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

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

The airborne radioactivity and electrical properties of ground level air

The data presented in this work are the result of systematic measurements of radionuclide concentrations in air, collected with an ASS-500 high volume air sampler of the ground air monitoring network supervised by the Central Laboratory of Radiological Protection. Sampling has been done since March 1991. Simultaneously, the routine complex meteorological observations were performed. In particular, the electrical properties of ground level atmospheric air were studied with measurements of electrical field intensity, positive and negative conductivity of air and density of vertical current. The airborne 7Be concentration changes similarly to the electrical conductivity of air, while other isotopes, antropogenic or originating from the ground are correlated with dust and other meteorological factors like watering and wind

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

Medical and military applications of 3D printing

3D printing, 3D scanning and reverse engineering may constitute a significant breakthrough in research all over the world, especially within medical and military technologies. Particularly 3D printing seems to be a promising method to produce 3D objects manufactured layer-by-layer. The broader use of the above technologies may allow customization of various products and lower costs of design and production. At the same time progress in 3D printing technologies needs to be monitored and analyzed in order to deal with possible future threats. This article aims at investigating the extent to which the military and biomedical applications of 3D scanners and 3D printers are exploited, including in the framework of the authors’ own concepts, studies and observations

Air aerosol sampling station AZA-1000 at Polish Polar Station in Hornsund, Spitsbergen

The high volume air sampler AZA-1000 was built in the Environmental Protection Laboratory of the Andrzej Sołtan Institute for Nuclear Studies. In July 2002, this air sampler AZA-1000 was installed in the Polish Polar Observatory of the Polish Academy of Science in Hornsund, Spitsbergen. The device was built with numerous specific features which make possible to operate such station in extra difficult climatic conditions of polar region. Since July 2002, radioactive aerosols were collected at the Petrianov filter tissue FPP-15-1.5 and measured using high resolution g spectrometry in the Environmental Protection Laboratory at Świerk. The concentration of the airborn, cosmogenic radionuclide 7Be and of other natural and man maid radionuclides like 137Cs was determined. A comparison of the preliminary results with those from the ASS-500 sampling station operating at Świder is presented

International observational campaigns of the last two eclipses in EE Cephei: 2003 and 2008/9

Context. EE Cep is an unusual long-period (5.6 yr) eclipsing binary discovered during the mid-twentieth century. It undergoes almost-grey eclipses that vary in terms of both depth and duration at different epochs. The system consists of a Be type star and a dark dusty disk around an invisible companion. EE Cep together with the widely studied ε Aur are the only two known cases of long-period eclipsing binaries with a dark, dusty disk component responsible for periodic obscurations. Aims. Two observational campaigns were carried out during the eclipses of EE Cep in 2003 and 2008/9 to verify whether the eclipsing body in the system is indeed a dark disk and to understand the observed changes in the depths and durations of the eclipses. Methods. Multicolour photometric data and spectroscopic observations performed at both low and high resolutions were collected with several dozen instruments located in Europe and North America. We numerically modelled the variations in brightness and colour during the eclipses. We tested models with different disk structure, taking into consideration the inhomogeneous surface brightness of the Be star. We considered the possibility of disk precession. Results. The complete set of observational data collected during the last three eclipses are made available to the astronomical community. The 2003 and 2008/9 eclipses of EE Cep were very shallow. The latter is the shallowest among all observed. The very high quality photometric data illustrate in detail the colour evolution during the eclipses for the first time. Two blue maxima in the colour indices were detected during these two eclipses, one before and one after the photometric minimum. The first (stronger) blue maximum is simultaneous with a bump that is very clear in all the UBV(RI)C light curves. A temporary increase in the I-band brightness at the orbital phase ∼0.2 was observed after each of the last three eclipses. Variations in the spectral line profiles seem to be recurrent during each cycle. The Na i lines always show at least three absorption components during the eclipse minimum and strong absorption is superimposed on the Hα emission. Conclusions. These observations confirm that the eclipsing object in EE Cep system is indeed a dark, dusty disk around a low luminosity object. The primary appears to be a rapidly rotating Be star that is strongly darkened at the equator and brightened at the poles. Some of the conclusions of this work require verification in future studies: (i) a complex, possibly multi-ring structure of the disk in EE Cep; (ii) our explanation of the bump observed during the last two eclipses in terms of the different times of obscuration of the hot polar regions of the Be star by the disk; and (iii) our suggested period of the disk precession (∼11-12 Porb) and predicted depth of about 2ṁ for the forthcoming eclipse in 2014. © 2012 ESO

International observational campaigns of the last two eclipses in EE Cephei: 2003 and 2008/9

Context. EE Cep is an unusual long-period (5.6 yr) eclipsing binary discovered during the mid-twentieth century. It undergoes almost-grey eclipses that vary in terms of both depth and duration at different epochs. The system consists of a Be type star and a dark dusty disk around an invisible companion. EE Cep together with the widely studied ε Aur are the only two known cases of long-period eclipsing binaries with a dark, dusty disk component responsible for periodic obscurations. Aims. Two observational campaigns were carried out during the eclipses of EE Cep in 2003 and 2008/9 to verify whether the eclipsing body in the system is indeed a dark disk and to understand the observed changes in the depths and durations of the eclipses. Methods. Multicolour photometric data and spectroscopic observations performed at both low and high resolutions were collected with several dozen instruments located in Europe and North America. We numerically modelled the variations in brightness and colour during the eclipses. We tested models with different disk structure, taking into consideration the inhomogeneous surface brightness of the Be star. We considered the possibility of disk precession. Results. The complete set of observational data collected during the last three eclipses are made available to the astronomical community. The 2003 and 2008/9 eclipses of EE Cep were very shallow. The latter is the shallowest among all observed. The very high quality photometric data illustrate in detail the colour evolution during the eclipses for the first time. Two blue maxima in the colour indices were detected during these two eclipses, one before and one after the photometric minimum. The first (stronger) blue maximum is simultaneous with a bump that is very clear in all the UBV(RI)C light curves. A temporary increase in the I-band brightness at the orbital phase ∼0.2 was observed after each of the last three eclipses. Variations in the spectral line profiles seem to be recurrent during each cycle. The Na i lines always show at least three absorption components during the eclipse minimum and strong absorption is superimposed on the Hα emission. Conclusions. These observations confirm that the eclipsing object in EE Cep system is indeed a dark, dusty disk around a low luminosity object. The primary appears to be a rapidly rotating Be star that is strongly darkened at the equator and brightened at the poles. Some of the conclusions of this work require verification in future studies: (i) a complex, possibly multi-ring structure of the disk in EE Cep; (ii) our explanation of the bump observed during the last two eclipses in terms of the different times of obscuration of the hot polar regions of the Be star by the disk; and (iii) our suggested period of the disk precession (∼11-12 Porb) and predicted depth of about 2ṁ for the forthcoming eclipse in 2014. © 2012 ESO