Periodic system of chemical elements

W roku bieżącym przypada 120. rocznica odkrycia polonu i radu. Liczby atomowe tych pierwiastków to odpowiednio: Z= 84 i Z=88. Dziś znamy 118 pierwiastków. W artykule przypomniano ważniejsze fakty z historii odkrycia nowych pierwiastków i badania ich właściwości. Szczególną uwagę poświęcono pierwiastkom promieniotwórczym z obszaru liczb atomowych Z= 104 -118, które odkryto w ostatnich kilkudziesięciu latach. Autor artykułu zwraca uwagę na złożoność i ważność procedur decydujących o ustalaniu nazwy nowych pierwiastków.In the current year is 120. anniversary of the discovery of polonium and radium. Atomic numbers of these elements is: Z = 84 and Z = 88. Today we know the 118 elements. The article pointed out important facts from the history of the discovery of new elements and study their properties. Particular attention was given to radioactive elements with atomic numbers Z = 104-118, which was discovered in recent decades. The author of the article draws attention to the complexity and validity procedures for determining the names of new elements

New method of pure 111In production by proton-induced nuclear reactions with enriched 112 Sn

We aimed at finding out a simple and reliable way of 111In production with the highest radionuclide purity from its grand parent 111Sb and parent 111Sn nuclei, produced by the 112Sn(p,2n)111Sb and 112Sn(p,pn)111Sn reactions, respectively. The target was a metallic 112Sn sample enriched to 84%. We have measured activation cross sections for seven reactions on an enriched 112Sn sample induced by 23.6 š 0.8 MeV energy protons. Gamma-ray spectroscopy with high-purity germanium detectors has been used. We also identified the activities of 55Co (T1/2 = 17.5 h) and 60Cu (T1/2 = 23.7 min) in proton beam monitoring Ni foils, induced in the natNi(p,X)55Co and natNi(p,X)60Cu reactions at 22.8 MeV proton energy. The cross sections determined for these reactions are: s[natNi(p,X)55Co] = 36.6 š 4 mb and s[natNi(p,X)60Cu] = 64.4 š 7 mb. The measured cross sections of reactions on tin isotopes are: sigma[112Sn(p,n)112Sb] = 4 š 0.8 mb; sigma[112Sn(p,2n)111Sb] = 182 š 26 mb; sigma[112Sn(p,pn)111Sn] = 307 š 35 mb; sigma[114Sn(p,2n)113Sb] = 442 š 52 mb; s[117Sn(p,n)117Sb] = 15 š 3 mb; sigma[117Sn(p,p’gamma)117mSn] = 0.37 š 0.06 mb; s[115Sn(p,2p)114m2In] = 0.01 š 0.002 mb. Our measurements indicated the expected yield of the 111In production to be 46 MBq/mAh (1.2 mCi/mi Ah). The contamination of 111In by the undesired nuclide 114m2In was determined and belongs to the smallest ones found in the literature. The measured cross sections were compared with theoretical calculations by two top-level nuclear reaction codes EMPIRE and TALYS

Rapid production of 18F fluoride from 2-fluoroaniline via the 19F(n,2n)18F reaction using 14 MeV neutrons

No carrier-added 18F fluoride was produced via the 19F(n,2n)18F reaction by 14 MeV neutron irradiation of 2-fluoroaniline and subsequent extraction of the produced 18F fluoride ion with water. The fluoride was then purified by liquid chromatography on a Chromabond-NO2 column. The time required for all chemical procedures was about 1 h. The average chemical separation yield was about 70%. The 18F activity obtained after 3 hours of irradiation at a flux rate of 108 n cm-2s-1 after a necessary 20-min delay was equal to several kBq per gram of fluorine in a 2-fluoroaniline sample, in accordance with the theoretically expected value. Improvement of the 18F production yield can be achieved by increasing neutron fluxes. Neutron generators with 14 MeV neutron fluxes of the order of 1010 n cm-2s-1 can produce tens MBq of 18F, sufficient for whole-day work in biomedical applications. Our results show that 14 MeV neutron irradiation of 2-fluoroaniline is a low cost alternative for the production of this nuclide in the countries which do not posses either cyclotrons or electron linear accelerator facilities

Production of 18F by proton irradiation of C6H6NF and C6H5NF2

Fluorin--18 can be produced directly by the (p,pn) reaction and also indirectly by the (p,2n) reaction on the 19F target. The overall cross section for both routes is 108 plus or minus 20 mb at 22.5 plus or minus 2.5 MeV. In this work, we obtained 18F, using 25 MeV protons on 2\--fluoroaniline and 2,4-difluoroaniline targets. The chemical separation yield was 46 š 7% and 47 plus or minus 12% for 2-fluoroaniline and 2,4-difluoroaniline, respectively. Low-current 1 h irradiations led to 90 mi Ci of 18F produced from 2-fluoroaniline bombarded with a 70 nA beam (in good agreement with the theoretical value, 96 mi Ci) and to 76 mi Ci of 18F in case of 2,4-difluoroaniline and a 33 nA beam (prediction 85 mi Ci). Both values are close to the thick target result reported by Dmitriev and Molin [4] for 22 MeV protons

EXPERIMENTAL AND THEORETICAL STUDIES OF THE RADIATIVE LIFETIME AND PREDISSOCIATION RATES OF THE A2△A^{2} \triangle STATE OF PH+PH^{+}

Author Institution: Research Institute of Physics; Institute of Nuclear Research, Swierk, 05-400, Poland.The High Frequency Deflection technique has been applied to obtain the radiative lifetime of the $A^{2} \triangle$ state of $PH^{+}$. The predissociation is known to occur for $N^{\prime}> 12$ for $v^{\prime} = 0$ and weakly for all $N^{\prime}$ values of $v^{\prime} = 1$, and the measured lifetime of the stable rotational levels of $v^{\prime} =0 (1.5\pm 0.2 \mu s)$. In order to deduce the predissociation rates for $v^{\prime}=1$ we have also carried out ab-initio CASSCF calculations of the electronic transition moment for the $A^{2} \triangle-X^{2}\Pi$ transition. The calculated radiative lifetime of $v^{\prime} =0$ was in good agreement with experiment $(1.4 \mu s)$. For further potential curves were improved by multireference CI calculations and corresponding calculations were carried out for the $^{2}\sigma^{-}$ and $^{4}\Pi$ states. Weyl's theory for second order differential equations were used to analyse the predissociation mechanism. The exact mechanism is at this moment not quite clear, although it appears that one state alone can not cause the observed predissociation pattern