12 research outputs found
Crystalline electric field effects in the electrical resistivity of PrOsSb
The temperature and magnetic field dependencies of the electrical
resistivity of the recently discovered heavy fermion superconductor
\PrOsSb{} have features that are associated with the splitting of the Pr
Hund's rule multiplet by the crystalline electric field (CEF). These features
are apparently due to magnetic exchange and aspherical Coulomb scattering from
the thermally populated CEF-split Pr energy levels. The data
in zero magnetic field can be described well by calculations based on CEF
theory for various ratios of magnetic exchange and aspherical Coulomb
scattering, and yield CEF parameters that are qualitatively consistent with
those previously derived from magnetic susceptibility, specific heat, and
inelastic neutron scattering measurements. Calculated isotherms for a
ground state qualitatively account for the `dome-shaped' feature
in the measured isotherms.Comment: 8 pages, 2 figures, submitted to Journal of Physics: Condensed Matte
Superconductivity and crystalline electric field effects in the filled skutterudite series Pr(OsRu)Sb
X-ray powder diffraction, magnetic susceptibility , and electrical
resistivity measurements were made on single crystals of the filled
skutterudite series Pr(OsRu)Sb. One end of the series
() is a heavy fermion superconductor with a superconducting critical
temperature K, while the other end () is a conventional
superconductor with K. The lattice constant decreases
approximately linearly with increasing Ru concentration . As Ru (Os) is
substituted for Os (Ru), decreases nearly linearly with substituent
concentration and exhibits a minimum with a value of K at , suggesting that the two types of superconductivity compete with one
another. Crystalline electric field (CEF) effects in and
due to the splitting of the Pr nine-fold degenerate Hund's
rule multiplet are observed throughout the series, with the splitting
between the ground state and the first excited state increasing monotonically
as increases. The fits to the and data are
consistent with a doublet ground state for all values of x,
although reasonable fits can be obtained for a ground state for
values near the end member compounds ( or ).Comment: 10 pages, 8 figures, submitted to Phys. Rev.
Superconductivity and the high field ordered phase in the heavy fermion compound PrOsSb
Superconductivity is observed in the filled skutterudite compound \PrOsSb{}
below a critical temperature temperature K and appears to
develop out of a nonmagnetic heavy Fermi liquid with an effective mass , where is the free electron mass.
Features associated with a cubic crystalline electric field are present in
magnetic susceptibility, specific heat, electrical resistivity, and inelastic
neutron scattering measurements, yielding a Pr energy level scheme
consisting of a nonmagnetic doublet ground state, a low lying
triplet excitied state at K, and much higher temperature
triplet and singlet excited states. Measurements also
indicate that the superconducting state is unconventional and consists of two
distinct superconducting phases. At high fields and low temperatures, an
ordered phase of magnetic or quadrupolar origin is observed, suggesting that
the superconductivity may occur in the vicinity of a magnetic or quadrupolar
quantum critical point.Comment: 11 pages, 4 figures, presented at the 3rd international symposium on
Advance Science Research (ASR 2002), JAERI Tokai, Ibaraki, Japa
Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar 1.3 GeV/c, vertical bar y vertical bar 1.3 GeV/c and vertical bar y vertical bar 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity
Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%
Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%
Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%