334 research outputs found
One-Particle Measurement of the Antiproton Magnetic Moment
\DeclareRobustCommand{\pbar}{\HepAntiParticle{p}{}{}\xspace}
\DeclareRobustCommand{\p}{\HepParticle{p}{}{}\xspace}
\DeclareRobustCommand{\mup}{{}{}\xspace}
\DeclareRobustCommand{\mupbar}{\mu_{\pbar}{}{}\xspace}
\DeclareRobustCommand{\muN}{{}{}\xspace
For the first time a single trapped \pbar is used to measure the \pbar
magnetic moment {\bm\mu}_{\pbar}. The moment {\bm\mu}_{\pbar} = \mu_{\pbar}
{\bm S}/(\hbar/2) is given in terms of its spin and the nuclear
magneton (\muN) by \mu_{\pbar}/\mu_N = -2.792\,845 \pm 0.000\,012. The 4.4
parts per million (ppm) uncertainty is 680 times smaller than previously
realized. Comparing to the proton moment measured using the same method and
trap electrodes gives \mu_{\pbar}/\mu_p = -1.000\,000 \pm 0.000\,005 to 5
ppm, for a proton moment ,
consistent with the prediction of the CPT theorem.Comment: 4 pages, 4 figures. arXiv admin note: substantial text overlap with
arXiv:1201.303
Neutron Beam Effects on Spin Exchange Polarized He-3
We have observed depolarization effects when high intensity cold neutron
beams are incident on alkali-metal-spin-exchange polarized He-3 cells used as
neutron spin filters. This was first observed as a reduction of the maximum
attainable He-3 polarization and was attributed to a decrease of alkali-metal
polarization, which led us to directly measure alkali-metal polarization and
spin relaxation over a range of neutron fluxes at LANSCE and ILL. The data
reveal a new alkali-metal spin-relaxation mechanism that approximately scales
as the square root of the neutron capture-flux density incident on the cell.
This is consistent with an effect proportional to the recombination-limited ion
concentration, but is much larger than expected from earlier work.Comment: submitted to Physical Review Letter
High-Precision Measurement of the 19Ne Half-Life and Implications for Right-Handed Weak Currents
We report a precise determination of the 19Ne half-life to be s. This result disagrees with the most recent precision
measurements and is important for placing bounds on predicted right-handed
interactions that are absent in the current Standard Model. We are able to
identify and disentangle two competing systematic effects that influence the
accuracy of such measurements. Our findings prompt a reassessment of results
from previous high-precision lifetime measurements that used similar equipment
and methods.Comment: 5 pages and 5 figures. Paper accepted for publication in Phys. Rev.
Let
Two-neutron transfer reaction mechanisms in C(He,He)C using a realistic three-body He model
The reaction mechanisms of the two-neutron transfer reaction
C(He,He) have been studied at 30 MeV at the TRIUMF ISAC-II
facility using the SHARC charged-particle detector array. Optical potential
parameters have been extracted from the analysis of the elastic scattering
angular distribution. The new potential has been applied to the study of the
transfer angular distribution to the 2 8.32 MeV state in C, using
a realistic 3-body He model and advanced shell model calculations for the
carbon structure, allowing to calculate the relative contributions of the
simultaneous and sequential two-neutron transfer. The reaction model provides a
good description of the 30 MeV data set and shows that the simultaneous process
is the dominant transfer mechanism. Sensitivity tests of optical potential
parameters show that the final results can be considerably affected by the
choice of optical potentials. A reanalysis of data measured previously at 18
MeV however, is not as well described by the same reaction model, suggesting
that one needs to include higher order effects in the reaction mechanism.Comment: 9 pages, 9 figure
Recommended from our members
Effects of organic additives on the formation of solids from hypersaline geothermal brine
Studies are underway to identify compounds that will, at cost-effective concentrations, inhibit scale and solids formation when added to the brine at the high-temperature (approximately 200{sup 0}C) front end of the plant. The study reported here constitutes a preliminary, bench-test screening of 49 substances, the most promising of which will be examined later in on-line pilot plant studies. A variety of substances were tested, including both simple and polymeric alcohols, ethers, aldehydes, carboxylic acids, amines, amides, cellulose derivatives, and classes of materials such as detergents, surfactants, and coupling agents. An inorganic phosphate, KH{sub 2}PO{sub 4}, and a chelating agent EDTA, also were tested. In the present work the additives were mixed with hypersaline brine that had been acidified to pH 4.0 +- 0.3 and flashed to 1 atm, approximately 100{sup 0}C, in the LLL Geothermal Field Test Apparatus near Niland, California. The rate of disappearance of dissolved silica from the treated brine was compared with the rate for untreated brine as a measure of the effectiveness of the additive. (JGB
New generalized fuzzy metrics and fixed point theorem in fuzzy metric space
In this paper, in fuzzy metric spaces (in the sense of Kramosil and Michalek (Kibernetika 11:336-344, 1957)) we introduce the concept of a generalized fuzzy metric which is the extension of a fuzzy metric. First, inspired by the ideas of Grabiec (Fuzzy Sets Syst. 125:385-389, 1989), we define a new G-contraction of Banach type with respect to this generalized fuzzy metric, which is a generalization of the contraction of Banach type (introduced by M Grabiec). Next, inspired by the ideas of Gregori and Sapena (Fuzzy Sets Syst. 125:245-252, 2002), we define a new GV-contraction of Banach type with respect to this generalized fuzzy metric, which is a generalization of the contraction of Banach type (introduced by V Gregori and A Sapena). Moreover, we provide the condition guaranteeing the existence of a fixed point for these single-valued contractions. Next, we show that the generalized pseudodistance J:X×X→[0,∞) (introduced by Włodarczyk and Plebaniak (Appl. Math. Lett. 24:325-328, 2011)) may generate some generalized fuzzy metric NJ on X. The paper includes also the comparison of our results with those existing in the literature
High-Precision Branching Ratio Measurement for the Superallowed + Emitter 74Rb
A high-precision branching-ratio measurement for the superallowed β
+ decay of 74Rb was performed at the
TRIUMF Isotope Separator and Accelerator (ISAC) radioactive ion-beam facility. The scintillating electronpositron
tagging array (SCEPTAR), composed of 10 thin plastic scintillators, was used to detect the emitted β
particles; the 8π spectrometer, an array of 20 Compton-suppressed HPGe detectors, was used for detecting γ rays
that were emitted following Gamow-Teller and nonanalog Fermi β
+ decays of 74Rb; and the Pentagonal Array
of Conversion Electron Spectrometers (PACES), an array of 5 Si(Li) detectors, was employed for measuring
β-delayed conversion electrons. Twenty-three excited states were identified in 74Kr following 8.241(4) × 108
detected 74Rb β decays. A total of 58 γ -ray and electron transitions were placed in the decay scheme, allowing
the superallowed branching ratio to be determined as B0 = 99.545(31)%. Combined with previous half-life and
Q-value measurements, the superallowed branching ratio measured in this work leads to a superallowed f t value
of 3082.8(65) s. Comparisons between this superallowed f t value and the world-average-corrected Ft value, as
well as the nonanalog Fermi branching ratios determined in this work, provide guidance for theoretical models
of the isospin-symmetry-breaking corrections in this mass region.IS
First-principles design and subsequent synthesis of a material to search for the permanent electric dipole moment of the electron
We describe the first-principles design and subsequent synthesis of a new
material with the specific functionalities required for a solid-state-based
search for the permanent electric dipole moment of the electron. We show
computationally that perovskite-structure europium barium titanate should
exhibit the required large and pressure-dependent ferroelectric polarization,
local magnetic moments, and absence of magnetic ordering even at liquid helium
temperature. Subsequent synthesis and characterization of
EuBaTiO ceramics confirm the predicted desirable
properties.Comment: Nature Materials, in pres
- …