Spin mass of an electron liquid

We show that in order to calculate correctly the spin current carried by a quasiparticle in an electron liquid one must use an effective "spin mass" m(s) that is larger than both the band mass m(b), which determines the charge current, and the quasiparticle effective mass m(*), which determines the heat capacity. We present two independent estimates of the spin mass enhancement, m(s)/m(b), in two- and three-dimensional electron liquids, based on (i) previously calculated values of the Landau parameters and (ii) a recent theory of the dynamical local field factor in the spin channel. Both methods yield a significant spin mass enhancement, which is larger in two dimensions than in three.     

Measurement of the mass difference between t and t quarks

We present a direct measurement of the mass difference between t and t quarks using tt candidate events in the lepton+jets channel, collected with the CDF II detector at Fermilab's 1.96 TeV Tevatron pp Collider. We make an event by event estimate of the mass difference to construct templates for top quark pair signal events and background events. The resulting mass difference distribution of data is compared to templates of signals and background using a maximum likelihood fit. From a sample corresponding to an integrated luminosity of 5.6 fb(-1), we measure a mass difference, ΔM(top) = M(t) - M(t) = -3.3 ± 1.4(stat) ± 1.0(syst) GeV/c2, approximately 2 standard deviations away from the CPT hypothesis of zero mass difference.     

Application of high-resolution ESI and MALDI mass spectrometry to metabolite profiling of small interfering RNA duplex

We investigated the application of a high-resolution Orbitrap mass spectrometer equipped with an electrospray ionization (ESI) source and a matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometer to the metabolite profiling of a model small interfering RNA (siRNA) duplex TSR#34 and compared their functions and capabilities. TSR#34 duplex was incubated in human serum in vitro, and the duplex and its metabolites were then purified by ion exchange chromatography in order to remove the biological matrices. The fraction containing the siRNA duplex and its metabolites was collected and desalted and then subjected to high-performance liquid chromatography (HPLC) equipped with a reversed phase column. The siRNA and its metabolites were separated into single strands by elevated chromatographic temperature and analyzed using the ESI-Orbitrap or the MALDI-TOF mass spectrometer. Using this method, the 5' and/or 3' truncated metabolites of each strand were detected in the human serum samples. The ESI-Orbitrap mass spectrometer enabled differentiation between two possible RNA-based sequences, a monoisotopic molecular mass difference which was less than 2 Da, with an intrinsic mass resolving power. In-source decay (ISD) analysis using a MALDI-TOF mass spectrometer allowed the sequencing of the RNA metabolite with characteristic fragment ions, using 2,4-dihydroxyacetophenone (2,4-DHAP) as a matrix. The ESI-Orbitrap mass spectrometer provided the highest mass accuracy and the benefit of on-line coupling with HPLC for metabolite profiling. Meanwhile, the MALDI-TOF mass spectrometer, in combination with 2,4-DHAP, has the potential for the sequencing of RNA by ISD analysis. The combined use of these methods will be beneficial to characterize the metabolites of therapeutic siRNA compounds. Copyright ? 2012 John Wiley & Sons, Ltd.     

Determination of the mass of polymer films using an AFM cantilever

There are no established methods that have a sensitivity during the determination of an adsorbed polymer film mass that is not worse than 1 ng that do not require additional calibration and the usage of reference measures. A highly sensitive method for measuring an adsorbed polymer is proposed in this work. The added mass was determined by the change of the resonance frequency of a cantilever used in atomic-force microscopy (AFM) as a probe. A modification of the cantilever surface is proposed that allows one to avoid the affect of the adsorbed polymer on the cantilever force constant. The mass of poly(diallyldimethylammonium) (PDDA) chloride adsorbed on the cantilever surface was obtained with a sensitivity of 0/01 ng using an AFM cantilever.     

Formation of double front detonations of a condensed-phase explosive with powdered aluminium

The performance characteristics of aluminised high explosive are considered by varying the aluminium (Al) mass fraction in a hybrid non-ideal detonation model. Since the time scales of the characteristic induction and combustion of high explosives and Al particles differ, the process of energy release behind the leading detonation wave front occurs over an extended period of time. Two cardinal observations are reported: a decrease in detonation velocity with an increase in Al mass fraction and a double front detonation (DFD) feature when anaerobic Al reaction occurs behind the front. In order to simulate the performance characteristics due to the varying Al mass fraction, the tetrahexamine tetranitramine (HMX) is considered as a base high explosive when formulating the multiphase conservation laws of mass, momentum, and energy exchanges between particles and HMX product gases. While experimental studies have been reported on the effect of Al mass fraction on both gas-phase and solid-phase detonations, the numerical investigations have been limited to only gas-phase detonation for the varying Al particles in the mixture. In the current study, a two-phase model is utilised for understanding the volumetric effects of Al mass fraction in condensed phase detonations. A series of unconfined and confined rate sticks are considered for characterising the performance of aluminised HMX with a maximum Al mass fraction of 50%. The simulated results are compared with the experimental data for 5–25% mass fractions, and the higher mass fraction behaviours are consistent with the experimental observations.     

Spin polarization dependence of carrier effective mass in semiconductor structures: spintronic effective mass

We introduce the concept of a spintronic effective mass for spin-polarized carriers in semiconductor structures, which arises from the strong spin-polarization dependence of the renormalized effective mass in an interacting spin-polarized electron system. The majority-spin many-body effective mass renormalization differs by more than a factor of 2 at r(s) = 5 between the unpolarized and the fully polarized two-dimensional system, whereas the polarization dependence (approximately 15%) is more modest in three dimensions around metallic densities (r(s) approximately 5). The spin-polarization dependence of the carrier effective mass is of significance in various spintronic applications.     

Hydrogenic donor impurity in a cubic quantum dot: effect of position-dependent effective mass

In this paper, we intend to study the effect of variable mass on the binding energy. In this regard, we apply an analytic expression for position-dependent effective mass in a cubic quantum dot. Then, we obtain the binding energies of a shallow donor in the quantum dot of GaAs/Al _x Ga_1−x As using a variational procedure within the effective mass approximation. Calculations are presented with a constant effective mass and position-dependent effective mass. It is found that (i) the binding energy decreases as the dot length increases in both the cases of constant and variable masses, (ii) an increase of binding energy is observed when the spatially varying mass is included, and (v) the binding energy shows complicated behavior when the position-dependent mass is included for the small dot size L ≤ 130 ?.     

Octupolar-excitation Penning-trap mass spectrometry for Q-value measurement of double-electron capture in (164)Er

The theory of octupolar-excitation ion-cyclotron-resonance mass spectrometry is presented which predicts an increase of up to several orders of magnitude in resolving power under certain conditions. The new method has been applied for a direct Penning-trap mass-ratio determination of the (164)Er-(164)Dy mass doublet. (164)Er is a candidate for the search for neutrinoless double-electron capture. However, the measured Q(??) value of 25.07(12) keV results in a half-life of 10(30) years for a 1 eV Majorana-neutrino mass.     

Discovery of a nuclear isomer in 65Fe with penning trap mass spectrometry

A new long-lived isomeric state in (65)Fe has been discovered with Penning trap mass spectrometry and high-precision mass measurements of the neutron-rich isotopes (63-65)Fe and (64-66)Co have been performed with the Low-Energy Beam and Ion Trap Facility at the NSCL. For the new isomer in (65)Fe an excitation energy of 402(5) keV has been determined from the measured mass difference between the isomeric and ground states. The mass uncertainties of all isotopes have been reduced by a factor of 10-100 compared to previous results. In the case of (64)Co the previous mass value was found to deviate by about 5 standard deviations from the new measurement.     

Observation of an exotic S = +1 baryon in exclusive photoproduction from the deuteron

In an exclusive measurement of the reaction gammad-->K(+)K(-)pn, a narrow peak that can be attributed to an exotic baryon with strangeness S=+1 is seen in the K(+)n invariant mass spectrum. The peak is at 1.542+/-0.005 GeV/c(2) with a measured width of 0.021 GeV/c(2) FWHM, which is largely determined by experimental mass resolution. The statistical significance of the peak is (5.2+/-0.6)sigma. The mass and width of the observed peak are consistent with recent reports of a narrow S=+1 baryon by other experimental groups.     

Investigation of the concentration gradient and extraction of helium atoms from copper deformed in a liquid-helium medium

A complex investigation of the penetration, accumulation, and extraction of helium atoms in porous copper samples deformed in a liquid-helium medium has been performed. The experiments have been carried out using three mass spectrometric techniques: (1) ionization of helium atoms by an electron impact in an MSCh-6 mass spectrometer, (2) secondary ion mass spectroscopy, and (3) an original high-resolution method with a sensitivity threshold of ∼10^{9 4}He atoms. The results obtained have made it possible to determine important characteristics of mechanodynamic diffusion of helium atoms, such as their penetration depth, the true concentration of helium trapped under deformation, and its gradient with an increase in the distance from the surface, as well as to estimate the binding energy of helium in traps.     

Emergent Newtonian dynamics and the geometric origin of mass

We consider a set of macroscopic (classical) degrees of freedom coupled to an arbitrary many-particle Hamiltonian system, quantum or classical. These degrees of freedom can represent positions of objects in space, their angles, shape distortions, magnetization, currents and so on. Expanding their dynamics near the adiabatic limit we find the emergent Newton’s second law (force is equal to the mass times acceleration) with an extra dissipative term. In systems with broken time reversal symmetry there is an additional Coriolis type force proportional to the Berry curvature. We give the microscopic definition of the mass tensor. The mass tensor is related to the non-equal time correlation functions in equilibrium and describes the dressing of the slow degree of freedom by virtual excitations in the system. In the classical (high-temperature) limit the mass tensor is given by the product of the inverse temperature and the Fubini–Study metric tensor determining the natural distance between the eigenstates of the Hamiltonian. For free particles this result reduces to the conventional definition of mass. This finding shows that any mass, at least in the classical limit, emerges from the distortions of the Hilbert space highlighting deep connections between any motion (not necessarily in space) and geometry. We illustrate our findings with four simple examples.     

Optimizing the energy filter of the “dihedral angle with end-face diaphragms” type

The 3D problem of determining the parameters of a charged particle energy filter for a monopole mass spectrometer is solved. Optimal geometry and operating conditions making it possible to raise the transmission of the instrument by an order of magnitude are found. Such an energy filter is intended for secondary ion (or atomic) mass spectrometry installations built around a monopole mass analyzer.     

Laser mass spectrometry study of the properties of fullerene structures

Fullerene films grown by various methods are studied using mass spectrometry. The mass spectra of the films formed onto an aluminum foil using thermal deposition (TD) or supersonic molecular beam (SMB) exhibit a small change in the mass peak distribution in the C₁₂₀ dimer range as compared to the initial fullerene powder during desorption by laser radiation irrespective of the radiation wavelength (λ = 259, 518 nm). Under the action of laser radiation with wavelength λ = 259 nm, fullerene films grown on a silicon substrate with an SMB also exhibit a small change in the mass peak distribution in the C₁₂₀ dimer range. At λ = 518 nm, the mass peak distribution in the dimer range shifts significantly toward small masses, so that the intensity maximum corresponds to M ≅ C₁₀₂. This fact is assumed to be related to the polymerization of an SMB fullerene film caused by heating due to the absorption of laser radiation with a wavelength λ = 518 nm.     

Traveling Waves for the Mass in Mass Model of Granular Chains

In the present work, we consider the mass in mass (or mass with mass) system of granular chains, namely, a granular chain involving additionally an internal (or, respectively, external) resonator. For these chains, we rigorously establish that under suitable “anti-resonance” conditions connecting the mass of the resonator and the speed of the wave, bell-shaped traveling-wave solutions continue to exist in the system, in a way reminiscent of the results proven for the standard granular chain of elastic Hertzian contacts. We also numerically touch upon settings, where the conditions do not hold, illustrating, in line also with recent experimental work, that non-monotonic waves bearing non-vanishing tails may exist in the latter case.     

Experimental analysis of the electrode products emitted byhigh-current vacuum arcs

The mass distribution of particles produced in the high-current vacuum arc was investigated. The experiments were concentrated on evaluating the spatial mass distribution emitted in the radial as well as in the azimuthal directions calculated from the mass deposition profile on collectors surrounding the arc discharge. The experiments were carried out in a vacuum chamber evacuated to an ambient pressure <10^-4 Pa. High-current arcs in the range from 2-7.5 kA were drawn between butt contacts of 31 and 55 mm in diameter (anode and cathode, respectively) both of a copper-chromium alloy (CuCr25). The surface mass deposited along multi-segment collectors was measured by a micro densitometer, and an inductively coupled plasma (ICP) spectrometer. Two angular mass deposit distributions were determined: the azimuthal distribution on the plane parallel to the cathode surface, and the radial distribution as a function of the angle with respect to the cathode plane. Both distributions were anisotropic and the structure of the deposition layer depended on the angle of incidence of the particles onto the substrate, the density of the particle flux and other factors. The mass deposited on the collectors consisted mostly of chromium molecules (approx. 80% of Cr and 20% Cu) for CuCr25 or CuCr40 electrodes     

极性晶体膜中的束缚极化子的有效质量

采用格林函数的方法,研究极性晶体膜中束缚极化子的有效质量随膜厚d的变化关系。得出电子-体LO声子相互作用以及电子-SO声子相互作用都对束缚极化子的有效质量有贡献。通过对KCl半导体膜的数值计算表明,束缚极化子的有效质量随膜厚d的增加而减少;当膜厚小于5 nm时电子-SO声子相互作用对束缚极化子的有效质量起主要贡献,但是当膜厚大于10 nm时,电子-体LO声子相互作用对束缚极化子的有效质量起主要贡献,当膜厚大于5 nm而小于10 nm时,二者共同影响束缚极化子的有效质量;另外,由于束缚势的存在,使束缚极化子的有效质量增大,这主要是由于束缚势的存在,使电子-声子间的相互作用增强,极化子效应增大而引起的。     

Ion-cyclotron-resonance mass spectrometry with a microwave plasmasource

The feasibility of coupling an electron-cyclotron-resonance (ECR) plasma-processing reactor directly to an omegatron mass spectrometer is demonstrated. The ECR plasma is created in a chamber that is coupled to the omegatron through a small, grounded orifice. Ions created in the ECR chamber flow along the magnetic field into the omegatron analysis cell, and the mass spectrum of these ions is recovered. Using this technique the mass spectra of both single-component (He) and two-component (N₂ and N) ECR plasmas were measured. The mass resolution as a function of the omegatron excitation voltage for He and N₂ plasmas was obtained and found to compare well to theoretical calculations     

Direct mass measurement of the four-neutron halo nuclide 8He

A high-precision Penning trap mass measurement of the exotic 8He nuclide (T(1/2)=119 ms) has been carried out resulting in a reduction of the uncertainty of the halo binding energy by over an order of magnitude. The new mass, determined with a relative uncertainty of 9.2 x 10(-8) (deltam=690 eV) is 13 keV less bound than the previously accepted value. The mass measurement is of great relevance for the recent charge-radius measurement of 8He [P. Mueller, Phys. Rev. Lett. 99, 252501 (2007).10.1103/PhysRevLett.99.252501]. The 8He mass is the first result from the newly-commissioned Penning trap: TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) at the ISAC (Isotope Separator and Accelerator) radioactive beam facility at TRIUMF.     

Gravitation and mass decrease

Consequences in physical theory of assuming the general relativistic time transformation for the de Broglie frequencies of matter, v = E/h = mc²/h, are investigated in this paper. Experimentally it is known that electromagnetic waves from a source in a gravitational field are decreased in frequency, in accordance with the Einstein general relativity time transformation. An extension to de Broglie frequencies implies mass decrease in a gravitational field. Such a decrease gives an otherwise missing energy conservation for some processes; also, a physical alteration is then associated with change in gravitational potential. Further, the general relativity time transformation that is the source of gravitational action in the weak field (Newtonian) approximation then has a physical correlate in the proposed gravitational mass loss. Rotational motion and the associated equivalent gravitational-field mass loss are considered; an essential formal difference between metric (gravitational) mass loss and special relativity mass increase is discussed. For a spherical, nonrotating mass collapsed to its Schwarzschild radius the postulated mass loss is found to give a 25% decrease in the mass acting as origin of an external gravitational field.