X-ray Spectroscopy Of Kaonic Atoms Research Articles

The SIDDHARTA-2 Veto-2 system for X-ray spectroscopy of kaonic atoms at DAΦNE

The Veto-2 is a fundamental component of a multiple-stage veto system for the SIDDHARTA-2 experiment installed at the DAΦNE collider at INFN-LNF in Italy. It was developed to improve the signal-to-background ratio for the challenging measurement of X-ray transitions to the fundamental level in kaonic deuterium. Its purpose is the suppression of hadronic background in the form of Minimum Ionizing Particles by using the topological correlation between signals in the X-ray and Veto-2 detectors. The Veto-2 system consists of a barrel of plastic scintillators read out by Silicon Photomultipliers. The system performed its first successful test run within the apparatus with a helium-4 target in 2022. The efficiency of the Veto-2 was determined and found to be 0.62 ± 0.01. The Veto-2 improved the signal-to-background ratio for the kaonic helium-4 Lα measurement by ∼ 16%, which is crucial due to the low expected X-ray yield of kaonic deuterium.

Potentialities of CdZnTe Quasi-Hemispherical Detectors for Hard X-ray Spectroscopy of Kaonic Atoms at the DAΦNE Collider.

Kaonic atom X-ray spectroscopy is a consolidated technique for investigations on the physics of strong kaon-nucleus/nucleon interaction. Several experiments have been conducted regarding the measurement of soft X-ray emission (<20 keV) from light kaonic atoms (hydrogen, deuterium, and helium). Currently, there have been new research activities within the framework of the SIDDHARTA-2 experiment and EXCALIBUR proposal focusing on performing precise and accurate measurements of hard X-rays (>20 keV) from intermediate kaonic atoms (carbon, aluminum, and sulfur). In this context, we investigated cadmium-zinc-telluride (CdZnTe or CZT) detectors, which have recently demonstrated high-resolution capabilities for hard X-ray and gamma-ray detection. A demonstrator prototype based on a new cadmium-zinc-telluride quasi-hemispherical detector and custom digital pulse processing electronics was developed. The detector covered a detection area of 1 cm2 with a single readout channel and interesting room-temperature performance with energy resolution of 4.4% (2.6 keV), 3% (3.7 keV), and 1.4% (9.3 keV) FWHM at 59.5, 122.1, and 662 keV, respectively. The results from X-ray measurements at the DAΦNE collider at the INFN National Laboratories of Frascati (Italy) are also presented with particular attention to the effects and rejection of electromagnetic and hadronic background.

Probing low-energy QCD with kaonic atoms at DAΦNE

X-ray spectroscopy of kaonic atoms provides a versatile tool to study the strong interaction at low energies via a direct observation of its influence on the ground state of kaonic hydrogen atoms. The SIDDHARTA experiment provided precise results on the energy shift and width of the kaonic hydrogen 1s state induced by the strong interaction. To enable the extraction of the antikaon-nucleon scattering lengths a0 and a1, SIDDHARTA-2 aims to determine the energy shift and width in kaonic deuterium with precisions of 30 eV and 75 eV, respectively. This measurement is aggravated by the low kaonic deuterium X-ray yield and a high background environment and will only be possible by implementing a severe upgrade on the SIDDHARTA apparatus.

Coevolution of the Technology on Transition-Edge-Sensor Spectrometer and Its Application to Fundamental Science

High-energy-resolution X-ray spectroscopy using X-ray microcalorimeters has been widely adopted for high-precision experiments on fundamental science. The technical difficulties come from its use at low temperatures and its high sensitivity to the external environment, though many countermeasures have been proposed through the experience of space applications. The limit of the number of pixels of the semiconductor-type X-ray microcalorimeters can be solved by using the transition-edge sensor (TES) superconducting detector. Recently, a study of the strong nuclear force via high-energy-resolution X-ray spectroscopy of kaonic atoms using TES at the J-PARC accelerator facility was successfully performed by the HEATES collaboration. Furthermore, muonic-atom spectroscopy using TES has been demonstrated at the J-PARC muon facility, and a physical experiment to test the electromagnetic force under a strong electric field is ready for commissioning. Material diagnostics at a hard X-ray synchrotron facility have been tested at SPring-8 and resulted in a successful operation for the first time. Other than X-rays, TES has been used as a mass spectrometer for neutral molecules in a cryogenic electrostatic ion ring. The entire design of the experiment is carefully considered to meet the science-specific requirement. We will summarize the latest and future applications of the microcalorimeter and present key technologies, such as digital electronics, data acquisition software, aperture, collimator, mechanical, and electrical interface. Our results will be helpful for other users to design new experiments for fundamental science.

Experimental studies of the kaon-nucleus interaction at low energy with x-ray spectroscopy of kaonic atoms

In the exotic atoms in which one electron is replaced by a negatively charged kaon, the kaon-nucleus hadronic interaction introduces an energy shift and broadening of the low-lying states of the kaonic atoms. The shift and width can be determined with high precision from the atomic x-ray spectroscopy, and this experimental method provides unique information to understand the low energy kaon-nucleus interaction at the production threshold.

Precision X-ray spectroscopy of kaonic atoms as a probe of low-energy kaon-nucleus interaction

In the exotic atoms where one atomic $1s$ electron is replaced by a $K^{-}$, the strong interaction between the $K^{-}$ and the nucleus introduces an energy shift and broadening of the low-lying kaonic atomic levels which are determined by only the electromagnetic interaction. By performing X-ray spectroscopy for Z=1,2 kaonic atoms, the SIDDHARTA experiment determined with high precision the shift and width for the $1s$ state of $K^{-}p$ and the $2p$ state of kaonic helium-3 and kaonic helium-4. These results provided unique information of the kaon-nucleus interaction in the low energy limit.

High-Resolution Kaonic-Atom X-ray Spectroscopy with Transition-Edge-Sensor Microcalorimeters

We are preparing for an ultra-high resolution x-ray spectroscopy of kaonic atoms using an x-ray spectrometer based on an array of superconducting transition-edge-sensor microcalorimeters developed by NIST. The instrument has excellent energy resolutions of 2 - 3 eV (FWHM) at 6 keV and a large collecting area of about 20 mm^2. This will open new door to investigate kaon-nucleus strong interaction and provide new accurate charged-kaon mass value.

X-ray spectroscopy of kaonic atoms at SIDDHARTA

The X-ray measurements of atoms play an important role for understanding the low-energy QCD in the strangeness sector. The SIDDHARTA experiment studied the X-ray transitions of 4 light atoms (H, D, 3 He, and 4 He) using the DAFNE electron-positron collider at LNF (Italy). Most precise values of the shift and width of the hydrogen 1s state were determined, which have been now used as fundamental information for the low-energy K − p interaction in theoretical studies. An upper limit of the X-ray yield of deuterium was derived, important for future K − d experiments. The shifts and widths of the 3 He and 4 He 2p states were obtained, confirming the end of the kaonic helium puzzle. In this contribution also the plans for new experiments of deuterium are being presented.

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 atoms studies at DAFNE by the SIDDHARTA experiment

The K ¯ N system at rest makes a sensitive testing ground for chiral SU(3) symmetry in QCD, especially for the explicit symmetry breaking induced by the relatively large mass of the strange quark. At the DAΦNE electron-positron collider of Laboratori Nazionali di Frascati we study kaonic atoms, taking advantage of the low-energy kaons from Φ-mesons decaying nearly at rest. The low-energy antikaon-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 atoms to measure the strong interaction induced shift and width of the ground state. SIDDHARTA is the first experiment on kaonic deuterium ever, and kaonic hydrogen is remeasured with improved precision. From the shift and width in K -p and K -d the isospin-dependent antikaon-nucleon scattering lengths can be determined, quantities essential as constraints for low-energy QCD.

SENSING STRONG INTERACTION EFFECTS IN SPECTROSCOPY OF HADRONIC ATOMS

The theoretical studying the strong interaction shifts and widths from X-ray spectroscopy of kaonic atoms is fulfilled. Sensing the strong interaction effects and theoretical estimating spectra of kaonic atomic systems can be considered as a new tool for studying nuclear structure and strong K-nucleus interaction