POLAR, an instrument to measure GRB polarization. Design and laboratory tests.

International audienceReliable polarization measurements of photons from Gamma Ray Bursts (GRB) would make the understanding of the GRB phenomenon progress enormously. POLAR is a concept for an instrument that would enable such a measurement. We report about performances predicted by of Monte-Carlo and on laboratory tests to validate some critical aspects of the desig

Observations of the Gamow-Teller resonance in the rare-earth nuclei above Gd 146 populated in β decay

13 págs.; 11 figs. ; 1 tab.The rare-earth region of the nuclear table around the quasi-doubly magic nucleus Gd146 is one of the very few places in which the Gamow-Teller (GT) resonance can be populated in β decay. The appropriate technique to study such a phenomenon is total absorption spectroscopy, thanks to which one can measure the B(GT) distribution in β-decay experiments even when it is very fragmented and lies at high excitation energy in the daughter nucleus. Results on the GT resonance measured in the β decay of the odd-Z, N=83 nuclei Tb148, Ho150, and Tm152 are presented in this work and compared with shell-model calculations. The tail of the resonance is clearly observed up to the limit imposed by the Q value. This observation is important in the context of the understanding of the >quenching> of the GT strength. ©2016 American Physical SocietyThe authors would like to thank the GSI accelerator crew and the MSEP group for their support. This work has been partially supported by the Spanish Ministry (Grants No. FPA2005-03993, No. FPA200806419-C02-01, No. FPA2011- 24553, No. FPA2012-32443, No. FPA2014-57196-C5, and No. FPA2014-52823-C2-1-P) and the Generalitat Valenciana (PROMETEOII/2014/019).Peer Reviewe

Fine structure of the Gamow-Teller resonance revealed in the decay of Ho-150 2(-) isomer

The γ rays following the 72s 150Ho 2- Gamow-Teller β decay have been investigated with the CLUSTER CUBE setup, an array of six EUROBALL CLUSTER Ge detectors in close cubic geometry, providing a γ ray detection sensitivity of 2×10-5 per β-parent decay for γ-ray energies up to 5 MeV. The fine structure of the Gamow-Teller resonance at 4.4-MeV excitation in 150Dy has been studied. The resolved levels are compared with Shell Model predictions

Mathematical modeling and comparison of protein size distribution in different plant, animal, fungal and microbial species reveals a negative correlation between protein size and protein number, thus providing insight into the evolution of proteomes

<p>Abstract</p> <p>Background</p> <p>The sizes of proteins are relevant to their biochemical structure and for their biological function. The statistical distribution of protein lengths across a diverse set of taxa can provide hints about the evolution of proteomes.</p> <p>Results</p> <p>Using the full genomic sequences of over 1,302 prokaryotic and 140 eukaryotic species two datasets containing 1.2 and 6.1 million proteins were generated and analyzed statistically. The lengthwise distribution of proteins can be roughly described with a gamma type or log-normal model, depending on the species. However the shape parameter of the gamma model has not a fixed value of 2, as previously suggested, but varies between 1.5 and 3 in different species. A gamma model with unrestricted shape parameter described best the distributions in ~48% of the species, whereas the log-normal distribution described better the observed protein sizes in 42% of the species. The gamma restricted function and the sum of exponentials distribution had a better fitting in only ~5% of the species. Eukaryotic proteins have an average size of 472 aa, whereas bacterial (320 aa) and archaeal (283 aa) proteins are significantly smaller (33-40% on average). Average protein sizes in different phylogenetic groups were: Alveolata (628 aa), Amoebozoa (533 aa), Fornicata (543 aa), Placozoa (453 aa), Eumetazoa (486 aa), Fungi (487 aa), Stramenopila (486 aa), Viridiplantae (392 aa). Amino acid composition is biased according to protein size. Protein length correlated negatively with %C, %M, %K, %F, %R, %W, %Y and positively with %D, %E, %Q, %S and %T. Prokaryotic proteins had a different protein size bias for %E, %G, %K and %M as compared to eukaryotes.</p> <p>Conclusions</p> <p>Mathematical modeling of protein length empirical distributions can be used to asses the quality of small ORFs annotation in genomic releases (detection of too many false positive small ORFs). There is a negative correlation between average protein size and total number of proteins among eukaryotes but not in prokaryotes. The %GC content is positively correlated to total protein number and protein size in prokaryotes but not in eukaryotes. Small proteins have a different amino acid bias than larger proteins. Compared to prokaryotic species, the evolution of eukaryotic proteomes was characterized by increased protein number (massive gene duplication) and substantial changes of protein size (domain addition/subtraction).</p

Determination of the emission rate for the 14 MeV neutron generator with the use of radio-yttrium

The neutron emission rate is a crucial parameter for most of the radiation sources that emit neutrons. In the case of large fusion devices the determination of this parameter is necessary for a proper assessment of the power release and the prediction for the neutron budget. The 14 MeV neutron generator will be used for calibration of neutron diagnostics at JET and ITER facilities. The stability of the neutron generator working parameters like emission and angular homogeneity affects the accuracy of calibration other neutron diagnostics. The aim of our experiment was to confi rm the usefulness of yttrium activation method for monitoring of the neutron generator SODERN Model: GENIE 16. The reaction rate induced by neutrons inside the yttrium sample was indirectly measured by activation of the yttrium sample, and then by means of the γ-spectrometry method. The pre-calibrated HPGe detector was used to determine the yttrium radioactivity. The emissivity of neutron generator calculated on the basis of the measured radioactivity was compared with the value resulting from its electrical settings, and both of these values were found to be consistent. This allowed for a positive verifi cation of the reaction cross section that was used to determine the reaction rate (6.45 × 10–21 reactions per second) and the neutron emission rate (1.04 × 108 n·s–1). Our study confi rms usefulness of the yttrium activation method for monitoring of the neutron generator