- Email: [email protected]
Preparing the ALICE-HMPID RICH for the high-luminosity LHC period 2021–2023
Nuclear Inst. and Methods in Physics Research, A xxx (xxxx) xxx
Contents lists available at ScienceDirect
Nuclear Inst. and Methods in Physics Research, A journal homepage: www.elsevier.com/locate/nima
Preparing the ALICE-HMPID RICH for the high-luminosity LHC period 2021–2023✩ , ✩✩ J.L. Gauci ∗, E. Gatt, O. Casha, on Behalf of ALICE Collaboration Department of Microelectronics and Nanoelectronics, University of Malta, Msida, Malta, Malta
ARTICLE Keywords: RICH Detector HMPID MWPC Upgrade CERN
INFO
ABSTRACT Approaching successfully the end of the LHC Run2 period (2015–2018), the RICH based High Momentum Particle IDentification detector (HMPID) prepares for the High Luminosity LHC (HL-LHC) Run 3 period (2020–2023) √ where the collider will provide up to 50 kHz of Pb-Pb collision rate at 𝑠NN = 5 TeV. The upgraded ALICE detector will be able to read out all interactions and it will exploit the fully scientific potential of the HL-LHC to study the properties of the Quark–Gluon Plasma phase (QGP), using proton–proton, nucleus–nucleus and proton– nucleus collisions at high energies. The ALICE continuous detector read out will ensure the Online/Offline (O2 ) identification of rare trigger topologies and an effective data compression factor. This paper presents the HMPID status and the activities under way to integrate the detector in the new ALICE O2 Trigger environments. The stable performance of the detector, the stability of the Multi-Wire Proportional Chamber (MWPC) during preliminary tests of high luminosity conditions in ALICE using pp collisions, and the progressing upgrading activities, support the participation of the HMPID in the ALICE scientific program defined for the HL-LHC period.
1. Introduction A Large Ion Collider Experiment (ALICE) is a general-purpose heavyion detector at the CERN LHC dedicated to the study and characterisation of QGP at extremely high energy density and temperature conditions. For this reason, ALICE consists of a number of detectors dedicated to performing particle identification in a wide momentum range from hundreds of MeV/𝑐 to 100 GeV/𝑐 through the combination of different detector techniques [1]. The High Momentum Particle Identification Detector (HMPID) [2], with its 5% of central barrel acceptance is one such detector. The acceptance is in the pseudo rapidity range |𝜂| < 0.5. The detector performs charged particle track-by-track identification by measuring the emission angle of Cherenkov photons, in conjunction with the momentum measured by the ALICE tracking detectors, ITS and TPC. It is capable of providing a three 𝜎 separation PID capability in the range of 1−5 GeV/c, thus extending the useful range for particle identification on a track-by-track bases up to 3 GeV/𝑐 for pions and kaons, and up to 5 GeV/𝑐 for (anti-)protons, in p-p collisions. HMPID is based on seven 1.3 × 1.3 m2 proximity focusing RICH counters, split into left and right photocathodes (RICH0-RICH6) for a total active area of approximately 10.7 m2 . Cherenkov photon detection
is achieved by pad segmented photocathodes (PCs) coated with a 300 nm thick Caesium Iodide (CsI) layer, installed in multiwire proportional chambers (MWPC) operated with CH4 . Liquid perfluorohexane (C6 F14 ) with 𝑛 = 1.2989 at 𝜆 =175 nm is used as Cherenkov radiator. In this paper, the HMPID status and the activities under way to integrate the detector in the new ALICE O2 [3] and Trigger environments are presented. The stable performance of the detector, the stability of the MWPC during preliminary tests of high luminosity conditions in ALICE using pp collisions, and the progressing upgrading activities, support the participation of the HMPID in the ALICE scientific program defined for the HL-LHC period. 2. The detector performance in the LHC run period 2015–2018 The HMPID performance during 2010–2013 is reported in [4] and [5]. During 2015–2018 (LHC Run2), the electronics, the power supply systems and the C6 F14 transparency system have operated in a stable manner. At the beginning of 2016 HV sector 1 on RICH1 failed and this therefore led to a decrease in detector acceptance from 72% to 70%. The reason could be a loose anode wire, since a few hundred volts can be applied before the overcurrent protection circuitry switches off the HV channel. The stability of the CsI QE can be affected by contaminants such
✩ This work is a collaborative effort between the University of Malta and ALICE-HMPID. ✩✩ The research work disclosed in this publication is partially funded by the ENDEAVOUR Scholarship Scheme (Malta). The scholarship are part-financed by the European Union – European Social Fund (ESF) under Operational Programme II – Cohesion Policy 2014–2020, ‘‘Investing in human capital to create more opportunities and promote the well being of society." ∗ Corresponding author. E-mail addresses: [email protected] (J.L. Gauci), [email protected] (E. Gatt), [email protected] (O. Casha).
https://doi.org/10.1016/j.nima.2019.01.025 Received 15 October 2018; Received in revised form 4 January 2019; Accepted 10 January 2019 Available online xxxx 0168-9002/© 2019 Elsevier B.V. All rights reserved.
Please cite this article as: J.L. Gauci, E. Gatt, O. Casha, Preparing the ALICE-HMPID RICH for the high-luminosity LHC period 2021–2023, Nuclear Inst. and Methods in Physics Research, A (2019), https://doi.org/10.1016/j.nima.2019.01.025.
J.L. Gauci, E. Gatt, O. Casha et al.
Nuclear Inst. and Methods in Physics Research, A xxx (xxxx) xxx
Fig. 4. Charge dose of CsI photocathodes per HV sector.
Fig. 1. Average maximum number of reconstructed photons per Cherenkov pattern (Nph) versus time (year).
threshold of several hundred ppm so no degradation of the CsI QE is expected [6]. In Fig. 1, a stable average number of reconstructed photons (Nph) per Cherenkov pattern at saturation (𝛽 ≈ 1), for the period 2010–2018, can be observed. Nph and gas-gain (Fig. 2) reduction in RICH2 is now under investigation [7]. The number of detected photoelectrons depends on the gas gain and CsI QE. From the observed stability of the gas gain one can infer that the almost symmetric distribution of the angular coefficient (gradients of the linear fits in Fig. 1), illustrated in Fig. 3, of the Nph is still compatible with a stable CsI QE, in the period 2010–2018. The slight asymmetry comes from the contribution of RICH2. One of the reasons for this could be due to the fact that two photocathodes were re-evaporated in 2005. The Charge Dose plot of CsI induced by bombardments of CH4 ion avalanches per high voltage sector (Fig. 4) shows that the charge density at the end of 2018 leaves a sufficient margin to maintain a stable QE until the end of Run3 (2023). In Fig. 4 the open bar represents the integration of the total anodic current, 𝐼𝑎 , while the yellow represents the total charge dose absorbed by the CsI photocathodes, given by 𝑡 0.6 × ∫0 𝐼𝑎 𝑑𝑡. This is determined by a charge sharing model for charged particle and photoelectrons.
Fig. 2. MWPC gas gain 𝐴0 vs. time (year).
3. Upgrading of HMPID for LHC Run3 (2021–2023) 3.1. Trigger Fan-In/Fan-Out module A new Fan-In/Fan-Out module is being developed to receive the Level-0 trigger, delay it, and distribute it to the 14 readout control boards (two per RICH module). This module is capable of being remotely-controlled and monitored via the IPBus protocol. In addition, the new module also receives 14 BUSY signals and combines them into one BUSY for handling by the Central Trigger Processor (CTP). Preliminary prototypes have been tested in Malta and at CERN. The results, together with a mathematical model of the delay against the control command may be found in [8]. Fig. 3. Distribution of angular coefficient of linear fit of Nph.
In [8], it was seen that through the use of a shift-register based delay architecture, a random offset is generated. This offset has a multimodal distribution and is difficult to model. As such, a time-to-digital converter was implemented on an FPGA to try and reduce the error, by fine-tuning the control command. The TDC utilises the Nutts interpolation method and is capable of achieving a 500 ps resolution. This method also allows the operator to obtain some feedback on the delay. Studies are being carried out to characterise the jitter of the Fan-In/Fan-Out module.
as O2 and water, or by the specific charge dose from ion bombardment. Physico-chemical ageing effects on the photocathodes may also affect the stability. The O2 and water level in the MWPC gas outlet have been monitored by the Detector Control System (DCS) via a dedicated device. The measured levels at approximately 10 ppm, are well below the safety 2
Please cite this article as: J.L. Gauci, E. Gatt, O. Casha, Preparing the ALICE-HMPID RICH for the high-luminosity LHC period 2021–2023, Nuclear Inst. and Methods in Physics Research, A (2019), https://doi.org/10.1016/j.nima.2019.01.025.
J.L. Gauci, E. Gatt, O. Casha et al.
Nuclear Inst. and Methods in Physics Research, A xxx (xxxx) xxx
4. MWPC test in Run3 environment To ensure that the MWPC can operate in a stable manner during Run3, where the track load will increase, a number of tests were run. A luminosity of 70 Hz/μb in ALICE in pp collisions produces a track load equivalent to 50 kHz in Pb-Pb collisions expected during Run3. The anode currents in the RICH modules increase linearly with charged particle rate (luminosity). In Fig. 6 it can be seen that, for RICH5, linearity and stability is preserved along the test up to 70 Hz/μb with no gas gain saturation or space/charge effects. The same behaviour was observed for all 7 RICH modules. 5. Perspectives and conclusions Fig. 5. Readout rate versus the percentage occupancy in the detector for Runs 2 and 3 (blue and red, respectively).
During the LHC run period 2015–2018 the HMPID has operated in a stable condition. This work has shown that the number of photons per Cherenkov patterns has remained stable in all RICH modules, with the exception of RICH2. This was also verified through the plot of the distribution of the angular coefficient, where the mean of this distribution is still close to zero; implying that there is no significant degradation to affect stability. The charge dose per HV sector for 2018 also illustrates that there is a sufficient margin to maintain a stable QE until the end of Run3, in 2023. While none of the electronics of the HMPID will be upgraded, a new trigger fan-in/fan-out module will be installed, together with an upgrade of the firmware. Preliminary results from the tests on these modules are promising. Furthermore, the MWPC linearity tests make us confident that the HMPID is ready for Run3 operations (2020–2023) at the HighLuminosity LHC at CERN.
Fig. 6. Ratio of current/luminosity vs. time for RICH5.
References [1] K. Aamodt, A.A. Quintana, R. Achenbach, S. Acounis, D. Adamová, C. Adler, M. Aggarwal, F. Agnese, G.A. Rinella, Z. Ahammed, et al., The ALICE experiment at the CERN LHC, J. Instrum. 3 (08) (2008) S08002. [2] ALICE Collaboration, F. Piuz, W. Klempt, L. Leistam, J. De Groot, J. Schükraft, ALICE High-Momentum Particle Identification: Technical Design Report, in: Technical Design Report ALICE, CERN, Geneva, 1998, URL https://cds.cern.ch/record/381431. [3] P. Buncic, M. Krzewicki, P. Vande Vyvre, Technical design report for the upgrade of the online-offline computing system, Tech. rep., CERN-LHCC, 2015. [4] ALICE collaboration, G. De Cataldo, et al., The ALICE–HMPID performance during the LHC run period 2010–2013, Nucl. Instrum. Methods Phys. Res. A 766 (2014) 19–21. [5] ALICE Collaboration, G. Volpe, et al., Pattern recognition and PID procedure with the ALICE-HMPID, Nucl. Instrum. Methods Phys. Res. A 766 (2014) 259–262. [6] F. Piuz, Ring Imaging CHerenkov systems based on gaseous photo-detectors: trends and limits around particle accelerators, Nucl. Instrum. Methods Phys Res. A 502 (1) (2003) 76–90. [7] A. Braem, G. De Cataldo, M. Davenport, A. Di Mauro, A. Franco, A. Gallas, H. Hoedlmoser, P. Martinengo, E. Nappi, F. Piuz, et al., Results from the ageing studies of large CsI photocathodes exposed to ionizing radiation in a gaseous RICH detector, Nucl. Instrum. Phys. Res. A 553 (1–2) (2005) 187–195. [8] J.L. Gauci, E. Gatt, G. De Cataldo, O. Casha, I. Grech, An analytical model of the delay generator for the triggering of particle detectors at CERN LHC, in: CAS (NGCAS), 2017 New Generation of, IEEE, 2017, pp. 69–72.
3.2. Read-out firmware Since for Run3, the trigger scheme will change slightly, a new firmware is required for correct handling of the trigger and readout sequence. In particular, each detector is only allowed a single synchronous trigger at either L0, L1 or L2 time. The HMPID will be using a faster version of the L0 trigger, called LM, and it will receive an asynchronous message containing information about the event to integrate the data with detectors in continuous event read out. A prototype firmware that removes the dependency on the L1 and L2 triggers has been developed. The firmware for each RICH half-module is remotely programmable, with an EtherBlaster used to upload firmware remotely via Ethernet. The occupancy of 0.3% is expected to remain the same as in Runs 1 and 2, whereas the collision rate will increase to 50 kHz. Preliminary tests of the firmware show that at this occupancy, the event readout rate was doubled from 4.5 kHz (Fig. 5 blue) to 9.3 kHz (Fig. 5 red).
3
Please cite this article as: J.L. Gauci, E. Gatt, O. Casha, Preparing the ALICE-HMPID RICH for the high-luminosity LHC period 2021–2023, Nuclear Inst. and Methods in Physics Research, A (2019), https://doi.org/10.1016/j.nima.2019.01.025.
Contents lists available at ScienceDirect
Nuclear Inst. and Methods in Physics Research, A journal homepage: www.elsevier.com/locate/nima
Preparing the ALICE-HMPID RICH for the high-luminosity LHC period 2021–2023✩ , ✩✩ J.L. Gauci ∗, E. Gatt, O. Casha, on Behalf of ALICE Collaboration Department of Microelectronics and Nanoelectronics, University of Malta, Msida, Malta, Malta
ARTICLE Keywords: RICH Detector HMPID MWPC Upgrade CERN
INFO
ABSTRACT Approaching successfully the end of the LHC Run2 period (2015–2018), the RICH based High Momentum Particle IDentification detector (HMPID) prepares for the High Luminosity LHC (HL-LHC) Run 3 period (2020–2023) √ where the collider will provide up to 50 kHz of Pb-Pb collision rate at 𝑠NN = 5 TeV. The upgraded ALICE detector will be able to read out all interactions and it will exploit the fully scientific potential of the HL-LHC to study the properties of the Quark–Gluon Plasma phase (QGP), using proton–proton, nucleus–nucleus and proton– nucleus collisions at high energies. The ALICE continuous detector read out will ensure the Online/Offline (O2 ) identification of rare trigger topologies and an effective data compression factor. This paper presents the HMPID status and the activities under way to integrate the detector in the new ALICE O2 Trigger environments. The stable performance of the detector, the stability of the Multi-Wire Proportional Chamber (MWPC) during preliminary tests of high luminosity conditions in ALICE using pp collisions, and the progressing upgrading activities, support the participation of the HMPID in the ALICE scientific program defined for the HL-LHC period.
1. Introduction A Large Ion Collider Experiment (ALICE) is a general-purpose heavyion detector at the CERN LHC dedicated to the study and characterisation of QGP at extremely high energy density and temperature conditions. For this reason, ALICE consists of a number of detectors dedicated to performing particle identification in a wide momentum range from hundreds of MeV/𝑐 to 100 GeV/𝑐 through the combination of different detector techniques [1]. The High Momentum Particle Identification Detector (HMPID) [2], with its 5% of central barrel acceptance is one such detector. The acceptance is in the pseudo rapidity range |𝜂| < 0.5. The detector performs charged particle track-by-track identification by measuring the emission angle of Cherenkov photons, in conjunction with the momentum measured by the ALICE tracking detectors, ITS and TPC. It is capable of providing a three 𝜎 separation PID capability in the range of 1−5 GeV/c, thus extending the useful range for particle identification on a track-by-track bases up to 3 GeV/𝑐 for pions and kaons, and up to 5 GeV/𝑐 for (anti-)protons, in p-p collisions. HMPID is based on seven 1.3 × 1.3 m2 proximity focusing RICH counters, split into left and right photocathodes (RICH0-RICH6) for a total active area of approximately 10.7 m2 . Cherenkov photon detection
is achieved by pad segmented photocathodes (PCs) coated with a 300 nm thick Caesium Iodide (CsI) layer, installed in multiwire proportional chambers (MWPC) operated with CH4 . Liquid perfluorohexane (C6 F14 ) with 𝑛 = 1.2989 at 𝜆 =175 nm is used as Cherenkov radiator. In this paper, the HMPID status and the activities under way to integrate the detector in the new ALICE O2 [3] and Trigger environments are presented. The stable performance of the detector, the stability of the MWPC during preliminary tests of high luminosity conditions in ALICE using pp collisions, and the progressing upgrading activities, support the participation of the HMPID in the ALICE scientific program defined for the HL-LHC period. 2. The detector performance in the LHC run period 2015–2018 The HMPID performance during 2010–2013 is reported in [4] and [5]. During 2015–2018 (LHC Run2), the electronics, the power supply systems and the C6 F14 transparency system have operated in a stable manner. At the beginning of 2016 HV sector 1 on RICH1 failed and this therefore led to a decrease in detector acceptance from 72% to 70%. The reason could be a loose anode wire, since a few hundred volts can be applied before the overcurrent protection circuitry switches off the HV channel. The stability of the CsI QE can be affected by contaminants such
✩ This work is a collaborative effort between the University of Malta and ALICE-HMPID. ✩✩ The research work disclosed in this publication is partially funded by the ENDEAVOUR Scholarship Scheme (Malta). The scholarship are part-financed by the European Union – European Social Fund (ESF) under Operational Programme II – Cohesion Policy 2014–2020, ‘‘Investing in human capital to create more opportunities and promote the well being of society." ∗ Corresponding author. E-mail addresses: [email protected] (J.L. Gauci), [email protected] (E. Gatt), [email protected] (O. Casha).
https://doi.org/10.1016/j.nima.2019.01.025 Received 15 October 2018; Received in revised form 4 January 2019; Accepted 10 January 2019 Available online xxxx 0168-9002/© 2019 Elsevier B.V. All rights reserved.
Please cite this article as: J.L. Gauci, E. Gatt, O. Casha, Preparing the ALICE-HMPID RICH for the high-luminosity LHC period 2021–2023, Nuclear Inst. and Methods in Physics Research, A (2019), https://doi.org/10.1016/j.nima.2019.01.025.
J.L. Gauci, E. Gatt, O. Casha et al.
Nuclear Inst. and Methods in Physics Research, A xxx (xxxx) xxx
Fig. 4. Charge dose of CsI photocathodes per HV sector.
Fig. 1. Average maximum number of reconstructed photons per Cherenkov pattern (Nph) versus time (year).
threshold of several hundred ppm so no degradation of the CsI QE is expected [6]. In Fig. 1, a stable average number of reconstructed photons (Nph) per Cherenkov pattern at saturation (𝛽 ≈ 1), for the period 2010–2018, can be observed. Nph and gas-gain (Fig. 2) reduction in RICH2 is now under investigation [7]. The number of detected photoelectrons depends on the gas gain and CsI QE. From the observed stability of the gas gain one can infer that the almost symmetric distribution of the angular coefficient (gradients of the linear fits in Fig. 1), illustrated in Fig. 3, of the Nph is still compatible with a stable CsI QE, in the period 2010–2018. The slight asymmetry comes from the contribution of RICH2. One of the reasons for this could be due to the fact that two photocathodes were re-evaporated in 2005. The Charge Dose plot of CsI induced by bombardments of CH4 ion avalanches per high voltage sector (Fig. 4) shows that the charge density at the end of 2018 leaves a sufficient margin to maintain a stable QE until the end of Run3 (2023). In Fig. 4 the open bar represents the integration of the total anodic current, 𝐼𝑎 , while the yellow represents the total charge dose absorbed by the CsI photocathodes, given by 𝑡 0.6 × ∫0 𝐼𝑎 𝑑𝑡. This is determined by a charge sharing model for charged particle and photoelectrons.
Fig. 2. MWPC gas gain 𝐴0 vs. time (year).
3. Upgrading of HMPID for LHC Run3 (2021–2023) 3.1. Trigger Fan-In/Fan-Out module A new Fan-In/Fan-Out module is being developed to receive the Level-0 trigger, delay it, and distribute it to the 14 readout control boards (two per RICH module). This module is capable of being remotely-controlled and monitored via the IPBus protocol. In addition, the new module also receives 14 BUSY signals and combines them into one BUSY for handling by the Central Trigger Processor (CTP). Preliminary prototypes have been tested in Malta and at CERN. The results, together with a mathematical model of the delay against the control command may be found in [8]. Fig. 3. Distribution of angular coefficient of linear fit of Nph.
In [8], it was seen that through the use of a shift-register based delay architecture, a random offset is generated. This offset has a multimodal distribution and is difficult to model. As such, a time-to-digital converter was implemented on an FPGA to try and reduce the error, by fine-tuning the control command. The TDC utilises the Nutts interpolation method and is capable of achieving a 500 ps resolution. This method also allows the operator to obtain some feedback on the delay. Studies are being carried out to characterise the jitter of the Fan-In/Fan-Out module.
as O2 and water, or by the specific charge dose from ion bombardment. Physico-chemical ageing effects on the photocathodes may also affect the stability. The O2 and water level in the MWPC gas outlet have been monitored by the Detector Control System (DCS) via a dedicated device. The measured levels at approximately 10 ppm, are well below the safety 2
Please cite this article as: J.L. Gauci, E. Gatt, O. Casha, Preparing the ALICE-HMPID RICH for the high-luminosity LHC period 2021–2023, Nuclear Inst. and Methods in Physics Research, A (2019), https://doi.org/10.1016/j.nima.2019.01.025.
J.L. Gauci, E. Gatt, O. Casha et al.
Nuclear Inst. and Methods in Physics Research, A xxx (xxxx) xxx
4. MWPC test in Run3 environment To ensure that the MWPC can operate in a stable manner during Run3, where the track load will increase, a number of tests were run. A luminosity of 70 Hz/μb in ALICE in pp collisions produces a track load equivalent to 50 kHz in Pb-Pb collisions expected during Run3. The anode currents in the RICH modules increase linearly with charged particle rate (luminosity). In Fig. 6 it can be seen that, for RICH5, linearity and stability is preserved along the test up to 70 Hz/μb with no gas gain saturation or space/charge effects. The same behaviour was observed for all 7 RICH modules. 5. Perspectives and conclusions Fig. 5. Readout rate versus the percentage occupancy in the detector for Runs 2 and 3 (blue and red, respectively).
During the LHC run period 2015–2018 the HMPID has operated in a stable condition. This work has shown that the number of photons per Cherenkov patterns has remained stable in all RICH modules, with the exception of RICH2. This was also verified through the plot of the distribution of the angular coefficient, where the mean of this distribution is still close to zero; implying that there is no significant degradation to affect stability. The charge dose per HV sector for 2018 also illustrates that there is a sufficient margin to maintain a stable QE until the end of Run3, in 2023. While none of the electronics of the HMPID will be upgraded, a new trigger fan-in/fan-out module will be installed, together with an upgrade of the firmware. Preliminary results from the tests on these modules are promising. Furthermore, the MWPC linearity tests make us confident that the HMPID is ready for Run3 operations (2020–2023) at the HighLuminosity LHC at CERN.
Fig. 6. Ratio of current/luminosity vs. time for RICH5.
References [1] K. Aamodt, A.A. Quintana, R. Achenbach, S. Acounis, D. Adamová, C. Adler, M. Aggarwal, F. Agnese, G.A. Rinella, Z. Ahammed, et al., The ALICE experiment at the CERN LHC, J. Instrum. 3 (08) (2008) S08002. [2] ALICE Collaboration, F. Piuz, W. Klempt, L. Leistam, J. De Groot, J. Schükraft, ALICE High-Momentum Particle Identification: Technical Design Report, in: Technical Design Report ALICE, CERN, Geneva, 1998, URL https://cds.cern.ch/record/381431. [3] P. Buncic, M. Krzewicki, P. Vande Vyvre, Technical design report for the upgrade of the online-offline computing system, Tech. rep., CERN-LHCC, 2015. [4] ALICE collaboration, G. De Cataldo, et al., The ALICE–HMPID performance during the LHC run period 2010–2013, Nucl. Instrum. Methods Phys. Res. A 766 (2014) 19–21. [5] ALICE Collaboration, G. Volpe, et al., Pattern recognition and PID procedure with the ALICE-HMPID, Nucl. Instrum. Methods Phys. Res. A 766 (2014) 259–262. [6] F. Piuz, Ring Imaging CHerenkov systems based on gaseous photo-detectors: trends and limits around particle accelerators, Nucl. Instrum. Methods Phys Res. A 502 (1) (2003) 76–90. [7] A. Braem, G. De Cataldo, M. Davenport, A. Di Mauro, A. Franco, A. Gallas, H. Hoedlmoser, P. Martinengo, E. Nappi, F. Piuz, et al., Results from the ageing studies of large CsI photocathodes exposed to ionizing radiation in a gaseous RICH detector, Nucl. Instrum. Phys. Res. A 553 (1–2) (2005) 187–195. [8] J.L. Gauci, E. Gatt, G. De Cataldo, O. Casha, I. Grech, An analytical model of the delay generator for the triggering of particle detectors at CERN LHC, in: CAS (NGCAS), 2017 New Generation of, IEEE, 2017, pp. 69–72.
3.2. Read-out firmware Since for Run3, the trigger scheme will change slightly, a new firmware is required for correct handling of the trigger and readout sequence. In particular, each detector is only allowed a single synchronous trigger at either L0, L1 or L2 time. The HMPID will be using a faster version of the L0 trigger, called LM, and it will receive an asynchronous message containing information about the event to integrate the data with detectors in continuous event read out. A prototype firmware that removes the dependency on the L1 and L2 triggers has been developed. The firmware for each RICH half-module is remotely programmable, with an EtherBlaster used to upload firmware remotely via Ethernet. The occupancy of 0.3% is expected to remain the same as in Runs 1 and 2, whereas the collision rate will increase to 50 kHz. Preliminary tests of the firmware show that at this occupancy, the event readout rate was doubled from 4.5 kHz (Fig. 5 blue) to 9.3 kHz (Fig. 5 red).
3
Please cite this article as: J.L. Gauci, E. Gatt, O. Casha, Preparing the ALICE-HMPID RICH for the high-luminosity LHC period 2021–2023, Nuclear Inst. and Methods in Physics Research, A (2019), https://doi.org/10.1016/j.nima.2019.01.025.