Chamber Detector Research Articles

Mass reconstruction of heavy neutral leptons from stopped mesons

Heavy neutral leptons (HNLs), depending on their mass and mixing, can be efficiently produced in meson decays from the target or absorber in short- to medium-baseline accelerator neutrino experiments, leaving detectable signals through their decays inside the neutrino detectors. We show that the currently running ICARUS experiment at Fermilab can reconstruct the HNL mass and explore new HNL parameter space in the mass range of 70–190 MeV. The mass reconstruction is enabled by two ingredients: (i) simple two-body kinematics of HNL production from stopped kaon decays at the NuMI absorber, followed by HNL decay into a charged-lepton pair and neutrino at the detector, and (ii) high resolution of Liquid Argon Time Projection Chamber (LArTPC) detectors in reconstructing final state particles. Our mass reconstruction method is robust under realistic energy resolution and angular smearing of the charged leptons, and is applicable to any LArTPC detector. We also discuss the synergy between ICARUS and future facilities like DUNE near detector and PIP-II beam dump in probing the HNL parameter space. Published by the American Physical Society 2025

SPHENIX Highlights: First Results from sPHENIX at RHIC

First results from the sPHENIX experiment on the π0 v2 and dET =dη in Au+Au collisions at √sNN = 200 GeV using detector commissioning data during the RHIC 2023 Run are presented. These results are shown across a large centrality range, and compared to previous PHENIX and STAR results. These measurements demonstrate the sPHENIX capabilities towards accomplishing the sPHENIX jet physics program. From the ongoing RHIC 2024 Run, p + p collisions at √s = 200 GeV, a first glimpse of the measurements KS0 and Λ0 obtained by the sPHENIX Time Projection Chamber (TPC) detector are shown.

(Invited) Development of Bipolar Electrochemical Microscopy for High-Speed and High-Resolution Monitoring of Biochemical Phenomena

Closed bipolar electrochemistry (cBPE) involves simultaneous oxidation and reduction at opposite poles of a conductor in two separated solutions. (Figure left). The unique property of cBPE to be operated without direct connection to an external power source is expected to lead to higher resolution in electrochemical imaging than the conventional microelectrode array type imaging platforms. We have applied cBPE to an electrochemical microscopy (BEM) (Figure right) for high-resolution biochemical imaging.1- 7 The operation principle of BEM has been successfully verified,1 then the current focus is on fabrication method of cBPE array. Previously, we filled Au into pores of a polyethylene terephthalate track-etched membrane having D=8 µm pores by electroless plating using 50 mM HAuCl4 aqueous solution and 50 mM NaBH4 EtOH solution.2 Using this cBPE array, an image of oxygen concentration distribution around cell spheroids was successfully obtained, but this method has a problem of the inability to completely fill the pores with gold, resulting in large ionic currents. In this study, we use conductive pastes for fabrication of vertical closed bipolar electrode array to completely fill the pores with conductive materials.Epoxy-based carbon paste (ECP) was prepared by mixing acetylene carbon black (ACB; particle size=42 nm; Strem Chemicals) and epoxy resin (mixture of Epok 812 (62 mL), DDSA (100 mL), and DMP-30 (1.5%); Okenshoji). Oil-based carbon paste (OCP) was prepared by mixing the ACB and the liquid paraffin. For Au paste (AuP), commercially available AURoFUSE (particle size (D50) 0.2–0.4 µm; Tanaka Kikinzoku Kogyo) was used as is. Vertical cBPE arrays using the carbon paste filled in pores of a glass capillary plate was fabricated by filling ECP (ACB: epoxy resin=1:4 in weight ratio) cured at 60°C for 15 h. After cooling, the surface was coated by OCP (ACB: liquid paraffin=1:1 in weight ratio) to fill the dented parts shrank by heat curing. For [Fe(CN)6]3 − imaging, a sample side of the array was modified with reduced graphene oxide (RGO) by coating OCP containing 5 wt.% RGO (RGO-OCP). For H2O2 imaging, a sample side of the array was modified with Prussian blue (PB) by coating commercially available PB containing carbon paste (Carbon Mediator Paste, C2070424P2; SunChemical Gwent). The BEM system was constructed using two solution chambers (detection/sample chambers), BPE array, and driving electrodes. The detection chamber located at the bottom side of the BPE array was filled with 10 mM [Ru(bpy)3] Cl2/20 mM tripropylamine (TPA) solution containing phosphate buffered saline (PBS). The sample chamber located at the bottom side was filled with the sample solution for each measurement. A platinum driving electrode inserted into the detection chamber, another platinum driving electrode and a Ag/AgCl reference electrode inserted into the sample chamber were connected WE, CE and RE connector of a potentiostat, respectively. The entire system was mounted on an inverted microscope with a high sensitivity CCD camera to observe the electrochemiluminescence (ECL) generated at the underside of the BPEs.By using RGO and PB modified carbon paste (PC) cBPE array for BEM element, we successfully obtained an image of 5 mM [Fe(CN)6]3− and H2O2 inflow, respectively.5 These results show that cBPE arrays for BEM can be fabricated by filling micropores with carbon paste taking advantage of the flexibility and ease of modification of the paste electrode. We are now investigating the use of AuP as an electrode material of cBPE array. We have obtained the result that ECL can be enhanced by using AuP as an electrode material.7 This may be due to the surface plasmon enhancement effect by the Au particles contained in the AuP. The establishment of a simple method for fabricating vertical cBPE arrays without ion leakage is expected to further accelerate the research and development of BEM.

Improving neutrino energy estimation of charged-current interaction events with recurrent neural networks in MicroBooNE

We present a deep learning-based method for estimating the neutrino energy of charged-current neutrino-argon interactions. We employ a recurrent neural network (RNN) architecture for neutrino energy estimation in the MicroBooNE experiment, utilizing liquid argon time projection chamber (LArTPC) detector technology. Traditional energy estimation approaches in LArTPCs, which largely rely on reconstructing and summing visible energies, often experience sizable biases and resolution smearing because of the complex nature of neutrino interactions and the detector response. The estimation of neutrino energy can be improved after considering the kinematics information of reconstructed final-state particles. Utilizing kinematic information of reconstructed particles, the deep learning-based approach shows improved resolution and reduced bias for the muon neutrino Monte Carlo simulation sample compared to the traditional approach. In order to address the common concern about the effectiveness of this method on experimental data, the RNN-based energy estimator is further examined and validated with dedicated data-simulation consistency tests using MicroBooNE data. We also assess its potential impact on a neutrino oscillation study after accounting for all statistical and systematic uncertainties and show that it enhances physics sensitivity. This method has good potential to improve the performance of other physics analyses. Published by the American Physical Society 2024

Development of an online cloud fog monitor: Design, laboratory, and field deployment at an unoccupied coastal site in Eastern China

Online detection of cloud water chemistry is a pressing issue in atmospheric outfield observation, with online detection modules representing a significant development direction for cloud water observation. Addressing the common problem of time-delayed errors in manual detection, particularly in the context of cloud water acidity, has remained challenging, with limited understanding and effective solutions available. We developed an Online Cloud Fog Monitor (OCFM) featuring automatic pH and electrical conductivity (EC) detection capabilities, and conducted comprehensive laboratory and field tests. The OCFM utilizes a peristaltic pump, water pipe, and diversion chamber to direct cloud samples to distinct detection chambers, enabling real-time analysis. The diversion chamber is equipped with dual liquid level sensors to segregate and preserve samples once the volume exceeds a predetermined threshold. Calibration results indicate that the instrument's background metal elements do not affect cloud water analysis, and detection occurs within the designed response time. Field tests demonstrate that the OCFM can collect over 50 ml of cloud water, with a response accuracy exceeding 63.6%, though influenced by meteorological conditions. The time-delay error for pH was notably larger than for EC. Comparative analysis with the Caltech Active Strand Cloudwater Collector (CASCC) revealed that the OCFM's sampling process does not introduce errors, and the online detection accuracy of pH and EC is comparable to manual methods. Additionally, water-soluble ions in samples collected by the OCFM showed no significant differences compared to those collected by CASCC. Overall, the OCFM effectively replaces manual testing, mitigating time-delay errors in chemical property testing. The introduction of this cloud water detector promises to significantly reduce labor costs and economic consumption associated with cloud water observation, thereby facilitating long-term, multi-site observation of cloud water chemistry.

Magnetic field influence on electron transport in planned GEM-based radiated power diagnostic for DEMO

This work relates to development of diagnostics for radiation power (Prad) and soft x-ray (SXR) intensity measurements in DEMO. A modular, multi-chamber, multi-channel SXR detection system based on gas electron multiplier technology in lateral configuration is currently in conceptual design phase. The high magnetic fields expected at the planned detector positions in the diagnostic ports of the tokamak must be considered in the design. The present study examines two contributions of its influence. The first one pertained to the electric field drifts of thermalized electrons. These were found to be significant, but mostly linear and mitigatable. The second contribution pertained to the impact of magnetic fields on the initial photoelectrons. This was particularly effective in the second detector chamber, which had been optimized for higher photon energies. The size and shape of the electron cloud in a working gas mixture created by primary ionizations have been evaluated as a function of x-ray energy, magnetic field strength, and angle. Moreover, a more direct analysis concerning the loss of electrons in the second chamber has been performed. In this context, the magnetic field was found to have a slightly beneficial effect on the operation of the detector, as it limited the range of ionization perpendicular to its direction and decreased the probability of a primary electron leaving the drift region. Potential design changes resulting from these findings were discussed.

Deep learning assisted, smartphone based universal Multi-RPA-CRISPR/Cas12a-G4 portable chip for simultaneous detection of CaMV35S and NOS

Portable and fast genetically modified organisms (GMOs) detection can achieve accurate labeling and precise regulation. Here, we build a universal and intelligent Multi-RPA-CRISPR/Cas12a-G4 detection chip platform for simultaneous CaMV35S and NOS detection. The use of multiple primer pairs for RPA enables one-tube amplification of dual targets. Independent cleavage of Cas12a for dual targets was controlled by flow amplification products into the respective detection chambers containing CaMV35S crRNA and NOS crRNA. The detection results are obtained based that uncut G4 in solution can produce peroxidase activity to catalyze ABTS2− making the negative result approaching dark green. The multi-RPA-CRISRP/Cas12a-G4 colorimetric platform achieves a 1 aM LOD for CaMV35S and NOS in 55 min. The Yolov5 deep learning algorithm and the analysis of gray values was trained and developed for colorimetric detection that is more sensitive than the naked eye. These algorithms are integrated into a smartphone app to automate the reading of test results. The 100% accuracy of colorimetry detection and the 93.3% accuracy of portable chip detection for rice and soy sauce samples demonstrate our method can rapidly and inexpensively detect samples of GMOs across species. Overall, our efficient, low-cost portable Multi-RPA-CRISPR/Cas12a-G4 detection platform coupled with deep learning algorithms enables portable GMOs detection with automated signal readout.

Unpaired Image Translation to Mitigate Domain Shift in Liquid Argon Time Projection Chamber Detector Responses

Abstract Deep learning algorithms often are developed and trained on a training dataset and deployed on test datasets. Any systematic difference between the training and a test dataset may severely degrade the final algorithm performance on the test dataset -- what is known as the domain shift problem. This issue is prevalent in many scientific domains where algorithms are trained on simulated data but applied to real-world datasets. Typically, the domain shift problem is solved through various domain adaptation methods. However, these methods are often tailored to a specific downstream task and may not easily generalize to different tasks. This work explores the feasibility of using an alternative way to solve the domain shift problem that is not specific to any downstream algorithm. The proposed approach relies on modern Unpaired Image-to-Image translation techniques, designed to find translations between different image domains in a fully unsupervised fashion. In this study, the approach is applied to a domain shift problem commonly encountered in Liquid Argon Time Projection Chamber detector research when seeking a way to translate samples between two differently distributed LArTPC detector datasets deterministically. This translation allows for mapping real-world data into the simulated data domain where the downstream algorithms can be run with much less domain-shift-related performance degradation. Conversely, using the translation from the simulated data in a real-world domain can increase the realism of the simulated dataset and reduce the magnitude of any systematic uncertainties. We adapted several popular UI2I translation algorithms to work on scientific data and demonstrated the viability of these techniques for solving the domain shift problem with LArTPC detector data. To facilitate further development of domain adaptation techniques for scientific datasets, the "Simple Liquid-Argon Track Samples" (SLATS) dataset used in this study also is published.

Detector upgrade for 222Rn concentration in high purity nitrogen measurement

To ensure the low background of the Jiangmen Underground Neutrino Observatory (JUNO) detector, high purity nitrogen (HPN) is used as a cover gas in direct contact with the liquid scintillator, which serves as the target material for neutrinos. The radon concentration in this nitrogen should be less than 10 μBq/m3. Given the background of the old detector, which is 2.20 ± 0.64 mBq/m3, combined with its enrichment efficiency of 51.0 % at a flow rate of 25 standard liters per minute (SLM), the effective measurement of radon concentrations below 10 μBq/m3 in HPN is a major challenge. A highly sensitive radon detector was upgraded to measure the radon concentration in HPN. A low background radon detection chamber was constructed based on the method of electrostatic collection and electrolytic polishing of low background steel with an internal surface roughness of ≤ 0.2 μm. The background of the radon detection chamber was reduced to 1.47 ± 0.19 mBq/m3. An automatic enrichment system based on 472 g low background activated carbon was developed. The introduction of a large amount of activated carbon has led to a significant increase in the enrichment flow rate to 200 SLM. In addition, the enrichment efficiency of the system simultaneously improved to 71 %. The relationship between the collection efficiency of the detection chamber and the applied voltage was calibrated. The result measured with this detector, shows that the radon concentration in HPN is 2.38 ± 0.30 μBq/m3.

Decay study of Be11 with an optical time-projection chamber

The β decay of one-neutron halo nucleus Be11 was investigated using the Warsaw Optical Time Projection Chamber (OTPC) detector to measure β-delayed charged particles. The results of two experiments are reported. In the first one, carried out in LNS Catania, the absolute branching ratio for β-delayed α emission was measured by counting incoming Be11 ions stopped in the detector and the observed decays with the emission of α particle. The result of 3.27(46)% is in good agreement with the literature value. In the second experiment, performed at the HIE-ISOLDE facility at CERN, bunches containing several hundreds of Be11 ions were implanted into the OTPC detector followed by the detection of decays with the emission of charged particles. The energy spectrum of β-delayed α particles was determined in the full energy range. It was analyzed in the R-matrix framework and was found to be consistent with the literature. The best description of the spectrum was obtained assuming that the two 3/2+ and one 1/2+ states in B11 are involved in the transition. The search for β-delayed emission of protons was undertaken. Only the upper limit for the branching ratio for this process of (2.2±0.6stat±0.6sys)×10−6 could be determined. This value is in conflict with the result published by Ayyad [] but does agree with the limit reported by Riisager []. Published by the American Physical Society 2024

Investigations on the dustiness of binary acetaminophen - lactose monohydrate powder blends

In this study, binary powder blends of acetaminophen (ACAM) and α-lactose monohydrate (LM) at different mixing ratios, with fine, medium-size, and coarse particles are investigated with a new two-chamber setup (TCS) to assess dustiness. The TCS consists of an emission and a detection chamber, allowing plain diffusive or convective particle transport. The aim is to compare the diffusive transport of ACAM with binary blends of ACAM and LM at different particle sizes and similar apparent density. Fine ACAM exhibits significantly higher dust emissions compared to medium and coarse ACAM. With increasing LM portion in the blends, ACAM dust emissions decrease. The blend of fine ACAM and coarse LM shows the highest dust emission, while the blend of coarse ACAM and fine LM reveals the lowest emissions. The TCS offers precise, reproducible measurements with good repeatability, making it beneficial for laboratory and industrial applications, even with small powder quantities.

ATLAS Level-0 Muon Barrel Trigger system status and integration tests for Phase-II

In preparation for the High-Luminosity Large Hadron Collider (HL-LHC), essential upgrades are underway for the ATLAS Level-0 Barrel Muon Trigger system in order to cope with the higher data rates and radiation level. These enhancements involve incorporating a new inner layer of Resistive Plate Chambers detectors (RPCs), and replacing the trigger and readout electronics, using a novel Data Collector and Transmitter (DCT) and new Sector Logic (SL) boards. DCT boards collect and process RPC data, while SL boards execute the trigger algorithm and transmit the muon candidates to the Central Trigger Processor.This paper presents the current status of the Phase-II Muon Barrel Level-0 Trigger system, focusing on the DCT and SL hardware and firmware developments. We detail the design and testing processes. Results from data communication tests and ongoing developments are also discussed.

Handheld microfluidic multiple detection device for concurrent blood urea nitrogen and creatinine ratio determination using colorimetric approach

A novel microfluidic multiple detection (MMD) platform consisting of a microfluidic chip and a self-built detection system is proposed for determining the creatinine (CRE) and blood urea nitrogen (BUN) concentrations in whole blood samples. In the proposed approach, a drop of whole blood is injected into the inlet of the microfluidic chip and filtered through strips of hemofiltration paper. The plasma enters the BUN and CRE detection chambers and is absorbed by pre-placed test strips embedded with analyte-specific reagents. Secondary reagents are then introduced into the detection chambers using a finger pump, and the chip is heated to induce Berthelot and Jaffe reactions. An image of the reaction compounds is captured by a CMOS camera and transmitted to a smartphone, where the BUN and CRE concentrations are derived from predetermined calibration curves using RGB analysis software. The proposed MMD platform is demonstrated by comparing the results obtained for 43 whole blood samples collected from patients with chronic kidney disease (CKD) and health volunteers with the measurements obtained using a traditional benchtop system. The results confirm that the proposed MMD platform offers a cost-effective, convenient, and rapid technique for BUN/CRE ratio (BCR) determination in point-of-care (POC) contexts.

Relative profile measurements in 1.5T MR-linacs: investigation of central axis deviations

Objective. In 1.5 T MR-linacs, the absorbed dose central axis (CAX) deviates from the beam's CAX due to inherent profile asymmetry. In addition, a measured CAX deviation may be biased due to potential lateral (to the beam) effective point of measurement (EPOML) shifts of the detector employed. By investigating CAX deviations, the scope of this study is to determine a set ofEPOMLshifts for profile measurements in 1.5 T MR-linacs.Approach. The Semiflex 3D ion chamber and microDiamond detector (PTW, Germany) were considered in the experimental study while three more detectors were included in the Monte Carlo (MC) study. CAX deviations in the crossline and inline profiles were calculated based on inflection points of the 10×10 cm2field, at five centers. In MC simulations, the experimental setup was reproduced. A small water voxel was simulated to calculate CAX deviation without the impact of the detector-specificEPOMLshift.Main results. All measurements were consistent among the five centers. MC-based and experimental measurements were in agreement within uncertainties. Placing the microDiamond in the vertical orientation does not appear to affect the detector'sEPOML, which is on its central longitudinal axis. For the Semiflex 3D in the crossline direction, the CAX deviation was 2.3 mm, i.e. 1 mm larger than the ones measured using the microDiamond and simulated considering the ideal water detector. Thus, anEPOMLshift of 1 mm is recommended for crossline profile measurements under both Semiflex 3D orientations. For the inline profile, anEPOMLshift of -0.5 mm was determined only for the parallel configuration. In the MC study, CAX deviations were found detector- and orientation-dependent. The dead volume is responsible for theEPOMLshift only in the inline profile and under the parallel orientation.Significance. This work contributes to data availability on the correction or mitigation of the magnetic field-induced changes in the detectors' response.

Versatile, reusable and highly sensitive SERS-based point-of-care testing microplatform for reliable ATP detection

The advancement in miniaturized Raman spectrometers, coupled with the single-molecule-level sensitivity and unique fingerprint identification capability of surface-enhanced Raman scattering (SERS), offers great potential for point-of-care testing (POCT). Despite this, accurately quantifying analyte molecules, particularly in complex samples with limited sample volumes, remains difficult. Herein, we present a versatile and reusable SERS microplatform for highly sensitive and reliable quantitative detection of adenosine triphosphate (ATP) in biological fluids. The platform utilizes gold-Prussian blue core-shell nanoparticles modified with polyethyleneimine (Au@PB@PEI NPs), embedded within gold nanoparticle-immobilized capillary-based silica monolithic materials. PB acts as an internal standard, while PEI enhances molecular capture. The periodic, bimodal porous structure of the silica monolithic materials provides uniform and abundant sites for nanoparticle attachment, facilitating rapid liquid permeation, intense SERS enhancement, and efficient enrichment. The platform regulates ATP capture and release through magnesium ions in the liquid phase, eliminating matrix interferences and enabling platform reuse. Integrating efficient molecular enrichment, separation, an interference-free internal standard, a liquid flow channel, and a detection chamber, our platform offers simplicity in operation, exceptional sensitivity and accuracy, and rapid analysis (∼10 min). Employing PB as an internal calibration standard, ratiometric Raman signals (I732/I2123) facilitate precise ATP quantification, achieving a remarkable limit of detection down to 0.62 pM. Furthermore, this platform has been proven to be highly reproducible and validated for ATP quantification in both mouse cerebrospinal fluid and human serum, underscoring its immense potential for POCT applications.

Towards more eco-friendly gaseous detectors

In the last years, the particle detector community faced a new challenge: how to convert existing and future gaseous detectors in more eco-friendly ones. Indeed, several detectors make use of greenhouse gases (GHGs) since they allow achieving excellent performance and long-term stability. With a growing concern on climate change and future restrictions, it is fundamental to look for solutions that can balance detector performance with an eco-friendly approach. CERN was a pioneer in developing strategies to reduce the use of GHGs in particle detection. Three different strategies have been implemented: the use of gas recirculation and recuperation systems for existing and future detector systems and the search of alternative eco-friendly gas mixtures. Thanks to the first two approaches, it is possible to recycle the gas mixture supplied to the detectors and to retrieve GHGs from the used gas mixtures, allowing a reduction of GHG emissions up to 95%–100% at the LHC experiments. By looking at the long-term operation and future particle detector applications, the search of alternative eco-friendly gas mixtures must be envisaged. A big effort is on-going for the C2H2F4 replacement for the Resistive Plate Chamber (RPC) detectors, which nowadays account for most of CERN particle detector emissions. Several eco-friendly gas mixtures have been identified and tested but finding a suitable replacement for the LHC experiments is particularly challenging. Alternatives to SF6, which is the most powerful GHG, are under studies for RPCs in term of detector performance and chemical characterisation. Last point is increasingly crucial since most of the so-called eco-friendly gases belong to the PFAS family which is very likely to be subject to new regulations soon.

Evaluation of radiation leakage in X-ray security inspection machine using a CZT spectrometer

Leakage radiation from X-ray security inspection machines is important, and measurement based on ionization chamber or scintillator detector is widely used. The leakage radiation is closely related to the size and the passing time of the luggage, the lead equivalent, the opening angle of the lead curtain, and the response time of the measuring instrument. To characterize the distribution of leakage radiation from the X-ray security inspection machine accurately, a small-volume CZT(CdZnTe) spectrometer was used to measure the energy spectra at a distance of 5 cm from the surface of the inspection machine. By designing and controlling the opening angle of the lead curtain according to the size of the luggage passing through the entrance and exit, the radiation dose was determined based on the measured energy spectra combined with the G(E)-function method. The results show that the maximum relative deviation between the air kerma rate and the ambient dose equivalent rate calculated by the G(E) function method with the standard dose rate does not exceed ±5%. The maximum relative deviation of the dose rate linear verification in the 137Cs radiation field is less than 2.5%. A calibrated CZT detector was utilized to measure the radiation leakage on the surface of the X-ray security inspection machine. It was discovered that the presence of the luggage items and the opening angle of the lead curtain will increase the leakage radiation dose on the surface of the security inspection machine system. This study provides a new approach for measuring scattered radiation of X-ray security inspection machines.

The ATLAS RPC Phase-II upgrade for High Luminosity LHC era

Resistive Plate Chambers (RPC) detectors play a crucial role in triggering events containing muons in the central region of ATLAS. In view of the High Luminosity-LHC program, the existing RPC system, consisting of six independent cylindrical detector layers each providing a full space time localization of hits, is currently undergoing a significant upgrade. In the next few years, 306 triplets of new generation RPCs will be installed in the innermost region of the ATLAS Muon Barrel Spectrometer, increasing from 6 to 9 the number of tracking layers, doubling the trigger lever arm. This allows a substantial enhancement of the present trigger redundancy, increasing the coverage from 76% to approximately 96%. Fitting new chambers in the narrow space left in ATLAS inner barrel was a challenge, achieved by optimizing RPC materials and thickness, featuring a 1 mm gas gap (instead of 2 mm), and 1.4 mm resistive electrodes (instead of 1.8 mm) while reaching an high rate capability. To achieve such results, a 100 ps precise Time-to-Digital Converter (TDC) has been integrated in the front-end electronics ASIC. The expected time resolution of a single 1 mm RPC gas gap is approximately 300 ps, and the possibility of a stand-alone Time of Flight measurement will have a huge impact on ATLAS searches for massive long-lived particles. An overview and the present status of the ATLAS RPC Phase-II project will be presented.

E-ΔE detection module of DGFRS-2 setup

Thе paper describes a new E-ΔE detection module which includes a position-sensitive double-sided strip detector (DSSD) and a low-pressure pentane-filled ΔE chamber for detection of Evaporation Residues (ERs) in complete fusion reactions. The goal is to synthesize superheavy isotopes at the new DC-280 (Dubna Cyclotron) cyclotron of the Joint Institute for Nuclear Research (JINR). With the 48Ca ion beam intensity of about 5–7 pμA (particle micro ampere) and the ΔE counter count rate of approximately 104 sec−1, we observe a decrease in the overall registration efficiency of the gas ΔE counter. The paper proposes a solution to this problem: introduction of an additional negatively biased electrode, which results in the stabilization of the ΔE detector operation.

First application of a liquid argon time projection chamber for the search for intranuclear neutron-antineutron transitions and annihilation in 40Ar using the MicroBooNE detector

We present a novel methodology to search for intranuclear neutron-antineutron transition (n⟶n̅) followed by n̅-nucleon annihilation within an 40Ar nucleus, using the MicroBooNE liquid argon time projection chamber (LArTPC) detector. A discovery of n⟶n̅ transition or a new best limit on the lifetime of this process would either constitute physics beyond the Standard Model or greatly constrain theories of baryogenesis, respectively. The approach presented in this paper makes use of deep learning methods to select n⟶n̅ events based on their unique features and differentiate them from cosmogenic backgrounds. The achieved signal and background efficiencies are (70.22 ± 6.04)% and (0.0020 ± 0.0003)%, respectively. A demonstration of a search is performed with a data set corresponding to an exposure of 3.32 ×1026 neutron-years, and where the background rate is constrained through direct measurement, assuming the presence of a negligible signal. With this approach, no excess of events over the background prediction is observed, setting a demonstrative lower bound on the n⟶n̅ lifetime in 40Ar of τm ≳ 1.1×1026 years, and on the free n⟶n̅ transition time of τn⟶n̅ ≳ 2.6×105 s, each at the 90% confidence level. This analysis represents a first-ever proof-of-principle demonstration of the ability to search for this rare process in LArTPCs with high efficiency and low background.