The activity of the 177Lu solution has been measured by means of the CIEMAT/NIST efficiency tracing method. This result has been compared to the previous obtained results received from 4πβ(LS)–γ ...coincidence and anticoincidence counting. The activities determined with various methods have been found to be consistent.
The decay curve of the 177Lu solution has been followed in the TDCR counter to determine the half-life of this isotope. The half-life has been separately determined for double and triple coincidence events. The arithmetic mean value of these two results has been found to be T1/2 = 6.6489(52) d.
•Activity standardization of 177Lu by means of the CIEMAT/NIST efficiency tracing method.•The activity result compared with previous results obtained from 4πβ(LS)–γ coincidence and anticoincidence counting.•The activities determined with various methods found to be consistent.•The half-life of 177Lu determined with small uncertainty.
On the night of October 31, 2015 two bright Southern Taurid fireballs occurred over Poland, being one of the most spectacular bolides of this shower in recent years. The first fireball – PF311015a ...Okonek – was detected by six video stations of Polish Fireball Network (PFN) and photographed by several bystanders, allowing for precise determination of the trajectory and orbit of the event. The PF311015a Okonek entered Earth's atmosphere with the velocity of 33.2 ± 0.1 km s−1 and started to shine at height of 117.88 ± 0.05 km. The maximum brightness of −16.0 ± 0.4 mag was reached at height of 82.5 ± 0.1 km. The trajectory of the fireball ended at height of 60.2 ± 0.2 km with terminal velocity of 30.2 ± 1.0 km s−1. The second fireball – PF311015b Ostrowite – was detected by six video stations of PFN. It started with velocity of 33.2 ± 0.1 km s−1 at height of 108.05 ± 0.02 km. The peak brightness of −14.8 ± 0.5 mag was recorded at height of 82.2 ± 0.1 km. The terminal velocity was 31.8 ± 0.5 km s−1 and was observed at height of 57.86 ± 0.03 km. The orbits of both fireballs are similar not only to orbits of Southern Taurids and comet 2P/Encke, but even closer resemblance was noticed for orbits of 2005 UR and 2005 TF50 asteroids. Especially the former object is interesting because of its close flyby during spectacular Taurid maximum in 2005. We carried out a further search to investigate the possible genetic relationship of Okonek and Ostrowite fireballs with both asteroids, that are considered to be associated with Taurid complex. Although, we could not have confirmed unequivocally the relation between fireballs and these objects, we showed that both asteroids could be associated, having the same origin in a disruption process that separates them.
A method for absolute measurements of the 225Ac activity in equilibrium with its progeny was developed. Measurements were performed using the triple-to-double coincidence ratio (TDCR) method in two ...different TDCR counters. The activity concentration of an 225Ac solution was determined and the solution was sent to the SIR system for a comparison. The half-life of 225Ac was determined by one of the TDCR counters and found to be 9.9150(63) days.
•Detailed determination of the counting efficiency of the 225Ac in radioactive equilibrium with its progeny.•Description of the measurements of the activity of 225Ac sources using the TDCR method.•Result of activity comparison in the International Reference System (SIR) at BIPM.•Results of half-life determination of 225Ac at POLATOM compared to other published values.
Application of a new coincidence module using the pulse-mixing method in the 4π(LS)-γ coincidence system with TDCR detector in the beta channel (TDCRG) is presented. The pulse-mixing method extended ...for the TDCR system with gamma channel was compared with the classical coincidence method where the coincidence resolving time is introduced. The characteristics of the resolving and dead time of the above two methods were investigated. The level of accidental coincidences in the system was determined. The new developed coincidence module was validated by activity measurement of a set of 51Cr, 54Mn, 60Co, 65Zn, 85Sr and 134Cs standards.
•Application of a new coincidence module in the TDCRG system.•The pulse-mixing method extended for the TDCR system with gamma detector.•Good agreement of 51Cr, 54Mn, 60Co, 65Zn, 85Sr and 134Cs activity measurement.•The level of accidental coincidence determined in the system.
Abstract
In this paper, we present an analysis of Polish Fireball Network (PFN) observations of enhanced activity of the Southern Taurid meteor shower in 2005 and 2015. In 2005, between October 20 ...and November 10, seven stations of the PFN determined 107 accurate orbits, with 37 of them belonging to the Southern Taurid shower. In the same period of 2015, 25 stations of the PFN recorded 719 accurate orbits with 215 orbits of the Southern Taurids. Both maxima were rich in fireballs, which accounted for 17 per cent of all observed Taurids. The whole sample of Taurid fireballs is uniform in the sense of starting and terminal heights of the trajectory. However, a clear decreasing trend in geocentric velocity with increasing solar longitude was observed. The orbital parameters of observed Southern Taurids were compared to orbital elements of near-Earth objects (NEOs) from the NEODyS-2 data base. Using the Drummond criterion D΄ with a threshold as low as 0.06, we found over 100 fireballs strikingly similar to the orbit of asteroid 2015 TX24. Several dozens of Southern Taurids have orbits similar to three other asteroids: 2005 TF50, 2005 UR and 2010 TU149. All mentioned NEOs have orbital periods very close to the 7 : 2 resonance with Jupiter's orbit. This confirms the theory of a resonant meteoroid swarm within the Taurid complex, which predicts that, in specific years, the Earth is hit by a greater number of meteoroids capable of producing fireballs.
Measurements were made using the TDCR method. POLATOM prepared and distributed for the key comparison participants the
55
Fe solution and
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Fe ready-to-measure sources in the Ultima Gold™ ...scintillator in polyethylene vials. The stability of the sources was confirmed. Source counting efficiency decreased proportionally with time by about 0.7% per month, possibly due to colour quenching. The POLATOM measurement result was consistent with the key comparison reference value. The nuclear data for
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Fe were adopted in accordance with the KCWG(II) recommendation. Measurement results obtained in non-diffusive (glass) vials were lower than in diffusive vials.
On 2010 October 13, the Apollo-type 20-m asteroid 2010 TB54 passed within 6.1 lunar distances from the Earth. On the same date, but 11.4 h earlier, exactly at 02:52:32 ut, the sky over central Poland ...was illuminated by the −8.6 mag PF131010 Ciechanów fireball. The trajectory and orbit of the fireball were computed using multi-station data from the Polish Fireball Network. The results indicate that the orbit of the meteoroid that caused the PF131010 fireball is similar to the orbit of asteroid 2010 TB54 and both bodies may be related. Moreover, 2 d before the appearance of the Ciechanów fireball, another small asteroid, 2010 SX11, passed close to the Earth–Moon system. Its orbit is even more similar to the orbit of the Ciechanów fireball's parent body than 2010 TB54. PF131010 Ciechanów entered Earth's atmosphere with a velocity of 12.9 ± 0.2 km s−1 and started to shine at a height of 82.5 ± 0.3 km. Clear deceleration started after the first 3 s of flight, and the terminal velocity of the meteor was only 5.8 ± 0.2 km s−1 at a height of 29.3 ± 0.1 km. Such a low terminal velocity indicates that fragments with a total mass of around 2 kg could survive the atmospheric passage and cause a fall of meteorites. The predicted area of possible meteorite impact is computed as being near Grabowo village south of Ostrołęka city.
The aim of the work was to develop new radioactive standard sources based on epoxy resins. The optimal proportions of the components and the homogeneity of the matrices were determined. The activity ...of multigamma sources prepared in Marinelli beakers was determined with reference to the National Standard of Radionuclides Activity in Poland. The difference of radionuclides activity values determined using calibrated gamma spectrometer and the activity of standard solutions used are in most cases significantly lower than measurement uncertainty limits. Sources production method and quality control procedure have been developed.
•An optimum composition and sample preparation method of homogeneous resin matrix was developed.•Matrices densities were equal 1.1gcm−3 and 1.5gcm−3.•Matrix production method was validated.•The sources activity was determined with reference to the national standard of radionuclides activity in Poland.•The sources activity was checked using the HPGe detector GEM20P4.
Activity measurements of 3H, 241Am and 60Co solutions were performed to compare digital coincidence modules used at PTB and POLATOM for TDCR and 4πβ(LS)-γ coincidence counting. The activities ...determined with various coincidence modules connected in parallel to the same counter at PTB were found to be consistent. Observed discrepancies caused by differences in the coincidence resolving time did not exceed 0.14%. Accidental coincidences simulated by a frequency generator were registered, and the coincidence resolving time was determined.
•Comparison of the PTB and POLATOM coincidence modules.•Good agreement of 3H, 241Am and 60Co activity measurements.•Coincidence resolving time determined using frequency generator.
In 2011 the joint research project Metrology for Radioactive Waste Management (MetroRWM)11This joint research project is financially supported by the European Commission in the frame of the European ...Metrology Research Programme EMRP (www.emrponline.eu) undertaken by several EU Member States under the Article 169 initiative, JRP contract identifier EMRP ENV09 MetroRWM. of the European Metrology Research Programme (EMRP) started with a total duration of three years. Within this project, new metrological resources for the assessment of radioactive waste, including their calibration with new reference materials traceable to national standards will be developed.
This paper gives a review on national, European and international strategies as basis for science-based metrological requirements in clearance and acceptance of radioactive waste.
•Legislation, requirements and standards in radioactive waste management.•Strategies and methods to maintain the relevant clearance levels and acceptance criteria.•International, European and national activity levels and limits for exemption and clearance of radioactive waste.•Requirements for acceptance for storage and final disposal of radioactive waste.•Metrological requirements for radioactive waste characterisation.
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