Origin and Post-Glacial Dispersal of Mitochondrial DNA Haplogroups C and D in Northern Asia

More than a half of the northern Asian pool of human mitochondrial DNA (mtDNA) is fragmented into a number of subclades of haplogroups C and D, two of the most frequent haplogroups throughout northern, eastern, central Asia and America. While there has been considerable recent progress in studying mitochondrial variation in eastern Asia and America at the complete genome resolution, little comparable data is available for regions such as southern Siberia – the area where most of northern Asian haplogroups, including C and D, likely diversified. This gap in our knowledge causes a serious barrier for progress in understanding the demographic pre-history of northern Eurasia in general. Here we describe the phylogeography of haplogroups C and D in the populations of northern and eastern Asia. We have analyzed 770 samples from haplogroups C and D (174 and 596, respectively) at high resolution, including 182 novel complete mtDNA sequences representing haplogroups C and D (83 and 99, respectively). The present-day variation of haplogroups C and D suggests that these mtDNA clades expanded before the Last Glacial Maximum (LGM), with their oldest lineages being present in the eastern Asia. Unlike in eastern Asia, most of the northern Asian variants of haplogroups C and D began the expansion after the LGM, thus pointing to post-glacial re-colonization of northern Asia. Our results show that both haplogroups were involved in migrations, from eastern Asia and southern Siberia to eastern and northeastern Europe, likely during the middle Holocene

The Readout Tests of Freiburg Hybrids using ABCD chips

New SCT forward hybrids have been completed in Freiburg. Their performance, based on readout tests using batches of ABCD chips is presented in this note. A so called Kapton hybrid (K1) was equipped with 6 n-type ABCD-2 chips and a 6 cm n-in-n forward detector. A subset of the 768 strips were ganged together to simulate 12 cm long strips. After careful grounding no oscillations were observed. The noise values measured are about 0.3 fC (1900 electrons) for 12 cm strips, 0.18 fC (1200 electrons) for 6 cm strips and below 0.09 fC (550 electrons) for unbonded channels. The gain, extracted with a 3 point response curve fit, was rather high (100 -140) and almost independent of FE-Bias current

Energy Acceptance of the St. George Recoil Separator

Radiative alpha-capture, (α,γ) , reactions play a critical role in nucleosynthesis and nuclear energy generation in a variety of astrophysical environments. The St. George recoil separator at the University of Notre Dame's Nuclear Science Laboratory was developed to measure (α,γ) reactions in inverse kinematics via recoil detection in order to obtain nuclear reaction cross sections at the low energies of astrophysical interest, while avoiding the γ -background that plagues traditional measurement techniques. Due to the γ ray produced by the nuclear reaction at the target location, recoil nuclei are produced with a variety of energies and angles, all of which must be accepted by St. George in order to accurately determine the reaction cross section. We demonstrate the energy acceptance of the St. George recoil separator using primary beams of helium, hydrogen, neon, and oxygen, spanning the magnetic and electric rigidity phase space populated by recoils of anticipated (α,γ) reaction measurements. We find the performance of St. George meets the design specifications, demonstrating its suitability for (α,γ) reaction measurements of astrophysical interest

Hydrogen Charging Effects in Pd/Ti/TiO2/Ti Thin Films Deposited on Si(111) Studied by Ion Beam Analysis Methods

Titanium and titanium dioxide thin films were deposited onto Si(111) substrates by magnetron sputtering from a metallic Ti target in a reactive Ar+O2 atmosphere, the composition of which was controlled by precision gas controllers. For some samples, 1/3 of the surface was covered with palladium using molecular beam epitaxy. Chemical composition, density, and layer thickness of the layers were determined by Auger electron spectroscopy (AES) and Rutherford backscattering spectrometry (RBS). The surface morphology was studied using high-resolution scanning electron microscopy (HRSEM). After deposition, smooth, homogenous sample surfaces were observed. Hydrogen charging for 5 hours under pressure of 1 bar and at temperature of 300°C results in granulation of the surface. Hydrogen depth profile was determined using secondary ion mass spectrometry (SIMS) and nuclear Reaction Analysis (N-15 method), using a 15N beam at and above the resonance energy of 6.417 MeV. NRA measurements proved a higher hydrogen concentration in samples with partially covered top layers, than in samples without palladium. The highest value of H concentration after charging was about 50% (in the palladium-covered part) and about 40% in titanium that was not covered by Pd. These values are in good agreement with the results of SIMS measurements