In this work, we present a method for absolute measurement of air fluorescence yield based on high resolution optical emission spectroscopy. The absolute measurement of the air fluorescence yield is ...feasible using the Cherenkov light, emitted by an electron beam simultaneously with the fluorescence light, as a “standard candle”. The separation of these two radiations can be accomplished exploiting the “dark” spectral regions of the emission band systems of the molecular spectrum of nitrogen. In these “dark” regions the net Cherenkov light can be recorded experimentally and be compared with the calculated one. The instrumentation for obtaining the nitrogen molecular spectra in high resolution and the noninvasive method for monitoring the rotational temperature of the emission process are also described. For the experimental evaluation of the molecular spectra analysis we used DC normal glow discharges in air performed in an appropriate spectral lamp considered as an air-fluorescence light emulator. The proposed method and the associated instrumentation could be tested and used in thin or thick target experiments in electron beam accelerators as a candidate optical system for this purpose.
Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a ...huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5–10 improvement in sensitivity in the 100 GeV–10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.
The fluorescence light, induced by showers of the extremely high energy cosmic rays, is produced through the excitation of, mainly, nitrogen molecules, atoms, and ions, in the atmosphere. The ...fluorescence telescopes of the Auger Project record this nitrogen radiation under the variable night sky optical noise (background radiation) and, therefore, the study of the latter is crucial. In this paper we present a parametrization of an experimental night sky background radiation spectrum that, to our knowledge, is being carried out for the first time, recorded in the range 3000-6000 Å. Although the parametrization described here refers to a particular spectrum, our results are generally applicable, and could be adapted to those prevailing in particular locations, where EAS fluorescence telescopes are operating if, in addition, the gradual time variations of the spectrum are taken into account. They could be useful in data analysis for the event reconstruction, during the operation of the fluorescence detector of the Auger Observatory, since they could be used for the experimental emulation of the optical noise. In addition, they could be used in the designing of air fluorescence observatory components, such as photomultipliers and their spectral sensitivity, as well as in the corresponding optical filters.
With an updated, flexible, highly efficient and easily installed system we obtained accurate refractivity (
n−1) values. This system is a refractometer based on a Fabry–Perot interferometer and was ...used to monitor the refractivity of DELPHI RICH Cherenkov radiators near the VUV region. By using a Pt–Ne spectral lamp and improved alignment and temperature control, the refractivities of C
5F
12 and C
4F
10 have been monitored since 1996. With this light source, selected to have large coherence lengths, we can extract the refractivity at several wavelengths from one data set only. The estimated errors of the refractivity measurements are less than 1.2%, and depend on wavelength and the type of gas used. The various parameters affecting the accuracy of the refractometer are also discussed. Finally, results from special sample refractivity measurements of the liquid radiator (C
6F
14) in its gas phase, are presented.
A prism spectrometer has been developed to operate in the VUV wavelength range from 120 to 200 nm. It can be used as a pre-disperser in conjunction with a Fabry-Perot based gas refractometer. This ...instrument has also been used to measure the refractive index of the liquid radiator C
6
F
14
in various spectral lines. This radiator is used in the RICH detectors of the DELPHI experiment and has been proposed for ALICE, and LHCb experiments. The spectral resolution of the system is improved as the wavelength decreases and the data are consistent with a wavelength accuracy about 0.4 nm at 140nm. The results for the dispersion curve of the above liquid are presented.
Operation, optimisation, and performance of the DELPHI RICH detectors Albrecht, E.; van Apeldoorn, G.; Augustinus, A. ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
1999, Letnik:
433, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
The Ring Imaging Cherenkov detectors of DELPHI represent a large-scale particle identification system which covers almost the full angular acceptance of DELPHI. The combination of liquid and gas ...radiators (C
4F
10, C
5F
12, and C
6F
14) provides particle identification over the whole secondary particle momentum spectrum at LEP I and LEP II. Continuing optimisation on the hardware as well as on the online and offline software level have resulted in a stable operation of the complete detector system for more than five years at full physics performance.
ATLAS (a toroidal LHC apparatus) is a general purpose experiment that will start its operation at the large hadron collider (LHC) at CERN in 2007. The ATLAS detector is designed to explore numerous ...physics processes by recording, measuring, and investigating the products emerging from proton-proton collisions at energies up to 14 TeV. High-precision muon momentum measurement (dp/p/spl sim/10% at p/sub T/=1 TeV/c) over large areas using monitored drift tube (MDT) chambers is crucial for the ATLAS experiment. More than 1200 MDT chambers, consisting of approximately 370 000 drift tubes, will provide a total coverage of 5500 m/sup 2/. Three Greek universities have taken the responsibility to construct 130 barrel inner small (BIS)-MDT chambers using 30 000 drift tubes of /spl sim/1.7 m length that have been quality tested before assembly. The design of the muon drift tubes aims at high detection efficiency (>95%) and a spatial single tube resolution of <80 /spl mu/m. This paper describes the cosmic ray test setup, which has been instrumented in order to verify that the BIS-MDT chamber Module-0 fulfills its design requirements. The analysis of its data shows that the chamber meets these requirements; it has low noise levels, uniform drift properties, good spatial resolution, and high particle detection efficiency.
Rutherford backscattering spectroscopy (RBS) has been used during the development of multilayer thin film optical filters, especially designed for the fluorescence detector of the Pierre AUGER ...Project. Depth profiles of the heavy components have been measured directly, while reliable results for the light components could also be extracted indirectly. Relative thickness and density of the individual layers and deviations from the desired thickness and stoichiometry have been deduced. The findings of the RBS method have been compared and discussed with results obtained by other characterization techniques.
The hadronic part of the electron structure function F2e has been measured for the first time, using e+e− data collected by the DELPHI experiment at LEP, at centre-of-mass energies of ...s=91.2–209.5 GeV. The data analysis is simpler than that of the measurement of the photon structure function. The electron structure function F2e data are compared to predictions of phenomenological models based on the photon structure function. It is shown that the contribution of large target photon virtualities is significant. The data presented can serve as a cross-check of the photon structure function F2γ analyses and help in refining existing parameterisations.
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