Emission patterns of neutral pions in 40 A MeV Ta+Au reactions

Differential cross sections of neutral pions emitted in 181Ta + 197Au collisions at a beam energy of 39.5A MeV have been measured with the photon spectrometer TAPS. The kinetic energy and transverse momentum spectra of neutral pions cannot be properly described in the framework of the thermal model, nor when the reabsorption of pions is accounted for in a phenomenological model. However, high energy and high momentum tails of the pion spectra can be well fitted through thermal distributions with unexpectedly soft temperature parameters below 10 MeV.Comment: 16 pages (double-spaced), 5 figures; corrections after referee's comments and suggestion

Systematics of pion emission in heavy ion collisions in the 1A GeV regime

Using the large acceptance apparatus FOPI, we study pion emission in the reactions (energies in GeV/nucleon are given in parentheses): 40Ca+40Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93), 96Ru+96Ru (0.4, 1.0, 1.5), 96Zr+96Zr (0.4, 1.0, 1.5), 197Au+197Au (0.4, 0.6, 0.8, 1.0, 1.2, 1.5). The observables include longitudinal and transverse rapidity distributions and stopping, polar anisotropies, pion multiplicities, transverse momentum spectra, ratios for positively and negatively charged pions of average transverse momenta and of yields, directed flow, elliptic flow. The data are compared to earlier data where possible and to transport model simulations.Comment: 56 pages,42 figures; to be published in Nuclear Physics

Calculated neutron energy dependence of the dose-response of large recombination chamber

A model of REM-2-type chamber was modeled with MCNPX code to study the dose-response to monoenergetic neutrons in wide energy range from thermal to 20 MeV for various compositions of gas in the chamber. The energy dependence of the total dose absorbed in the fi lling gas was compared with the energy dependence of ambient absorbed dose D*(10) and with experimental data. The results of the studies will be useful for designing new, improved generation of recombination chambers

Geophysical investigation of spatial distribution of the Jurassic raft in Gołaszyn near Łuków, E Poland

The paper deals with the study of the Middle Jurassic clays near the town of Łuków, to identify its position, depth and thickness defined using geoelectrical techniques. The electrical properties of the ground were determined by a non-invasive 2D Resistivity Imaging Method which involves the investigation of the distribution of resistivity in the ground in X and Z direction. The measurements were carried out on four survey profiles that allowed to distinguish the horizontal and vertical extent of the Jurassic raft. It is not regular, but represents a more complicated structure. The values of resistivity, identified with the Jurassic clays, were very low and reached about 1-20 Q,m, which allowed interpreting, on each resistivity cross-section, its thickness changing from a few metres up to tens of metres

Electronic structure of iron porphyrin adsorbed to the Pt(111) surface

Systematic density functional theory calculations that treat the strong on-site 3d electron–electron interactions on iron via a Hubbard <i>U</i>_eff = 3.0 eV and the van der Waals (vdW) interactions between the substrate and adsorbate within the vdW-DF framework are employed to study the adsorption of the iron porphyrin (FeP) molecule to the Pt(111) surface. The more accurate vdW-DF-optPBE and vdW-DF-optB88 functionals found the same binding site to be the most stable and yielded binding energies that were within ∼20% of each other, whereas the binding energies computed with the vdW-DF-revPBE functional were substantially weaker. This work highlights the importance of vdW interactions for organometallic molecules chemisorbed to transition metal surfaces. The stability of the binding sites was found to depend upon the number of Fe–Pt and C–Pt bonds that were formed. Whereas in the gas phase the most stable spin state of FeP is the intermediate spin <i>S</i> = 1 state, the high spin <i>S</i> = 2 state is preferred for the FeP–Pt(111) system on the binding sites considered herein. The spin switch results from the elongation of the Fe–N bonds that occur upon adsorption

Research on BNCT in Poland and in the world

Przy Reaktorze MARIA w Narodowym Centrum Badań Jądrowych (NCBJ) powstaje stanowisko do badań nad terapią borowo-neutronową (BNCT). Terapia polega na napromienianiu nowotworu wiązką neutronów o odpowiednich parametrach po uprzednim podaniu pacjentowi związku boru, który w wyniku określonych mechanizmów gromadzi się głównie w komórkach rakowych. W wyniku reakcji 10B(n,α)7Li emitowane są cząstki jonizujące powodujące zniszczenie tylko tych komórek, w których zgromadzony jest bor [1]. Badania kliniczne prowadzone na świecie potwierdzają skuteczność metody, otwierając nowe perspektywy dla jej zastosowania w terapii konwencjonalnej.The stand for research on Boron Neutron Capture Therapy (BNCT) at the MARIA Reactor at the National Centre for Nuclear Research is being created. The therapy consists of irradiation of the tumour with a neutron beam with specific parameters after prior administration of the boron compound to the patient, which accumulates mainly in cancer cells as a result of specific mechanisms. As a result of 10B(n,α)7Li reaction, ionising particles are emitted and destroy only those cells, in which boron is accumulated. Clinical trials conducted in the world show relatively high efficiency of BNCT, opening new perspectives for its use in conventional therapy