Contributions to QCD from ARGUS Ressing, D.
Nuclear physics. Section B, Proceedings supplement,
03/1995, Letnik:
39, Številka:
2
Journal Article
Recenzirano
We present precise branching ratios for
D
0 →
K
−
π
+,
K
−
π
+
π
+
π
−,
K
S
0π+π−
decays. We also obtained new values for the
D
* →
D
γ
branching fractions previously measured to be unexpectingly ...large. A partial wave analysis of the
γγ →
ωρ
0 resonance is reported as well as cross sections for
γγ →
ρ
0 and
γγ →
ω.
HERA-B framework for online calibration and alignment Hernández, J.M.; Ressing, D.; Rybnikov, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2005, Letnik:
546, Številka:
3
Journal Article
Recenzirano
Odprti dostop
This paper describes the architecture and implementation of the HERA-B framework for online calibration and alignment. At HERA-B the performance of all trigger levels, including the online ...reconstruction, strongly depends on using the appropriate calibration and alignment constants, which might change during data taking. A system to monitor, recompute and distribute those constants to online processes has been integrated in the data acquisition and trigger systems.
The HERA-B Outer Tracker is a large detector with 112,674 drift chamber channels. It is exposed to a particle flux of up to
2
×
10
5
cm
-
2
s
-
1
thus coping with conditions similar to those expected ...for the LHC experiments. The front-end readout system, based on the ASD-8 chip and a customized TDC chip, is designed to fulfil the requirements on low noise, high sensitivity, rate tolerance, and high integration density.
The TDC system is based on an ASIC which digitizes the time in bins of about 0.5
ns within a total of 256 bins. The chip also comprises a pipeline to store data from 128 events which is required for a deadtime-free trigger and data acquisition system.
We report on the development, installation, and commissioning of the front-end electronics, including the grounding and noise suppression schemes, and discuss its performance in the HERA-B experiment.
HERA-B data acquisition system Dam, M.; Egorytchev, V.; Essenov, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2004, Letnik:
525, Številka:
3
Journal Article
Recenzirano
The HERA-B Data Acquisition System implements a
50
kHz
dead-timeless readout of
500
kB
events requiring unprecedented speed of storing and data processing. The system is based on Digital Signal ...Processors (DSP) minimizing the number of components. A high bandwidth, low-latency DSP switching network provides full connectivity between the readout buffers and a PC farm which runs the higher level trigger. The design of the system and the achieved performance are described in this paper.
HERA-B is a fixed target spectrometer which uses
920
GeV
protons incident on various target materials. The experiment is aimed to study various aspects of beauty and charm physics. The detector is ...designed to operate at high interaction rates with an average of 4–5 interactions per event. The First-Level Trigger (FLT) is required to reduce the input rate by more than two orders of magnitude while keeping high efficiency for beauty and charm channels. The trigger performs online track reconstruction and takes decisions based on particle momenta or pair masses. A pipeline architecture is implemented on about 100 pipelined hardware processors to perform this job. The working principle and first results of the FLT performance based on the data acquired during the run in the year 2000 are described.
The HERA-B Outer Tracker consists of drift tubes folded from polycarbonate foil and is operated with Ar/CF
4/CO
2 as drift gas. The detector has to stand radiation levels which are similar to LHC ...conditions. The first prototypes exposed to radiation in HERA-B suffered severe radiation damage due to the development of self-sustaining currents (Malter effect). In a subsequent extended R&D program major changes to the original concept for the drift tubes (surface conductivity, drift gas, production materials) have been developed and validated for use in harsh radiation environments. In the test program various aging effects (such as Malter currents, gain loss due to anode aging and etching of the anode gold surface) were observed, and cures by tuning of operation parameters were developed.
The fast control system for HERA-B Fuljahn, T.; Hochweller, G.; Ressing, D.
IEEE transactions on nuclear science,
08/1999, Letnik:
46, Številka:
4
Journal Article
Recenzirano
The HERA-B experiment is dedicated to measure CP-violation in decays of neutral B-mesons. The B-mesons are produced in a nearly overwhelming background of inelastic proton-nucleon interactions. To ...reconstruct a sufficient number of B-decays the experiment has to be operated with multiple interactions at a 10 MHz event rate. A granularity of 540,000 channels is required. The challenge for the DAQ system is deadtimeless readout. This requires unprecedented speed of storing and labeling the data. A 50 kHz first level trigger rate needs a fast distribution of accepted-event identifiers. Ambitious plans for drift time measurements require a high precision time reference for the front end electronics. A fast control system has been developed to fulfil these requirements. The system consists of a VME-accessible mother unit with trigger and command processing logic, a two-stage signal distribution system and one individually configurable daughter module with timing adjustment capabilities in each of more than 200 front end electronics crates.
The CP violation experiment HERA-B at DESY requires highly selective on-line filtering of data due to high interaction rates and low signal to background ratio. This demands a hierarchical trigger ...system and data acquisition with high bandwidth. A complete level of the trigger hierarchy and the DAQ chain can be built from a single unit type: a single slot 6U VME unit carrying six ADSP21060 (SHARC) DSPs. The six SHARCs communicate via the common bus or via their link ports, which are all accessible from the front panel. Up to 350 units will be used in the experiment. Prototype units have been built and are operating successfully.
Track finding at 10-MHz hadronic event rate Bruinsma, M.; Fleckenstein, H.; Gerndt, E.K.E. ...
IEEE transactions on nuclear science,
04/2002, Letnik:
49, Številka:
2
Journal Article
Recenzirano
Hera-B is a fixed target experiment using a halo target inside the HERA proton ring to generate B mesons in 920 GeV proton-nucleus interactions. The first-level trigger (FLT) of the experiment has to ...reduce the primary 10-MHz input rate by a factor 200 in less than 10 /spl mu/s to make it acceptable to the second level trigger (SLT). The trigger strategy is based on the tracking of charged particles and on the reconstruction of their kinematic parameters. The combination of track pairs can also be used for the final decision. A parallel and pipelined set of approximately 60 dedicated boards was designed and built to perform this job. In this paper, the working principle of the system and some results obtained by analyzing the data collected during the run in the year 2000 are described.
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