Recent developments on the ALICE central Trigger processor

The ALI CE Central Trigger Processor has been constructed and tested, and will shortly be installed in the experimental area. In this review, we introduce the new developments in hardware and software, present a measurement of the minimum propagation time, and illustrate various trigger applications

Timing in the ALICE trigger system

In this paper we discuss trigger signals synchronisation and trigger input alignment in the ALICE trigger system. The synchronisation procedure adjusts the phase of the input signals with respect to the local Bunch Crossing (BC) clock and, indirectly, with respect to the LHC bunch crossing instant. The synchronisation delays are within one clock period: 0-25 ns. The alignment assures that the trigger signals originating from the same bunch crossing reach the processor logic in the same clock cycle. It is achieved by delaying signals by an appropriate number of full clock periods. We propose a procedure which will allow us to nd alignment delays during the system con guration, and to monitor them during the data taking

The ALICE trigger electronics

The ALICE trigger system (TRG) consists of a Central Trigger Processor (CTP) and up to 24 Local Trigger Units (LTU) for each sub-detector. The CTP receives and processes trigger signals from trigger detectors and the outputs from the CTP are 3 levels of hardware triggers: L0, L1 and L2. The 24 sub-detectors are dynamically partitioned in up to 6 independent clusters. The trigger information is propagated through the LTUs to the Front-end electronics (FEE) of each sub-detector via LVDS cables and optical fibres. The trigger information sent from LTU to FEE can be monitored online for possible errors using the newly developed TTCit board. After testing and commissioning of the trigger system itself on the surface, the ALICE trigger electronics has been installed and tested in the experimental cavern with appropriate ALICE experimental software. Testing the Alice trigger system with detectors on the surface and in the experimental cavern in parallel is progressing very well. Currently one setup is used for testing on the surface; another is installed in experimental cavern. This paper describes the current status of ALICE trigger electronics, online error trigger monitoring and appropriate software for this electronics

Azimuthal anisotropy of heavy-flavor decay electrons in p-Pb collisions at √s_NN = 5.02 TeV

Angular correlations between heavy-flavor decay electrons and charged particles at midrapidity (|η|&lt;0.8) are measured in p-Pb collisions at sNN=5.02 TeV. The analysis is carried out for the 0%-20% (high) and 60%-100% (low) multiplicity ranges. The jet contribution in the correlation distribution from high-multiplicity events is removed by subtracting the distribution from low-multiplicity events. An azimuthal modulation remains after removing the jet contribution, similar to previous observations in two-particle angular correlation measurements for light-flavor hadrons. A Fourier decomposition of the modulation results in a positive second-order coefficient (v2) for heavy-flavor decay electrons in the transverse momentum interval 1.5&lt;pT&lt;4 GeV/c in high-multiplicity events, with a significance larger than 5σ. The results are compared with those of charged particles at midrapidity and those of inclusive muons at forward rapidity. The v2 measurement of open heavy-flavor particles at midrapidity in small collision systems could provide crucial information to help interpret the anisotropies observed in such systems.</p