This paper presents the front-end electronics upgrades of the ALICE Time Projection Chamber detector for the coming years, with a focus on the upgrades for Long Shutdown 2. The Large Hadron Collider ...is currently in Long Shutdown 1 following a successful first run, and upgrades of the detectors are underway to support the higher particle interaction rates planned for the next run. For the Time Projection Chamber, the increase in data due to the higher interaction rate and higher energy will cause a bottleneck in the Readout Control Unit and a new board is in development which increases the data-link speed to the back-end. Another more general upgrade of the ALICE experiment is planned for Long Shutdown 2, foreseen to start in 2018. In this case the goal is to cope with an even higher interaction rate of 50 kHz for Pb-Pb collisions. The present Multi Wire Proportional Chambers of the Time Projection Chamber will then be replaced by Gas Electron Multiplier technology. At the same time, the front-end electronics and readout system will also be replaced.
A neutron detector based on registration of radiation effects in Static Random Access Memories (SRAMs) has been developed at the University of Bergen for applications in particle therapy. Nine ...different SRAMs were tested and a 16 Mibit SRAM from Cypress was chosen for the final detector. The SRAMs were irradiated in beam lines at PTB Braunschweig, the Oslo Cyclotron Laboratory, The Svedberg Laboratory, The Institute for Energy Technology (IFE, Kjeller) and the CERN-EU high-energy reference field. The results from the measurements demonstrate the feasibility of using the selected SRAMs for neutron detection. The results indicate low or no sensitivity to thermal neutrons while the cross section for fast neutrons increases with neutron energy before reaching a more stable level at energies of several tenths of MeV.
The ALICE experiment at the CERN LHC will feature several upgrades for Run 3, one of which is a new Inner Tracking System (ITS). The ITS upgrade is currently under development and commissioning, and ...will be installed during the ongoing long shutdown 2.
A number of factors will have an impact on the performance and readout efficiency of the ITS in run 3, and to that end, a simulation model of the readout logic in the ALPIDE pixel sensor chips for the ITS was developed, using the SystemC library for system level modeling in C++. This simulation model is three orders of magnitude faster than a normal HDL simulation of the chip and facilitates simulations of an increased number of events for a large portion of the detector.
In this paper, we present simulation results, where we have been able to quantify detector performance under different running conditions. The results are used for system configuration as well as for the ongoing development of the readout electronics.
During the Long Shutdown 2 of CERN's Large Hadron Collider, foreseen to start in 2019, the ALICE experiment will upgrade its time projection chamber (TPC) detector to cope with a Pb-Pb collision rate ...of 50 kHz in the next running phase. In the upgraded TPC, the gas electron multiplier (GEM) technology and continuous readout will replace the existing multiwire proportional chambers and triggered readout system. The GEM signals will be processed using a new custom designed mixed-signal front-end chip named SAMPA. The first version of SAMPA was delivered in 2014, and the production of the final version is in progress. This paper gives an overview of the design of the data acquisition system used in testing of the analog behavior of the first SAMPA version and the performance results of a SAMPA coupled to a pulse generator and a GEM detector prototype.
In proton therapy, neutrons produced in collimators or in the patient body will contribute to unwanted additional radiation dose to the patient. This neutron dose is primarily associated with an ...increased risk of secondary cancer after treatment. Neutron detection in proton therapy has previously, to a large extent, been based on the use of passive detectors or detectors of large physical size which are not applicable for measurements inside phantoms. In this study, we present the first application of a neutron detector based on registration of radiation induced effects in Static Random Access Memories (SRAMs) which enables in-phantom fast neutron measurements. Measurements were performed in a water phantom irradiated by a 178 MeV proton pencil beam in a setup mimicking internally produced neutrons in pencil beam scanning (PBS) proton therapy. A neutron energy response model was developed for the SRAM detector to increase the accuracy of measurements in radiation fields with a broad range of neutron energies, and thereby make the detector applicable in the proton therapy setting. FLUKA Monte Carlo (MC) simulations and thermal neutron measurements with thermoluminescence detectors (TLDs) were conducted to evaluate the SRAM detector performance.
Both experimental results (SRAM detector and TLDs) and MC simulations indicated a steep decrease in the neutron fluence with increasing lateral distance from the beam axis, while less variation was observed with depth. At Bragg peak depth, experimental values of fast neutron dose (H*(10)) were reduced from 1.4 mSv/Gy at 5.2 cm lateral distance to the beam axis to 0.22 mSv/Gy at 13.7 cm lateral distance. The MC simulations also showed that the SRAM detection threshold of 3 MeV was sufficiently low to capture approximately 90% of the neutron dose in PBS proton therapy. The differences in detector response due to variations in the neutron energy spectrum were small (<10%), and may be corrected using position-specific calibration factors. The results demonstrate the potential for estimating spatial out-of-field neutron dose based on the SRAM detector measurements in combination with the neutron energy response model.
•SRAM detector can detect majority of neutron dose in proton therapy.•SRAM detector can measure in-phantom neutron dose with cm resolution.•SRAM detector shows steep reduction of neutron dose with distance from proton beam.
First experimental results are presented on event-by-event net-proton fluctuation measurements in Pb–Pb collisions at sNN=2.76 TeV, recorded by the ALICE detector at the CERN LHC. The ALICE detector ...is well suited for such studies due to its excellent particle identification capabilities and large acceptance, which is crucial for fluctuation analysis. The studies are focussed on second order cumulants, but the analysis technique used is more general and will be applied, in the near future, also to higher order cumulants.
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