2,542 research outputs found
Total Hadronic Cross-Section for Photon-Photon Interactions at LEP
The total hadronic cross-section for the interaction of real photons is
extracted from a measurement of the cross-section of the process e+e->e+e- +
hadrons using a luminosity function for the photon flux and form factors for
extrapolating to Q**2=0. The data was taken with the OPAL detector at LEP at
e+e- centre-of-mass energies of 161 GeV and 172 GeV. In the energy range 10 < W
< 110 GeV the total hadronic photon-photon cross-section is consistent with the
Regge behaviour of the total cross-section observed in \gamma p and
hadron-hadron interactions.Comment: 7 pages, 7 figues, needs espcrc2.sty, to be published in proceedings
of the XXVII INTERNATIONAL SYMPOSIUM ON MULTIPARTICLE DYNAMICS, INFN,
Frascati (Rome), Italy, 8-12 September 199
Verarbeitung und Vermarktung von ökologischem Schweinefleisch in Baden-Württemberg
Die Zielsetzung dieser Arbeit ist, Qualitätsansprüche an ökologisch erzeugtes Schweinefleisch und dessen Verarbeitungsprodukte aufzuzeigen. Dabei sollen einerseits die Qualitätsansprüche und mögliche Probleme auf der Verbraucherebene erfasst und andererseits auf der Verarbeiterebene auftretende Probleme hinsichtlich des Bezugs, der Verarbeitung und Vermarktung von Ökoschweinefleisch und Ökoschweinefleischerzeugnissen aufgezeigt werden. Um Informationen zur Thematik zu erhalten, wurden Verbraucher und Verarbeiter unabhängig voneinander befragt. Die Befragungen der Verbraucher und Verarbeiter erfolgte im Großraum Stuttgart
The ARGUS Vertex Trigger
A fast second level trigger has been developed for the ARGUS experiment which
recognizes tracks originating from the interaction region. The processor
compares the hits in the ARGUS Micro Vertex Drift Chamber to 245760 masks
stored in random access memories. The masks which are fully defined in three
dimensions are able to reject tracks originating in the wall of the narrow
beampipe of 10.5\,mm radius.Comment: gzipped Postscript, 27 page
Photon-Photon and Photon-Hadron Interactions at Relativistic Heavy Ion Colliders
In central collisions at relativistic heavy ion colliders like the
Relativistic Heavy Ion Collider RHIC/Brookhaven and the Large Hadron Collider
LHC (in its heavy ion mode) at CERN/Geneva, one aims at detecting a new form of
hadronic matter --- the Quark Gluon Plasma. We discuss here a complementary
aspect of these collisions, the very peripheral ones. Due to coherence, there
are strong electromagnetic fields of short duration in such collisions. They
give rise to photon-photon and photon-nucleus collisions with high flux up to
an invariant mass region hitherto unexplored experimentally. After a general
survey photon-photon luminosities in relativistic heavy ion collisions are
discussed. Then photon-photon physics at various gamma-gamma-invariant mass
scales is discussed. The region of several GeV, relevant for RHIC is dominated
by QCD phenomena (meson and vector meson pair production). Invariant masses of
up to about 100 GeV can be reached at LHC, and the potential for new physics is
discussed. Lepton-pair production, especially electron-positron pair production
is copious. Due to the strong fields there will be new phenomena, especially
multiple e+e- pair production.Comment: 10 pages, Proceedings of the Erice Summer School on Heavy Ion Physics
199
Characterization of a CdZnTe detector for a low-power CubeSat application
We report spectral and imaging performance of a pixelated CdZnTe detector
custom designed for the \emph{MeVCube} project: a small Compton telescope on a
CubeSat platform. \emph{MeVCube} is expected to cover the energy range between
and , with performance comparable to the
last generation of larger satellites. In order to achieve this goal, an energy
resolution of few percent in full width at half maximum (FWHM) and a -D
spatial resolution of few millimeters for the individual detectors are needed.
The severe power constraints present in small satellites require very low power
read-out electronics for the detector. Our read-out is based on the VATA450.3
ASIC developed by \emph{Ideas}, with a power consumption of only
, which exhibits good performance in terms of
dynamic range, noise and linearity. A CdZnTe detector, with a custom pixel
anode structure read-out by a VATA450.3 ASIC, has been tested. A preliminary
read-out system for the cathode, based on a discrete \emph{Amptek} A250F charge
sensitive pre-amplifier and a DRS4 ASIC, has been implemented. An energy
resolution around FWHM has been measured at a gamma energy of
; at the average energy resolution is
, decreasing to at energies above . A
-D spatial resolution of is achieved
Characterization of a CdZnTe detector for a low-power CubeSat application
We report spectral and imaging performance of a pixelated
CdZnTe detector custom designed for the MeVCube project: a
small Compton telescope on a CubeSat platform. MeVCube is
expected to cover the energy range between 200 keV and
4 MeV, with a sensitivity comparable to the one of the
last generation of larger satellites. In order to achieve this goal,
an energy resolution of few percent in full width at half maximum
(FWHM) and a 3-D spatial resolution of few millimeters for the
individual detectors are needed. The severe power constraints
present in small satellites require very low power read-out
electronics for the detector. Our read-out is based on the VATA450.3
ASIC developed by Ideas, with a power consumption of only
0.25 mW/channel, which exhibits good performance in
terms of dynamic range, noise and linearity. A
2.0 cm× 2.0 cm× 1.5 cm
CdZnTe detector, with a custom 8 × 8 pixel anode structure
read-out by a VATA450.3 ASIC, has been tested. A preliminary
read-out system for the cathode, based on a discrete Amptek
A250F charge sensitive pre-amplifier and a DRS4 ASIC, has been
implemented. An energy resolution around 3% FWHM has been
measured at a gamma energy of 662 keV; at
200 keV the average energy resolution is 6.5%,
decreasing to ≲ 2% at energies above 1 MeV. A
3-D spatial resolution of ≈ 2 mm is achieved in
each dimension.Peer Reviewe
- …