1,429 research outputs found
Photon Antibunching in the Photoluminescence Spectra of a Single Carbon Nanotube
We report the first observation of photon antibunching in the
photoluminescence from single carbon nanotubes. The emergence of a fast
luminescence decay component under strong optical excitation indicates that
Auger processes are partially responsible for inhibiting two-photon generation.
Additionally, the presence of exciton localization at low temperatures ensures
that nanotubes emit photons predominantly one by one. The fact that multiphoton
emission probability can be smaller than 5% suggests that carbon nanotubes
could be used as a source of single photons for applications in quantum
cryptography.Comment: content as publishe
A High-resolution Scintillating Fiber Tracker With Silicon Photomultiplier Array Readout
We present prototype modules for a tracking detector consisting of multiple
layers of 0.25 mm diameter scintillating fibers that are read out by linear
arrays of silicon photomultipliers. The module production process is described
and measurements of the key properties for both the fibers and the readout
devices are shown. Five modules have been subjected to a 12 GeV/c proton/pion
testbeam at CERN. A spatial resolution of 0.05 mm and light yields exceeding 20
detected photons per minimum ionizing particle have been achieved, at a
tracking efficiency of more than 98.5%. Possible techniques for further
improvement of the spatial resolution are discussed.Comment: 31 pages, 27 figures, pre-print version of an article published in
Nuclear Instruments and Methods in Physics Research Section A, Vol. 62
Human hair follicle equivalents in vitro for transplantation and chip-based substance testing
GDR in Superdeformed Nuclei
A search for the gamma decay of the Giant Dipole Resonance built on superdeformed nuclear configurations was made. The superdeformed states of the Eu-143 nucleus were populated using the reaction Pd-110(Cl-37, 4n)Eu-143 at a beam energy of 165 MeV. High energy gamma-rays were detected in 8 large BaF2 scintillators in coincidence with discrete transitions measured with part of the NORDBALL array (17 HPGe detectors and a 2 pi multiplicity filter). Spectra of high-energy gamma-rays gated by low-energy transitions from states fed by the superdeformed bands show an excess yield in the 7-10 MeV region with respect to those gated by transitions from states not populated by the superdeformed bands. Because the dipole oscillation along the superdeformed axis of the nucleus is expected to have a frequency corresponding to approximate to 8 MeV (low energy component of the GDR strength function), the present result gives the first experimental indication of gamma-ray emission of the GDR built on a superdeformed states
Spin entanglement using coherent light and cavity-QED
A scheme for probabilistic entanglement generation between two distant single
electron doped quantum dots, each placed in a high-Q microcavity, by detecting
strong coherent light which has interacted dispersively with both subsystems
and experienced Faraday rotation due to the spin selective trion transitions is
discussed. In order to assess the applicability of the scheme for distant
entanglement generation between atomic qubits proposed by T.D. Ladd et al. [New
J. Phys. 8, 184 (2006)] to two distant quantum dots, one needs to understand
the limitations imposed by hyperfine interactions of the quantum dot spin with
the nuclear spins of the material and by non-identical quantum dots.
Feasibility is displayed by calculating the fidelity for Bell state generation
analytically within an approximate framework. The fidelity is evaluated for a
wide range of parameters and different pulse lengths, yielding a trade-off
between signal and decoherence, as well as a set of optimal parameters.
Strategies to overcome the effect of non-identical quantum dots on the fidelity
are examined and the timescales imposed by the nuclear spins are discussed,
showing that efficient entanglement generation is possible with distant quantum
dots. In this context, effects due to light hole transitions become important
and have to be included. The scheme is discussed for one- as well as for
two-sided cavities, where one must be careful with reflected light which
carries spin information. The validity of the approximate method is checked by
a more elaborate semiclassical simulation which includes trion formation.Comment: 17 pages, 13 figures, typos corrected, reference update
Beam test results for the FiberGLAST instrument
The FiberGLAST scintillating fiber telescope is a large-area instrument concept for NASA\u27s GLAST program. The detector is designed for high-energy gamma-ray astronomy, and uses plastic scintillating fibers to combine a photon pair tracking telescope and a calorimeter into a single instrument. A small prototype detector has been tested with high energy photons at the Thomas Jefferson National Accelerator Facility. We report on the result of this beam test, including scintillating fiber performance, photon track reconstruction, angular resolution, and detector efficiency
Recommended from our members
Wire bond vibration of forward pixel tracking detector of CMS
Wire bonds of the Forward Pixel (FPix) tracking detectors are oriented in the direction that maximizes Lorentz Forces relative to the 4 Tesla field of the Compact Muon Solenoid (CMS) Detector's magnet. The CMS Experiment is under construction at the Large Hadron Collider at CERN, Geneva, Switzerland. We were concerned about Lorentz Force oscillating the wires at their fundamental frequencies and possibly fracturing or breaking them at their heels, as happened with the CDF wire bonds. This paper reports a study to understand what conditions break such bonds
Estimation of GRB detection by FiberGLAST
FiberGLAST is one of several instrument concepts being developed for possible inclusion as the primary Gamma-ray Large Area Space Telescope (GLAST) instrument. The predicted FiberGLAST effective area is more than 12,000 cm2 for energies between 30 MeV and 300 GeV, with a field of view that is essentially flat from 0°–80°. The detector will achieve a sensitivity more than 10 times that of EGRET. We present results of simulations that illustrate the sensitivity of FiberGLAST for the detection of gamma-ray bursts
Development and testing of a fiber/multianode photomultiplier system for use on FiberGLAST
A scintillating fiber detector is currently being studied for the NASA Gamma-Ray Large Area Space Telescope (GLAST) mission. This detector utilizes modules composed of a thin converter sheet followed by an x, y plane of scintillating fibers to examine the shower of particles created by high energy gamma-rays interacting in the converter material. The detector is composed of a tracker with 90 such modular planes and a calorimeter with 36 planes. The two major component of this detector are the scintillating fibers and their associated photodetectors. Here we present current status of development and test result of both of these. The Hamamatsu R5900-00-M64 multianode photomultiplier tube (MAPMT) is the baseline readout device. A characterization of this device has been performed including noise, cross- talk, gain variation, vibration, and thermal/vacuum test. A prototype fiber/MAPMT system has been tested at the Center for Advanced Microstructures and Devices at Louisiana State University with a photon beam and preliminary results are presented
- …