Recently, the possibility of LPA-produced muon beams has gained significant interest within the accelerator application community. Directional, multi-GeV muons can be produced via Bethe-Heitler interactions when multi-GeV electrons hit solid targets. They are highly penetrating and, thanks to the compactness of the LPA, offer a path toward a deployable, active muon source. At the BELLA Center of the Lawrence Berkeley National Laboratory, we previously unambiguously detected muons generated during the interaction of multi-GeV electron beams with a 4 meter-thick electron beam dump. A new campaign has now extended our diagnostic capabilities to single-muon trajectory reconstruction and energy measurements. The setup allowed us to individually reconstruct each muon trajectory, defined by us as a muon passing through three detectors used for the reconstruction. For a subset of events, we extracted the muon energy from the magnetic-field bending angle, demonstrating production of GeV-scale muons. This work provides a key demonstration of track-based active-source muography, which enables non-invasive 3D density mapping of concealed or inaccessible samples, and it will accelerate the development of active LPA-based muon sources where compactness, controlled directionality, low divergence, and deep penetration are required.

The next generation of particle physics experiments will face a new era of challenges in data acquisition, due to unprecedented data rates and volumes along with extreme environments and operational constraints. Harnessing this data for scientific discovery demands real-time inference and decision-making, intelligent data reduction, and efficient processing architectures beyond current capabilities. Crucial to the success of this experimental paradigm are several emerging technologies, such as artificial intelligence and machine learning (AI/ML), silicon microelectronics, and the advent of quantum algorithms and processing. Their intersection includes areas of research such as low-power and low-latency devices for edge computing, heterogeneous accelerator systems, reconfigurable hardware, novel codesign and synthesis strategies, readout for cryogenic or high-radiation environments, and analog computing. This white paper presents a community-driven vision to identify and prioritize research and development opportunities in hardware-based ML systems and corresponding physics applications, contributing towards a successful transition to the new data frontier of fundamental science.

We present the detection of directional muon beams produced using a PW laser facility at the Lawrence Berkeley National Laboratory. The muon source is a multi-GeV electron beam generated in a 30 cm laserplasma accelerator interacting with a high-Z converter target. The GeV photons resulting from the interaction are converted into a high-flux, directional muon beam via pair production. By employing scintillators to capture delayed events, we were able to identify the produced muons and characterize the source. Using theoretical knowledge of the muon production process combined with simulations that are in excellent agreement with the experiments, we demonstrate that laser-plasma accelerators have the capability of generating electron beams with characteristics suitable to produce GeV-scale muons that offer unique advantages with respect to the cosmic background. Laser-plasma-accelerator-based muon sources can therefore enhance muon imaging applications thanks to their compactness, directionality, and high yields, which reduce the exposure time by orders of magnitude compared to cosmic ray muons. Using the Geant4-based simulation code we developed to gain insight into the experimental results, we can design future experiments and applications based on LPA-generated muons.

The ITkPixV2 chip is the final production readout chip for the ATLAS Phase 2 Inner Tracker (ITk) upgrade at the upcoming High-Luminosity LHC (HL-LHC). Due to the extraordinarily high peak luminosity at the HL-LHC of 5 × 10 34 cm -1 s -1 , ITkPixV2 must meet significant increases in nearly all design requirements compared to the current ATLAS Inner Detector (ID), including a 10× increase in trigger rate, a 7.5× increase in hit rate, a 3× increase in radiation tolerance, and a 12.5× decrease in pixel current draw per unit area, all while maintaining a similar power per unit area as present pixel detectors. Here we present the first measurements of the ITkPixV2 chip operated at the limits of the full chip design requirements, including in particular a measurement of the activity-induced current of the chip as a function of increasing hit rate.

Precision timing is a key requirement for emerging 4D particle tracking, Positron Emission Tomography (PET), beam and fusion plasma diagnostics, and other systems. Time-to-Digital Converters (TDCs) are commonly used to provide digital estimates of the relative timing between events, but the jitter performance of a TDC can be no better than the performance of the circuits that acquire the pulses and deliver them to the TDC. Several clock receiver and distribution circuits were evaluated, and a differential amplifier with resistive loads driving a pseudo-differential clock distribution network, developed using design guidelines for radiation tolerance and cryogenic compatibility, was fabricated as part of three prototypes: an analog front-end testbed chip for high-precision timing pixel readout, a dedicated TDC evaluation chip, and a Low-Gain Avalanche Detector (LGAD) readout circuit. Based on TDC measurements of the prototypes, we infer that the jitter added by the clock receiver and distribution circuits is less than 2.25 ps-rms. This performance meets the requirements of many future precision timing systems. The clock receiver and on-chip pseudo-differential driver were fabricated in commercial 28-nm CMOS technology and occupy 2288 µm2.

The ATLAS inner detector will be completely replaced to cope with the increased occupancy and radiation damage that will be posed by the High Luminosity phase of the Large Hadron Collider. The new all-silicon Inner Tracker will consist of pixel sensors in the innermost part. They will be realized using different silicon sensor technologies and will be read out with ITkPixV2 ASICs. Their connection is realized by bump bonding. n-in-p planar hybrid modules 100 µm and 150 µm thick will instrument the four outer layers of the pixel detector. Due to their radiation hardness, 3D sensors will be installed in the innermost layer, where a fluence up to 2.0 × 10 16 n eq /cm 2 is expected. Their production is distributed among different vendors, and the pre-production sensors from each vendor are progressively being tested before and after irradiation with test beams. The most recent results will be presented here.

Amorphous Selenium (a-Se) has been extensively studied as a direct conversion detector material for x-ray imaging, and can be readily deposited as uniform layer by thermal evaporation. On the other hand, readout ASICs developed for high-energy physics experiments provide front-end electronics with low noise, high granularity and fast charge readout. Thin film technology to enable large-area, low-cost precision tracking is in turn also of interest to the HEP community. In our initial study presented at SPIE 2023, we verified the fabrication process of the a-Se layer for integration on a CMOS ASIC using the RD53B (ITkpix v.1.0) chip. The hybrid detector concept consists of the pixelated readout ASIC with 50x50 mu m pixel pitch, a polyimide hole-blocking layer, the active a-Se layer with 15-100 mu m thickness, and a gold top electrode layer. In this work, we now present the evaluation of the a-Se detector with an advanced version of the chip, RD53C or ATLAS ITkpix v.2, which provides full time-over-threshold control and functionality and allows operation in self-triggered hit counting mode. We demonstrate the detection of low-energy beta electrons as well as x-rays of energies between 20 and 50 keV with this a-Se/ITkpixv2 assembly. We study the impact of the operation bias voltage of the a-Se layer on the hit rate and signal charge as represented through the time-over-threshold. The charge collection efficiency of the a-Se, as expected, strongly depends on the electric field applied across the layer. This manifests as both higher hit rates when more interactions pass the trigger threshold, as well as increased ToT for larger amounts of collected charge. As this ASIC was originally designed for hybrid silicon pixel detector readout, some operation parameters of the front-end preamplifier circuit were adjusted in data acquisition for more efficient readout of the small charges provided by the thin a-Se layer.

To be ready for the challenging conditions of the High Luminosity phase of the LHC accelerator at CERN, the ATLAS Inner Detector will be completely replaced with a new all-silicon Inner Tracker, the ITk. Sensors in the innermost layer will be exposed to a fluence up to 1.9$\cdot$10$^{16}$~n$_{eq}$/cm$^2$ (considering a safety factor of 1.5) at the half of the HL-LHC program, after which it is scheduled to be replaced together will the full innermost system. Pixel sensors with 3D technology have been chosen to instrument it due to their radiation hardness. Sensors with 25x100~$\mu$m$^2$ pixel pitch will be used in the central region of the innermost layer (barrel) while sensors with a pitch of 50x50~$\mu$m$^2$ will instrument its two side regions (end-caps). The Fondazione Bruno Kessler (FBK) has been chosen as one of the two vendors for the production of these sensors. This paper will present the performance of 3D pre-production sensors with both pixel pitches produced by FBK measured in test beams with devices irradiated up to and beyond the sensor end-of-life fluence.

In this study, we powered in series 4 triplets based on the pre-production ATLAS FE chip for HL-LHC. We ensured that the chosen operational parameters were within our theoretical specs and resulted in the stable operation of the modules within the serial power chain. Triplets were also powered in Low Power mode (LP), used to operate the module at a lower current, and their performance was tested without cooling requirements. The performance of the under-shunt and over-voltage protection were also analyzed.

This contribution presents test beam results of SINTEF 3D pixel sensors designed for the Inner Tracker (ITk) of the ATLAS detector at the High Luminosity LHC (HL-LHC). The sensors are required to withstand extreme radiation doses and to maintain efficiency above 96-97% after a lifetime operation at the ITk. We present details on the production and design of these sensors, the setup for the experiment at CERN, and the analysis of the test beam data. Results are promising, showing excellent position resolution and high efficiency after irradiation. The sensors meet the operational efficiency targets for both perpendicular and tilted configurations, validating their design and performance for future HL-LHC operations.

The ATLAS Inner Tracker (ITk) upgrade for the High-Luminosity LHC (HL-LHC) requires a radiation-tolerant pixel readout chip, which must withstand a total ionising dose (TID) of up to 1 Grad. The readout ASIC for the ITk upgrade has been designed by the RD53 collaboration using 65 nm CMOS technology. In order to characterise the radiation tolerance of the chip digital logic, the RD53 ASICs include ring oscillators, which can be used to measure gate delay degradation. Extensive X-ray irradiation studies of the ring oscillators have been performed on the ITk Pixel pre-production readout ASIC, ITkPixV1. A dependence of radiation damage on dose rate has been observed in 65 nm CMOS technology. This paper aims to quantify the dose rate dependence of TID damage to the ITkPix ring oscillators and, therefore, the ITkPix ASIC digital logic. X-ray irradiations at different dose rates between 20 krad/h and 30 Mrad/h are compared. A dose rate dependence is observed, with 2-3 times more damage at the lowest dose rate of 20 krad/h, compared to 4 Mrad/h. The dose rate dependence was also observed to be dependent on transistor size and type.

An initial characterization of the BigRock high-speed, low -power Analog Front End (AFE) is presented. The BigRock AFE previously described in [1] has been refined in a second generation testbed ASIC, Pebbles. The AFE utilizes a current -mode signal path that has been designed for 4D tracking applications with precision time resolution of order 50 ps. The preamplifier concept is based on a prior art current -feedback CMOS topology in [2]. An on -chip test bench comprised of a variable injection circuit and high -resolution TDC measures the AFE timing resolution. An array of integrated load capacitors and IO IPs enhance the characterization capability. These full -custom pads include LVDS and clock receivers, CML output driver, and simple analog buffer pads designed at the process core voltage (0.9 V) on a 90 mu m/180 mu m pitch. Critical noise and timing metrics for an array of input detector capacitance ranging 0 to 100 fF have been measured.

The ITk detector, the new ATLAS silicon tracking system for the High Luminosity LHC (HL-LHC), will be equipped with 3D pixel sensor modules in the innermost layer (L0).The pixel cell dimensions will be 25×100 µm 2 in the barrel and 50×50 µm 2 in the end-caps, with one readout electrode at the centre of each pixel and four bias electrodes at the corners.Sensors from pre-production wafers (50×50 µm 2 ) produced by FBK have been bump-bonded to ITkPixV1.1 chips at IZM. Bare modules have been assembled in Genoa on Single Chip Cards (SCCs) and characterized in laboratory measurements and in test beam campaigns.Some of these modules have been irradiated in Bonn and at the CERN IRRAD facility.Preliminary results of their characterization after irradiation are shown, including measurements performed during test beam campaigns at CERN SPS in Summer 2022.

In order to cope with increasing lifetime radiation damage expected at collider experiments, silicon sensors are becoming increasingly thin. To achieve adequate detection efficiency, the next generation of detectors may have to operate with thresholds below 1000 electron-hole pairs. The readout chips attached to these sensors should be calibrated to some known external charge, but there is a lack of traditional sources in this charge regime. We present a new method for absolute charge calibration based on Compton scattering. In the past, this method has been used for calibration of scintillators, but to our knowledge never for silicon detectors. Here it has been studied using a 150 micron thick planar silicon sensor on an RD53A readout integrated circuit.

The same charge sensitive preamplifier and discriminator circuit with different isolation strategies has been tested to compare the isolation of both analog and digital circuits from the substrate of a 65nm bulk CMOS process to the isolation of only digital circuits, tying analog ground locally to the substrate. This study will show that the circuit with analog on the substrate and digital in deep N-well has better noise isolation between analog and digital.

RD53A is a large scale 65 nm CMOS pixel demonstrator chip that has been developed by the RD53 collaboration for very high rate (3 GHz/cm$^2$) and very high radiation levels (500 Mrad, possibly 1 Grad) for ATLAS and CMS phase 2 upgrades. It features serial powering operation and design variations in the analog and digital pixel matrix for different testing purposes. The design and verification of RD53A are described together with an outline of the plans to develop final pixel chips for the two experiments.

A search is presented for the direct pair production of the stop, the supersymmetric partner of the top quark, that decays through an R-parity-violating coupling to a final state with two leptons and two jets, at least one of which is identified as a b-jet. The data set corresponds to an integrated luminosity of 36.1 fb(-1) of proton-proton collisions at a center-of-mass energy of root s = 13 TeV, collected in 2015 and 2016 by the ATLAS detector at the LHC. No significant excess is observed over the Standard Model background, and exclusion limits are set on stop pair production at a 95% confidence level. Lower limits on the stop mass are set between 600 GeV and 1.5 TeV for branching ratios above 10% for decays to an electron or muon and a b-quark.

A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb(-1) of proton-proton collision data at root s = 13 TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle Xis assumed to decay to a pair of light quarks, and the fully hadronic final state XH -> q (q) over bar 'b (b) over bar is analysed. The search considers the regime of high XH resonance masses, where the X and H bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of XH mass versus X mass is scanned for evidence of a signal, over a range of XH resonance mass values between 1 TeV and 4 TeV, and for X particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of XH and X masses, on the production cross-section of the XH -> q (q) over bar 'b (b) over bar resonance. (c) 2018 The Author(s). Published by Elsevier B.V.