We report on an exclusive and kinematically complete high-statistics measurement of the basic double-pionic fusion reaction $pn\to d{\pi }^0{\pi }^0$ over the full energy region of the ABC effect, a pronounced low-mass enhancement in the $\pi \pi$-invariant mass spectrum. The measurements, which cover also the transition region to the conventional $t$-channel $\Delta \Delta$ process, were performed with the upgraded WASA detector setup at COSY. The data reveal the Abashian-Booth-Crowe effect to be uniquely correlated with a Lorentzian energy dependence in the integral cross section. The observables are consistent with a narrow resonance with $m=2.37\mathrm{GeV}$, $\Gamma \approx 70\mathrm{MeV}$ and $I(J^P)=0(3^{+})$ in both $pn$ and $\Delta \Delta$ systems. Necessary further tests of the resonance interpretation are discussed.

Exclusive and kinematically complete high-statistics measurements of quasifree polarized $\overrightarrow{n}p$ scattering have been performed in the energy region of the narrow resonancelike structure $d^{*}$ with $I(J^P)=0(3^{+})$, $M\approx 2380\mathrm{MeV}$, and $\mathrm{\Gamma }\approx 70\mathrm{MeV}$ observed recently in the double-pionic fusion channels $pn\to d{\pi }^0{\pi }^0$ and $pn\to d{\pi }^{+}{\pi }^{-}$. The experiment was carried out with the WASA detector setup at COSY having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process $\overrightarrow{d}p\to np+p_{\text{spectator}}$. This allowed the $np$ analyzing power, $A_y$, to be measured over a broad angular range. The obtained $A_y$ angular distributions deviate systematically from the current SAID SP07 NN partial-wave solution. Incorporating the new $A_y$ data into the SAID analysis produces a pole in the ${}^3{D}_3-{}^3{G}_3$ waves in support of the $d^{*}$ resonance hypothesis.

Positronium created in a human body during PET scans hallmarks neoplastic tissues.

A detection system of the conventional PET tomograph is set-up to record data from [Formula: see text] annihilation into two photons with energy of 511 keV, and it gives information on the density distribution of a radiopharmaceutical in the body of the object. In this paper we explore the possibility of performing the three gamma photons imaging based on ortho-positronium annihilation, as well as the possibility of positronium mean lifetime imaging with the J-PET tomograph constructed from plastic scintillators. For this purposes simulations of the ortho-positronium formation and its annihilation into three photons were performed taking into account distributions of photons' momenta as predicted by the theory of quantum electrodynamics and the response of the J-PET tomograph. In order to test the proposed ortho-positronium lifetime image reconstruction method, we concentrate on the decay of the ortho-positronium into three photons and applications of radiopharmaceuticals labeled with isotopes emitting a prompt gamma. The proposed method of imaging is based on the determination of hit-times and hit-positions of registered photons which enables the reconstruction of the time and position of the annihilation point as well as the lifetime of the ortho-positronium on an event-by-event basis. We have simulated the production of the positronium in point-like sources and in a cylindrical phantom composed of a set of different materials in which the ortho-positronium lifetime varied from 2.0 ns to 3.0 ns, as expected for ortho-positronium created in the human body. The presented reconstruction method for total-body J-PET like detector allows to achieve a mean lifetime resolution of ∼40 ps. Recent positron annihilation lifetime spectroscopy measurements of cancerous and healthy uterine tissues show that this sensitivity may allow to study the morphological changes in cell structures.

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.Comment: Presented at the 2nd Jagiellonian Symposium on Fundamental and Applied Subatomic Physics, Krak\'ow, Poland, June 4-9, 2017. To be published in Acta Phys. Pol.