Effect of Partial Dependence of Photopeak Data on The Calculations of NaI(Tl) Detector Spectrum

Partial dependence of photopeak data of ɣ-ray energies is considering apart of peak channels after subtracting background (including Compton distribution) and obtaining symmetric Gaussian distribution, then considering this part to obtain other total data of peak. This was investigated by using NaI(Tl) detector with Eu-152, Ra-226 and Cs-137 point sources. For the isolated peaks of Eu-152, Gaussian shape is obtained, and the areas between ±σ and ±0.5σ were determined and efficiency is obtained. The calculated transformation to total data of peaks gave excellent agreement with the ordinary case. The overlap between the two peaks at 609.3 (Ra-226) and 661.6 keV (Cs-137) is studied with using σ values from data when sources are separated, and counts in peaks centroids. The data of each peak is "restored" and compared with that when sources are separated and gave a 98% agreement. Also the overlap between the two peaks at 1120 and 1238 keV (Ra-226) is studied with adopting the σ values from the shape calibration curve of Eu-152 and centroid counts in the same way as for the Ra-226 and Cs-137 case. The resultant peaks areas are compared with those obtained from efficiency calibration curve of Eu-152. However results here are of lower agreement. http://dx.doi.org/10.25130/tjps.24.2019.014

TA Spectrum

The Telescope Array (TA) experiment is measuring cosmic rays of energies from PeV to 100 EeV and higher in the Northern hemisphere. TA has two parts: main TA and the TA low energy extension (TALE). Main TA is a hybrid detector that consists of 507 plastic scintillation counters on a 1200m - spaced square grid that are overlooked by three fluorescence detector stations. TALE is also a hybrid detector that consists of additional fluorescence telescopes arranged to view higher elevations and an infill array of 103 plastic scintillation counters. In this work, we describe the combined TA surface detector (SD) and TALE fluorescence detector spectrum, check the calculation of the TA SD spectrum at the highest energies using an alternative, Constant Intensity Cut, method and discuss the declination dependence of the TA SD spectrum at the highest energies. Details of the TALE spectrum calculation have been presented in a separate work at this conference.

The Influence of Trace Elements on the Nature of the Nuclei of the Graphite in Ductile Iron

Nucleation mechanisms and the effect of minor elements added with the inoculants are still a subject of extensive research in ductile iron. Oxides, sulfides, silicates and nitrides have been reported to be nuclei for graphite precipitation. Those compounds originate both from the nodulizing treatment and the inoculation process. Previous research works have shown that titanium nitrides or carbonitrides play an active role in graphite nucleation. In order to determine the efficiency and nature of nitrides that can act as nuclei for graphite, and the possible effect of the trace elements added with the inoculant, melts with titanium contents ranging from 0.007% to 0.036% were produced and poured into standard thermal analysis cups, with and without inoculation. Different inoculants rich in titanium, cerium, aluminum or zirconium were used. Two cups were produced with each inoculant, one cooled down to room temperature, and the other quenched in brine immediately after pouring. Nucleation sites were characterized through detector, spectrum, mapping and line scans of a FEG-SEM equipment. Most of the analyzed nuclei exhibited two or three different inclusions: magnesium sulfides or Mg-Ca oxy-sulfides, Mg or Al oxides, and Ti carbo-nitrides or Mg-Si-Al nitrides. The appearance of each type of nitrides is directly related to the titanium content in the base melt. When titanium was added in the inoculant, no titanium nitrides were noticeable. The zirconium added with the inoculant promoted more complex nitrides that appeared in higher amount. Cerium appears occasionally forming sulfides. Aluminum stimulates the formation of complex nitrides. No differences in the nature of the nuclei were observed between the samples quenched and the ones obtained at room temperature, which assures the methodology approach.