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J. Marton

Publications and source records attributed to J. Marton.

At least 73 records · Page 4Linked to original sources
arXiv2015

Beyond quantum mechanics? Hunting the 'impossible' atoms (Pauli Exclusion Principle violation and spontaneous collapse of the wave function at test)

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.

quant-ph↗
arXiv2014

Influence of $ϕ$ mesons on negative kaons in Ni+Ni collisions at 1.91A GeV beam energy

$ϕ$ and K$^-$ mesons from Ni+Ni collisions at the beam energy of 1.91A GeV have been measured by the FOPI spectrometer, with a trigger selecting central and semi-central events amounting to 51% of the total cross section. The phase space distributions, and the total yield of K$^-$, as well as the kinetic energy distribution and the total yield of $ϕ$ mesons are presented. The $ϕ$\K$^-$ ratio is found to be $0.44 \pm 0.07(\text{stat}) ^{+0.18}_{-0.12} (\text{syst})$, meaning that about 22% of K$^-$ mesons originate from the decays of $ϕ$ mesons, occurring mostly in vacuum. The inverse slopes of direct kaons are up to about 15 MeV larger than the ones extracted within the one-source model, signalling that a considerable share of gap between the slopes of K$^+$ and K$^-$ could be explained by the contribution of $ϕ$ mesons to negative kaons.

nucl-ex↗
arXiv2014

Azimuthal Emission Patterns of $K^{+}$ and of $ K^{-} $ Mesons in Ni + Ni Collisions near the Strangeness Production Threshold

Azimuthal emission patterns of $K^\pm$ mesons have been measured in Ni + Ni collisions with the FOPI spectrometer at a beam kinetic energy of 1.91 A GeV. The transverse momentum $p_{T}$ integrated directed and elliptic flow of $K^{+}$ and $K^{-}$ mesons as well as the centrality dependence of $p_{T}$ - differential directed flow of $K^{+}$ mesons are compared to the predictions of HSD and IQMD transport models. The data exhibits different propagation patterns of $K^{+}$ and $K^{-}$ mesons in the compressed and heated nuclear medium and favor the existence of a kaon-nucleon in-medium potential, repulsive for $K^{+}$ mesons and attractive for $K^{-}$ mesons.

nucl-ex↗
arXiv2014

Testing the Pauli Exclusion Principle for electrons at LNGS

High-precision experiments have been done to test the Pauli exclusion principle (PEP) for electrons by searching for anomalous $K$-series X-rays from a Cu target supplied with electric current. With the highest sensitivity, the VIP (VIolation of Pauli Exclusion Principle) experiment set an upper limit at the level of $10^{-29}$ for the probability that an external electron captured by a Cu atom can make the transition from the 2$p$ state to a 1$s$ state already occupied by two electrons. In a follow-up experiment at Gran Sasso, we aim to increase the sensitivity by two orders of magnitude. We show proofs that the proposed improvement factor is realistic based on the results from recent performance tests of the detectors we did at Laboratori Nazionali di Frascati (LNF).

quant-ph↗
arXiv2014

Time resolution below 100 ps for the SciTil detector of PANDA employing SiPM

The barrel time-of-flight (TOF) detector for the PANDA experiment at FAIR in Darmstadt is planned as a scintillator tile hodoscope (SciTil) using 8000 small scintillator tiles. It will provide fast event timing for a software trigger in the otherwise trigger-less data acquisition scheme of PANDA, relative timing in a multiple track event topology as well as additional particle identification in the low momentum region. The goal is to achieve a time resolution of sigma ~ 100 ps. We have conducted measurements using organic scintillators coupled to Silicon Photomultipliers (SiPM). The results are encouraging such that we are confident to reach the required time resolution.

physics.ins-det↗
arXiv2013

Over saturation behavior of SiPMs at high photon exposure

Several types of Silicon Photomultipliers were exposed to short pulsed laser light (~ 30 ps FWHM) with its intensity varying from single photon to well above the number of microcells of the device. We observed a significant deviation of the output of SiPMs from the expected behavior although such response curve is considered to be rather trivial. We also noticed that the output exceeds the maximum expected pulse height, which should be defined as the total number of pixels times the single photon pulse height. At the highest light intensity (~ 500 times the number of pixels) that we tested, the signal output reached up to twice the maximum theoretical pulse height, and still did not fully saturate.

physics.ins-det↗
arXiv2013

Studies on the Cherenkov Effect for Improved Time Resolution of TOF-PET

With the newly gained interest in the time of flight method for positron emission tomography (TOF-PET), many options for pushing the time resolution to its borders have been investigated. As one of these options the exploitation of the Cherenkov effect has been proposed, since it allows to bypass the scintillation process and therefore provides almost instantaneous response to incident 511keV annihilation photons. Our simulation studies on the yield of Cherenkov photons, their arrival rate at the photon detector and their angular distribution reveal a significant influence by Cherenkov photons on the rise time of inorganic scintillators - a key-parameter for TOF in PET. A measurement shows the feasibility to detect Cherenkov photons in this low energy range.

physics.ins-det↗
arXiv2013

X-ray transition yields of low-Z kaonic atoms produced in Kapton

The X-ray transition yields of kaonic atoms produced in Kapton polyimide (C22H10N2O5) were measured for the first time in the SIDDHARTA experiment. X-ray yields of the kaonic atoms with low atomic numbers (Z = 6, 7, and 8) and transitions with high principal quantum numbers (n = 5-8) were determined. The relative yield ratios of the successive transitions and those of carbon-to-nitrogen (C:N) and carbon-to-oxygen (C:O) were also determined. These X-ray yields provide important information for understanding the capture ratios and cascade mechanisms of kaonic atoms produced in a compound material, such as Kapton.

nucl-ex↗
arXiv2013

Testing the Pauli Exclusion Principle for Electrons

One of the fundamental rules of nature and a pillar in the foundation of quantum theory and thus of modern physics is represented by the Pauli Exclusion Principle. We know that this principle is extremely well fulfilled due to many observations. Numerous experiments were performed to search for tiny violation of this rule in various systems. The experiment VIP at the Gran Sasso underground laboratory is searching for possible small violations of the Pauli Exclusion Principle for electrons leading to forbidden X-ray transitions in copper atoms. VIP is aiming at a test of the Pauli Exclusion Principle for electrons with high accuracy, down to the level of 10$^{-29}$ - 10$^{-30}$, thus improving the previous limit by 3-4 orders of magnitude. The experimental method, results obtained so far and new developments within VIP2 (follow-up experiment at Gran Sasso, in preparation) to further increase the precision by 2 orders of magnitude will be presented.

nucl-ex↗
arXiv2013

Kaon-nuclei interaction studies at low energies (the AMADEUS project)

The AMADEUS experiment aims to perform dedicated precision studies in the sector of low-energy kaon-nuclei interaction at the DAΦNE collider at LNF-INFN. In particular the experiment plans to perform measurements of the debated deeply bound kaonic nuclear states (by stopping kaons in cryogenic gaseous targets 3He and 4He) to explore the nature of the Λ(1405) in nuclear environment and to measure the cross section of K- on light nuclei, for K- momentum lower than 100 MeV/c. The AMADEUS dedicated setup will be installed in the central region of the KLOE detector.

nucl-ex↗
arXiv2013

Preliminary study of kaonic deuterium X-rays by the SIDDHARTA experiment at DAFNE

The study of the KbarN system at very low energies plays a key role for the understanding of the strong interaction between hadrons in the strangeness sector. At the DAFNE 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 Phi-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 Kp and of Kd 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(K_tot)<0.0143 and Y(K_alpha)<0.0039 (CL 90%). Also, the upcoming SIDDHARTA-2 kaonic deuterium experiment is introduced.

nucl-ex↗
arXiv2012

Measurements of the strong-interaction widths of the kaonic 3He and 4He 2p levels

The kaonic 3He and 4He X-rays emitted in the 3d-2p transitions were measured in the SIDDHARTA experiment. The widths of the kaonic 3He and 4He 2p states were determined to be Gamma_2p(3He) = 6 \pm 6 (stat.) \pm 7 (syst.) eV, and Gamma_2p(4He) = 14 \pm 8 (stat.) \pm 5 (syst.) eV, respectively. Both results are consistent with the theoretical predictions. The width of kaonic 4He is much smaller than the value of 55 \pm 34 eV determined by the experiments performed in the 70's and 80's, while the width of kaonic 3He was determined for the first time.

nucl-ex↗
arXiv2012

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$Φ$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.

nucl-ex↗
arXiv2011

Energy Level Displacement of Excited np State of Kaonic Deuterium In Faddeev Equation Approach

We calculate the energy level displacement of the excited $np$ state of kaonic deuterium in terms of the P-wave scattering length of $K^-d$ scattering. We solve the Faddeev equations for the amplitude of $K^-d$ scattering in the fixed centre approximation and derive the complex P-wave scattering length of $K^-d$ scattering in terms of the S-wave and P-wave scattering lengths of $\bar{K}N$ scattering. The estimated uncertainty of the complex P-wave scattering length is of about $15\,%$. For the calculated width $Γ_{2p} = 10.203\,{\rm meV}$ of the excited $2p$ state of kaonic deuterium we evaluate the yield $Y_{K^-d} = 0.27\,%$ of $X$-rays for the $K_α$ emission line of kaonic deuterium. Using the complex S-wave and P-wave scattering lengths of $\bar{K}N$ scattering, calculated in \cite{ECL1,Weise1}, we get the width $Γ_{2p} = 2.675\,{\rm meV}$ of the excited $2p$ state and the yield $Y_{K^-d} = 1.90 \,%$ of $X$-rays for the $K_α$ emission line of kaonic deuterium. The results, obtained in this paper, can be used for the planning of experiments on the measurements of the energy level displacement of the ground state of kaonic deuterium, caused by strong low-energy interactions.

nucl-th↗
arXiv2011

Position sensitive SiPM detector for Cherenkov applications

A prototype of a position sensitive photo-detector with 5.6 x 5.6 cm2 detection area readout with 64 Hamamatsu MPPCs (S10931-100P) with 3 x 3 mm2 active area each has been built and tested. The photo-sensors are arranged in a 8 x 8 array with a quadratic mirror light guide on top. The module is currently readout by in-house developed preamplifier boards but employing existing ASIC chips optimized for SiPM readout is also planned. Such a device is one of the candidates to be used for photon detection in the PANDA DIRC detectors.

physics.ins-det↗
arXiv2011

Kaonic 3He and 4He X-ray measurements in SIDDHARTA

The strong-interaction shift of kaonic 3He and 4He 2p states was measured using gaseous targets for the first time in the SIDDHARTA experiment. The determined shift of kaonic 4He is much smaller than the values obtained in the experiments performed in 70's and 80's. Thus, the problems in kaonic helium (the "kaonic helium puzzle") was definitely solved by our measurements. The first observation of the kaonic 3He X-rays was also achieved. The shift both of kaonic 3He and 4He was found to be as small as a few eV.

nucl-ex↗
arXiv2011

A New Measurement of Kaonic Hydrogen X rays

The $\bar{K}N$ 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 DA$Φ$NE 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 $ε_{1s} = -283 \pm 36 \pm 6 {(syst)}$ eV and $Γ_{1s} = 541 \pm 89 {(stat)} \pm 22 {(syst)}$ eV, respectively. The new values will provide vital constraints on the theoretical description of the low-energy $\bar{K}N$ interaction.

nucl-ex↗