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M. Silarski

Publications and source records attributed to M. Silarski.

At least 127 records · Page 7Linked to original sources
arXiv2013

Application of WLS strips for position determination in Strip PET tomograph based on plastic scintillators

A method of determination of a gamma quantum absorption point in a plastic scintillator block using a matrix of wavelength-shifting (WLS) strips is proposed. Application of this method for improvement of position resolution in newly proposed PET detectors based on plastic scintillators is presented. The method enables to reduce parallax errors in reconstruction of images which occurs in the presently used Positron Emission Tomography scanners.

physics.ins-det↗
arXiv2013

A novel method based solely on FPGA units enabling measurement of time and charge of analog signals in Positron Emission Tomography

This article presents a novel technique for precise measurement of time and charge based solely on FPGA (Field Programmable Gate Array) device and few satellite discrete electronic components used in Positron Emission Tomography (PET). Described approach simplifies electronic circuits, reduces the power consumption, lowers costs, merges front-end electronics with digital electronics and also makes more compact final design. Furthermore, it allows to measure time when analog signals cross a reference voltage at different threshold levels with a very high precision of $\sim$ 10ps (rms) and thus enables sampling of signals in a voltage domain.

physics.ins-det↗
arXiv2013

System Response Kernel Calculation for List-mode Reconstruction in Strip PET Detector

Reconstruction of the image in Positron Emission Tomographs (PET) requires the knowledge of the system response kernel which describes the contribution of each pixel (voxel) to each tube of response (TOR). This is especially important in list-mode reconstruction systems, where an efficient analytical approximation of such function is required. In this contribution, we present a derivation of the system response kernel for a novel 2D strip PET.

physics.med-ph↗
arXiv2013

Applications of neutron activation spectroscopy

Since the discovery in 1932, neutrons became a basis of many methods used not only in research, but also in industry and engineering. Among others, the exceptional role in the modern nuclear engineering is played by the neutron activation spectroscopy, based on the interaction of neutron flux with atomic nuclei. In this article we shortly describe application of this method in medicine and detection of hazardous substances.

physics.med-ph↗
arXiv2013

Study of the $K^+K^-$ final state interaction in proton-proton and electron-positron collisions

The strength of the kaon--antikaon interaction is a crucial quantity for many physics topics. It is for example, an important parameter in the discussion on the nature of the scalar resonances $a_{0}(980)$ and $f_{0}(980)$, in particular for their interpretation as $K\bar{K}$ molecules. So far, one of the few possibilities to study this interaction is the kaon pair production in multi particle exit channels like $pp \to ppK^+K^-$. In this article we present the latest results of the $K^+K^-$ interaction preformed based on near threshold data gathered at the Cooler Synchrotron COSY. We discuss also shortly perspectives for a new measurement of the kaon--antikaon scattering length in the $e^+e^-$ collisions.

hep-ph↗
arXiv2013

Recent results on hadron physics at KLOE

One of the basic motivations of the KLOE and KLOE-2 collaborations is the test of fundamental symmetries and the search for phenomena beyond the Standard Model via the hadronic and leptonic decays of ground-state mesons and via their production in the fusion of virtual gamma quanta exchanged between colliding electrons and positrons. This contribution includes brief description of results of recent analysis of the KLOE data aimed at (i) the search for the dark matter boson, (ii) determination of the hadronic and light-by-light contributions to the g-2 muon anomaly and (iii) tests of QCD anomalies.

hep-ex↗
arXiv2013

TOF-PET detector concept based on organic scintillators

In this contribution we present a new concept of the large acceptance detector systems based on organic scintillators which may allow for simultaneous diagnostic of large fraction of the human body. Novelty of the concept lies in employing large blocks of polymer scintillators instead of crystals as detectors of annihilation quanta, and in using predominantly the timing of signals instead of their amplitudes.

physics.ins-det↗
arXiv2013

STRIP-PET: a novel detector concept for the TOF-PET scanner

We briefly present a design of a new PET scanner based on strips of polymer scintillators arranged in a barrel constituting a large acceptance detector. The solution proposed is based on the superior timing properties of the polymer scintillators. The position and time of the reaction of the gamma quanta in the detector material will be determined based on the time of arrival of light signals to the edges of the scintillator strips.

physics.ins-det↗
arXiv2013

Novel detector systems for the Positron Emission Tomography

In this contribution we describe a novel solution for the construction of Positron Emission Tomograph. We present the device allowing for determination of the impact position as well as time and deph of interaction of the annihilation gamma quanta. The device is comprised of scintillation chamber consisting of organic scintillators surrounding the body of the patient. We discuss two possible solutions: (i) the tomograph built out of scintillator strips, and (ii) the tomograph built out of the scintillator plates. The application of the fast scintillators will enable to take advantage of the difference between time of the registration of the annihilation quanta. The invented method will permit to use a thick layers of detector material with the possibility of measuring the depth of the gamma quantum interaction (DOI) and the determination of their time of flight (TOF), and will allow for increasing the size of the diagnostic chamber without a significant increase of costs. The method is a subject of two patent applications which are based on the techniques used in the particle physics experiments.

physics.med-ph↗
arXiv2013

A new limit on the CP violating decay KS -> 3pi0 with the KLOE experiment

We have carried out a new direct search for the CP violating decay KS -> 3pi0 with 1.7 fb^-1 of e+e- collisions collected by the KLOE detector at the phi-factory DAFNE. We have searched for this decay in a sample of about 5.9 x 10^8 KS KL events tagging the KS by means of the KL interaction in the calorimeter and requiring six prompt photons. With respect to our previous search, the analysis has been improved by increasing of a factor four the tagged sample and by a more effective background rejection of fake KS tags and spurious clusters. We find no candidates in data and simulated background samples, while we expect 0.12 standard model events. Normalizing to the number of KS -> 2pi0 events in the same sample, we set the upper limit on BR(KS -> 3pi0 < 2.6 x 10^-8 at 90% C.L., five times lower than the previous limit. We also set the upper limit on the eta_000 parameter, |eta_000 | < 0.0088 at 90% C.L., improving by a factor two the latest direct measurement.

hep-ex↗
arXiv2013

Search for the CP violating $K_S \to 3π^0$ decay with the KLOE detector

We present a new search for the $K_S \to 3π^0$ decay performed with the KLOE detector operating at the DA$Φ$NE $ϕ$--factory. The $K_S$ mesons were tagged via registration of $K_L$ mesons which crossed the drift chamber without decaying and interacted with the KLOE electromagnetic calorimeter. The $K_S \to 3π^0$ decay was then searched requiring six prompt photons. To suppress background, originating from fake $K_S$ tags and $K_S \to 2π^0$ decays with additional two spurious clusters, we have performed a discriminant analysis based on kinematical fit, testing of the signal and background hypotheses and exploiting of the differences in kinematics of the $K_S$ decays into $2π^0$ and $3π^0$. In a sample of about 1.7$\cdot 10^9$ $ϕ\to K_S K_L$ events we have found no candidates in data and simulated background samples. Normalizing to the number of $K_S \to 2π^0$ events in the same sample, we have set the upper limit on the $K_S \to 3π^0$ branching ratio BR($K_S \to 3π^0) < 2.6 \cdot 10^{-8}$ at 90% C.L., five times lower than the previous limit. This upper limit can be translated into a limit on the modulus of the $η_{000}$ parameter amounting to $|η_{000}| < 0.0088$ at 90% C.L., improving by a factor two the latest direct measurement.

hep-ex↗
arXiv2013

Precision measurement of $σ(e^+e^-\rightarrowπ^+π^-γ)/σ(e^+e^-\rightarrow μ^+μ^-γ)$ and determination of the $π^+π^-$ contribution to the muon anomaly with the KLOE detector

We have measured the ratio $σ(e^+e^-\rightarrowπ^+π^-γ)/σ(e^+e^-\rightarrow μ^+μ^-γ)$, with the KLOE detector at DA$Φ$NE for a total integrated luminosity of $\sim$ 240 pb$^{-1}$. From this ratio we obtain the cross section $σ(e^+e^-\rightarrowπ^+π^-)$. From the cross section we determine the pion form factor $|F_π|^2$ and the two-pion contribution to the muon anomaly $a_μ$ for $0.592<M_{ππ}<0.975$ GeV, $Δ^{ππ} a_μ$= $({\rm 385.1\pm1.1_{stat}\pm2.7_{sys+theo}})\times10^{-10}$. This result confirms the current discrepancy between the Standard Model calculation and the experimental measurement of the muon anomaly.

hep-ex↗
arXiv2013

Search for the CP symmetry violation in the decays of Ks mesons using the KLOE detector

The aim of this work was to determine the KS -> 3pi0 decay branching ratio and a modulus of the eta000 parameter, defined as the ratio of amplitudes for KS -> 3 pi0 to KL -> 3pi0 decays, which characterizes the CP symmetry violation in this decay. The measurement has been carried out with the KLOE detector operating at the phi-factory DAFNE in the Italian National Center for Nuclear Physics in Frascati. The KS mesons were identified with high efficiency via registration of these KL mesons which crossed the drift chamber without decaying and then interacted with the KLOE electromagnetic calorimeter. The KS four-momentum vector was then determined using the registered position of the KL meson and the known momentum of the phi meson. Next, the search for the KS -> 3pi0 -> 6gamma decay was carried out by the selection of events with six gamma quanta which momenta were reconstructed using time and energy measured by the electromagnetic calorimeter. To increase the signal over background ratio after identification of the KS meson and requiring six reconstructed photons a discriminant analysis is performed. It is based on kinematical fit, testing of the signal and background hypotheses and exploiting of the differences in kinematics of the KS decays into 2pi0 and 3pi0. Hence, we have obtained the upper limit on the KS -> 3pi0 branching ratio at the 90% confidence level BR(KS -> 3pi0)< 2.7 x 10^-8, which is almost five times lower than the latest published result. The search for the KS -> 3pi0 decay presented in this work failed to detect a signal of sufficient statistical significance. This upper limit can be translated into a limit on the modulus of the eta000 parameter amounting to: |eta000| < 0.009 at the 90% confidence level.

hep-ex↗
arXiv2013

Search for the $ K_S to 3 π^0$ decay with the KLOE detector

The $K_S \to 3 π^0$ decay is a pure CP violating process which, assuming CPT invariance, allows one to investigate direct CP violation. This decay has not been observed so far, and the best upper limit on the branching ratio $BR(K_S to 3π^0) < 1.2 \cdot 10^{-7}$ is two orders of magnitude larger than predictions based on the Standard Model: $BR(K_S \to 3π^0) \sim 2 \cdot 10^{-9}$. In this article we present the search for the $K_S \to 3π^0$ decay performed with the KLOE detector operating at the DAFNE Φ-factory at the Frascati Laboratory. We describe the analysis techniques used in the background rejection and signal events selection as well as the evaluation of almost five times lower upper limit on the $K_S \to 3π^0$ branching ratio. We discuss shortly also the perspectives for a new measurement using the KLOE-2 apparatus equipped with a new inner tracker and the calorimeters at low theta angle.

hep-ex↗
arXiv2013

Limit on the production of a light vector gauge boson in phi meson decays with the KLOE detector

We present a new limit on the production of a light dark-force mediator with the KLOE detector at DAPHNE. This boson, called U, has been searched for in the decay phi --> eta U, U --> e+ e-, analyzing the decay eta --> pi0 pi0 pi0 in a data sample of 1.7 fb-1. No structures are observed in the e+e- invariant mass distribution over the background. This search is combined with a previous result obtained from the decay eta --> pi+ pi- pi0, increasing the sensitivity. We set an upper limit at 90% C.L. on the ratio between the U boson coupling constant and the fine structure constant of alpha'/alpha < 1.7x10^-5 for 30<M_U<400 MeV and alpha'/alpha < 8x10^-6 for the sub-region 50<M_U<210 MeV. This result assumes the Vector Meson Dominance expectations for the phietagamma^* transition form factor. The dependence of this limit on the transition form factor has also been studied.

hep-ex↗
arXiv2012

Measurement of η meson production in γγ interactions and Γ(η-->γγ) with the KLOE detector

We present a measurement of η meson production in photon-photon interactions produced by electron-positron beams colliding with \sqrt{s}=1 GeV. The measurement is done with the KLOE detector at the ϕ-factory DAΦNE with an integrated luminosity of 0.24 fb^{-1}. The e^+e^- --> e^+e^-η cross section is measured without detecting the outgoing electron and positron, selecting the decays η-->π^+π^-π^0 and η-->π^0π^0π^0. The most relevant background is due to e^+e^- --> ηγ when the monochromatic photon escapes detection. The cross section for this process is measured as σ(e^+e^- -->ηγ) = (856 \pm 8_{stat} \pm 16_{syst}) pb. The combined result for the e^+e^- -->e^+e^-η cross section is σ(e^+e^- -->e^+e^-η) = (32.72 \pm 1.27_{stat} \pm 0.70_{syst}) pb. From this we derive the partial width Γ(η-->γγ) = (520 \pm 20_{stat} \pm 13_{syst}) eV. This is in agreement with the world average and is the most precise measurement to date.

hep-ex↗
arXiv2012

Measurement of Γ(η-> π^+π^-γ)/Γ(η-> π^+π^-π^0) with the KLOE Detector

The ratio R_η=Γ(η-> π^+π^-γ)/Γ(η-> π^+π^-π^0) has been measured by analyzing 22 million ϕ\to ηγdecays collected by the KLOE experiment at DA\PhiNE, corresponding to an integrated luminosity of 558 pb^{-1}. The η\to π^+π^-γproceeds both via the ρresonant contribution, and possibly a non-resonant direct term, connected to the box anomaly. Our result, R_η= 0.1856\pm 0.0005_{stat} \pm 0.0028_{syst}, points out a sizable contribution of the direct term to the total width. The di-pion invariant mass for the η-> π^+π^-γdecay could be described in a model-independent approach in terms of a single free parameter, α. The determined value of the parameter αis α= (1.32 \pm 0.08_{stat} +0.10/-0.09_{syst}\pm 0.02_{theo}) GeV^{-2}

hep-ex↗