1,587 research outputs found
A three-dimensional Monte Carlo calculation of the photon initiated showers and Kiel result
The Kiel experimental results indicate an existence of the ultra high-energy gamma-rays coming from Cyg. X-3. However the result indicates that the number of the muons included in the photon initiated shower is the same as the number included in the proton initiated showers. According to our Monte Carlo calculation as shown in the graph of underpart, the number of muons included in the photon initiated showers should be less than 1/15 of the photon's. The previous simulation was made under one dimensional approximation. This time the result of three dimensional calculation is reported
Simultaneous Excitation of Spins and Pseudospins in the Bilayer Quantum Hall State
The tilting angular dependence of the energy gap was measured in the bilayer
quantum Hall state at the Landau level filling by changing the density
imbalance between the two layers. The observed gap behavior shows a continuous
transformation from the bilayer balanced density state to the monolayer state.
Even a sample with 33 K tunneling gap shows the same activation energy anomaly
reported by Murphy {\it et al.}. We discuss a possible relation between our
experimental results and the quantum Hall ferromagnet of spins and pseudospins.Comment: 4 pages, 4 figure
Voltage-controlled Group Velocity of Edge Magnetoplasmon in the Quantum Hall Regime
We investigate the group velocity of edge magnetoplasmons (EMPs) in the
quantum Hall regime by means of time-of-flight measurement. The EMPs are
injected from an Ohmic contact by applying a voltage pulse, and detected at a
quantum point contact by applying another voltage pulse to its gate. We find
that the group velocity of the EMPs traveling along the edge channel defined by
a metallic gate electrode strongly depends on the voltage applied to the gate.
The observed variation of the velocity can be understood to reflect the degree
of screening caused by the metallic gate, which damps the in-plane electric
field and hence reduces the velocity. The degree of screening can be controlled
by changing the distance between the gate and the edge channel with the gate
voltage.Comment: 5 pages, 6 figures, to be published in Physical Review
Ballistic transport in induced one-dimensional hole systems
We have fabricated and studied a ballistic one-dimensional p-type quantum
wire using an undoped AlGaAs/GaAs heterostructure. The absence of modulation
doping eliminates remote ionized impurity scattering and allows high mobilities
to be achieved over a wide range of hole densities, and in particular, at very
low densities where carrier-carrier interactions are strongest. The device
exhibits clear quantized conductance plateaus with highly stable gate
characteristics. These devices provide opportunities for studying spin-orbit
coupling and interaction effects in mesoscopic hole systems in the strong
interaction regime where rs > 10.Comment: 6 pages, 4 figures (accepted to Applied Physics Letters
Interplay between one-dimensional confinement and crystallographic anisotropy in ballistic hole quantum wires
We study the Zeeman splitting in induced ballistic 1D quantum wires aligned
along the [233] and [011] axes of a high mobility (311)A undoped
heterostructure. Our data shows that the g-factor anisotropy for magnetic
fields applied along the high symmetry [011] direction can be explained by the
1D confinement only. However when the magnetic field is along [233] there is an
interplay between the 1D confinement and 2D crystal anisotropy. This is
highlighted for the [233] wire by an unusual non-monotonic behavior of the
g-factor as the wire is made narrower
A new ultra high energy gamma ray telescope at Ohya mine
The search for ultra high energy gamma rays coming from point sources is one of the main experimental aims. A fast air shower timing system was constructed at ICRR for the study of the angular resolution of the system and operated approximately half a year. The characteristics of the surface array of Ohya air shower telescope is described
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