To extend the physics reach of the LHC, accelerator upgrades are planned which will increase the integrated luminosity to beyond 3000 fb^-1 and the pile-up per bunch-crossing by a factor 5 to 10. To ...cope with the increased occupancy and radiation damage, the ATLAS experiment plans to introduce an all-silicon inner tracker with the HL-LHC upgrade. To investigate the suitability of pixel sensors using the proven planar technology for the upgraded tracker, the ATLAS Upgrade Planar Pixel Sensor R&D Project (PPS) was established comprising 19 institutes and more than 80 scientists. Main areas of research are the performance assessment of planar pixel sensors with different designs and substrate thicknesses up to the HL-LHC fluence, the achievement of slim or active edges to provide low geometric inefficiencies without the need for shingling of modules and the exploration of possibilities for cost reduction to enable the instrumentation of large areas. This paper gives an overview of recent accomplishments and ongoing work of the R&D project.
We report on further developments of our proposed design approach for a full in-pixel signal processing chain of deep N-well monolithic active pixel sensor, by exploiting the triple well option of a ...CMOS 130
nm process. Two different geometries of the collecting electrode (namely “Apsel 3
T
1
M
1” and “Apsel 3
T
1
M
2”) was implemented to compare their charge collection efficiency. The results of the characterization of the various versions of pixel matrices with a pion beam of 120
GeV/
c at the SPS H6 CERN facility will be presented. The performances of an “Apsel 3
T
1” chip irradiated with a dose up to 10
Mrad (Co
60) was also measured. Comparison will be presented among the irradiated and the new chip showing the impact of radiation damages on tracking efficiencies.
The results obtained by the Slim5 collaboration on a low material budget tracking silicon demonstrator put on a 12
GeV/
c
proton test beam at CERN are reported. Inside a reference telescope, two ...different and innovative detectors were placed for careful tests. The first was a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130
nm CMOS Technology, square pixels
50
μ
m
wide, thinned down to
100
μ
m
and equipped with a digital sparsified readout running up to 50
MHz. The other was a high resistivity double sided silicon detector,
200
μ
m
thick, with short strips with
50
μ
m
pitch at
45
∘
angle to the detector's edge. The detectors were equipped with dedicated fast readout architectures performing on-chip data sparsification and providing the timing information for the hits. The criteria followed in the design of the pixel sensor and of the pixel readout architecture will be reviewed. Preliminary measurements of the pixel charge collection, track detection efficiencies and resolutions of pixel and strip sensors are discussed.
The data driven architecture of the readout chips has been fully exploited in the test beam by a data acquisition system able to collect on electronic board up to 2.5 Million events per second before triggering. By using a dedicated Associative Memory board, we were able to perform a level 1 trigger system, with minimal latency, identifying cleanly tracks traversing the detectors. System architecture and main performances are shown.
The radiation hardness of the AToM chips of the BaBar silicon vertex tracker has been investigated by means of irradiations with photons from a Co60 source and 0.9 GeV electrons. The increase in ...noise and the decrease in gain of the amplifier have been measured as a function of the applied capacitive load and the absorbed dose. Different beam intensities have been used to study the effect of different dose rates to the AToM radiation damage. The chip digital functionalities have been tested up to a dose of 5.5 Mrads for the Co60 photons and 9 Mrads for the 0.9 GeV electrons. In addition a pedestal shift for the irradiated channels has been observed in the test with electrons but is not present in the irradiation with photons. This effect reproduces qualitatively the behavior observed since 2002 in the front-end electronics of the installed BaBar silicon vertex tracker. After some investigation of the chip layout, this peculiar behavior could be associated to radiation damage in a well-identified component of the AToM. The results of the radiation tests are presented and used to extrapolate the performance and lifetime of the installed detector in the next few years.
A search for new phenomena in ttbar events with large missing transverse momentum in proton-proton collisions at a center-of-mass energy of 7 TeV is presented. The measurement is based on 1.04 fb^-1 ...of data collected with the ATLAS detector at the LHC. The search is carried out in the single-lepton channel, characterized by an isolated lepton of high transverse momentum, four or more jets and large missing transverse momentum. Contributions to this final state may arise from a number of Standard Model extensions. The results are interpreted in terms of a model where new top-quark partners are pair-produced and each decay to an on-shell top (or antitop) quark and a long-lived undetected neutral particle. The data are found to be consistent with Standard Model expectations. A limit at 95% confidence level is set excluding a cross-section times branching ratio of 1.1 pb for a top-partner mass of 420 GeV and a neutral particle mass less than 10 GeV. In a model of exotic fourth generation quarks, top-partner masses are excluded up to 420 GeV and neutral particle masses up to 140 GeV.
A search for the Higgs boson has been performed in the H->WW->lvlv channel (l=e/mu) with an integrated luminosity of 2.05/fb of pp collisions at sqrt{s} = 7 TeV collected with the ATLAS detector at ...the Large Hadron Collider. No significant excess of events over the expected background is observed and limits on the Higgs boson production cross section are derived for a Higgs boson mass in the range 110
This Letter presents a measurement of WZ production in 1.02 fb^-1 of pp collision data at sqrt(s) = 7 TeV collected by the ATLAS experiment in 2011. Doubly leptonic decay events are selected with ...electrons, muons and missing transverse momentum in the final state. In total 71 candidates are observed, with a background expectation of 12.1 +/- 1.4(stat.) +4.1/-2.0(syst) events. The total cross section for WZ production for Z gamma^* masses within the range 66 GeV to 116 GeV is determined to be sigma_WZ^tot = 20.5 +3.1/-2.8(stat.) +1.4/-1.3(syst.) +0.9/-0.8(lumi.)pb, which is consistent with the Standard Model expectation of 17.3 +1.3/-0.8 pb. Limits on anomalous triple gauge boson couplings are extracted.
We report a search for first generation scalar leptoquarks using 1.03 fb^-1 of proton-proton collisions data produced by the Large Hadron Collider at sqrt{s}=7 TeV and recorded by the ATLAS ...experiment. Leptoquarks are sought via their decay into an electron or neutrino and a quark, producing events with two oppositely charged electrons and at least two jets, or events with an electron, missing transverse momentum and at least two jets. Control data samples are used to validate background predictions from Monte Carlo simulation. In the signal region, the observed event yields are consistent with the background expectations. We exclude at 95% confidence level the production of first generation scalar leptoquark with masses m_LQ< 660 (607)GeV when assuming the branching fraction of a leptoquark to a charged lepton is equal to 1.0 (0.5).
The high rate data acquisition system for the SLIM5 beam test Fabbri, L.; Bruschi, M.; Di Sipio, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
In September 2008 the Slim5 collaboration submitted a low material budget silicon demonstrator to test with protons at the PS beam at CERN. The beam test setup was composed of a four double sided ...microstrip reference telescope and different detectors (DUTs) placed inside: a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130
nm CMOS Technology and a high resistivity double sided silicon detector, with short strips at
45
∘
angle to the detectors edge, read out by the FSSR2 chip. All the systems were self-triggered and read out by a fast DAQ system. In the poster the beam test setup as the data acquisition and the trigger system are explained and the data acquisition performances are shown.
The S uperB silicon vertex tracker Forti, F.; Avanzini, C.; Batignani, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2011, Letnik:
636, Številka:
1
Journal Article
Recenzirano
The S
uperB asymmetric e
+e
− collider, to be built near the INFN National Frascati Laboratory in Italy, has been designed to deliver a luminosity greater than 10
36
cm
−2
s
−1 with moderate beam ...currents, allowing precision measurements in the flavour sector sensitive to New Physics. The conceptual design of the Silicon Vertex Tracker for the S
uperB Detector is presented, based on double-sided silicon strip detectors for the outer layers, with the addition of an innermost Layer 0 close to the interaction point, with low material budget and capable of sustaining a background rate of several MHz/cm
2.
PDF
