Architecture and performance of the DELPHI trigger system Bocci, V; Booth, P.S.L; Bozzo, M ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/1995, Letnik:
362, Številka:
2
Journal Article
Recenzirano
Odprti dostop
This paper describes the trigger system of the DELPHI detector at LEP. It reports on the most relevant aspects of the hardware and shows the software strategies that have been developed to optimize ...its use.
In 1993 the structure of the trigger in four decision levels has become fully operational and data collected during this period have been used to study the trigger performance. Various final state channels such as
μ
+
μ
−, e
+e
− and
hadronic events were selected and their trigger efficiencies were calculated as a function of the polar angle θ. The results obtained indicate that, for any of the event topologies considered, the DELPHI trigger efficiency is independent of the θ angle, and, furthermore, the attained efficiency values are determined to be very close to 100% within an extremely good precision. This is a consequence of the high redundancy presently provided by all the DELPHI subdetectors. In addition to this analysis, events containing isolated particles either in the barrel or in the forward regions have been selected to evaluate the trigger response to single particles. Hence, trigger efficiencies for single particles have also been computed for charged tracks as a function of the momentum and for photons as a function of the deposited electromagnetic energy.
The STIC calorimeter was installed in the DELPHI detector in 1994. The main goal is to measure the luminosity with an accuracy better than 0.1%. The calorimeter was built using the “Shashlik” ...technique. The light is collected by wavelength shifting fibers and readout by phototetrodes that can operate inside the magnetic field. The detector performance during the 1994–1995 data taking is presented. The different contributions to the systematic error on the luminosity measurement are discussed.
By exploiting the triple-well option available in a deep-submicron CMOS process, we developed monolithic active pixel sensors (MAPS) with the unique features of full analog signal processing and ...digital functionality implemented at the pixel level. After briefly reviewing the results achieved with the first prototype chip, we report on the extensive measurements on the second prototype, containing both single-channel sensors, with an improved noise figure, and an
8
×
8
pixel array. For the pixel having a collecting electrode area of
900
μ
m
2
we measured an equivalent noise charge of about 40 electrons. Using the
Fe
55
5.9
keV line, we obtained a Signal-to-noise (S/N) ratio of about 30. The pixel matrix
(
50
×
50
μ
m
2
)
has been successfully readout up to 30
MHz. Through noise scans, an expected significant threshold dispersion has been measured.
The measurements presented in this paper confirm the capability of our MAPS, based on the deep n-well concept, to be operated as ionizing radiation detectors and suggest a series of improvements we are already implementing in the design of the next prototype chip.
The Belle-II VerteX Detector (VXD) is a 6 layers silicon tracker device that will cope with an unprecedented luminosity of 8 x 10^35 cm-2 s-1 achievable by the new SuperKEKB e+e- collider, now under ...commissioning at the KEK laboratory (Tsukuba, Japan). A radiation monitoring and beam abort system has been developed based on single-crystal s-CVD diamond sensors. The sensors will be placed in 20 key positions in the vicinity of the interaction region. The severe space limitations require a remote readout of the sensors. In this contribution we present the system design, along with the sensor characterisation procedure. We present also the preliminary results with the prototype system during the first SuperKEKB commissioning phase in February-June 2016.
The Belle II experiment at the SuperKEKB electron-positron collider aims to collect an unprecedented data set of \(50~{\rm ab}^{-1}\) to study \(CP\)-violation in the \(B\)-meson system and to search ...for Physics beyond the Standard Model. SuperKEKB is already the world's highest-luminosity collider. In order to collect the planned data set within approximately one decade, the target is to reach a peak luminosity of \(\rm 6 \times 10^{35}~cm^{-2}s^{-1}\) by further increasing the beam currents and reducing the beam size at the interaction point by squeezing the betatron function down to \(\beta^{*}_{\rm y}=\rm 0.3~mm\). To ensure detector longevity and maintain good reconstruction performance, beam backgrounds must remain well controlled. We report on current background rates in Belle II and compare these against simulation. We find that a number of recent refinements have significantly improved the background simulation accuracy. Finally, we estimate the safety margins going forward. We predict that backgrounds should remain high but acceptable until a luminosity of at least \(\rm 2.8 \times 10^{35}~cm^{-2}s^{-1}\) is reached for \(\beta^{*}_{\rm y}=\rm 0.6~mm\). At this point, the most vulnerable Belle II detectors, the Time-of-Propagation (TOP) particle identification system and the Central Drift Chamber (CDC), have predicted background hit rates from single-beam and luminosity backgrounds that add up to approximately half of the maximum acceptable rates.
Position sensitive photomultipliers coupled to scintillating fibers allow the construction of compact and fast particle tracking detectors. We describe a detector based on these techniques, and ...discuss its measured performances. Efficiency, space resolution and the effects of cross-talk between neighboring channels are studied in detail.
The silicon shower maximum detector for the STIC Alvsvaag, S.J.; Maeland, O.A.; Klovning, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/1995, Letnik:
360, Številka:
1-2
Journal Article
Recenzirano
The structure of a shashlik calorimeter allows the insertion of tracking detectors within the longitudinal sampling to improve the accuracy in the determination of the direction of the showering ...particle and the eπ separation ability. The new forward calorimeter of the DELPHI detector has been equipped with two planes of silicon pad detectors respectively after 4 and 7.4 radiation lengths. The novelty of these silicon detectors is that to cope with the shashlik readout fibers, they had to incorporate 1.4 mm holes every cm2. The detector consists of circular strips with a radial pitch of 1.7 mm and an angular granularity of 22.5°, read out by means of the MX4 preamplifier. The preamplifier is located at 35 cm from the silicon detector and the signal is carried by Kapton cables bonded to the detector. The matching to the MX4 input pitch of 44 μm was made by a specially developed fanin hybrid.
We present a new approach to the design of monolithic active pixel sensors (MAPS) in CMOS technology. By exploiting the triple well option, available in modern deep-submicron processes, it was ...possible to implement at the pixel level a full analog signal processor and to increase the area of the sensing electrode. These two new features aim to address some limiting aspects of conventional MAPS, such as the read-out speed and the charge collection efficiency. We report on the characterization of the first prototype chip, in particular the calibration with soft X-rays and the response to
β
-rays, demonstrating the capability of the sensor in detecting ionizing radiation.
The high luminosity asymmetric e + e - collider SuperB, recently approved by the Italian Government, is designed to deliver a luminosity greater than 10 36 cm -2 s -1 with moderate beam currents and ...a reduced center of mass boost with respect to earlier B-Factories. An improved vertex resolution is required for precise time-dependent measurements and the SuperB Silicon Vertex Tracker will be equipped with an innermost layer of small radius (about 1.5 cm), resolution of 10 μm in both coordinates, low material budget (<;1% X 0 ), and able to withstand a hit background rate of several tens of MHz/cm 2 . The ambitious goal of designing a thin pixel device matching these stringent requirements is being pursued with specific R&D programs on different technologies: CMOS MAPS, pixel sensors in vertical integration technology and hybrid pixels with small pitch and reduced material budget. The latest results on the characterization of the various pixel devices realized for the SuperB Layer0 will be presented.
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