195 research outputs found
Comment on "Magnetic field effects on neutron diffraction in the antiferromagnetic phase of UPt3"
Moreno and Sauls [Phys. Rev. B 63, 024419 (2000)] have recently tried to
reanalyze earlier neutron scattering studies of the antiferromagnetic order in
UPt3 with a magnetic field applied in the basal plane. In their calculation of
the magnetic Bragg peak intensities, they perform an average over different
magnetic structures belonging to distinct symmetry representations. This is
incorrect. In addition, they have mistaken the magnetic field direction in one
of the experiments, hence invalidating their conclusions concerning the
experimental results.Comment: Revised 5 June 2001: Added group theory analysis and modified
discussion of S and K domain
Reply to ``Comment on `Magnetic field effects on neutron diffraction in the antiferromagnetic phase of '''
Fak, van Dijk and Wills (FDW) question our interpretation of elastic
neutron-scattering experiments in the antiferromagnetic phase of UPt_3. They
state that our analysis is incorrect because we average over magnetic
structures that are disallowed by symmetry. We disagree with FDW and reply to
their criticism. FDW also point out that we have mistaken the magnetic field
direction in the experiment reported by N. H. van Dijk et al. [Phys. Rev. B 58,
3186 (1998)]. We correct this error and note that our previous conclusion is
also valid for the correct field orientation.Comment: 3 page
Suppression of ferromagnetism in URhGe doped with Ru
In the correlated metal URhGe ferromagnetic order (T_C = 9.5 K) and
superconductivity (T_s= 0.25 K) coexist at ambient pressure. Here we report on
alloying URhGe by Ru, which enables one to tune the Curie temperature to 0 K.
URuGe has a paramagnetic ground state and is isostructural to URhGe. We have
prepared a series of polycrystalline URh_{1-x}Ru_{x}Ge samples over a wide
range of x values. Magnetization and electrical resistivity data (T > 2 K)
show, after an initial increase, a linear suppression of T_C with increasing x.
The critical Ru concentration for the suppression of ferromagnetic order is
x_cr ~ 0.38.Comment: pdf file (2 pages, 1 figure); submitted to the Proceedings of the
Int. Conf. SCES'0
A comparative three-dimensional neutron depolarization study on RCrO4 oxides (R=Y, Er, Tm, Yb)
Three-dimensional neutron depolarization experiments have been performed on RCrO4 (R=Y, Er, Tm, Yb) powder samples in order to gain insight into their magnetic domain structure in the submicrometer range. The temperature evolution of both the average domain size and the net magnetization of each compound has been studied for different applied magnetic fields. The largest average domain size at zero external magnetic field was found in YbCrO4. The effect of an applied magnetic field on the magnetic domain structure is relatively small in ErCrO4 and TmCrO4, when compared to YCrO4 and YbCrO4 where the average domain size even surpasses the average particle size determined by Scanning Electron Microscopy studies.</p
TORCH: A Cherenkov Based Time-of-Flight Detector
TORCH is a novel high-precision time-of-flight detector suitable for large area applications and
covering the momentum range up to 10 GeV/c. The concept uses Cherenkov photons produced
in a fused silica radiator which are propagated to focussing optics coupled to fast photodetectors.
For this purpose, custom MCP-PMTs are being produced in collaboration with industrial partners.
The development is divided into three phases. Phase 1 addresses the lifetime requirements for
TORCH, Phase 2 will customize the MCP-PMT granularity and Phase 3 will deliver prototypes
that meet the TORCH requirements. Phase 1 devices have been successfully delivered and initial
tests show stable gain performance for integrated anode current >5 C/cm2
and a single photon
time resolution of ≤ 30 ps. Initial simulations indicate the single photon timing resolution of the
TORCH detector will be ∼70 ps
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