H8 Beam Line Research Articles

On-beam system test of the new readout electronics for the CMS Electromagnetic Calorimeter upgrade

Starting in 2029, the High Luminosity LHC (HL-LHC) at CERN is projected to achieve unparalleled instantaneous luminosity (7.5 × 1034 cm-2s-1) for an integrated luminosities of 4500 fb-1. To cope with the extreme conditions of 200 collisions per bunch crossing (pile-up), both on-detector and off-detector electronics of the CMS Electromagnetic Calorimeter (ECAL) will be upgraded. The new system will incorporate a dual-gain trans-impedance amplifier alongside an Application-Specific Integrated Circuit (ASIC) that includes dual 160 MHz ADC channels and features for gain selection and data compression. The lead tungstate crystals and avalanche photodiodes (APDs) will remain in service due to their proven reliability. To counteract the noise amplification in the APDs, attributed to radiation-induced dark currents, the operational temperature of the ECAL will be reduced from 18°C to roughly 9°C. Preliminary tests of these new electronics have yielded promising results. During tests beams at the CERN H4 beamline using an electron beam, the new electronics met both required energy resolution and linearity and achieved a timing resolution of 30 ps for energies above 50 GeV.

Measurement of the intrinsic hadronic contamination in the NA64[formula omitted] high-purity [formula omitted] beam at CERN

We present the measurement of the intrinsic hadronic contamination at the CERN SPS H4 beamline configured to transport electrons and positrons at 100 GeV/c. The analysis, performed using data collected by the NA64-e experiment in 2022, is based on calorimetric measurements, exploiting the different interaction mechanisms of electrons and hadrons in the NA64 detector. We determined the contamination by comparing the results obtained using the nominal electron/positron beamline configuration with those from a dedicated setup, in which only hadrons impinged on the detector. We also obtained an estimate of the relative protons, anti-protons and pions yield by exploiting the different absorption probabilities of these particles in matter. We cross-checked our results with a dedicated Monte Carlo simulation for the hadron production at the primary T2 target, finding a good agreement with the experimental measurements.

Performance of the CMS High Granularity Calorimeter prototype to charged pion beams of 20–300 GeV/c

The upgrade of the CMS experiment for the high luminosity operation of the LHC comprises the replacement of the current endcap calorimeter by a high granularity sampling calorimeter (HGCAL). The electromagnetic section of the HGCAL is based on silicon sensors interspersed between lead and copper (or copper tungsten) absorbers. The hadronic section uses layers of stainless steel as an absorbing medium and silicon sensors as an active medium in the regions of high radiation exposure, and scintillator tiles directly read out by silicon photomultipliers in the remaining regions. As part of the development of the detector and its readout electronic components, a section of a silicon-based HGCAL prototype detector along with a section of the CALICE AHCAL prototype was exposed to muons, electrons and charged pions in beam test experiments at the H2 beamline at the CERN SPS in October 2018. The AHCAL uses the same technology as foreseen for the HGCAL but with much finer longitudinal segmentation. The performance of the calorimeters in terms of energy response and resolution, longitudinal and transverse shower profiles is studied using negatively charged pions, and is compared to GEANT4 predictions. This is the first report summarizing results of hadronic showers measured by the HGCAL prototype using beam test data.

Towards robust PICOSEC Micromegas precise timing detectors

The PICOSEC Micromegas (MM) detector is a precise timing gaseous detector consisting of a Cherenkov radiator combined with a photocathode and a MM amplifying structure. A 100-channel PICOSEC MM prototype with 10 × 10 cm2 active area equipped with a Cesium Iodide (CsI) photocathode demonstrated a time resolution below σ = 18 ps. The objective of this work is to improve the PICOSEC MM detector robustness aspects, i.e. integration of resistive MM and carbon-based photocathodes, while maintaining good time resolution. The PICOSEC MM prototypes have been tested in laboratory conditions and successfully characterised with 150 GeV/c muon beams at the CERN SPS H4 beam line. The excellent timing performance below σ = 20 ps for an individual pad obtained with the 10 × 10 cm2 area resistive PICOSEC MM of 20 MΩ/□ showed no significant time resolution degradation as a result of adding a resistive layer. A single-pad prototype equipped with a 12 nm thick Boron Carbide (B4C) photocathode presented a time resolution below σ = 35 ps, opening up new possibilities for detectors with robust photocathodes. The results made the concept more suitable for the experiments in need of robust detectors with good time resolution.

Sub-10 ps time tagging of electromagnetic showers with scintillating glasses and SiPMs

The high energy physics community has recently identified an e+e− Higgs factory as one of the next-generation collider experiments, following the completion of the High Luminosity LHC program at CERN. The moderate radiation levels expected at such colliders compared to hadron colliders, enable the use of less radiation tolerant but cheaper technologies for the construction of the particle detectors. This opportunity has triggered a renewed interest in the development of scintillating glasses for the instrumentation of large detector volumes such as homogeneous calorimeters. While the performance of such scintillators remains typically inferior in terms of light yield and radiation tolerance compared to that of many scintillating crystals, substantial progress has been made over the recent years. In this paper we discuss the time resolution of cerium-doped Alkali Free Fluorophosphate scintillating glasses, read-out with silicon photo-multipliers in detecting single charged tracks and at different positions along the longitudinal development of an electromagnetic shower, using respectively 150 GeV pions and 100 GeV electron beams at the CERN SPS H2 beam line. A single sensor time resolution of 14.4 ps and 5–7 ps was measured respectively in the two cases. With such a performance the present technology has the potential to address an emerging requirement of future detectors at collider experiments: measuring the time-of-flight of single charged particles as well as that of neutral particles showering inside the calorimeter and the time development of showers.

Particle identification with the cluster counting technique for the IDEA drift chamber

IDEA (Innovative Detector for an Electron–positron Accelerator) is a general-purpose detector concept, designed to study electron–positron collisions in a wide energy range in a very large circular leptonic collider. Its drift chamber is designed to provide an efficient tracking, a high precision momentum measurement and an excellent particle identification by exploiting the application of the cluster counting technique. To investigate the potential of the cluster counting techniques on physics events, a simulation of the ionization cluster generation is needed, therefore we developed an algorithm which can use the energy deposit information provided by the Geant4 toolkit to reproduce, in a fast and convenient way, the cluster number and cluster size distributions. The results obtained confirm that the cluster counting technique allows to reach a resolution two times better than the traditional dE/dx method. A beam test has been performed during November 2021 at CERN on the H8 beam line to validate the simulations results, to define the limiting effects for a fully efficient cluster counting and to count the number of electron clusters released by an ionizing track at a fixed βγ as a function of the track angle. The simulation and the beam test results will be described briefly in this issue.

Experimental layout for the direct measurement of electromagnetic shower acceleration in an oriented crystal scintillator

Progress in experimental high-energy physics has been closely tied to developments of high-performance calorimeters. Since their invention, crystal calorimeters have consistently achieved the best resolution for measurements of the energies of electromagnetic (e.m.) particles (electrons and photons). Recently, we experimentally demonstrated the possibility of significantly accelerating the e.m. shower development inside lead tungstate (PWO) crystal when the incident beam is aligned with the crystal axes within some tenths of a degree. Here, we present the innovative photodetection system, based on Silicon PhotoMultipliers, implemented for the direct measurement of the scintillation light enhancement in case of beam aligned to the main crystal axes, along with its characterization performed with cosmic rays at the Insulab laboratory (Insubria University, Como). In 2021 we performed a test at H2 beam line of CERN SPS with a hundred-GeV electron beam with two PWO samples (1 and 2 X0 thick) directly coupled with SiPMs. Since the angular acceptance of the crystal strong field depends weakly on particle energy, while instead the decreasing of the shower length remains pronounced at very high-energy, a crystal calorimeter based on oriented crystals would feature a consistent compactness enhancement while rivaling the current state of the art in terms of resolution in the range of interest of present and future forward detectors, beam dumps for light dark matter search and source-pointing space-borne γ-ray telescopes.

Upgrade of the CMS Barrel Electromagnetic Calorimeter for the High Luminosity LHC

The high luminosity upgrade of the LHC (HL-LHC) at CERN will provide unprecedented instantaneous and integrated luminosities of up to 7.5×1034 cm−2s−1 and 4500 fb−1, respectively, from 2029 onwards. To cope with the extreme conditions of up to 200 collisions per bunch crossing, and increased data rates, the on- and off-detector electronics of the CMS electromagnetic calorimeter (ECAL) will be replaced. A dual gain trans-impedance amplifier and an ASIC providing two 160 MHz ADC channels, gain selection, and data compression will be used. The lead tungstate crystals and avalanche photodiodes (APDs) in the current ECAL will keep performing well and will therefore be maintained. The noise increase in the APDs, due to radiation-induced dark currents, will be minimised by reducing the ECAL operating temperature from 18 °C to around 9 °C. Prototype HL-LHC electronics have been tested and have shown promising results. In two test beam periods using the CERN SPS H4 beamline and an electron beam, the new electronics achieved the target energy resolution and a timing resolution consistent that is consistent with our requirements of 30 ps timing for energies greater than 50 GeV.

Spatial resolution and efficiency of prototype sensors for the LHCb VELO Upgrade

A comprehensive study of the spatial resolution and detection efficiency of sensor prototypes developed for the LHCb VELO upgrade is presented. Data samples were collected at the CERN SPS H8 beam line using a hadron mixture of protons and pions with momenta of approximately 180 GeV/c. The sensor performance was characterised using both irradiated and non-irradiated sensors. Irradiated samples were subjected to a maximum fluence of 8 × 1015 1 MeV neq cm-2, of both protons and neutrons. The spatial resolution is measured comparing the detected hits to theposition as predicted by tracks reconstructed by the Timepix3 telescope. The resolution is presented for different applied bias voltages and track angles, sensor thickness and implant size.

Design, construction and operation of the ProtoDUNE-SP Liquid Argon TPC

The ProtoDUNE-SP detector is a single-phase liquid argon time projection chamber (LArTPC) that was constructed and operated in the CERN North Area at the end of the H4 beamline. This detector is a prototype for the first far detector module of the Deep Underground Neutrino Experiment (DUNE), which will be constructed at the Sandford Underground Research Facility (SURF) in Lead, South Dakota, U.S.A. The ProtoDUNE-SP detector incorporates full-size components as designed for DUNE and has an active volume of 7 × 6 × 7.2 m3. The H4 beam delivers incident particles with well-measured momenta and high-purity particle identification. ProtoDUNE-SP's successful operation between 2018 and 2020 demonstrates the effectiveness of the single-phase far detector design. This paper describes the design, construction, assembly and operation of the detector components.

Strangeness production in the NA61/SHINE experiment at the CERN SPS energy range

NA61/SHINE is a multi-purpose fixed-target experiment located at the H2 beamline of the CERN North Area. One of the main goals of the experiment is to study the phase transition and search for the critical point of the strongly interacting matter. Strangeness production is a long-known valuable probe for understanding particle production in high-energy physics due to the absence of strange valence quarks in the initial collision state. This talk will present the results of strangeness production in p+p, Be+Be, and Ar+Sc collisions in the SPS energy range (√sNN = 5.1 − 17.3 GeV) measured by NA61/SHINE. The talk will emphasise the importance of the results for discussion of the onset of deconfinement and onset of fireball. The obtained results will be compared to available world data and selected theoretical models.

Optimisation of a silicon microstrip telescope for UA9 crystal channeling studies

A charged particle telescope based on silicon microstrip sensors has been used for several years for data taking at high rates in the CERN H8 beam line using a range of different incident particles. The electronic readout and data acquisition system is based on that developed for the CMS Tracker, and provides almost deadtime-free operation at trigger rates of up to about 10 kHz. The telescope was designed to characterise crystals in channeling studies by the UA9 experiment with the primary objective to validate them for use in a future LHC beam collimation system, hence is optimised for measurement of a single particle in the outgoing arm. The telescope has also been used for other studies of fundamental phenomena associated with the channeling process and further LHC applications. Some of these require a different layout of the telescope, for example to achieve a larger angular acceptance to study longer channeling crystals, or modifications to sensor operating conditions because of the very large electric charge and consequent ionisation energy loss associated with heavy ions. The telescope and its performance are described. Possible improvements are discussed.

Development and performance tests of μ-PIC with DLC electrodes

Micro pixel chambers (μ-PIC) with resistive cathodes have been developed as particle tracking/imaging detectors in high-rate high ionizing particle (HIP) environments. A main target of their development is as a forward muon detector in the ATLAS phase-2 upgrade. The cathode is made from DLC (diamond-like carbon) thin foil by the liftoff method. Using the resistive cathodes, the discharge (spark) probability within the HIP environment was reduced (10-1000 times) and two-dimensional readouts for the incident particles are available using a 400-micron pitch separated pixel array. We measured the tracking performances for the charged particles using a 140 GeV muon beam in CERN’s H4 beam line and also measured the imaging properties of 8 keV X-rays. Two-dimensional fine position resolutions (< 100 micron) were obtained. These results show that the resistive μ-PIC is one of strong candidate for forthcoming high-rate particle experiments.

Test Beam Results and Performance Studies of ATLAS Micromegas Production Modules

The LHC at CERN plans to have a series of upgrades to increase its instantaneous luminosity up to 7.5 × 1034 cm−2·s−1. The ATLAS experiment will upgrade its inner end-cap muon chambers to cope with the increased collision rate expected from the High-Luminosity-LHC. This project, called New Small Wheel, includes resistive Micromegas chambers together with small-strip Thin Gap Chambers, forming a system of ˜2.4 million readout channels in total. This is the first time that Micromegas detectors are built in such a large scale. In total, 128 Micromegas modules up to 3 m2 in size, will be produced in different sites spread across Europe, targetting for an installation at the end of the Long Shutdown 2 of the LHC. One of the first series modules, equipped with a prototype of the final front-end electronics based on the VMM chip, was tested in a muon/pion beam at the H8 beam line of SPS at CERN during the summer of 2018. We present the test setup and performance results, namely effciency and resolution, for perpendicular and inclined tracks. These studies were focused on determining the high voltage working point of the ATLAS Micromegas detectors. Studies with several gas mixtures were also carried out and will be presented.

A modular mini-pad photon detector prototype for RICH application at the Electron Ion Collider

Experiments at the future Electron Ion Collider require excellent hadron identification in a broad momentum range, in harsh conditions. A RICH capable to fulfill the PID requirements of the EIC could use MPGD-based photon detectors with solid photocathodes for covering large surfaces at affordable cost, providing good effciency, high resolution and compatibility with magnetic field. Photon detectors realized by coupling THGEMs and Micromegas have been successfully operated at the RICH-1 detector of the COMPASS Experiment at CERN since 2016. A similar technology could be envisaged for an EIC RICH, provided a large improvement in the photon position resolution is achieved. An R&D effort in this direction is ongoing at INFN Trieste. Few prototypes with smaller pixel size (down to 3 mm x 3 mm) have been built and tested in the laboratory with X-Ray and UV LED light sources. A modular mini-pad detector prototype has also been tested at the CERN SPS H4 beamline. New data acquisition and analysis software called Raven DAQ and Raven Decoder have been developed and used with the APV-25 based Scalable Readout System (SRS), for the modular mini-pad prototype tests.The main characteristics of the new mini-pad hybrid MPGD-based detector of single photons are described and preliminary results of laboratory and beam tests are presented.

Development of a new Front End electronics in Silicon and Silicon-Germanium technology for the Resistive Plate Chamber detector for high rate experiments

The upgrade of the Resistive Plate Chamber (RPC) detector, in order to increase the detector rate capability and to be able to work efficiently in high rate environment, consists in the reduction of the operating voltage along with the detection of signals which are few hundred μV small. The approach chosen by this project to achieve this objective is to develop a new kind of Front End electronics which, thanks to a mixed technology in Silicon and Silicon-Germanium, enhance the detector performances increasing its rate capability. The Front End developed is composed by a preamplifier in Silicon BJT technology with a very low inner noise (1000 e− rms) and an amplification factor of 0.3–0.4 mV/fC and a new kind of discriminator in SiGe HJT technology which allows a minimum threshold of the order of 0.5 mV. The performances of this kind of Front End will be shown. The results are obtained by using the CERN H8 beamline with a full-size RPC chamber of 1 mm gas gap and 1.2 mm thickness of electrodes equipped with this kind of Front End electronics.

Particle production, transport, and identification in the regime of 1−7 GeV/c

The recently constructed H4-VLE beam line, a tertiary extension branch of the existing H4 beam line in the CERN North Area, was commissioned in October 2018. The beam line was designed with the purpose of providing very low energy (VLE) hadrons and positrons to the NP-04 experiment, in the momentum range of $1--7\text{ }\mathrm{GeV}/c$. The production of these low-energy particles is achieved with a mixed hadron (pions, kaons, protons), $80\text{ }\text{ }\mathrm{GeV}/c$ secondary beam impinging on a thick target. The H4-VLE beam line has been instrumented with prototype scintillating fiber detectors providing the beam profile, intensity, and time-of-flight measurement of the beam particles, that, together with Cherenkov threshold counters, permit an event-by-event particle identification over the entire momentum spectrum. In this paper, we present detailed results of the beam line performance and the measured beam composition, as well as the comparison of these measurements with simulations performed during the design phase using fluka and geant-4-based Monte-Carlo codes.

Front-end readout electronics system of ProtoDUNE-SP LAr TPC

As a prototype of Deep Underground Neutrino Experiment far detector, ProtoDUNE single-phase Liquid Argon (LAr) Time Projection Chamber (TPC) sits in H4 beam line at CERN to characterize detector response. It consists of 6 full-size Anode Plane Assemblies (APAs) plus 18 Cathode Plane Assembly (CPA) modules to form two 3.6-m drift regions with a total of 15,360 readout channels. To achieve a good signal-to-noise ratio with this noble liquid detector (770ton LAr), cold electronics developed at BNL for extremely low temperature (77K–89K) operation is an optimal solution, which decouples the electrode and cryostat design from the readout design. With CMOS front end ASICs integrated with the TPC electrodes, the electronic noise is independent of the fiducial volume and much lower than with readout electronics at room temperature. In addition, signal digitization and multiplexing to high-speed links inside the cryostat result in large reduction in the quantity of cables and the number of cryostat penetrations, giving the designers of both the TPC and the cryostat the freedom to choose the optimum configurations. By April 2018, we have successfully instrumented 6 APAs with cold electronics, and the results of the integration test before the final installation in the cryostat look very promising.

Development of FELIX based readout system for HV-CMOS sensor testbeam

The High Voltage CMOS (HV-CMOS) sensors are extensively investigated by the ATLAS collaboration for the High-Luminosity LHC (HL-LHC) upgrade of the Inner Tracker (ITk) detector. The HV-CMOS technology is a commercial integrated circuit process with the advantages of monolithic readout and fast charge collection. A front-end test platform of CaRIBOu (Control and Readout Itk BOard) and a testbeam Telescope based on the ATLAS IBL (Insertable B-Layer) silicon pixel modules, have been developed for the HV-CMOS sensor study and characterization in testbeam experiments. The Front-End LInk eXchange (FELIX) system is a new approach to function as the gateway between detector front-end electronics and the commodity switched network in the ATLAS upgrade. A FELIX based readout system has been developed for both the CaRIBOu and the testbeam Telescope. It has been deployed successfully in the testbeam at the CERN SPS H8 beamline in August 2017. The test results show that the readout system is capable of sensor calibration and readout of a high-density pixel detector with high trigger rate in testbeam experiments.

Test beam measurement of ams H35 HV-CMOS capacitively coupled pixel sensor prototypes with high-resistivity substrate

In the context of the studies of the ATLAS High Luminosity LHC programme, radiation tolerant pixel detectors in CMOS technologies are investigated. To evaluate the effects of substrate resistivity on CMOS sensor performance, the H35DEMO demonstrator, containing different diode and amplifier designs, was produced in ams H35 HV-CMOS technology using four different substrate resistivities spanning from 80-1000 ohm cm-1. A glueing process using a high-precision flip-chip machine was developed in order to capacitively couple the sensors to FE-I4 Readout ASIC using a thin layer of epoxy glue with good uniformity over a large surface. The resulting assemblies were measured in beam test at the Fermilab Test Beam Facilities with 120 GeV protons and CERN SPS H8 beamline using 180 GeV pions. The in-time efficiency and tracking properties measured for the different sensor types are shown to be compatible with the ATLAS ITk requirements for its pixel sensors.