In view of High Luminosity LHC upgrade, the ATLAS experiment will add a new layer of Resistive Plate Chambers (RPC) trigger chambers into the barrel muon spectrometer. These next-generation RPC chambers will use a 1 mm gap and a single type of readout strips coupled to front-end electronics capable of providing both coordinates in the detector plane. The procedures for assembling the readout panels and the results of Quality Assurance and Quality Control (QA/QC) tests on the pre-series panels is reported here

Carducci, G.

Falsetti, G.

Passarelli, D.

Perrone, M.

Schioppa, M.

Turco, P.

Scientific Open-access Literature Archive and Repository

DOI 10.1393/ncc/i2024-24117-9Colloquia: IFAE 2023IL NUOVO CIMENTO 47 C (2024) 117Results on pre-series production and QA/QC testsof the double-ends readout panels of the new layer of triggerchambers for the ATLAS muon spectrometer phase 2 upgrade(∗)G. Carducci, G. Falsetti, D. Passarelli, M. Perrone, M. Schioppaand P. TurcoINFN, Sezione di Cosenza - Cosenza, Italyreceived 13 February 2024Summary. — In view of High Luminosity LHC upgrade, the ATLAS experimentwill add a new layer of Resistive Plate Chambers (RPC) trigger chambers into thebarrel muon spectrometer. These next-generation RPC chambers will use a 1 mmgap and a single type of readout strips coupled to front-end electronics capable ofproviding both coordinates in the detector plane. The procedures for assembling thereadout panels and the results of Quality Assurance and Quality Control (QA/QC)tests on the pre-series panels is reported here.1. – IntroductionThe High-Luminosity upgrade of the LHC (HL-LHC) will provide pp collisions at acenter-of-mass energy of√s = 14 TeV with luminosities up to 7·1034 cm−2 s−1 and atotal integrated luminosity of 3000 fb−1. The ATLAS detector [1] will undergo a secondand last upgrade before the start of HL-LHC physics runs: the Phase-II upgrade duringLS3 (2024–2026). The challenge for the muon spectrometer (MS) is to preserve itsmuon identification and tracking performance in much harsher conditions in terms ofparticle rates, radiation, and number of inelastic pp interactions per bunch crossing. Inparticular the muon trigger has to become more selective, so that the low pT thresholdsrequired for many physics studies and searches result in an acceptable trigger rate, andacceptance should possibly overcome the present geometrical limitations. To achievethis performance, a new layer of Resistive Plate Chambers (RPC) will be mounted inthe inner region of the barrel Muon Spectrometer (BI).(∗) IFAE 2023 - “Poster” sessionc© CERN on behalf of the ATLAS CollaborationCreative Commons Attribution 4.0 License (http://creativecommons.org/licenses/by/4.0) 12 G. CARDUCCI et al.Fig. 1. – Left: x-y view of the MS layout with in green and blue the new RPC chamberswhich have two types: Small (blue) and Large (green). In grey the present RPC chambers andin orange the BOM/BOL: RPC in the outer region that will be mounted to better cover theregion with the bearing structure of the experiment [2]. Right: R-z view of a quarter of thelongitudinal cross-section of ATLAS small sector, showing the New Small Wheel (NSW) of thePhase-I ATLAS upgrade (orange), installed during the long shutdown LS2, and the new RPC0layer to be installed during Phase-II upgrades [2]. On top of the NSW structure the are theBIS78 chambers made of sMDT and RPC, installed during LS2.2. – The Muon SpectrometerThe ATLAS muon spectrometer (MS) [3] consists of three large air-core superconduct-ing toroidal magnets (two endcaps and one barrel) providing a magnetic field up to 3.5T. The deflection of the muon trajectories in the bending plane orthogonal to the mag-netic field is measured via hits in three layers of monitored drift tube (MDT) chamberscovering the region in pseudo-rapidity |η| < 2.7. The innermost forward wheels, SmallWheels (SW), of the MS [4], have been replaced during the Phase-I ATLAS update withNew Small Wheels (NSW) using TGC (sTGC) and micro-mesh Gaseous Structure (MM)chambers for both triggering than precision tracking. The locations of the new Phase-Iupgrade detectors are shown in fig. 1 (right). The present hardware trigger level is basedon hit coincidences between different RPC or TGC detector layers inside programmedgeometrical windows which define the muon pT . The maximum rate and latency of thisfirst-level trigger are 100 kHz and 2.5 μ s , respectively. The high-level trigger level per-forms a full track reconstruction and a refined pT measurement by using also precisionchamber hits.3. – Muon spectrometer Phase-II upgradeThe reconstruction efficiency and momentum resolution of the MDT system will berobust against high pile-up and high background rates and the muon identification andreconstruction performance will not be degraded by the higher particle rates and back-grounds of the HL-LHC. The muon trigger requires instead significant upgrades to main-tain the same trigger momentum thresholds while keeping the trigger rates at a manage-able level. The efficiency of the trigger is high in the endcap regions, but is limited in thebarrel region by the geometrical acceptance of the RPC system, which is below 80% fortracks detected in three RPC chambers. The Phase-II upgrade of the MS [2] comprisesthe installation of new chambers, the replacement of some existing chambers, and thereplacement of a large part of the front-end, trigger and readout electronics. Indeed, theelectronics currently mounted in the ATLAS Muon Spectrometer cannot be used for aL0 trigger able to handle a 1 MHz frequency. Programmable external FPGAs will beused to make coincidences, instead of the present custom ASICs on detectors, makingRPC-BI PRODUCTION AND TEST FOR ATLAS PHASE-II UPGRADE 3Fig. 2. – Left: Cross-section of a singlet. The ionization electrons, under the influence of theelectric field present in the gap, trigger avalanche multiplications. These charges induce chargesof opposite sign on the conductors facing them, and with them electrical signals in the circuitsconnected to these conductors. Right: 3D view of a singlet highlighting the strips hit by aparticle and the two arrival times used to calculate the coordinate along the strips.the new trigger more robust, simple and flexible. The readout electronics on detectorswill be replaced by data multiplexers and high bandwidth optical links to send out hitinformation from the detectors to the L0 trigger logic.3.1. RPC chambers. – To maintain high trigger efficiency, new RPC chambers will beinstalled. Due to the very limited space for small sectors, MDT chambers will be replacedwith others having smaller diameter drift tubes (sMDT). The present RPCs, to ensuretheir continued operation at the HL-LHC, will have to be operated at reduced voltageto respect the original design limits on currents and integrated charge. The single hitefficiencies at this working voltage will be reduced to about 65%. Despite the reducedsingle hit efficiencies, the trigger efficiency can exceed 98% by requiring the coincidence ofRPC0 with at least two of RPC1, RPC2 and RPC3. The installation of these chamberswill also cover most of the acceptance holes of the current barrel muon trigger, achieving96% coverage. In total more than 250 new RPC chambers will be built. Similar chambersare currently being built for the BIS78 project. This new RPC has 1.5 mm thin bakeliteelectrodes 1 mm apart (fig. 2). On both sides of the gas gap there are two planes withthe strips oriented in the same direction. The signal is read from one end of the upperstrips and from the opposite end of the lower strips and the coordinate along the strip ismeasured by the difference in the time of arrival of the signal to the electronics [2]. Thechamber consists of three layers with single gap efficiency greater than 95%. The ratecapability can reach 9 kHz with efficiency greater than 80%, 400 ps time resolution and1-2 mm spatial resolution at 5.6 kV operating voltage [5]. The layers of RPC took placein an aluminium box, which base and cover are pre-bent aluminium sheets.3.2. BIL Strip panel assembly . – The strip panels are made of aramid paper honeycomb(3 mm thick) with two halogen-free copper-clad halogen-free FR4 (0.4 mm thin) plates,one acting as a ground plate and the second photoengraved to form parallel strips. Thesethree elements are glued all together with Araldite 2011. The assembly site dedicated tothe production of the RPC-BI type Small (RPC-BIS) will be the University of Scienceand Technology of China (USTC) while the RPC-BI type Large (RPC-BIL) will beproduced at the Laboratorio Alte Energie of Università della Calabria in Cosenza; thelaboratory has produced some prototypes of these panels, proving to be able to buildthem with the required accuracy and on schedule. A precise template is used to align theFR4 sheets with respect to each other during gluing, and an accurate Quality Assuranceand Quality Control (QA/QC) procedure is applied to both the FR4 plates, honeycomb4 G. CARDUCCI et al.Fig. 3. – Left: the stand table used to measure the lateral dimension of the panel. Right: tenanalog linear probes measure the thickness of the panel with respect the granite table with agranularity 70x70 mm and a precision of 10 μm.foils and the assembled panels to verify dimensions and thickness of the assembled panelthat must not exceed the nominal values of ±0.25 mm and ±0.1, respectively. Figure 3(left) shows the support for measuring width and length. On the upper part of the tablethree non-aligned washers are screwed and the panel is firmly pressed against them. Twodigital micrometers measure the size against the calibrated bars. The panel is turnedover and the measurement is repeated. Finally, the panel is rotated 180 degrees withrespect to a vertical axis, and the measurement is repeated again. With these 6 measures,two are redundant, it is possible to reconstruct the geometric shape of the panel and itslateral dimensions. Figure 3 (right) shows the system used to measure the thickness ofthe panel. The assembly site also takes care of the soldering of the termination resistors(3 SMD resistors per strip) and the taping of the edges of the panel with copper adhesivetape. Finally, the site should check for electrical shorting between adjacent strips andfor interruption of electrical continuity along each strip. The site in Cosenza is able toproduce two complete strip panels per day.4. – ConclusionsPaper honeycomb structure and photoengraved plates will be used in the readoutpanel for ATLAS Phase-II RPC upgrade, leading to better mechanical and electricalperformances and stability in prevision of High Luminosity LHC. Some prototypes havebeen successfully built. In total, ∼600 BIS read-out panels will be produced and qualifiedin USTC, ∼700 BIL read-out panels will be produced and qualified in Cosenza. Finally,the RPC chambers assembly and commissioning will mostly be performed at CERN.REFERENCES[1] ATLAS Collaboration,; JINST, 3 (2008) S08003.[2] ATLAS Collaboration, Technical Design Report for the Phase-II Upgrade of the ATLASMuon Spectrometer, CERN-LHCC-2017-017 (2017).[3] ATLAS Collaboration, ATLAS muon spectrometer: Technical Design Report, CERN-LHCC-97-022 (1997).[4] ATLAS Collaboration, New Small Wheel Technical Design Report, CERN-LHCC-2013-006 (2013).[5] Pizzimento L., JINST, 15 (2020) C11010.

Results on pre-series production and QA/QC tests of the double-ends readout panels of the new layer of trigger chambers for the ATLAS muon spectrometer phase 2 upgrade

http://eprints.bice.rm.cnr.it/23019/1/ncc12967.pdf

Results on pre-series production and QA/QC tests of the double-ends readout panels of the new layer of trigger chambers for the ATLAS muon spectrometer phase 2 upgrade

Abstract

Similar works

Full text

Available Versions

Scientific Open-access Literature Archive and Repository