrogen up to now. DEAR and its follow-up experiment SIDDHARTA (Silicon Drift Detector for Hadronic Atom Research by Timing Application) are using X-ray spectroscopy of kaonic hydrogen and kaonic deuterium atoms to measure the strong interaction-induced shift and width of the ground state. From these quantities the isospin-dependent antikaon–nucleon scattering lengths can be determined, quantities useful for testing the understanding of chiral symmetry breaking in the strangeness sector. Within the SIDDHARTA project new X-ray detectors are being developed. We will use an array of large area silicon drift detectors (SDDs) having excellent energy resolution but also providing a timing capability that will result in a huge suppression of background and so overcome the precision limits of the former experiments.PACS Nos.: 36.10.k, 13.75.Jz, 32.30.Rj and 29.40.Wk

Measurement of the Kaonic Hydrogen X-Ray Spectrum

The DEAR (DAPhiNE exotic atom research) experiment measured the energy of x rays emitted in the transitions to the ground state of kaonic hydrogen. The measured values for the shift epsilon and the width Gamma of the 1s state due to the K(-)p strong interaction are epsilon(1s)=-193 +/- 37 (stat) +/- 6 (syst) eV and Gamma(1s)=249 +/- 111 (stat) +/- 30 (syst) eV, the most precise values yet obtained. The pattern of the kaonic hydrogen K-series lines, K(alpha), K(beta), and K(gamma), was disentangled for the first time.

OBSERVATION OF KAONIC HYDROGEN ATOM X-RAY

We successfully observed clear K-series kaonic hydrogen X-rays for the first time taking advantage of two charged pions tagging technique and a gaseous hydrogen target. The strong-interaction energy shift and width of 1s state of K −p atom were determined to be ΔE 1s = -323 ± 63 (statistical) ± 11 (systematic) eV and Г1s = 407 ± 208 ± 100 eV. Our result means that the K −p strong interaction near threshold is repulsive and the long-standing kaonic hydrogen puzzle is solved.

Observation of kaonic hydrogen atom x rays

We successfully observed clear K-series kaonic hydrogen X-rays for the first time taking advantage of two charged pions tagging technique and a gaseous hydrogen target. The strong-interaction energy shift and width of 1s state of K−p atom were determined to be ΔE1s = -323 ± 63 (statistical) ± 11 (systematic) eV and Г1s = 407 ± 208 ± 100 eV. Our result means that the K−p strong interaction near threshold is repulsive and the long-standing kaonic hydrogen puzzle is solved.

Discovery of the repulsive energy shift of the kaonic hydrogen 1 s state

The aim in this manuscript is to clarify the progress in understanding the nature of the K ¯ N interaction at the lowest energy, given by the recent kaonic hydrogen X-ray experiment at KEK [1]. We have observed a clear spectrum showing the kaonic hydrogen K α line, for the first time. The analysis gives the repulsive energy shift to be Δ E(1 s) = −323 ± 63(statistical) ± 11 (systematic) eV and the energy width to be Λ(1 s) = 407 ± 208 ± 100 eV. This result is consistent with analyses of the previous low-energy scattering data and resolves the long-standing kaonic hydrogen puzzle.

A new approach to measure kaonic hydrogen X-rays

Previous kaonic hydrogen X-ray experiments suffered from a poor signal-to-background level. This has been overcome in the present measurement through the use of a gaseous hydrogen target and the imposition of a two-charged-pion tagging requirement. In this paper a full technical description is given of the experimental methods employed.

Kaonic hydrogen X-ray experiment at KEK

For the further understanding of the K -N interaction in the low energy region, we are performing a measurement of K −p X rays at KEK which adopts a new technique to improve the signal-to-background ratio (S/N); specifying the final state of the K −p reaction and using a gaseous hydrogen target (4 atm at 100 K). With this technique three orders of magnitude better S/N and one order higher statistics are expected as compared to previous experiments.