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M. Bocker,
M. Adams,
P. Bechtle,
P. Buchholz,
C. Cruse,
U. Husemann,
E. Klaus,
N. Koch,
M. Kolander,
I. Kolotaev, H. Riege,
J. Schutt,
B. Schwenninger,
R. van Staa,
D. Wegener
[show abstract]
[hide abstract]
ABSTRACT: One of the main goals of the HERA-B experiment at DESY in Hamburg,
Germany, is to study the properties of B-mesons with the emphasis on CP
violation. B-mesons are produced in hadronic interactions of a 920-GeV
proton beam with an internal wire target. An effective bunch crossing
rate of about 8.5 MHz leads to about 200 charged tracks per event.
Therefore, a highly selective and efficient trigger system providing
high suppression of background events is required. The HERA-B trigger
system consists of four levels. A rate reduction factor of 200 is aimed
at by the first-level trigger (FLT). The muon pretrigger system, as a
part of the FLT, is a modular system consisting of about 100 large-size
VME modules of three different types: the pretrigger link board (PLB),
the pretrigger coincidence unit (PCU), and the pretrigger message
generator (PMG). The data rate processed by the pretrigger system is
about 19.5 GByte/s. The PLBs process digitized hit information in eight
independent electronic channels in parallel. Every electronic channel
handles 32 bits of hit information received from the front-end driver
buffer system. Optical links operating at 800 Mb/s transmit the data
after serialization to PCUs, which calculate coincidences using complex
programmable logic devices. The PMGs transform this coincidence
information into messages for the FLT processors. The concept and design
as well as results of the muon pretrigger running at HERA-B are
presented
IEEE Transactions on Nuclear Science 09/2001; · 1.45 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The high-p<sub>T</sub> trigger to select tracks with high
transverse momenta has been developed. The concept, design criteria, and
system components are described. A dedicated data processing (pretrigger
logic) system has been developed to select and process in real time
pretrigger signals out of 3×10<sup>12</sup> combinations per
second. The operational performance of the data-processing system and
other components of the trigger system are presented
IEEE Transactions on Nuclear Science 09/2001; · 1.45 Impact Factor
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P. van Esch,
M. Kapichine,
A. Morozov,
V. Spaskov,
W. Bartel,
B. List,
H. Mahlke-Krüger,
V. Schröder,
T. Wilksen,
F.W. Büsser, [......],
S.K. Kotelnikov,
A. Lebedev,
S. Rusakov,
A. Astvatsatourov,
J. Bähr,
U. Harder,
K. Hiller,
B. Hoffmann,
H. Lüdecke,
R. Nahnhauer
[show abstract]
[hide abstract]
ABSTRACT: The forward proton spectrometer is part of the H1 detector at the HERA collider. Protons with energies above 500 GeV and polar angles below 1 mrad can be detected by this spectrometer. The main detector components are scintillating fiber detectors read out by position-sensitive photo-multipliers. These detectors are housed in the so-called Roman Pots which allow them to be moved close to the circulating proton beam. Four Roman Pot stations are located at distances between 60 and 90 m from the interaction point.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 02/2000;
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M. Adams,
P. Buchholz,
C. Cruse,
N. Koch,
M. Kolander,
I. Kolotaev, H. Riege,
J. Schutt,
B. Schwenninger,
R. Van Staa,
D. Wegener
[show abstract]
[hide abstract]
ABSTRACT: This paper describes the muon pretrigger system of the HERA-B experiment. The muon pretrigger is designed to detect track candidates for muons in order to generate seeds for the first level trigger (FLT) search algorithm. Muons provide the cleanest event signature in the large amount of hadronic background. In order to achieve the required precision the muon pretrigger system has to cope with an interaction rate of about 40 MHz at the HERA bunch crossing rate of 10.4 MHz. This results in a total input data rate of about 10 Gbyte/s. A total rate reduction by a factor of 200 is aimed at by the complete FLT, including the pretrigger systems (electromagnetic calorimeter, muon and high-p/sub T/), within at most 12 /spl mu/s.
IEEE Transactions on Nuclear Science 01/2000; · 1.45 Impact Factor
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P. Adams,
P. Buchholz,
C. Cruse,
N. Koch,
M. Kolander,
I. Kolotaev, H. Riege,
J. Schutt,
B. Schwenninger,
R. van Staa,
D. Wegener
[show abstract]
[hide abstract]
ABSTRACT: This paper describes the muon pretrigger system of the HERA-B
experiment. The muon pretrigger is designed to detect track candidates
for muons in order to generate seeds for the first level trigger (FLT)
search algorithm. Muons provide the cleanest event signature in the
large amount of hadronic background. In order to achieve the required
precision the muon pretrigger system has to cope with an interaction
rate of about 40 MHz at the HERA bunch crossing rate of 10.4 MHz. This
results in a total input data rate of about 10 Gbyte/s. A total rate
reduction by a factor of 200 is aimed at by the complete FLT, including
the pretrigger systems (electromagnetic calorimeter, muon and
high-p<sub>T</sub>), within at most 12 μs
Nuclear Science Symposium, 1998. Conference Record. 1998 IEEE; 02/1998
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I. Abt,
T. Ahmed,
S. Aid,
V. Andreev,
B. Andrieu,
R.-D. Appuhn,
C. Arnault,
M. Arpagaus,
A. Babaev,
H. Bärwolff, [......],
J. ŽáČek,
D. Zarbock,
P. Závada,
C. Zeitnitz,
Z. Zhang,
H. Ziaeepour,
M. Zimmer,
W. Zimmermann,
F. Zomer,
K. Zuber
[show abstract]
[hide abstract]
ABSTRACT: Technical aspects of the three major components of the H1 detector at
the electron-proton storage ring HERA are described. This paper covers
the detector status up to the end of 1994 when a major upgrading of some
of its elements was undertaken. A description of the other elements of
the detector and some performance figures from luminosity runs at HERA
during 1993 and 1994 are given in a paper previously published in this
journal.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/1997; 386:348-396. · 1.21 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: A sample of lead‐lanthanum‐zirconium‐titanate (PLZT 9/65/35) has been exposed to 6‐ns‐long laser pulses of 266 nm wavelength. The maximum output pulse energy of the laser beam was 300 μJ, the output power density on the sample 5×10<sup>5</sup> W/cm<sup>2</sup>, and the beam diameter 3 mm. By applying a moderate extraction voltage of several kilovolts, intense electron beam pulses are emitted from the free sample surface. Their time structure corresponds to the time structure of the laser pulse. Electron beam current intensities of up to 0.1 A and 2 A/cm<sup>2</sup> and total charges of 1 nC (corresponding to 20 nC/cm<sup>2</sup> ) were measured with a simple Faraday cup. In the range where the parameters of laser intensity and of extraction voltage could be varied their influence on the emitted electron beam current amplitude was determined.
Applied Physics Letters 04/1990; · 3.84 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Construction and use of a function generator are presented. The flexible outline allows a high precision control for all required
velocity profiles.
Hyperfine Interactions 01/1986; 29(1):1555-1558. · 0.21 Impact Factor
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D. Bloess,
I. Kamber, H. Riege,
G. Bittner,
V. Brückner,
J. Christiansen,
K. Frank,
W. Hartmann,
N. Lieser,
Ch. Schultheiss,
R. Seeböck,
W. Steudtner
[show abstract]
[hide abstract]
ABSTRACT: The pseudo-spark phenomenon opens a wide field of applications in accelerator, high-voltage, and high-current handling technology. A basic model is described which explains the initialization and the growth of the pseudo-spark discharge process in two phases. The discharge characteristics of single-gap and multigap pseudo-spark chambers have been investigated. In both types of chambers the breakdown can be triggered easily. With single-gap chambers one can switch voltages in the kV range and currents in the kA range. Multigap chambers generate pulsed, pinched electron beams with peak currents up to 5 kA with fwhm of 2 ns to 20 ns and densities greater than 106 A/cm2. With the aid of these intenseelectron beams, highly charged ions such as Kr13+ have been produced. From multigap chambers one can also extract well-focused ion beams. The experimental results are compared with a model describing the pseudo-spark phenomenon. The applications of the pseudo-spark chamber as a triggerable, fast, high-voltage, high-current switch and as a pulsed, high-density electron- and ion-beam source are discussed.
Nuclear Instruments and Methods in Physics Research.
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[show abstract]
[hide abstract]
ABSTRACT: The emission from ferroelectric material is dominated by surface electrons, which screen a large part of the spontaneous polarization. The surface charge compensation of the polarization can be modified by various methods in certain limits and, hence, also the efficiency of the electron emission. An increase of the emitted charge by laser irradiation of more than two orders of magnitude was measured after switching the polarization of polycrystalline lead-lanthanum-zirconium-titanate ceramics (PLZT). An enhancement of electron emission is also observed by pre-illumination with laser light in absence of an extraction voltage compared to regular illumination under a dc extraction field. The laser-induced emission is shown to be dependent on the ferroelectric state and on the full absorption of the laser light in the material.
Physics Letters A.
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JADE Collaboration,
W Bartel,
T Canzler,
D Cords,
P Dittmann,
R Eichler,
R Felst,
E Gadermann,
D Haidt,
S Kawabata, [......],
M. Koshiba,
M Minowa,
S Orito,
A Sato,
T Suda,
H Takeda,
Y Totsuka,
Y Watanabe,
S Yamada,
C Yanagisawa
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JADE Collaboration,
S Orito,
W Bartel,
T Canzler,
D Cords,
P Dittmann,
R Eichler,
R Felst,
E Gadermann,
D Haidt, [......],
S Komamiya,
M. Koshiba,
M Minowa,
A Sato,
T Suda,
H Takeda,
Y Totsuka,
Y Watanabe,
S Yamada,
C Yanagisawa
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[show abstract]
[hide abstract]
ABSTRACT: The efficiency of laser-induced electron emission from ferroelectric (FE) cathodes has been measured by illumination with a Ti:sapphire laser at a pulse length of 140 fs and is compared to earlier measurements at 40 ps and 5 ns pulse lengths. Two modes of emission are observed: (i) a “normal steady-state” emission in the presence of a constant extraction field and (ii) a transient mode after a polarization switching of the FE cathode by a high-voltage pulse. The latter mode leads to “self-emission” of high electron currents with kinetic electron energies of several kilovolts. The physical interpretation and the potential applications of laser-induced electron emission from FE cathodes are briefly pointed out.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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H1 Collaboration,
I Abt,
T Ahmed,
S Aid,
V Andreev,
B Andrieu,
RD Appuhn,
C Arnault,
M Arpagaus,
A Babaev, [......],
J Zacek,
D Zarbock,
P. Zavada,
C Zeitnitz,
Z Zhang,
H Ziaeepour,
M Zimmer,
W Zimmermann,
F Zomer,
K Zuber
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H1 Collaboration,
I Abt,
T Ahmed,
S Aid,
V Andreev,
B Andrieu,
RD Appuhn,
C Arnault,
M Arpagaus,
A Babaev, [......],
J Zacek,
D Zarbock,
P. Zavada,
C Zeitnitz,
Z Zhang,
H Ziaeepour,
M Zimmer,
W Zimmermann,
F Zomer,
K Zuber
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[show abstract]
[hide abstract]
ABSTRACT: For the first time a ferroelectric cathode has been tested in an accelerator-like structure. In the CLIC dc test stand electron pulses with ns duration and with charges up to 2.5 nC were generated by laser light using 308, 266 and 213 nm wavelength. Electron emission has been investigated as a function of the extraction voltage, the laser energy density, and for one particular material for two different prepoling conditions. The results show that the amount of emitted charge is influenced by the ferroelectric state of the sample; laser illumination and simultaneously electrically switching the materials polarization enhances emission. Two long term tests at a laser repetition rate of 10 Hz prove the reliability of ferroelectric cathode material up to more than 2×106 pulses.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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W. Bartel,
T. Canzler,
D. Cords,
P. Dittmann,
R. Eichler,
R. Felst,
E. Gadermann,
D. Haidt,
S. Kawabata,
H. Krehbiel, [......],
M. Koshiba,
M. Minowa,
S. Orito,
A. Sato,
T. Suda,
H. Takeda,
Y. Totsuka,
Y. Watanabe,
S. Yamada,
C. Yanagisawa
[show abstract]
[hide abstract]
ABSTRACT: The cross section for the process e+e− → multihadrons has been measured at the highest PETRA energies. We measure R (the total cross section in units of the point-like e+e- → μ+μ- cross section) to be 2.9 ± 0.7, 4.0 ± 0.5, 4.6 ± 0.4 and 4.2 ± 0.6 at of 22, 27.7, 30 and 31.6 GeV, respectively. The observed average multiplicity, together with existing low energy data, indicate a rapid increase in multiplicity with increasing energy.
Physics Letters B.
