The ATLAS luminosity monitor, LUCID (LUminosity Cherenkov Integrating Detector), had to be upgraded for the second run of the LHC accelerator that started in spring 2015. The increased energy of the ...proton beams and the higher luminosity required a redesign of LUCID to cope with the more demanding conditions. The novelty of the LUCID-2 detector is that it uses the thin quartz windows of photomultipliers as Cherenkov medium and a small amounts of radioactive 207Bi sources deposited on to these windows to monitor the gain stability of the photomultipliers. The result is a fast and accurate luminosity determination that can be kept stable during many months of data taking. LUCID-2 can also measure the luminosity accurately online for each of the up to 2808 colliding bunch pairs in the LHC . These bunch pairs are separated by only 25 ns and new electronics has been built that can count not only the number of pulses above threshold but also integrate the pulses.
The upgrade of the ATLAS 1 tracking detector for the High-Luminosity Large Hadron Collider (LHC) at CERN requires novel radiation hard silicon sensor technologies. Significant effort has been put ...into the development of monolithic CMOS sensors but it has been a challenge to combine a low capacitance of the sensing node with full depletion of the sensitive layer. Low capacitance brings low analog power. Depletion of the sensitive layer causes the signal charge to be collected by drift sufficiently fast to separate hits from consecutive bunch crossings (25 ns at the LHC) and to avoid losing the charge by trapping. This paper focuses on the characterization of charge collection properties and detection efficiency of prototype sensors originally designed in the framework of the ALICE Inner Tracking System (ITS) upgrade 2. The prototypes are fabricated both in the standard TowerJazz 180nm CMOS imager process 3 and in an innovative modification of this process developed in collaboration with the foundry, aimed to fully deplete the sensitive epitaxial layer and enhance the tolerance to non-ionizing energy loss. Sensors fabricated in standard and modified process variants were characterized using radioactive sources, focused X-ray beam and test beams before and after irradiation. Contrary to sensors manufactured in the standard process, sensors from the modified process remain fully functional even after a dose of 1015neq/cm2, which is the the expected NIEL radiation fluence for the outer pixel layers in the future ATLAS Inner Tracker (ITk) 4.
The LUCID-2 detector Sbarra, C.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2019, Letnik:
936
Journal Article
Recenzirano
LUCID-2 (LUminosity Cherenkov Integrating Detector) is the upgrade of the main detector dedicated to luminosity monitoring and measurements in the ATLAS Experiment at CERN. Most changes were ...motivated by the large (average ∼50) number of interactions per bunch-crossing and short (25 ns) bunch-spacing expected in LHC run 2 (2015–2018). Both fast online information used by LHC for luminosity optimisation and levelling in ATLAS, and per-bunch data to be used offline, come from LUCID-2.
We present the results of the analysis of Markarian 180 (1ES 1133+704), a BL Lac object embedded in a giant elliptical galaxy, obtained for a period of 45 day, during which multi-wavelength ...observations were ongoing. The multi-wavelength campaign on Mrk180 was in 2008 (from 2008-10-24 to 2008-12-08) and was coordinated by Stefan Rugamer (MAGIC Collaboration). The Mrk 180 is associated with a quasar-like object whose distance can be determined unambiguously, thanks to the measurement of absorption line that gives the redshift (z=0.046; Ulrich 1978). The source was observed by the LAT of the Fermi satellite, and it was possible to discover a change of flux, at the energies 100MeV–300GeV, during the multi-wavelength campaign period. Results of the analysis are shown.
The “Time-Of-Flight” (TOF) system of the AMS-02 superconducting spectrometer, to be installed in the ISS International Space Station, consists of four layers of plastic scintillation counters. During ...the precursor mission AMS-01 (June 1998), a similar system successfully operated in space for 10 days. However, the AMS-02 TOF had to be redesigned taking into account the more stringent mass and power constraints of the AMS-02 detector. The main characteristics of the new TOF system are (a) capability to stand the high fringing field of AMS-02 superconducting magnet; (b) high redundancy of electronic components for unmanned operation of at least three years in the space station; (c) capability to operate in the space environment on the ISS. Counters and electronics have been extensively tested before the installation in the spectrometer.
Performance of a six gap MRPC built for large area coverage Abbrescia, M.; Alici, A.; An, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2008, Letnik:
593, Številka:
3
Journal Article
Recenzirano
We have constructed an MRPC with an active area of
82
×
158
cm
2
. It has six gas gaps each of
300
μ
m
width. The performance of this chamber measured at a CERN test beam is presented. Details ...concerning the construction are also given.
Silicon Photomultipliers (SiPM) are considered very promising in many application where high timing performances, low cost, hardness to radiation damage and single photon counting are requested. Such ...applications go from astrophysics, high energy accelerator physics to medical physics. A group of SiPM from Hamamatsu has been tested with a low noise fast amplifier based on a hetero-junction FET, mounted on a proper front end board. A first telescope prototype has been used to test the electronics and results are shown. The SiPM time resolution has been measured to be σ∼30ps, in agreement with other studies reported in literature. The SiPM gain depends critically on temperature and a thermoelectric module to control the circuit was also studied in order to use the system for space detectors.
The luminosity monitor LUCID (LUminosity Cherenkov Integrating Detector) employed in the ATLAS experiment at the LHC had to be upgraded for the second run of LHC (Run 2) that started in spring 2015. ...The increased energy of the proton beams and the higher luminosity implied that the Photomultipliers of the original LUCID detector had to be replaced for Run 2 to cope with the more demanding conditions. This paper deals with choice and characterisation of the Photomultipliers used for the new version of LUCID.
In the frame of INFN-ITC-irst collaboration new Silicon PhotoMultiplier (SiPM) prototypes have been produced at ITC-irst (Trento, Italy). Each SiPM covers an area of 1
mm
2 and brings together 625 ...micro-cells of 40×40
μm
2 size connected in parallel as to form a single read-out element. Each micro-cell consists of a Geiger Mode Avalanche Photodiode (GM-APD) in series with its quenching resistance. This article reports the main characteristics of these prototypes as well as the ongoing activity of our collaboration on the development of SiPM devices for medical and space physics applications.
Recent advancements in CMOS technologies enable Depleted Monolithic Active Pixel Sensor (DMAPS) realizations by exploiting high resistivity and/or high voltage biasing to deplete a large active ...sensing volume. DMAPS have emerged as a promising alternative for particle detection in high energy physics due to their low cost, reduced manufacturing complexity and high granularity. In the framework of the ALICE Inner Tracking System (ITS) upgrade, prototype sensors have been designed and characterized in the TowerJazz 180nm standard CMOS imaging process and in a novel modification of this process to achieve full depletion. Measurement results demonstrate that the sensors manufactured using the modified process are fully functional even after a dose of 1015neq/cm2, which is the expected NIEL of the outer layers of the ATLAS Inner Tracker (ITk) during the future High Luminosity Large Hardon Collider (HL-LHC) operation. Based on these encouraging results, two highly granular, low power DMAPS chips with different readout architectures have been designed and are being proposed for the ATLAS ITk upgrade.
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