The surface detectors of the Pierre Auger Observatory are being upgraded by adding new detectors and replacing electronics.
						The upgrade project, called "AugerPrime," includes the addition of a small PMT to increase the dynamic range of particle counting, a plastic scintillator above each water-Cherenkov detector to improve the discrimination between the electromagnetic and muonic shower components, a radio detector to measure radio emission from inclined air showers, and a set of underground muon counters to provide additional information on muon content in atmospheric showers.
					The new electronics, dubbed Upgraded Unified Board (UUB), is designed to acquire all of these additional detectors and includes improved GPS receiver, higher sampling rate, increased dynamic range, greater processing capacity, and improved calibration and monitoring systems. In the following, we will describe the UUB design and discuss its performance as observed in the first data from the upgraded array

Convenga, Fabio

English

KITopen

Journal of Physics: Conference SeriesPAPER • OPEN ACCESSThe upgraded electronics of the Pierre Augersurface detectorTo cite this article: Fabio Convenga and on behalf of the Pierre Auger Collaboration 2022 J. Phys.:Conf. Ser. 2374 012076 View the article online for updates and enhancements.You may also likeRadio emission from extensive air showersA D Filonenko-Limits on point-like sources of ultra-high-energy neutrinos with the Pierre AugerObservatoryA. Aab, P. Abreu, M. Aglietta et al.-Probing the origin of ultra-high-energycosmic rays with neutrinos in the EeVenergy range using the Pierre AugerObservatoryA. Aab, P. Abreu, M. Aglietta et al.-This content was downloaded from IP address 141.52.248.4 on 16/01/2023 at 15:12Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing LtdInternational Conference on Technology and Instrumentation in Particle PhysicsJournal of Physics: Conference Series 2374 (2022) 012076IOP Publishingdoi:10.1088/1742-6596/2374/1/0120761The upgraded electronics of the Pierre Auger surfacedetectorFabio Convengaa on behalf of the Pierre Auger Collaborationb,1aKarlsruhe Institute of Technology (KIT), Karlsruhe, GermanybObservatorio Pierre Auger, Av. San Mart́ın Norte 304, 5613 Malargüe, ArgentinaE-mail: bauger_spokespersons@fnal.govAbstract. The surface detectors of the Pierre Auger Observatory are being upgraded byadding new detectors and replacing electronics.The upgrade project, called “AugerPrime,” includes the addition of a small PMT toincrease the dynamic range of particle counting, a plastic scintillator above each water-Cherenkov detector to improve the discrimination between the electromagnetic and muonicshower components, a radio detector to measure radio emission from inclined air showers, anda set of underground muon counters to provide additional information on muon content inatmospheric showers.The new electronics, dubbed Upgraded Unified Board (UUB), is designed to acquire all ofthese additional detectors and includes improved GPS receiver, higher sampling rate, increaseddynamic range, greater processing capacity, and improved calibration and monitoring systems.In the following, we will describe the UUB design and discuss its performance as observed inthe first data from the upgraded array.1. IntroductionThe Pierre Auger Observatory [1] is the most extensive experiment to study ultrahigh-energycosmic rays (UHECRs), understand their nature, and identify their sources. It is a hybridobservatory and consists primarily of two kinds of detectors, the surface detector (SD) and thefluorescence detector (FD).The SD [2] consists of 1600 water Cherenkov detectors (WCDs) deployed in a 1.5 km gridover a total area of about 3000 km2 and is used to measure the density and the arrival timedistribution of the shower particles at the ground. A map view of the Observatory is shown inthe figure 1. The FD [3] is divided into four sites surrounding the SD’s area, each composed ofsix telescopes with elevation angle from 1◦ to 30◦, for the measurement of the energy deposit ofthe showers in the atmosphere.In the northwestern part of the experimental site, two denser arrays with reduced spacingsof 750 m and 433 m are present as part of the Underground Muon Detector (UMD) thataims to extend the measurable energy range down to 1016.5 eV. This region also containsthree fluorescence telescopes with high elevation from 30◦ to 60◦. Finally, to complete themeasurements on the low energy showers, the Auger Engineering Radio Array (AERA) is usedto detect the radio emission released by the secondary cosmic rays in the atmosphere.1 Full author list: https://www.auger.org/archive/authors_2020_11.htmlInternational Conference on Technology and Instrumentation in Particle PhysicsJournal of Physics: Conference Series 2374 (2022) 012076IOP Publishingdoi:10.1088/1742-6596/2374/1/0120762Currently, an upgrade project dubbed “AugerPrime” [4] is being implemented on theObservatory. The upgrade project foresees a series of technological improvements to theObservatory: an additional small PMT (SPMT) in the WCD to increase the dynamic range;a surface scintillator detector (SSD) (a plastic scintillator) installed on top of the WCD tooperate a complementary measurement of the shower particles; a radio antenna [5] (RD) thatwill be mounted on top of the WCD to detect radio signals (30 to 80 MHz) and provide acomplementary measurement to the SSDs of the electromagnetic component of the showers. Inaddition, an underground muon detector (UMD) is starting to be deployed beside each WCD inthe denser arrays of the observatory to provide direct measurements of the shower muon content.Figure 1. Layout of the PierreAuger Observatory.Figure 2. The latest versionof the UUB during a test proce-dure.As part of AugerPrime, an upgrade of SD station electronics was also arranged. The newelectronics [6] (figure 2), dubbed Upgraded Unified Board or UUB, is designed to process thenew signals of SSD and RD. With a new ADC, it is now possible to obtain a faster samplingof traces (120 MHz and 12-bit of accuracy) and increased data quality; moreover, with a morepowerful station processor and a new Xilinx Zynq7020 FPGA, the local trigger and processingcapabilities have been improved.2. Digital functionality of the UUBThe firmware of the UUB’s FPGA is written in IEEE standard synthesizable Verilog. XilinxVivado is used for the global framework and standard modules such as memories and interfaces.It is connected to a 4 Gbit LP-DDR2 memory and a 2 Gbit flash memory.The logic functions encoded in the firmware include ADC reading, trigger generation, andinterfaces with the LED flasher, GPS receiver, and memories. The pre-upgrade trigger logic hasbeen transferred to the UUB FPGA. To not interfere with the data taking during the deploymentof the UUBs, the ADC traces of the three WCD PMTs are digitally filtered and downsampled.However, the increased processing capabilities of the FPGA also allow new trigger types suchas combined SSD and WCD triggers to be implemented.The Xilinx PetaLinux operating system runs on the ARM processor. The data acquisitionsoftware (DAQ) installed implements high-level functions such as data management andcommunications with the communications radio transmitter.The detector synchronization is done by tracking the variations of the local 120 MHz clockrelative to the GPS 1 PPS signal. For the new electronics, the Synergy SSR-6TF timing GPSreceivers were chosen. The FPGA, through the time-tagging module, manages the GPS and thedata timing in an entirely consistent way with the one that was designed for the old electronics.International Conference on Technology and Instrumentation in Particle PhysicsJournal of Physics: Conference Series 2374 (2022) 012076IOP Publishingdoi:10.1088/1742-6596/2374/1/0120763On UUB, there are also two connectors with eight differential LVDS lines (so-called digitalinterfaces), each of which can be, in the FPGA, individually defined as input or output. One ofthese is used for the RD, and the other is used for the UMD.3. Front-end and Slow controlThe ADCs at the front-end of the UUB are fed with signals coming from the SPMT, the PMTs(XP1805 PMTs) detecting Cherenkov light from the WCD, called large PMTs (LPMTs), andthe PMT collecting light from the SSD. The five signals are divided into five high-gain andfive low-gain signals, respectively. They are obtained by using two amplifiers in parallel withdifferent gains; the signals of the LPMTs are divided with a gain ratio of 32 while the signal ofthe PMT of the SSD is divided to reach a gain ratio of 128, allowing for it a dynamic range of20,000 MIP (minimum-ionizing particle).As mentioned earlier, to increase the dynamic range of the WCD, an SPMT, a 1-inchHamamatsu R8619 PMT dedicated to measuring significant signals, has been included. Asshown in figure 3, the SPMT gain and amplification are set such that the dynamic range isextended by a factor of 30 at 20,000 VEM (vertical muon equivalent).Figure 3. Charge spectrum in one of the upgraded WCD stations. The LPMTs is in purpleand green and the SPMT is in brown and blue.The VEM signal is used to calibrate the high-gain channels of the WCD; the procedure iscarried out by the DAQ software and has been mainly inherited from the one carried out withthe old electronics [7]. In addition, each WCD is equipped with two LEDs used for monitoringand linearity tests.The SPMT cannot be calibrated using atmospheric muons, so a selection of small showers isused to cross-calibrate it with the VEM signals of the LPMTs. The SSD calibration is based onthe signal of a minimum-ionizing particle (MIP) passing through the detector.The management of slow control is performed by the MSP430 micro-controller. It controlsthe high voltage monitoring of the PMT, the supervision of the various supply voltages and thereset functionality. In addition, the micro-controller also provides a USB interface, which is veryuseful if you need to perform tests on the UUB. The 90 variables collected by the slow-controlsoftware are acquired by the DAQ software and sent to the Auger monitoring database.4. Deployment and PerformanceUUBs have been in production since 2020 by the SITAEL company in Mola di Bari. Theyundergo a general test before being taken to the experiment site [8].The field deployment of the UUBs that have passed the test procedure began in December2020. There are currently a total of 79 surface stations that have UUBs. These stations all haveInternational Conference on Technology and Instrumentation in Particle PhysicsJournal of Physics: Conference Series 2374 (2022) 012076IOP Publishingdoi:10.1088/1742-6596/2374/1/0120764SPMTs and SSDs. An Engineering Array of twelve AugerPrime stations has been in place since2016 to test and monitor the performance of the upgraded detectors. Currently, two stationsremain in this portion of the array.Currently, the stations with the UUBs are under control and monitoring by the Collaboration.Noise studies, timing studies, and calibration studies for SPMT and SSD are being done on thearray. Noise levels measured in the array are consistent with those in the design phase. Thefigure 4 shows the baseline RMS distribution in April 2021 acquired from all the stations withUUBs data.Timing resolution was measured using showers triggering two neighboring upgraded teststations dubbed Clais and Trak in the EA. The end-to-end timing accuracy (figure 5) of a singlestation in real showers was measured to be better than 10 ns (vs. the current 13 ns).Figure 4. The baseline RMS of thehigh gain ADC signals of PMTs atsurface stations with UUB.Figure 5. Measured timingresolution on showers using twonearby test stations.5. Summary and outlookThe design aspects of the new electronics of the Pierre Auger Observatory were presented.Currently, 79 UUBs are in data taking and constantly monitored.The observed performance of the UUBs was discussed and it was seen that they are stableand well within the initial requirements. New trigger studies are planned to take into accountthe newly installed detectors. Production continues without interruption and a full deploymentis expected one year from now.References[1] The Pierre Auger Collaboration, ”The Pierre Auger Cosmic Ray Observatory”, Nucl. Instrum. Meth. A 798(2015) 172-213.[2] Allekotte, I. et al. ”The surface detector system of the Pierre Auger Observatory” Nucl. Instrum. Meth. A586 (2008) 409420.[3] Allekotte, I. et al. ”The fluorescence detector of the Pierre Auger Observatory” Nucl. Instrum. Meth. A 620(2010) 227251.[4] A. Aab et al. ”The Pierre Auger Observatory Upgrade - Preliminary Design Report” arXiv:1604.03637 [astro-ph.IM](2015).[5] B. Pont for for the Pierre Auger Collaboration ”A large radio detector at the Pierre Auger Observatorymeasuring the properties of cosmic rays up to the highest energies” in PoS(ICRC2019) 395 (2019).[6] D. Nitz for for the Pierre Auger Collaboration ”New Electronics for the Surface Detectors of the Pierre AugerObservatory” in PoS(ICRC2019) 370 (2019).[7] X. Bertou et al. ”Calibration of the surface array of the Pierre Auger Observatory” Nucl. Instrum. Meth. A568 (2006) 839-846.[8] M. Bohcov for for the Pierre Auger Collaboration ”Test benches for the upgrade of the Pierre AugerObservatory electronics” in PoS(ICRC2019) 199 (2019).

The upgraded electronics of the Pierre Auger surface detector

https://publikationen.bibliothek.kit.edu/1000154544/150078596

The upgraded electronics of the Pierre Auger surface detector

Abstract

Similar works

Full text

Available Versions

KITopen