717 research outputs found
Interference spectroscopy with coherent anti-Stokes Raman scattering of noisy broadband pulses
We propose a new technique for comparing two Raman active samples. The method
employs optical interference of the signals generated via coherent anti-Stokes
Raman scattering (CARS) of broadband laser pulses with noisy spectra. It does
not require spectrally resolved detection, and no prior knowledge about either
the Raman spectrum of the samples, or the spectrum of the incident light is
needed. We study the proposed method theoretically, and demonstrate it in a
proof-of-principle experiment on Toluene and ortho-Xylene samples.Comment: 15 pages, 6 figure
FPGA Based Data Read-Out System of the Belle 2 Pixel Detector
The upgrades of the Belle experiment and the KEKB accelerator aim to increase
the data set of the experiment by the factor 50. This will be achieved by
increasing the luminosity of the accelerator which requires a significant
upgrade of the detector. A new pixel detector based on DEPFET technology will
be installed to handle the increased reaction rate and provide better vertex
resolution. One of the features of the DEPFET detector is a long integration
time of 20 {\mu}s, which increases detector occupancy up to 3 %. The detector
will generate about 2 GB/s of data. An FPGA-based two-level read-out system,
the Data Handling Hybrid, was developed for the Belle 2 pixel detector. The
system consists of 40 read-out and 8 controller modules. All modules are built
in {\mu}TCA form factor using Xilinx Virtex-6 FPGA and can utilize up to 4 GB
DDR3 RAM. The system was successfully tested in the beam test at DESY in
January 2014. The functionality and the architecture of the Belle 2 Data
Handling Hybrid system as well as the performance of the system during the beam
test are presented in the paper.Comment: Transactions on Nuclear Science, Proceedings of the 19th Real Time
Conference, Preprin
Narrowband spectroscopy by all-optical correlation of broadband pulses
High peak power ultrafast lasers are widely used in nonlinear spectroscopy
but often limit its spectral resolution because of the broad frequency
bandwidth of ultrashort laser pulses. Improving the resolution by achieving
spectrally narrow excitation of, or emission from, the resonant medium by means
of multi-photon interferences has been the focus of many recent developments in
ultrafast spectroscopy. We demonstrate an alternative approach, in which high
resolution is exercised by detecting narrow spectral correlations between
broadband excitation and emission optical fields. All-optical correlation
analysis, easily incorporated into the traditional spectroscopic setup, enables
direct, robust and simultaneous detection of multiple narrow resonances with a
single femtosecond pulse.Comment: 5 pages, 4 figures, submitted to PR
First Results of the PixelGEM Central Tracking System for COMPASS
For its physics program with a high-intensity hadron beam of up to 2e7
particles/s, the COMPASS experiment at CERN requires tracking of charged
particles scattered by very small angles with respect to the incident beam
direction. While good resolution in time and space is mandatory, the challenge
is imposed by the high beam intensity, requiring radiation-hard detectors which
add very little material to the beam path in order to minimize secondary
interactions.
To this end, a set of triple-GEM detectors with a hybrid readout structure
consisting of pixels in the beam region and 2-D strips in the periphery was
designed and built. Successful prototype tests proved the performance of this
new detector type, showing both extraordinary high rate capability and
detection efficiency. The amplitude information allowed to achieve spatial
resolutions about a factor of 10 smaller than the pitch and a time resolution
close to the theoretical limit imposed by the layout.
The PixelGEM central tracking system consisting of five detectors, slightly
improved with respect to the prototype, was completely installed in the COMPASS
spectrometer in spring 2008
FPGA based data acquisition system for COMPASS experiment
This paper discusses the present data acquisition system (DAQ) of the COMPASS
experiment at CERN and presents development of a new DAQ. The new DAQ must
preserve present data format and be able to communicate with FPGA cards. Parts
of the new DAQ are based on state machines and they are implemented in C++ with
usage of the QT framework, the DIM library, and the IPBus technology. Prototype
of the system is prepared and communication through DIM between parts was
tested. An implementation of the IPBus technology was prepared and tested. The
new DAQ proved to be able to fulfill requirements.Comment: 8 pages, CHEP 201
Nonlinear optics with stationary pulses of light
We show that the recently demonstrated technique for generating stationary
pulses of light [Nature {\bf 426}, 638 (2003)] can be extended to localize
optical pulses in all three spatial dimensions in a resonant atomic medium.
This method can be used to dramatically enhance the nonlinear interaction
between weak optical pulses. In particular, we show that an efficient Kerr-like
interaction between two pulses can be implemented as a sequence of several
purely linear optical processes. The resulting process may enable coherent
interactions between single photon pulses.Comment: 4 pages, 2 figure
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