Abstract
The ALICE detector is undergoing an upgrade for run 3 at the LHC. A new Inner Tracking System (ITS) is part of this upgrade. The upgraded ALICE ITS features the ALPIDE, a monolithic active ...pixel sensor. Due to IC fabrication variations and radiation damage, the threshold values for the ALPIDE chips in the ITS need to be measured and adjusted periodically to ensure the quality of data. The calibration is implemented within the ALICE Online-Offline (O
2
) computing system, thus it runs in the same framework as the normal operations. This paper describes the concept and first implementation of the charge sensitivity scanning procedures for the upgraded ALICE ITS in the ALICE O
2
system, and demonstrates the first results of the scanning of the data taken from the installed ITS.
A prototype of a new type of calorimeter has been designed and constructed, based on a silicon–tungsten sampling design using pixel sensors with digital readout. It makes use of the ALPIDE sensor ...developed for the ALICE Inner Tracking System (ITS) upgrade. A binary readout is possible due to the pixel size of ≈30×30μm2. This prototype has been successfully tested with cosmic muons and with test beams at DESY and the CERN SPS. We report on performance results obtained at DESY, showing good energy resolution and linearity, and compare to detailed MC simulations. Also shown are preliminary results of the high-energy performance as measured at the SPS. The two-shower separation capabilities are discussed.
•First fully digital electromagnetic calorimeter with high-speed readout built.•ALPIDE pixel sensors work well in high particle-density environment.•Basic calorimetric performance of pixel calorimeter on par with state of the art.•Has unique capabilities in terms of position resolution and two-shower separation.
This paper presents the solution for optimization of the ALICE TPC readout for running at full energy in the Run2 period after 2014. For the data taking with heavy ion beams an event readout rate of ...400 Hz with a low dead time is envisaged for the ALICE central barrel detectors during these three years. A new component, the Readout Control Unit 2 (RCU2), is being designed to increase the present readout rate by a factor of up to 2.6. The immunity to radiation induced errors will also be significantly improved by the new design.
A prototype of a highly segmented electromagnetic calorimeter has been developed. The detector tower is made of 24 layers of PHASE2/MIMOSA23 silicon sensors sandwiched between tungsten plates, with 4 ...sensors per layer, a total of 96 MIMOSA sensors, resulting in 39 MPixels for the complete prototype detector tower. The paper focuses on the electronics of this calorimeter prototype. Two detector readout and control systems are used, each containing two Spartan 6 and one Virtex 6 FPGA, running embedded Linux, each system serving 12 detector layers. In 550 ms a total of 4 Gbytes of data is read from the detector, stored in memory on the electronics and then shipped to the DAQ system via Gigabit ethernet.
This paper presents the first performance results of the ALICE TPC Readout Control Unit 2 (RCU2). With the upgraded hardware typology and the new readout scheme in FPGA design, the RCU2 is designed ...to achieve twice the readout speed of the present Readout Control Unit. Design choices such as using the flash-based Microsemi Smartfusion2 FPGA and applying mitigation techniques in interfaces and FPGA design ensure a high degree of radiation tolerance. This paper presents the system level irradiation test results as well as the first commissioning results of the RCU2. Furthermore, it will be concluded with a discussion of the planned updates in firmware.
This paper will discuss the performance of the PHOS level-0 trigger and planned improvements for RUN 2. Due to hardware constraints the Trigger Region Unit boards are limited to an operating ...frequency of 20 MHz. This has led to some ambiguity and biases of the trigger inputs. The trigger input generation scheme was therefore optimized to improve the performance. The PHOS level-0 trigger system has been working with an acceptable efficiency and purity. Proposed actions to further improve the performance and possibly eliminate the impact of the biased trigger inputs will also be presented.
This paper describes how fault injection has been implemented as a test method for an FPGA in an existing hardware configuration setup. As this FPGA is in charge of data readout for a large tracking ...detector, the reliability of this FPGA is of high importance. Due to the complexity of the readout electronics, irradiation testing is technically difficult at this stage of the system commissioning. The work presented in this paper is therefore motivated by introducing fault injection as an alternative method to characterize failures caused by SEUs. It is a method to study the effect that a configuration upset may have on the operation of the FPGA.
The target platform consists of two independent modules for data acquisition and detector control functionality. Fault injection to test the response of the data acquisition module is made possible by implementing the solution as part of the detector control functionality.
Correct implementation is validated by a simple shift register design. Our results demonstrate that fault injection can assist in measuring the effect of an implemented mitigation technique in the final design of the FPGA.
This paper presents the first measurement of Single Event Upsets (SEUs) in the configuration memory of the readout control FPGA of the ALICE Time Projection Chamber. The measurements have been ...performed during pp collisions at a center-of-mass energy of square root S = 7 TeV in the period from May to August 2011. A linear dependence was observed between the number of SEUs and the luminosity seen by ALICE. In addition the spatial distribution of SEUs have been analysed for the 216 FPGA installed on the two end-plates of the TPC detector.
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