Search

The interaction of antikaons with nucleons and nuclei in the low-energy regime represents an active research field in hadron physics with still many important open questions. The investigation of light kaonic atoms is, in this context, a unique tool to obtain precise information on this interaction. The most precise kaonic hydrogen measurement to date, together with an exploratory measurement of kaonic deuterium, were carried out by the SIDDHARTA Collaboration at the DAΦNE electron-positron collider of LNF-INFN, by combining the excellent quality kaon beam delivered by the collider with new experimental techniques, as fast and precise Silicon-Drift X-ray detectors. The measurement of kaonic deuterium will be realized in the near future by SIDDHARTA-2, a major upgrade of SIDDHARTA. [ABSTRACT FROM AUTHOR]

The precision of the charged kaon mass is an order of magnitude worse than the precision of the charged pion mass mainly due to two inconsistent measurements. We plan to improve this precision by determining the charged kaon mass with the requested accuracy in the measurements of X-ray transitions in kaonic atoms of selected solid targets with the HPGe detector at DAΦNE in Laboratori Nazionali di Frascati, Italy. The measurements will be performed in parallel with SIDDHARTA-2 measurements of X-ray transitions in gaseous targets. The status of the preparation of the measurements will be presented. [ABSTRACT FROM AUTHOR]

Recent results obtained by the AMADEUS Collaboration on the experimental investigation of the K-low-energy interaction with light nuclei are summarised. The step 0 of AMADEUS consists in the analysis of the data collected at the DAΦNE collider with the KLOE detector during the 2004/2005 data taking campaign. The low momentum K- particles (pK ~ 127 MeV/c) are absorbed in the light nuclei contained in the detector setup (H, 4He, 9Be and 12C) and hyperon-pion/hyperon-nucleons, emitted in the final state, are reconstructed. From the study of Aπ and Ap correlated production, important information on the KN strong interaction in the non-perturbative QCD regime are extracted. [ABSTRACT FROM AUTHOR]

The DAΦNE electron-positron collider of the Laboratori Nazionali di Frascati of INFN has made available a unique quality low-energy negatively charged kaons "beam", which is being used to study the kaon-nucleon/nuclei interactions by the SIDDHARTA-2 experiment and the AMADEUS Collaboration. The dynamics of the strong interaction processes in the non-perturbative regime is approached by lattice calculations and effective field theories (ChPT) which are still lacking experimental results in the low-energy regime, fundamental for their good understanding. The studies of kaonic atoms and of the kaonic nuclear processes performed by SIDDHARTA-2 and AMADEUS play in this context a key-role. [ABSTRACT FROM AUTHOR]

The VOXES project's goal is to realize the first prototype of a highresolution and high-precision X-ray spectrometer for diffused sources, using Highly Annealed Pyrolitic Graphite (HAPG) crystals combined with precision position detectors. The aim is to deliver a cost-effective and easy to handle system having an energy resolution at the level of few eV for X-ray energies from about 2 keV up to tens of keV. There are many applications of the proposed spectrometer, going from fundamental physics (precision measurements of exotic atoms at DAΦNE collider and J-PARC, precision measurement of the K- mass solving the existing puzzle, quantum mechanics tests) to synchrotron radiation and applications (X-FEL), astronomy, medicine and industry. Here, the basic concept of such a spectrometer and the first results from a measurement of the characteristic Cu Kα1 and Kα2 X-ray lines are presented. [ABSTRACT FROM AUTHOR]

The Jagiellonian Positron Emission Tomograph (J-PET) is a detector for medical imaging of the whole human body as well as for physics studies involving detection of electron-positron annihilation into photons. J-PET has high angular and time resolution, and allows for measurement of spin of the positronium and the momenta and polarization vectors of annihilation quanta. In this article, we present the potential of the J-PET system for the background rejection in the decays of positronium atoms. [ABSTRACT FROM AUTHOR]

The AMADEUS experiment deals with the investigation of the lowenergy kaon-nuclei hadronic interaction at the DAΦNE collider at LNFINFN, which is fundamental to solve longstanding questions in the nonperturbative strangeness QCD sector. AMADEUS step 0 consisted in the reanalysis of the 2004/2005 KLOE data, exploiting K- absorptions in H, 4He, 9Be and 12C, leading to the first invariant mass spectroscopy study with very low-momentum (100 MeV) in-flight K- captures. With AMADEUS step 1, a dedicated pure carbon target was implemented in the central region of the KLOE detector, providing a high statistic sample of pure at-rest K- nuclear interaction. The results obtained in the analyses of the hyperon-pion correlated events, searching for the resonant shapes of Y states, will be described. [ABSTRACT FROM AUTHOR]

We present a method and preliminary results of the image reconstruction in the Jagiellonian PET tomograph. Using GATE (Geant4 Application for Tomographic Emission), interactions of the 511 keV photons with a cylindrical detector were generated. Pairs of such photons, flying backto- back, originate from e+e- annihilations inside a 1 mm spherical source. Spatial and temporal coordinates of hits were smeared using experimental resolutions of the detector. We incorporated the algorithm of the 3D Filtered Back Projection, implemented in the STIR and TomoPy software packages, which differ in approximation methods. Consistent results for the Point Spread Functions of ~ 5÷7 mm and ~ 9÷20 mm were obtained, using STIR, for transverse and longitudinal directions, respectively, with no time-of-flight information included. [ABSTRACT FROM AUTHOR]

Samples of uterine leiomyomatis and normal tissues taken from patients after surgery were investigated using the Positron Annihilation Lifetime Spectroscopy (PALS). Significant differences in all PALS parameters between normal and diseased tissues were observed. For all studied patients, it was found that the values of the free annihilation and orthopositronium lifetime are larger for the tumorous tissues than for the healthy ones. For most of the patients, the intensity of the free annihilation and ortho-positronium annihilation was smaller for the tumorous than for the healthy tissues. For the first time, in this kind of studies, the 3γfraction of positron annihilation was determined to describe changes in the tissue porosity during morphologic alteration. [ABSTRACT FROM AUTHOR]

The Jagiellonian Positron Emission Tomograph (J-PET) is the first PET built from plastic scintillators. J-PET prototype consists of 192 detection modules arranged axially in three layers forming a cylindrical diagnostic chamber with the inner diameter of 85 cm and the axial field-of-view of 50 cm. An axial arrangement of long strips of plastic scintillators, their small light attenuation, superior timing properties, and relative ease of the increase of the axial field-of-view opens promising perspectives for the cost effective construction of the whole-body PET scanner, as well as construction of MR and CT compatible PET inserts. Present status of the development of the J-PET tomograph will be presented and discussed. [ABSTRACT FROM AUTHOR]

In this paper, we extend the state-of-the-art filtered backprojection (FBP) method with application of the concept of Total Variation regularization. We compare the performance of the new algorithm with the most common form of regularizing in the FBP image reconstruction via apodizing functions. The methods are validated in terms of cross-correlation coefficient between reconstructed and real image of radioactive tracer distribution using the standard Derenzo-type phantom. We demonstrate that the proposed approach results in higher cross-correlation values with respect to the standard FBP method. [ABSTRACT FROM AUTHOR]

The Jagiellonian Positron Emission Tomograph (J-PET) was constructed as a prototype of the cost-effective scanner for the simultaneous metabolic imaging of the whole human body. Being optimized for the detection of photons from the electron-positron annihilation with high time- and high angular-resolution, it constitutes a multi-purpose detector providing new opportunities for studying the decays of positronium atoms. Positronium is the lightest purely leptonic object decaying into photons. As an atom bound by a central potential, it is a parity eigenstate, and as an atom built out of an electron and an anti-electron, it is an eigen- state of the charge conjugation operator. Therefore, the positronium is a unique laboratory to study discrete symmetries whose precision is limited, in principle, by the effects due to the weak interactions expected at the level of (~ 10-14) and photon-photon interactions expected at the level of (~ 10-9). The J-PET detector enables to perform tests of discrete symmetries in the leptonic sector via the determination of the expectation values of the discrete-symmetries-odd operators, which may be constructed from the spin of ortho-positronium atom and the momenta and polarization vectors of photons originating from its annihilation. In this article, we present the potential of the J-PET detector to test the C, CP, T and CPT symmetries in the decays of positronium atoms. [ABSTRACT FROM AUTHOR]

The development of mathematically complete and consistent models solving the so-called "measurement problem", strongly renewed the interest of the scientific community for the foundations of quantum mechanics, among these the Dynamical Reduction Models posses the unique characteristic to be experimentally testable. In the first part of the paper, an upper limit on the reduction rate parameter of such models will be obtained, based on the analysis of the X-ray spectrum emitted by an isolated slab of germanium and measured by the IGEX experiment. The second part of the paper is devoted to present the results of the VIP (Violation of the Pauli exclusion principle) experiment and to describe its recent upgrade. The VIP experiment established a limit on the probability that the Pauli Exclusion Principle (PEP) is violated by electrons, using the very clean method of searching for PEP forbidden atomic transitions in copper. [ABSTRACT FROM AUTHOR]

The AMADEUS experiment aims to provide unique quality data of K- hadronic interactions in light nuclear targets, in order to solve fundamental open questions in the non-perturbative strangeness QCD sector, like the controversial nature of the Λ(1405) state, the yield of hyperon formation below threshold, the yield and shape of multi-nucleon K- absorption, processes which are intimately connected to the possible existence of exotic antikaon multi-nucleon clusters. AMADEUS takes advantage of the DAΦNE collider, which provides a unique source of monochromatic low momentum kaons and exploits the KLOE detector as an active target, in order to obtain excellent acceptance and resolution data for K- nuclear capture on H, 4He, 9Be and 12C, both at-rest and in-flight. During the second half of 2012, a successful data taking was performed with a dedicated pure carbon target implemented in the central region of KLOE, providing a high statistic sample of pure at-rest K- nuclear interactions. For the future, dedicated setups involving cryogenic gaseous targets are under preparation. [ABSTRACT FROM AUTHOR]

The antikaon-nucleon (KN) interaction close to threshold provides crucial information on the interplay between spontaneous and explicit chiral symmetry breaking in low-energy QCD. In this context, the importance of kaonic deuterium X-ray spectroscopy has been well recognized, but no experimental results have yet been obtained due to the difficulty of the measurement. We propose to measure the shift and width of the kaonic deuterium 1s state with an accuracy of 60 eV and 140 eV, respectively, at J-PARC. These results, together with the kaonic hydrogen data (KpX at KEK, DEAR and SIDDHARTA at DAΦNE), will then permit the determination of values of both the isospin I = 0 and I = 1 antikaon-nucleon scattering lengths and will provide the most stringent constraints on the antikaon-nucleon interaction, promising a breakthrough. Refined Monte Carlo studies were performed, including the investigation of background suppression factors for the described setup. These studies have demonstrated the feasibility of determining the shift and width of the kaonic deuterium atom 1s state with the desired accuracy of 60 eV and 140 eV. [ABSTRACT FROM AUTHOR]

The AMADEUS experiment deals with the investigation of the low-energy kaon-nuclei hadronic interaction at the DAΦNE collider at LNF-INFN, which is fundamental to solve longstanding open questions in the non-perturbative strangeness QCD sector. AMADEUS step 0 consisted in the analysis of 2004-2005 KLOE data, exploring the K- absorptions in H, 4He, 9Be and 12C in-flight and at-rest. With AMADEUS step 1, a dedicated pure carbon target was implemented in the central region of the KLOE detector, providing a high statistic sample of pure at-rest K- nuclear interaction. For the future, a dedicated setup to perform detailed studies is under preparation. Our present analysis deals with the major open questions in hadron nuclear physics in the strangeness sector, namely how hadron masses and interactions change in nuclear environment, with a search ranging from kaonic nuclear clusters to strange baryon resonances and in-medium modification of the resonance parameters. [ABSTRACT FROM AUTHOR]

The mass shift of the vector mesons in nuclei is known to be a powerful tool for investigating the mechanism of generating hadron mass from the QCD vacuum. The mechanism is known to be the spontaneous breaking of chiral symmetry. One of the approach to investigate spontaneous breaking of chiral symmetry in nuclear media is formation of meson nucleus bound state and measurring energy level of the state which will be a direct connection to the (...q) expectation value in nucleus. We propose the experiment to study in-medium mass modification of the φ meson using the formation of φ-meson bound state at J-PARC/Japan. We demonstrate that a clear missing-mass spectrum can be obtained efficiently by (..., φ) spectroscopy together with the Λ tagging, using the primary reaction channel ...p → φφ. A systematic study over several nuclear targets will yield a unique, definitive and precise determination of the in-medium mass modification of the vector meson φ(s...). This paper gives an overview of the physics motivation and the detector concept, and explains the direction of the initial research and development effort. [ABSTRACT FROM AUTHOR]

Studies of the low-energy ...N interaction have been performed based on X-ray spectroscopy of light kaonic atoms by the SIDDHARTA experiment, where the K-series lines of kaonic hydrogen and deuterium, and the L-series lines of kaonic ³He and 4He were measured, as well as kaonic atom X-ray transitions produced in Kapton. This article deals with the short summary of the results of these measurements in the SIDDHARTA experiment. [ABSTRACT FROM AUTHOR]

We report on preliminary results of the J-PARC E15 experiment aiming to search for the simplest kaonic-nuclear bound-state, K-pp, via in-flight ³He(K-,n) reaction. The first physics data-taking was performed with 5 x 109 incident kaons on the ³He target, and 3 x 105 neutrons were collected by a forward neutron counter placed 15 m away from center of the target at 0 degrees. The semi-inclusive neutron spectrum shows clear peak structure composed of the quasi-elastic K-n → K-n and the charge exchange K- p → ... 0n reactions as expected. [ABSTRACT FROM AUTHOR]