Regular Series


Vol. 47 (2016), No. 2, pp. 245 – 571


An Introduction to Mesic Nuclei

abstract

There is much speculation and a modest amount of evidence that certain mesons might form quasi-bound states with nuclei to produce really exotic states of matter. For this to be a practical possibility, the interaction between the meson and nucleons at low energies must be strong and attractive and the production rates “healthy”. The conditions for this are surveyed for the \(\bar {K}\), \(\eta \), \(\omega \), \(\eta ^{\prime }\), and \(\phi \) mesons. How this might lead to quasi-bound states is then discussed in a few typical cases. Though some interesting effects have been seen in above-threshold data, the search for experimental signals for these exotic states with different mesons in bound state regions has generally been rather frustrating, with positive claims only being made for the \(\eta \) and the \(K^-\).


Direct CP Violation and Rare \(K\) Decays Perspectives

abstract

Quark mixing and CP violation has been a very active area of investigation over the past decades. Owing to the last round of experiments in \(K\) and \(B\) mesons, our understanding is now completely compatible with the existence of just one phase in the Cabibbo–Kobayashi–Maskawa mixing matrix. The precision of the tests in the quark sector can further improve thanks to the interplay of theory and experiments. Flavour transitions are so sensitive to short distance mechanisms that we are compelled to press for more quantitative tests of the Standard Model (SM) studying rare processes involving quarks and leptons. This is especially important because the direct exploration of the energy frontier is currently limited at the LHC energies and may remain so for many years to come.


all authors

P. Adrich, A. Zając, P. Wilk, M. Chorowski, J. Poliński, P. Bogdan

Development of a Dedicated Beam-forming System for Material and Bioscience Research with High Intensity, Small Field Electron Beam of LILLYPUT 3 Accelerator at Wrocław Technology Park

abstract

The primary use of the LILLYPUT 3 accelerator at the Nondestructive Testing Laboratory at Wrocław Technology Park is X-ray radiography for nondestructive testing, including R&D of novel techniques for industrial and medical imaging. The scope of possible applications could be greatly extended by providing a system for irradiation with the electron beam. The purpose of this work was to design such a system, especially for high dose rate, small field irradiations under cryogenic conditions for material and bioscience research. In this work, two possible solutions, based either on the beam scanning or scattering and collimation, were studied and compared. It was found that under existing conditions, efficiency of both systems would be comparable. The latter one was adopted due to its simplicity and much lower cost. The system design was optimized by means of detailed Monte Carlo modeling. The system is being currently fabricated at the National Centre for Nuclear Research in Świerk.


X-ray Radiation Damage in Silicon Strip Detectors

abstract

The radiation damage effects in silicon strip and silicon pixel detectors caused by X-rays have become recently an important research topic driven mainly by development of new detectors for applications at the European X-ray Free Electron Laser (E-XFEL), where they will be exposed to extreme ionisation doses up to 1 GGy. Our investigation of radiation damage effects in a custom developed silicon strip detector to be used in laboratory diffractometers equipped with X-ray tubes shows that significant degradation of the detector performance occurs at low doses well below 100 Gy, which can be easily reached during normal operation of laboratory instruments. In the paper, basic mechanisms of radiation damage effects in silicon strip detectors are discussed and experimental results for a custom designed silicon strip detector for powder diffraction are presented.


MicroPattern Gaseous Detectors — New Developments and Applications

abstract

In recent years, there has been rapid research and development in the field of MicroPattern Gaseous Detectors (MPGDs). A variety of new applications have been implemented in many scientific disciplines, where the advantages of MPGD technology play a really important role. In this paper, a brief description of the evolution of MPGDs is presented, with particular focus on large projects and imaging applications.


Inside the Hydrogen Atom

abstract

We apply the non-linear Euler–Heisenberg theory to calculate the electric field inside the hydrogen atom. We will demonstrate that the electric field calculated in the Euler–Heisenberg theory can be much smaller than the corresponding field emerging from the Maxwellian theory. In the hydrogen atom, this happens only at very small distances. This effect reduces the large electric field inside the hydrogen atom calculated from the electromagnetic form-factors via the Maxwell equations. The energy content of the field is below the pair production threshold.


On Quasibound \(N^*\)–Nuclei

abstract

The possibility for the existence of unstable bound states of the \(S\)11 nucleon resonance \(N^*\)(1535) and nuclei is investigated. These quasibound states are speculated to be closely related to the existence of the quasibound states of the eta mesons and nuclei. Within a simple model for the \(N N^*\) interaction involving a pion and eta meson exchange, \(N^*\)–nucleus potentials for \(N^*\)–\(^3\)He and \(N^*\)–\(^{24}\)Mg are evaluated and found to be of a Woods–Saxon-like form which supports two to three bound states. In the case of \(N^*\)–\(^3\)He, one state bound by only a few keV and another by 4 MeV is found. The results are however quite sensitive to the \(N N^*\pi \) and \(N N^* \eta \) vertex parameters. A rough estimate of the width of these states, based on the mean free path of the exchanged mesons in the nuclei, leads to very broad states with \({\mit \Gamma } \sim 80\) and 110 MeV for \(N^*\)–\(^3\)He and \(N^*\)–\(^{24}\)Mg respectively.


Recent Results from LHCb

abstract

The LHCb detector is a single-arm forward spectrometer that collects data at the LHC. In this review, a few of recent results in the field of \(b\)-hadron decays performed by the LHCb Collaboration are presented. The analyses use proton–proton collision data corresponding to 3 fb\(^{-1}\) collected by the LHCb detector during 2011 and 2012 physics runs with the center-of-mass energies of 7 and 8 TeV.


Use of MAGIC Gel for Diagnostic Nuclear Medicine Dosimetry

abstract

Dosimetry using polymer gel is a promising technique used by medical physicists to check the spatial distribution of the dose delivered by radiation techniques. In this study, MAGIC gel was used as a dosimeter in nuclear medicine. Different amounts of Tc-99m solution were mixed with the polymer gel in six glass vials. The normoxic MAGIC gel was used to study its sensitivity to unsealed sources, the range of radioactivity introduced in the polymer gel is between 0 and 666 MBq. MRI was used to evaluate the response of the polymer gels after the radioactive decay of the radionuclide. \(D\) dose is calculated using the formalism of MIRD. Preliminary results of this work were used to study the effect of low energies on the polymerization rate, and to establish a relationship between the absorbed dose and the activity of radioactive sources considered based on the calculated values of the polymer gel T2.


all authors

I. Ciepał, A. Kozela, B. Głowacz, P. Kulessa, T. Pałasz, I. Skwira-Chalot, B. Włoch

Possibility of Measurement of Cross Section and Vector Analyzing Powers of \(p-^{3}\)He Scattering at the Bronowice Cyclotron Center

abstract

A new possibility of continuation of few-nucleon dynamics studies at medium energies has appeared together with a new facility at the Institute of Nuclear Physics PAN in Kraków — The Bronowice Cyclotron Center (CCB). The new cyclotron PROTEUS provides a proton beam in an energy range of 70–230 MeV. Current progress in the theoretical calculations for four-nucleon (\(4N\)) systems is a main motivation to investigate \(p-^{3}\)He scattering. Due to the fact that the beam cannot be polarized, the only possibility to study spin observables is to build a polarized \(^{3}\)He target system. A planned experiment assumes the construction of a cylindrical double Pyrex cell with separated pumping and target chambers with an additional polyamide film covering apertures for the passing beam and the reaction products. To polarize \(^{3}\)He gas, the spin-exchange optical pumping method will be used.


all authors

A.K. Biegun, J. Takatsu, M-J. van Goethem, E.R. van der Graaf, M. van Beuzekom, J. Visser, S. Brandenburg

Proton Radiography to Improve Proton Radiotherapy: Simulation Study at Different Proton Beam Energies

abstract

To improve the quality of cancer treatment with protons, a translation of X-ray Computed Tomography (CT) images into a map of the proton stopping powers needs to be more accurate. Proton stopping powers determined from CT images have systematic uncertainties in the calculated proton range in a patient of typically \(3\)–\(4\%\) and even up to 10% in a region containing bone. As a consequence, part of a tumor may receive no dose, or a very high dose can be delivered in healthy tissues and organs at risks (e.g.  brain stem). A transmission radiograph of high-energy protons measuring proton stopping powers directly will allow to reduce these uncertainties, and thus improve the quality of treatment. The best way to obtain a sufficiently accurate radiograph is by tracking individual protons traversing the phantom (patient). In our simulations, we have used an ideal position sensitive detectors measuring a single proton before and after a phantom, while the residual energy of a proton was detected by a BaF\(_{2}\) crystal. To obtain transmission radiographs, different phantom materials have been irradiated with a \(3\times 3\) \(\mathrm {cm}^{2}\) scattered proton beam, with various beam energies. The simulations were done using the Geant4 simulation package. In this study, we focus on the simulations of the energy loss radiographs for various proton beam energies that are clinically available in proton radiotherapy.


Optimisation of the X-ray Fluorescence Imaging System for Mapping of Pigments in Historical Paintings

abstract

The basic principle of operation of the X-ray fluorescence imaging system of cultural heritage painting has already been proven and presented elsewhere. In this paper, we report on optimisation of the pilot imaging system based on Gas Electron Multiplier (GEM) detector, a pinhole camera and a dedicated data acquisition system (DAQ). We focus on evaluation of detection capability of the system for various combinations of the pigments layouts. Carefully designed and prepared painting phantom with stripes, which overlay each other, has been investigated. The selected pigments and their composition were chosen in such a way that the energy resolution of the system was critical capability of reviling hidden layers. Even though the investigated pigments are based on elements which differ in \(Z\) by one, the system is capable to distinguish them well.


A Discovery of the Dibaryon State with WASA-at-COSY

abstract

The Juelich Cooler Synchrotron (COSY) has been dedicated to the investigation of nucleon–nucleon interactions. Together with the Wide Angular Shower Apparatus (WASA) detector, it has been particularly well-suited for the search of exotic phenomena in baryon–baryon systems. Recent experiments with WASA-at-COSY have now found support for a new resonant state in the two-baryon system with mass 2380 MeV and a width of 70 MeV — the first non-trivial dibaryon resonance. A review on this issue is given in this paper.


Beta-decay Correlations in the LHC Era

abstract

Neutron and nuclear beta-decay correlation coefficients are linearly sensitive to the exotic scalar and tensor interactions that are not included in the Standard Model. The proposed experiment will measure simultaneously 11 neutron correlation coefficients (\(a\), \(A\), \(B\), \(D\), \(H\), \(L\), \(N\), \(R\), \(S\), \(U\), \(V\)) where 5 of them (\(H\), \(L\), \(S\), \(U\), \(V\)) were never addressed before. Silicon pixel detectors are considered as promising alternative to multi-wire gas chambers devoted to electron tracking in the original setup. The expected sensitivity limits for \(\epsilon _{\mathrm {S}}\) and \(\epsilon _{\mathrm {T}}\) — EFT parameters describing the scalar and tensor contributions to be extracted from the transverse electron polarization related coefficients \(H\), \(L\), \(N\), \(R\), \(S\), \(U\), \(V\) are discussed.


all authors

E. Oset, M. Bayar, A. Doté, T. Hyodo, K.P. Khemchandani, W.H. Liang, A. Martinez Torres, M. Oka, L. Roca, T. Uchino, C.W. Xiao

Two-, Three-, Many-body Systems Involving Mesons. Multimeson Condensates

abstract

In this paper, we review results from studies with unconventional many-hadron systems containing mesons: systems with two mesons and one baryon, three mesons, some novel systems with two baryons and one meson, and finally, systems with many vector mesons, up to six, with their spins aligned forming states of increasing spin. We show that in many cases, one has experimental counterparts for the states found, while in some other cases, they remain as predictions, which we suggest to be searched in BESIII, Belle, LHCb, FAIR and other facilities.


Formation of \(\eta '(958)\) Bound States by \((\gamma ,d)\) Reaction

abstract

We have investigated the \(^6{\rm Li}(\gamma ,{d})\) reaction theoretically for the formation of the \(\eta '(958)\) mesic nucleus. We have reported the numerical results in this article.


\(\eta '\) Interactions with Nucleons and Nuclei

abstract

We summarise recent progress in theory and experiment towards understanding of \(\eta '\)-meson interactions with nucleons and nuclei. Highlights include the production mechanism of \(\eta '\) mesons in proton–proton collisions close to the threshold, the \(\eta '\) effective mass shift in nuclei and the determination of the \(\eta '\)-nucleon scattering length in free space.


Search for Pentaquark \({\mit \Theta }^{+}\) in Hadronic Reaction at J-PARC

abstract

A variety of nuclear and hadron physics experiments are being performed using meson beams at the J-PARC Hadron Facility. As the first experiment at the facility, the pentaquark \({\mit \Theta }^{+}\) was searched for in the \(\pi ^{-}p \rightarrow K^{-}X\) reaction with a missing-mass resolution of 2 MeV (FWHM). The number of accumulated beam pions are \(7.8\times 10^{10}\) and \(8.1\times 10^{10}\) for different beam momenta of 1.92 and 2.01 GeV/\(c\), respectively. No significant structure was observed in the missing-mass spectra. Upper limits of the production cross section are obtained to be \(0.28~\mu \)b/sr in the laboratory frame at \(90\%\) confidence level for each beam momenta. With a help of theoretical models, an upper limit of the total decay width of \({\mit \Theta }^{+}\) was estimated to be 0.36 and 1.9 MeV for \(J^{P}=1/2^{+}\) and \(1/2^{-}\) states, respectively.


Statistical Features of the Thermal Neutron Capture Cross Sections

abstract

We discuss the existence of huge thermal neutron capture cross sections in several nuclei. The values of the cross sections are several orders of magnitude bigger than expected at these very low energies. We lend support to the idea that this phenomenon is random in nature and is similar to what we have learned from the study of parity violation in the actinide region. The idea of statistical doorways is advanced as a unified concept in the delineation of large numbers in the nuclear world. The average number of maxima per unit mass, \(\langle n_A\rangle \) in the capture cross section is calculated and related to the underlying cross section correlation function and found to be \(\langle n_A\rangle = 3/(\pi \sqrt {2}\gamma _{A})\), where \(\gamma _{A}\) is a characteristic mass correlation width which designates the degree of remnant coherence in the system. We trace this coherence to nucleosynthesis which produced the nuclei whose neutron capture cross sections are considered here.


Populating Low-spin States in Radioactive Nuclei to Measure Magnetic Moments Using the Transient Field Technique

abstract

The experimental study of magnetic moments for nuclear states near the ground state, \(I \ge 2\), provides a powerful tool to test nuclear structure models. The study of magnetic moments in nuclei far away from the stability line is the next frontier in such studies. Two techniques have been utilized to populated low-spin states in radioactive nuclei: Coulomb excitation reactions using radioactive nuclei, and the transfer of \(\alpha \) particles to stable beams. A presentations of these two techniques, along with the experimental challenges presented for future uses with nuclei far away from the stability line, will be presented.


all authors

G. Khatri, W. Parol, K. Bodek, I. Ciepał, B. Jamroz, N. Kalantar-Nayestanaki, St. Kistryn, B. Kłos, A. Kozela, P. Kulessa, A. Magiera, I. Mazumdar, J.G. Messchendorp, D. Rozpędzik, I. Skwira-Chalot, E. Stephan, A. Wilczek, B. Włoch, A. Wrońska, J. Zejma

Deuteron–Deuteron Collision at 160 MeV

abstract

The experiment was carried out using BINA detector at KVI in Groningen. For the first time, an extensive analysis of the data collected in back part of the detector is presented, where a clusterization method is utilized for angular and energy information. We also present differential cross sections for the (\(dd \rightarrow dpn\)) breakup reaction within \(dp\) quasi-free scattering limit and their comparison with first calculations based on Single Scattering Approximation (SSA) approach.


Discrete Symmetries CP, T, CPT

abstract

The role of symmetry breaking mechanisms to search for new physics is of highest importance. We discuss the status and prospects of the discrete symmetries CP, T, CPT looking for their separate violation in LHC experiments and meson factories.


all authors

M. Kaczmarska, I. Habina, A. Orzechowska, K. Niemiec-Murzyn, M. Fornal, W. Pohorecki, K. Matlak, J. Korecki, T. Grodzicki, K. Burda

Influence of Neutron Radiation on the Stability of the Erythrocyte Membrane and an Oxyhemoglobin Formation — Petkau Effect Studies

abstract

This paper examines the influence of a low dose of neutron radiation of 111 \(\mu \)Gy (1.418 mSv — ICRP21, 1.277 mSv — ICRP74) on the stability of human red blood cells (RBCs). In the range of \(\mu \)Gy doses, ionizing radiation may cause a serious oxidative stress in living organisms due to the Petkau effect. RBCs were chosen because their structure and function are well known, so they can be used as a model system for studying the influence of ionizing radiation on mammalian cell membranes. Atomic force microscopy (AFM) is applied to analyze the topography of RBCs, their shape and membrane-skeleton network, along with the Mössbauer spectroscopy to monitor different states of hemoglobin (Hb) and its ability to bind or release O\(_2\) in untreated and irradiated erythrocytes. We find that neutron radiation at a dose of 111 \(\mu \)Gy causes a shape change of RBCs and a stretching of the spectrin network. In addition, it modifies the permeability of erythrocyte membrane to gases and slows down the O\(_2\) rebinding by Hb by a factor of 4 in comparison to untreated red cells. We also observe that a new form of Hb\(_{\mathrm {irr}}\) occurs at a level of about 6%.


Study of the Radiation Induced Effects in the LHCb Vertex Locator

abstract

LHCb is a dedicated heavy-flavour physics experiment at the Large Hadron Collider at CERN. The VErtex LOcator (VELO) is a critical part of a LHCb tracking system, enabling the full topological reconstruction of beauty and charm mesons’ decays and providing essential input for the High Level Trigger (HLT) system used by the experiment to select events. The VELO comprises 42 modules made of two \(n^{+}\)-on-\(n~300~\mu \)m thick half-disc silicon sensors with \(R\)- and \({\mit \Phi }\)-measuring micro-strips, arranged in two retractable halves, operating only about 8 mm from the proton beams. In these paper, selected aspects of the VELO performance during the Run 1 data-taking period is shortly summarised along with the radiation damage studies. The track finding efficiency is typically greater than 98%. An impact parameter resolution of less than \(35~\mu \)m is achieved for particles with transverse momentum greater than 1 GeV/\(c\). An overview of all important performance parameters will be given. The VELO sensors have received a large and non-uniform radiation dose of up to \(1.2 \times 10^{14}\) 1 MeV neutron equivalent cm\(^{-2}\). Silicon-type inversion has been observed in regions close to the interaction point.


Unconventional Imaging in Ion Beam Therapy: Status and Perspectives

abstract

Owing to their favorable physics interaction properties, ion beams can offer unprecedented ballistic accuracy for highly conformal irradiation of complex-shaped tumour volumes, with excellent sparing of surrounding healthy tissue and critical organs. However, these advantageous dosimetric properties also bear enhanced sensitivity to uncertainties in treatment planning and delivery, calling for an increasing need of advanced imaging to ensure safe application of the intended dose to the targeted area during the entire course of fractionated therapy. Although it is common perception that in-room image-guidance of particle therapy is still lagging behind modern integrated solutions of photon therapy, new technological developments are being pursued by several groups to exploit the unique features of ion beam interaction in matter for innovative image-guidance concepts, with particular focus on in vivo verification of the ion beam range.


all authors

B. Jasińska, M. Gorgol, M. Wiertel, R. Zaleski, D. Alfs, T. Bednarski, P. Białas, E. Czerwiński, K. Dulski, A. Gajos, B. Głowacz, D. Kamińska, Ł. Kapłon, G. Korcyl, P. Kowalski, T. Kozik, W. Krzemień, E. Kubicz, M. Mohammed, Sz. Niedźwiecki, M. Pałka, L. Raczyński, Z. Rudy, O. Rundel, N.G. Sharma, M. Silarski, A. Słomski, A. Strzelecki, A. Wieczorek, W. Wiślicki, B. Zgardzińska, M. Zieliński, P. Moskal

Determination of the \(3\gamma \) Fraction from Positron Annihilation in Mesoporous Materials for Symmetry Violation Experiment with J-PET Scanner

abstract

Various mesoporous materials were investigated to choose the best material for experiments requiring high yield of long-lived positronium. We found that the fraction of \(3\gamma \) annihilation determined using \(\gamma \)-ray energy spectra and positron annihilation lifetime spectra (PAL) changed from 20% to 25%. The \(3\gamma \) fraction and o-Ps formation probability in the polymer XAD-4 is found to be the largest. Elemental analysis performed using scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscope EDS shows high purity of the investigated materials.


Dark Forces Searches at KLOE-2

abstract

Direct searches of dark matter are performed at accelerator facilities. The existence of a new vector boson has been postulated in different scenarios where in the most basic scheme the coupling to the SM can be achieved via a kinetic mixing term due to the \(U\) boson. The KLOE experiment at DA\(\Phi \)NE searched for the \(U\) boson both in Dalitz decays of the \(\phi \) meson and in continuum events. For all of these searches, an upper limit for the \(U\) boson coupling \(\epsilon ^{2}\) has been established in the mass range of \(50~{\rm MeV} \lt m_U \lt 1000\) MeV. A summary of the different models and searches along with results are presented.


Meson Assisted Dibaryons

abstract

We discuss a new type of \(L=0\) positive-parity dibaryons, \(\pi BB'\), where the dominant binding mechanism is provided by resonating p-wave pion–baryon interactions. Recent calculations of such pion assisted dibaryons are reviewed with special emphasis placed on the non-strange \(I(J^P)=1(2^+)\) \(N\!{\mit \Delta }\) dibaryon \({\cal D}_{12}(2150)\) studied recently at JLab, and on the \(0(3^+)\) \({\mit \Delta \Delta }\) dibaryon \({\cal D}_{03}(2380)\) discovered recently by the WASA-at-COSY Collaboration. We discuss recent searches by the HADES Collaboration at GSI and by the E15 and E27 Experiments at J-PARC for a strangeness \({\cal S}=-1\) \(I(J^P)=\frac {1}{2}(0^-)\) \(K^{-}pp\) dibaryon and perhaps also for a strange \(I(J^P)=\frac {3}{2}(2^+)\) \(N{\mit \Sigma }(1385)\) pion assisted dibaryon \({\cal Y}_{\frac {3}{2}2}(2270)\). Charm \({\cal C}=+1\) dibaryons, predicted with the same \(I(J^P)\) values, are also briefly reviewed.


The Cosmological Constant and Stability of the Higgs Vacuum

abstract

We discuss the cosmological constant puzzle and possible connections to the (meta-)stability of the Higgs vacuum suggested by recent LHC results. A possible explanation involves new critical phenomena in the ultraviolet, close to the Planck scale.


all authors

G. Korcyl, D. Alfs, T. Bednarski, P. Białas, E. Czerwiński, K. Dulski, A. Gajos, B. Głowacz, B. Jasińska, D. Kamińska, Ł. Kapłon, P. Kowalski, T. Kozik, W. Krzemień, E. Kubicz, M. Mohammed, Sz. Niedźwiecki, M. Pałka, M. Pawlik-Niedźwiecka, L. Raczyński, Z. Rudy, O. Rundel, N.G. Sharma, M. Silarski, A. Słomski, K. Stoła, A. Strzelecki, A. Wieczorek, W. Wiślicki, B.K. Zgardzińska, M. Zieliński, P. Moskal

Sampling FEE and Trigger-less DAQ for the J-PET Scanner

abstract

In this paper, we present a complete Data Acquisition System (DAQ) together with the readout mechanisms for the J-PET tomography scanner. In general, detector readout chain is constructed out of Front-End Electronics (FEE) measurement devices such as Time-to-Digital or Analog-to-Digital Converters (TDCs or ADCs), data collectors and storage. We have developed a system capable for maintaining continuous readout of digitized data without preliminary selection. Such operation mode results in up to 8 Gbps data stream, therefore, it is required to introduce a dedicated module for on-line event building and feature extraction. The Central Controller Module, equipped with Xilinx Zynq SoC and 16 optical transceivers, serves as such true real time computing facility. Our solution for the continuous data recording (trigger-less) is a novel approach in such detector systems and assures that most of the information is preserved on the storage for further, high-level processing. Signal discrimination applies a unique method of using LVDS buffers located in the FPGA fabric.


Design of the SABAT System for Underwater Detection of Dangerous Substances

abstract

We present status of simulations used to design a novel device for the detection of hazardous substances in the aquatic environment using neutron activation. Unlike the other considered methods based on this technique, we propose to use guides for neutron and gamma quanta which speeds up and simplifies identification. First preliminary results show that both the neutron guide and the \(\gamma \)-ray guide increase the performance of underwater threats detection.


Upper Limits for the Production of the \(\eta \)-mesic Helium in the \(dd\rightarrow ^{3}\)He\(n\pi ^0\) and \(dd\rightarrow ^3\)He\(p\pi ^-\) Reactions

abstract

We performed a search for \(^{4}\mathrm {He}\)–\(\eta \) bound state in \(dd\rightarrow \) \(^{3}\mathrm {He} n \pi {}^{0}\) and \(dd\rightarrow \) \(^{3}\mathrm {He} p \pi {}^{-}\) reactions with the WASA-at-COSY facility using a ramped beam technique. The measurement was carried out with high statistics and high acceptance. The signature of \(\eta \)-mesic nuclei was searched for by the measurement of the excitation functions in the vicinity of the \(\eta \) production threshold for each of the considered channels. We did not observe the narrow structure which could be interpreted as a bound state. The preliminary upper limits of the total cross sections for the bound state production and decay varies from 21 nb to 36 nb for the \(dd\rightarrow \) \(^{3}\mathrm {He} n \pi {}^{0}\) channel, and from 5 nb to 9 nb for the \(dd\rightarrow \mathrm {^{3}He} p \pi ^{-}\) channel for the bound state width ranging from 5 to 50 MeV.


all authors

P. Moskal, D. Alfs, T. Bednarski, P. Białas, E. Czerwiński, C. Curceanu, A. Gajos, B. Głowacz, M. Gorgol, B.C. Hiesmayr, B. Jasińska, D. Kamińska, G. Korcyl, P. Kowalski, T. Kozik, W. Krzemień, N. Krawczyk, E. Kubicz, M. Mohammed, Sz. Niedźwiecki, M. Pawlik-Niedźwiecka, L. Raczyński, Z. Rudy, M. Silarski, A. Wieczorek, W. Wiślicki, M. Zieliński

Potential of the J-PET Detector for Studies of Discrete Symmetries in Decays of Positronium Atom — A Purely Leptonic System

abstract

The Jagiellonian Positron Emission Tomograph (J-PET) was con- structed 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 eigenstate 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 (\(\sim \!10^{-14}\)) and photon–photon interactions expected at the level of (\(\sim \!10^{-9}\)). 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.


all authors

E. Kubicz, M. Silarski, A. Wieczorek, D. Alfs, T. Bednarski, P. Białas, E. Czerwiński, A. Gajos, B. Głowacz, B. Jasińska, D. Kamińska, G. Korcyl, P. Kowalski, T. Kozik, W. Krzemień, M. Mohammed, I. Moskal, S. Niedźwiecki, M. Pawlik-Niedźwiecka, L. Raczyński, Z. Rudy, A. Strzelecki, W. Wiślicki, M. Zieliński, B. Zgardzińska, P. Moskal

Beam Profile Investigation of the New Collimator System for the J-PET Detector

abstract

Jagiellonian Positron Emission Tomograph (J-PET) is a multi-purpose detector which will be used for search for discrete symmetries violations in the decays of positronium atoms and for investigations with positronium atoms in life-sciences and medical diagnostics. In this article, we present three methods for determination of the beam profile of collimated annihilation gamma quanta. Precise monitoring of this profile is essential for time and energy calibration of the J-PET detector and for the determination of the library of model signals used in the hit-time and hit-position reconstruction. We have shown that usage of two lead bricks with dimensions of \(5 \times 10 \times 20\) cm\(^{3}\) enables to form a beam of annihilation quanta with Gaussian profile characterized by 1 mm FWHM. Determination of this characteristic is essential for designing and construction the collimator system for the 24-module J-PET prototype. Simulations of the beam profile for different collimator dimensions were performed. This allowed us to choose optimal collimation system in terms of the beam profile parameters, dimensions and weight of the collimator taking into account the design of the 24-module J-PET detector.


all authors

P. Kowalski, W. Wiślicki, L. Raczyński, D. Alfs, T. Bednarski, P. Białas, E. Czerwiński, A. Gajos, B. Głowacz, J. Jasińska, D. Kamińska, G. Korcyl, T. Kozik, W. Krzemień, E. Kubicz, M. Mohammad, Sz. Niedźwiecki, M. Pałka, M. Pawlik-Niedźwiecka, Z. Rudy, M. Silarski, A. Wieczorek, B. Zgardzińska, M. Zieliński, P. Moskal

Scatter Fraction of the J-PET Tomography Scanner

abstract

A novel Positron Emission Tomography system, based on plastic scintillators, is being developed by the J-PET Collaboration. In this article, we present the simulation results of the scatter fraction, representing one of the parameters crucial for background studies defined in the NEMA-NU-2-2012 norm. We elaborate an event selection methods allowing to suppress events in which gamma quanta were scattered in the phantom or underwent the multiple scattering in the detector. The estimated scatter fraction for the single-layer J-PET scanner varies from 37% to 53% depending on the applied energy threshold.


all authors

W. Krzemień, D. Alfs, P. Białas, E. Czerwiński, A. Gajos, B. Głowacz, B. Jasińska, D. Kamińska, G. Korcyl, P. Kowalski, T. Kozik, E. Kubicz, Sz. Niedźwiecki, M. Pawlik-Niedźwiecka, L. Raczyński, Z. Rudy, M. Silarski, A. Strzelecki, A. Wieczorek, W. Wiślicki, M. Zieliński, P. Moskal

Overview of the Software Architecture and Data Flow for the J-PET Tomography Device

abstract

Modern TOF-PET scanner systems require high-speed computing resources for efficient data processing, monitoring and image reconstruction. In this article, we present the data flow and software architecture for the novel TOF-PET scanner developed by the J-PET Collaboration. We discuss the data acquisition system, reconstruction framework and image reconstruction software. Also, the concept of computing outside hospitals in the remote centers such as Świerk Computing Centre in Poland is presented.


ERRATUM for Acta Phys. Pol. B 46, 757 (2015)

Search for \(\eta \)-mesic Nuclei with WASA-at-COSY


ERRATUM for Acta Phys. Pol. B 46, 133 (2015)

Luminosity Determination for the Deutron–Deutron Reactions Using Free and Quasi-free Reactions with WASA-at-COSY Detector


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