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Examines the characteristics of electron multiplier-based pulse counting systems for mass spectrometry. Process for obtaining the dead time measurements of titanium isotopes; Determination of multiplier gain, preamplifier gain and discriminator threshold; Description of pulse detection and counting circuits.

Presents a method of isotope dilution mass spectroscopy for the determination of traces of heavy metals in high-purity titanium primary materials. Isotope ratios; Separation techniques for trace/matrix separation and element-specific isolation; Detection limits; Analysis of titanium samples.

A heterometallic metal--organic framework incorporating Zn2+ and Ti4+ is successfully synthesized. The unique coordination mode of each metal ion to 2-oxido-l,4-benzenedicarboxylate leads to Zn6Ti2 building blocks, which extend to form a double-walled primitive cubic net. This material possesses a permanent porosity and long-term stability [ABSTRACT FROM AUTHOR]

Ti70Zr10Co20 containing an icosahedral quasicrystalline phase has been fabricated, and presents high activity and selectivity in catalyzing the oxidation of cyclohexane with oxygen under solvent-free conditions. [ABSTRACT FROM AUTHOR]

Dielectric relaxation and ultrasonic attenuation spectra of Sr4La2Ti4Nb6O30 tungsten bronze ceramics were investigated over a broad temperature range. A broad permittivity peak with strong frequency dispersion was observed around 200 K, which followed well the Vogel-Fulcher relationship, and is attributed to relaxor ferroelectric behavior with spin glass nature. The ultrasonic investigation provided further evidence on this thermally activated process, and both the dielectric relaxation and the freezing of polar clusters were clearly observed in the ultrasonic velocity shift and ultrasonic attenuation spectra. [ABSTRACT FROM AUTHOR]

The potential sub-shell closures N = 32 and N = 34 are analyzed at high spins in the titanium isotopes within the generalized beyond mean field theory considering triaxial deformations and the angular frequency as generator coordinates together with the particle number and the angular momentum conservation. A good description of bulk properties, high angular momenta spectra and transition probabilities is obtained. The outcome at high spin in these nuclei is consistent with the magic number character of N = 32 but not of N = 34. [ABSTRACT FROM AUTHOR]

Indirect evidence for the presence of a felsic continental crust, such as the elevated 49 Ti/ 47 Ti ratios in Archean shales, has been used to argue for ongoing subduction at that time and therefore plate tectonics. However, rocks of intermediate to felsic compositions can be produced in both plume and island arc settings. The fact that Ti behaves differently during magma differentiation in these two geological settings might result in contrasting isotopic signatures. Here, we demonstrate that, at a given SiO 2 content, evolved plume rocks (tholeiitic) are more isotopically fractionated in Ti than differentiated island arc rocks (mainly calc-alkaline). We also show that the erosion of crustal rocks from whether plumes (mafic in average) or island arcs (intermediate in average) can all produce sediments having quite constant 49 Ti/ 47 Ti ratios being 0.1-0.3 per mille heavier than that of the mantle. This suggests that Ti isotopes are not a direct tracer for the SiO 2 contents of crustal rocks. Ti isotopes in crustal sediments are still a potential proxy to identify the geodynamical settings for the formation of the crust but only if combined with additional SiO 2 information., Competing Interests: The authors declare no conflict of interest.

We have previously focused on studying the electron-capture isotopes within the dynamic spiral-arms cosmic-rays propagation model and empirically derived the energy dependence of the electron attachment rate using the observation of 49Ti/49V and 51V/51Cr ratios in cosmic rays. We have also shown how this relation recovers the energy dependence seen in the lab measurements. In this work, we use this relation to construct the 44Ti/44Ca ratio and place a lower limit on the amount of 44Ti that is required for it to be nucleosynthesized at the source. The results also imply that the acceleration process of the radioisotopes cannot be much longer than a century timescale (or else the required nucleosynthesized amount has to be correspondingly larger). We also provide a similar lower limit on the source 60Fe by comparing to the recently observed 60Fe/56Fe. [ABSTRACT FROM AUTHOR]

A precision mass investigation of the neutron-rich titanium isotopes 51-55Ti was performed at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The range of the measurements covers the N=32 shell closure, and the overall uncertainties of the 52-55Ti mass values were significantly reduced. Our results conclusively establish the existence of the weak shell effect at N=32, narrowing down the abrupt onset of this shell closure. Our data were compared with state-of-the-art ab initio shell model calculations which, despite very successfully describing where the N=32 shell gap is strong, overpredict its strength and extent in titanium and heavier isotones. These measurements also represent the first scientific results of TITAN using the newly commissioned multiple-reflection time-of-flight mass spectrometer, substantiated by independent measurements from TITAN's Penning trap mass spectrometer. [ABSTRACT FROM AUTHOR]

Excited states of the N=32 nucleus 54Ti have been studied, via both inverse-kinematics proton scattering and one-neutron knockout from 55Ti by a liquid hydrogen target, using the GRETINA γ-ray tracking array. Inelastic proton-scattering cross sections and deformation lengths have been determined. A low-lying octupole state has been tentatively identified in 54Ti for the first time. A comparison of (p,p') results on low-energy octupole states in the neutron-rich Ca and Ti isotopes with the results of random phase approximation calculations demonstrates that the observed systematic behavior of these states is unexpected. [ABSTRACT FROM AUTHOR]

In core-collapse supernovae, titanium-44 (44Ti) is produced in the innermost ejecta, in the layer of material directly on top of the newly formed compact object. As such, it provides a direct probe of the supernova engine. Observations of supernova 1987A (SN1987A) have resolved the 67.87- and 78.32--kilo--electron volt emission lines from decay of 44Ti produced in the supernova explosion. These lines are narrow and redshifted with a Doppler velocity of ~700 kilometers per second, direct evidence of large-scale asymmetry in the explosion. [ABSTRACT FROM AUTHOR]

The results of a neutron inelastic scattering experiment performed at the Geel Electron Linear Accelerator pulsed white neutron source of the European Commission Joint Research Centre are reported. The neutrons with energies up to 18 MeV interacted with a natTi sample and the γ rays resulting from inelastic scattering reactions on the stable isotopes were detected using the Gamma Array for Inelastic Neutron Scattering (GAINS) spectrometer. We were able to measure the γ-production cross sections for 21 transitions in the five stable Ti isotopes. From these, the level cross sections and the total inelastic cross sections were determined. Our experimental results are compared with theoretical calculations performed using the talys 1.8 code, evaluated nuclear data libraries, and also with previously reported results. [ABSTRACT FROM AUTHOR]

Hematite (α-Fe2O3) is a promising photoanode material for solar water splitting due to its suitable band gap, earth-abundance, excellent stability and non-toxicity. However, a short hole diffusion length limits its performance. A nanorod array structure can shorten hole transfer distance to photoelectrode/electrolyte interface and decrease recombination of photo-generated carriers. However, average diameters of all previously reported nanorods are over 50 nm, thus being too thick for holes to transfer to the interface. It is still a big challenge to prepare a Fe2O3 nanorod array photoelectrode with finer diameter. In this study, we prepare an ultrafine α-Fe2O3 nanorod array film with average diameter about 25 nm by calcining γ-FeOOH for the first time. The ultrafine nanorod array photoanode indicates much higher carrier separation efficiency and performance than a conventional nanorod array film. [ABSTRACT FROM AUTHOR]

The spatial and velocity distributions of nuclear species synthesized in the innermost regions of core-collapse supernovae can yield important clues about explosion asymmetries and the operation of the still disputed explosion mechanism. Recent observations of radioactive 44Ti with high-energy satellite telescopes (Nuclear Spectroscopic Telescope Array [NuSTAR], INTEGRAL) have measured gamma-ray line details, which provide direct evidence of large-scale explosion asymmetries in SN 1987A and in Cassiopeia A (Cas A) even by mapping of the spatial brightness distribution (NuSTAR). Here we discuss a 3D simulation of a neutrino-driven explosion, using a parameterized neutrino engine, whose 44Ti distribution is mostly concentrated in one hemisphere pointing opposite to the neutron star (NS) kick velocity. Both exhibit intriguing resemblance to the observed morphology of the Cas A remnant, although neither the progenitor nor the explosion was fine-tuned for a perfect match. Our results demonstrate that the asymmetries observed in this remnant can, in principle, be accounted for by a neutrino-driven explosion, and that the high 44Ti abundance in Cas A may be explained without invoking rapid rotation or a jet-driven explosion, because neutrino-driven explosions generically eject large amounts of high-entropy matter. The recoil acceleration of the NS is connected to mass ejection asymmetries and is opposite to the direction of the stronger explosion, fully compatible with the gravitational tugboat mechanism. Our results also imply that Cas A and SN 1987A could possess similarly “one-sided” Ti and Fe asymmetries, with the difference that Cas A is viewed from a direction with large inclination angle to the NS motion, whereas the NS in SN 1987A should have a dominant velocity component pointing toward us. [ABSTRACT FROM AUTHOR]

The experimental fusion excitation functions of the reactions 48Ti + 58Fe and 58Ni + 54Fe, measured down to the low sub-barrier energies, are described within the quantum diffusion approach and the universal fusion function representation. For these systems, the s -wave capture probabilities are extracted from the experimental excitation functions and are also analyzed. An enhancement of the sub-barrier fusion cross section observed in the 48Ti + 58Fe reaction in comparison to the relatively close system 58Ni + 54Fe is explained. [ABSTRACT FROM AUTHOR]

The distribution of elements produced in the innermost layers of a supernova explosion is a key diagnostic for studying the collapse of massive stars. Here we present the results of a 2.4 Ms NuSTAR observing campaign aimed at studying the supernova remnant Cassiopeia A (Cas A). We perform spatially resolved spectroscopic analyses of the 44Ti ejecta, which we use to determine the Doppler shift and thus the three-dimensional (3D) velocities of the 44Ti ejecta. We find an initial 44Ti mass of (1.54 ± 0.21) × 10−4M⊙, which has a present-day average momentum direction of 340° ± 15° projected onto the plane of the sky (measured clockwise from celestial north) and is tilted by 58° ± 20° into the plane of the sky away from the observer, roughly opposite to the inferred direction of motion of the central compact object. We find some 44Ti ejecta that are clearly interior to the reverse shock and some that are clearly exterior to it. Where we observe 44Ti ejecta exterior to the reverse shock we also see shock-heated iron; however, there are regions where we see iron but do not observe 44Ti. This suggests that the local conditions of the supernova shock during explosive nucleosynthesis varied enough to suppress the production of 44Ti by at least a factor of two in some regions, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium. [ABSTRACT FROM AUTHOR]

The article focuses on the synthesis of carbon in the massive stars during evolution, and the supernovae through which stars end their lives. Topics discussed include measurement of the spatial distribution of the nuclear-decay products of radioactive nucleus, titanium-44, energy liberated in the collapse is radiated as neutrinos, and Titanium-44 is always produced co-spatially with Nickel-56 which decays radioactively to Cobalt-56 and Iron-56.