Performance of the LHCb Vertex Locator
By R. Aaij, A. Affolder, K. Akiba, M. Alexander, S. Ali, R. Appleby, M. Artuso, A. Bates, A. Bay, O. Behrendt and 93 more. Nuclear Science Symposium and Medical Imaging Conference, 2011
499 citations recorded by the source corpus.
The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stability of these characteristic features of the detector are described, and details of the material budget are given. The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described. The system performance is fully characterised. The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 μm is achieved at the optimal track angle. The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 0.5%, and the detector has less than 1% of faulty strips. The proximity of the detector to the beam means that the inner regions of the n+-on-n sensors have undergone space-charge sign inversion due to radiation damage. The VELO performance parameters that drive the experiment's physics sensitivity are also given. The track finding efficiency of the VELO is typically above 98% and the modules have been aligned to a precision of 1 μm for translations in the plane transverse to the beam. A primary vertex resolution of 13 μm in the transverse plane and 71 μm along the beam axis is achieved for vertices with 25 tracks. An impact parameter resolution of less than 35 μm is achieved for particles with transverse momentum greater than 1 GeV/c.
Subfields: Nuclear and High Energy Physics, Radiation
View Paper: https://www.semanticscholar.org/paper/19eb47f5071081eedc6c4beecc2d6eb3776eb3de
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Citations in the corpus
- Measurement of the Z+b-jet cross-section in pp collisions at s$$ \sqrt{s} $$ = 7 TeV in the forward region (2014, methodology): “The detector includes a high-precision tracking system consisting of a silicon-strip vertex detector surrounding the pp interaction region [7], a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about 4 Tm, and three stations of silicon-strip detectors an”
- Measurement of the forward Z boson production cross-section in pp collisions at s=7$$ \sqrt{s}=7 $$ TeV (2015, methodology): “The detector includes a high-precision tracking system consisting of a silicon-strip vertex detector surrounding the pp interaction region [16], a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about 4 Tm, and three stations of silicon-strip detectors a”
- Precision luminosity measurements at LHCb (2014, background): “Interactions with a transverse vertex position more than 4 mm from the nominal beam line were not accepted in order to reject interactions with the material of the RF foil of the VELO [29].”
- Observation of $J/\psi p$ Resonances Consistent with Pentaquark States in $\Lambda_b^0 \to J/\psi K^- p$ Decays (2015, methodology): “The detector includes a high-precision tracking system consisting of a siliconstrip vertex detector surrounding the pp interaction region [14], a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about 4 Tm, and three stations of silicon-strip detectors an”