2S Modules Research Articles

Beam test performance studies of CMS Phase-2 Outer Tracker module prototypes

A new tracking detector will be installed as part of the Phase-2 upgrade of the CMS detector for the high-luminosity LHC era. This tracking detector includes the Inner Tracker, equipped with silicon pixel sensor modules, and the Outer Tracker, consisting of modules with two parallel stacked silicon sensors. The Outer Tracker front-end ASICs will be able to correlate hits from charged particles in these two sensors to perform on-module discrimination of transverse momenta (p T). The p T information is generated at a frequency of 40 MHz and will be used in the Level-1 trigger decision of CMS. Prototypes of the so-called 2S modules were tested at the Test Beam Facility at DESY Hamburg between 2019 and 2020. These modules use the final front-end ASIC, the CMS Binary Chip (CBC), and for the first time the Concentrator Integrated Circuit (CIC), optical readout and on-module power conversion. In total, seven modules were tested, one of which was assembled with sensors irradiated with protons. An important aspect was to show that it is possible to read out modules synchronously. A cluster hit efficiency of about 99.75 % was achieved for all modules. The CBC p T discrimination mechanism has been verified to work together with the CIC and optical readout. The measured module performance meets the requirements for operation in the upgraded CMS tracking detector.

Assembly and testing of 2S module prototypes for the CMS Phase-2 outer tracker upgrade

The HL-LHC necessitates a Phase-2 upgrade for the CMS detector, which includes the complete replacement of the existing tracker. The new Outer Tracker incorporates two types of silicon module, 2S and PS, based on an innovative transverse momentum (pT) discrimination idea. By using these modules, the information from the tracker will be sent to the Level-1 (L1) trigger for the first time. They will identify charged particles with pT > 2 GeV, helping to reduce the data sent to the L1 trigger. This paper offers a comprehensive overview of the 2S module prototyping process, which include the precise assembly and testing procedures to ensure their performance and quality before integration into the Outer Tracker. Additionally, to assess the performance of a 2S module in beam, the data from a DESY test beam is reconstructed and analyzed using the Corryvreckan offline reconstruction framework. The results demonstrate agreement to within 1% with those obtained using the EUTelescope framework.

Beam test studies with silicon sensor module prototypes for the CMS Phase-2 Outer Tracker

The Large Hadron Collider (LHC) at CERN will be upgraded to the High-Luminosity LHC (HL-LHC) by 2029. In order to fully exploit the physics potential of the high luminosity era the experiments must undergo major upgrades. In the context of the upgrade of the Compact Muon Solenoid (CMS) experiment the silicon tracker will be fully replaced. The outer part of the new tracker (Outer Tracker) will be equipped with about 13,000 double-layer silicon sensor modules with two different flavors: PS modules consisting of a macro-pixel and a strip sensor and 2S modules using two strip sensors. These modules can discriminate between trajectories of charged particles with low and high transverse momentum. The different curvature of the trajectories in the CMS magnetic field leads to different hit signatures in the two sensor layers. By reading out both sensors, matching hits in the seed and correlation layer “stubs” are identified. This stub information is generated at the LHC bunch crossing frequency of 40 MHz and serves as input for the first stage of the CMS trigger. In order to quantify the hit and stub detection efficiency, beam tests have been performed. This article comprises selected studies from measurements gathered during two beam tests at the DESY test beam facility with 2S prototype modules assembled in 2021, featuring the Low Power Gigabit Transceiver (lpGBT). In order to compare the module performance at the beginning and end of the CMS runtime, a module with irradiated components has been built and intensively tested.

Influence of high-frequency magnetic fields on the noise behavior of CMS 2S module prototypes

For the CMS tracker Phase-2 upgrade new modules with silicon strip sensors are being developed.Each module features a Service Hybrid (SEH), which is responsible for the distribution of low voltages to the module components using a two-stage DC-DC conversion scheme.For modules equipped with the latest generation of SEHs an increase in module noise has been observed.A setup for inducing radiative noise with external magnetic fields that are frequency- and location-dependent is presented.Measurements carried out on modules from different prototyping phases show that the sensitivity is similar across generations, which indicates that radiative coupling into the sensor or readout electronics is not responsible for the observed noise increase.

Lessons learnt from the first vertical slice of the CMS Outer Tracker

A vertical slice of the CMS Outer Tracker has been tested at the tracker integration facility and at the M2 muon beam facility at CERN. It includes the final prototype of the 2S module with an optical link to the back-end ATCA system. The performance of the system will be described, including cooling limits of racks, robustness of 25 Gbit/s trigger optical links, and readiness of firmware.

Prototyping and qualification of 2S modules for the CMS Outer Tracker upgrade at the HL-LHC

In preparation for the High Luminosity LHC, the entire tracker detector of the CMS experiment will be exchanged as part of the Phase-2 Upgrade. The new Outer Tracker will comprise approximately 13,000 silicon sensor modules, of which 7608 are “2S modules” consisting of two parallel mounted silicon strip sensors, and 5592 are “PS modules” consisting of one pixel and one strip sensor in a single module. These modules provide tracking information to the level 1 trigger by correlating the hit information of both sensor layers, allowing discrimination of particle tracks by their transverse momentum. To guarantee successful operation during data-taking, the production of the outer tracker modules has to fulfill strict requirements. This note will discuss the assembly procedures as well as some key results of the electronic, thermal and vibration tests performed at CERN for qualifying the 2S module design and for preparing the module assembly procedures.

Test system for the service hybrid of the 2S module for the CMS Phase-2 Outer Tracker upgrade

Alongside the High Luminosity LHC upgrade, the silicon tracker of the CMS detector will be replaced within the scope of the so-called Phase-2 upgrade. The new tracker will consist of an inner part (Inner Tracker with pixelated modules) and at larger radii the Outer Tracker with two different module types (PS and 2S modules). One hybrid type used on these modules is the 2S service hybrid. It provides the optical link connection of a 2S module via the Low Power Giga Bit Transceiver (lpGBT) and a Versatile Transceiver Plus module (VTRx+). It is also responsible for the module power distribution. The different responsibilities of the hybrid require a complete testing, which is performed by a dedicated custom made test card. After a hybrid has been installed on the test card, all signal connections can be tested and verified. The test system is designed to handle a high throughput during mass production. The requirements and the design for the 2S service hybrid test card are presented together with testing results of the first final 2S service hybrid prototypes.

Beam test results of silicon sensor module prototypes for the Phase-2 Upgrade of the CMS Outer Tracker

The start of the High-Luminosity LHC (HL-LHC) in 2027 requires upgrades to the Compact Muon Solenoid (CMS) experiment. In the scope of the upgrade program the complete silicon tracking detector will be replaced. The new CMS Tracker will be equipped with silicon pixel detectors in the inner layers closest to the interaction point and silicon strip detectors in the outer layers. The new CMS Outer Tracker will consist of two different kinds of detector modules called PS and 2S modules. Each module will be made of two parallel silicon sensors (a macro-pixel sensor and a strip sensor for the PS modules and two strip sensors for the 2S modules). Combining the hit information of both sensor layers, it is possible to estimate the transverse momentum of particles in the magnetic field of 3.8 T at the full bunch-crossing rate of 40 MHz directly on the module. This information will be used as an input for the first trigger stage of CMS. It is necessary to validate the Outer Tracker module functionality before installing the modules in the CMS experiment. Besides laboratory-based tests several 2S module prototypes have been studied at test beam facilities at CERN, DESY and FNAL. This article concentrates on the beam tests at DESY during which the functionality of the module concept was investigated using the full final readout chain for the first time. Additionally the performance of a 2S module assembled with irradiated sensors was studied. By choosing an irradiation fluence expected for 2S modules at the end of HL-LHC operation, it was possible to investigate the particle detection efficiency and study the trigger capabilities of the module at the beginning and end of the runtime of the CMS experiment.

Blasting pressure for LiNi1/3Mn1/3Co1/3O2 battery evaluated by thermally adiabatic testing

Gas evolution that resulted in the pressure elevation on LiNi1/3Mn1/3Co1/3O2 (NMC111) battery in case of a runaway reaction was discussed with the thermally explosive behaviors. The NMC111 cell and 2 series-connected (2S) NMC111 module both with 100% SoCs (state of charges) were examined the pressure rise rates in an open-circuit voltage (OCV) state using VSP2 adiabatic calorimetry. The charged NMC111 module underwent an extremely runaway reaction at elevated temperatures and caused a thermal explosion due to high potential energy inside the battery and interaction with the cell components. The surface temperature of the cell during the charge-discharge cycle was measured to compare with the difference in heat accumulation at 0.75, 1, 2 C-rates. Furthermore, the blasting pressure that propagated a thermal explosion for both single cell and 2S module were evaluated. The significant explosion potential increased with the electric potential. Moreover, the considerable quantities of gases eruption from the full-charged batteries can result in battery rupture and flames from a confined battery housing.

First Implementation of a two-stage DC-DC conversion powering scheme for the CMS Phase-2 outer tracker

The ``2S'' silicon strip modules for the CMS Phase-2 tracker upgrade will require two operating voltages. These will be provided via a two-step DC-DC conversion powering scheme, in which one DC-DC converter delivers 2.5 V while the second DC-DC converter receives 2.5 V at its input and converts it to 1.2 V. The DC-DC converters will be mounted on a flex PCB, the service hybrid, together with an opto-electrical converter module (VTRx+) and a serializer (LP-GBT). The service hybrid will be mounted directly on the 2S module. A prototype service hybrid has been developed and its performance has been evaluated, including radiative and conductive noise emissions, and efficiency. In addition system tests with a prototype module have been performed. In this work the service hybrid will be described and the test results will be summarized.

Exploring the quality of latest sensor prototypes for the CMS Tracker Phase II Upgrade

The luminosity of the LHC will be increased by a factor of five to seven after the third long shutdown (LS3) scheduled in the mid of the next decade. The significant increase in luminosity along with the limitations of the current Tracker require a complete renewal of the CMS Outer Tracker, the Tracker Phase-2 Upgrade, during the LS3. New types of modules called PS and 2S modules are foreseen offering enhanced functionality and radiation hardness. Milestones in sensor R&D for the 2S modules as well as first characterization results are presented. AC-coupled silicon strip sensors of two vendors, produced on 6-inch as well as on 8-inch wafers, are considered which both are in n-on-p technology. Global as well as single strip parameters were measured providing insights into the quality of the sensors.

Silicon sensor prototypes for the Phase II upgrade of the CMS tracker

The High-Luminosity LHC (HL-LHC) has been identified as the highest priority program in High Energy Physics in the mid-term future. It will provide the experiments an additional integrated luminosity of about 2500fb−1 over 10years of operation, starting in 2025. In order to meet the experimental challenges of unprecedented p–p luminosity, especially in terms of radiation levels and occupancy, the CMS collaboration will need to replace its entire strip tracker by a new one.In this paper the baseline layout option for this new Phase-II tracker is shown, together with two variants using a tilted barrel geometry or larger modules from 8-inch silicon wafers. Moreover, the two module concepts are discussed, which consist either of two strip sensors (2S) or of one strip and one pixel sensor (PS). These two designs allow pT discrimination at module level enabling the tracker to contribute to the L1 trigger decision. The paper presents testing results of the macro-pixel-light sensor for the PS module and shows the first electrical characterization of unirradiated, full-scale strip sensor prototypes for the 2S module concept, both on 6- and 8-inch wafers.