The CMS preshower is a fine grain detector that comprises 4288 silicon sensors, each containing 32 strips. The raw data are transferred from the detector to the counting room via 1208 optical fibres. ...Each fibre carries a 600-byte data packet per event. The maximum average level-1 trigger rate of 100 kHz results in a total data flow of ~72 GB/s from the preshower. For the readout of the preshower, 56 links to the CMS DAQ have been reserved, each having a bandwidth of 200 MB/s (2 kB/event). The total available downstream bandwidth of GB/s necessitates a reduction in the data volume by a factor of at least 7. A modular VME-based system is currently under development. The main objective of each VME board in this system is to acquire on-detector data from at least 22 optical links, perform on-line data reduction and pass the concentrated data to the CMS DAQ. The principle modules that the system is based on are being developed in collaboration with the TOTEM experiment.
The neural network first level trigger for the DIRAC experiment Kokkas, P; Steinacher, M; Tauscher, L ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2001, Letnik:
471, Številka:
3
Journal Article
Recenzirano
The neural network first level trigger for the DIRAC experiment at CERN is presented. Both the neural network algorithm used and its actual hardware implementation are described. The system uses the ...fast plastic scintillator information of the DIRAC spectrometer. In 210 ns it selects events with two particles having low relative momentum; such events are selected with an efficiency of more than 0.94. The corresponding rate reduction for background events is a factor of 2.5.
An already existing, sub-critical arrangement made of natural uranium and water moderator has been exposed to a low intensity (≈ 10
9 ppp) proton beam from CERN-PS at several kinetic energies from ...600 MeV to 2.75 GeV. The energy delivered by the hadronic cascade induced by the beam in the device has been measured by the temperature rise of small sampling blocks of uranium located in several different positions inside the device and counting the fissions in thin probe foils of natural uranium. We find typically
G ≈ 30 in reasonable agreement with calculations, where
G is the ratio of the energy produced in the device to the energy delivered by the beam. This result opens the way to the realisation of the so-called Energy Amplifier, a practical device to produce energy from thorium or depleted uranium targets exposed to an intense high energy proton beam. Results show that the optimal kinetic is ≥ 1 GeV, below which
G decreases but is still acceptable in the energy range explored
The multilevel trigger system of the DIRAC experiment Afanasyev, L.; Gallas, M.; Goldin, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2002, Letnik:
491, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The multilevel trigger system of the DIRAC experiment at CERN is presented. It includes a fast first level trigger as well as various trigger processors to select events with a pair of pions having a ...low relative momentum typical of the physical process under study. One of these processors employs the drift chamber data, another one is based on a neural network algorithm and the others use various hit-map detector correlations. Two versions of the trigger system used at different stages of the experiment are described. The complete system reduces the event rate by a factor of 1000 with respect to detectors’ single rates, the detection efficiency of events in the relative momentum range of interest being ⩾95%.
We report on a new measurement of the K
L–K
S mass difference
Δm using the CPLEAR full data sample of neutral-kaon decays to e
πν. The result is
Δm=(0.5295±0.0020
stat±0.0003
syst)×10
10 ℏ/s. It ...includes earlier data reported in R. Adler et al., CPLEAR Collaboration, Phys. Lett. B 363 (1995) 237. A measurement of the
ΔS=
ΔQ violating parameter Re(
x) is also obtained.
The goal of the DIRAC experiment at CERN (PS212) is to measure the π+π− atom lifetime with 10% precision. Such a measurement would yield a precision of 5% on the value of the S-wave ππ scattering ...lengths combination |a0−a2|. Based on part of the collected data we present a first result on the lifetime, τ=2.91−0.62+0.49×10−15 s, and discuss the major systematic errors. This lifetime corresponds to |a0−a2|=0.264−0.020+0.033mπ−1.
Noise measurements on Si sensors Evangelou, I; Kokkas, P; Manthos, N ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2002, Letnik:
493, Številka:
1
Journal Article
Recenzirano
Developing silicon strip sensors for the CMS Preshower detector we have noticed that some strips have a noise higher than the average and not correlated to a high leakage current. In order to ...investigate this effect we have developed a set-up for noise measurement on wafers and diced sensors that does not require bonding. The set-up is based on the DeltaStream chip coupled to a probe card. We have tested 45 sensors and found that the strips with an above average noise have a higher relative current increase as a function of voltage, Δ
I/(
IΔ
V). We also observed that, on these strips, the breakdown occurs within about
60
V
from the voltage at which the noise is observed. We describe our measurement method and present the results.
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