Drift Tube Research Articles

Test result of the new ASD2 chips for Phase-II upgrade of the ATLAS MDT chambers at HL-LHC

For the Phase-II upgrade of the ATLAS Muon Spectrometer to High-Luminosity LHC, new front-end readout electronics for the Monitored Drift Tube chambers is required, as the old one no longer meets the demands. The first stage in the Monitored Drift Tubes readout chain is the Amplifier-Shaper-Discriminator chip. For the upgrade, the new ASD2 ASIC chip in IBM 130 nm CMOS technology has been developed. For the ATLAS experiment, 80000 ASD2 chips are produced, which have to be tested before integration in order to obtain the required 50000 well-performing chips in the end. Using a prototype tester board and pre-production ASD2 chips, the overall performance and the influence on programmable parameters is investigated. Based on these results, 1775 production chips are tested to define final optimized cut values for the automated production testing of all chips in the company.

The study and design of a deuteron drift tube linear accelerator for middle energy neutron source

The paper concerns a room-temperature cross-bar H-mode (CH) drift tube linac (DTL) with KONUS (Kombinierte Null Grad Struktur) [1,2] beam dynamics. To make the acceleration in DTL cell more efficient, we studied the correlation between transit time factor (TTF) and structural coefficients, first. Furthermore, we developed a new code with Python to demonstrate the longitudinal dynamics more clearly. The code computationally generates clusters, bunch centers, and emittance growth in a single figure. Thus, the stabilization region and cluster evolution at various negative phases can be studied. Based on the above studies, we designed a 162.5 MHz CH-DTL to accelerate 10 mA D+ from 2.11 MeV to 3.25 MeV in continuous-wave (CW) mode. The proposed CH-DTL is a part of the Middle Energy Neutron Source (MENS). The dynamics and RF design were iterated to make the gap voltage error lower than 1 %. The initial beam is assumed to come from a Radio Frequency Quadrupole accelerator (RFQ). The geometries of the CH-DTL are optimized by using CST. Multiparticle tracking from LEBT to RFQ is performed with TraceWin and the transmission efficiency in the CH-DTL is 100 %.

Design of the waveform distinction algorithm for the main drift chamber at the Super Tau-Charm facility

Drift chambers are essential in high-energy collider experiments for tracking the trajectory of charged particles. With the increase in peak luminosity, the detector's counting rate also rises, leading to challenges such as high beam backgrounds and an increased probability of signal pile-up in a single drift chamber channel. The Super Tau-Charm Facility (STCF) is a new electron-positron collider proposed by the Chinese particle physics community and the Main Drift Chamber (MDC) is the primary component of the STCF tracking system. The average hit rate of the innermost layer is 440 kHz with the cell size of 1 cm. This high count rate increases the pile-up probability of waveforms, making it difficult to achieve waveform discrimination even with optimized readout electronics performance. Modifying the cell size from approximately 1 cm to 5 mm is expected to decrease the innermost layer hit rate to approximately 210 kHz per channel. This paper presents a novel algorithm for waveform distinction using digital waveform data and integration curves. The algorithm is implemented on an evaluation board based on the Xilinx FPGA to achieve real-time waveform distinction. The algorithm's performance is validated through testing with the evaluation board. The test results indicate that the probability of distinction closely matches the theoretical value, the efficiency of the algorithm is about 96%, and the error probability is less than 4%. This result can serve as a reference for optimizing the MDC structure.

Ion-molecule collision cross-section calculations using trajectory parallelization in distributed systems

Ion Mobility coupled with Mass Spectrometry (IM-MS) stands as a strong analytical method for structurally characterizing complex molecules. In IM-MS, the sample under investigation is ionized and propelled by an electric field into a drift tube, which collides against a buffer gas. The separation of the ion gas phase is then measured through the differences in their rotationally averaged Collision Cross-Section (CCS) values. The effectiveness of the measured Collision Cross-Section (CCS) for structural characterization critically depends on the validation against theoretical calculations. This validation process relies on intensive molecular mechanics simulations, which can be computationally demanding, especially for large systems such as molecular assemblies and viruses. Therefore, reliable and fast CCS calculations are needed to help interpret IM-MS experimental data. This work presents the MassCCS software, which considerably increases the CCS simulation performance by implementing a linked-cell-based algorithm, incorporating High-Performance Computing (HPC) techniques. We performed extensive tests regarding the system size, shape, and number of CPU cores. Experimental results reveal speedups up to 3 orders of magnitude faster than Collision Simulator for Ion Mobility Spectrometry (CoSIMS) and High-Performance Collision Cross Section (HPCCS), optimized solutions for CCS simulations, for a single node execution. In addition, we extended MassCCS at the inter-node level by employing OpenMP Cluster (OMPC). OMPC is an innovative programming model designed for the development of HPC applications. It streamlines the development process and simplifies software maintenance using only OpenMP directives. Notably, OMPC delivers a performance level comparable to a pure MPI implementation. This enhancement enabled expensive CCS calculations using nitrogen buffer gas for large systems such as human adenovirus with ∼11 million atoms in just ∼4 min, making MassCCS the most performant software nowadays, to the best of our knowledge. MassCCS is available as free software for Academic use at https://github.com/cces-cepid/massccs.

Long-term irradiation study of sMDT drift tubes with an integrated accumulated charge of 60 C per wire using beta-electrons from a 90Sr source

Two ATLAS sMDT drift tubes have been irradiated for almost 1 year using a 90Sr beta-decay source. An integrated charge of 62C has been accumulated on each of both anode wires over an anode-wire region of about 7.5 cm. Taking into account the intensity distribution of the irradiation corresponds to a maximum accumulated line charge density of about 14C/cm. At the innermost position of the ATLAS forward muon spectrometer 10C/cm are expected for 10 years of high-luminosity LHC operation and for this detector type at gas gain 20000. To investigate potential outgassing, the endplug region of the drift-tubes, where no gas amplification occurs, was irradiated additionally using about half the beta-electrons emitted from the source. The other beta-electrons were irradiating an active part of the gas volume for monitoring purpose. During four months the endplugs were irradiated by 5C/cm equivalent. All observed anode currents were very stable over the whole period of irradiation and thus no sign of deterioration in the performance of both drift tubes was observed. This indicates that no ageing effects occurred and that no performance loss due to outgassing of any plastic surfaces has been observed. All components that have potential contact to the detector gas Ar:CO2 with a mixture of 93:7 (percent volume) have been carefully and properly chosen. The required cleanliness of all tube- and gas components has been achieved during construction and operation of these drift tubes.

Field flattening concepts for linac cavities of the cross-bar H type

The development of cross-bar H-type cavities (CH-DTL, H21 mode) is ongoing to improve the technology of this attractive type of drift tube linac (DTL). In comparison with the conventional DTL, the H-type cavities can reach a higher effective field gradient and are competitive in shunt impedance at an energy range up to 100 A MeV. H-mode DTL’s profit in shunt impedance additionally when applying the KONUS beam dynamics. They are in use at research laboratories as well as at hospitals. This paper describes a new concept to approach the zero mode in CH-type cavities, by extending the cavity diameter at the tank ends in combination with tilted drift tube stems. RFQs of the four-vane type are operated as well in the H210 mode and the strategy for voltage flattening can be partly applied there too if conventional vane undercuts are causing problems. Up to around 35 MeV, it is attractive to integrate one or more triplet lenses into each cavity, as one KONUS section is relatively short and would not exploit the full rf power of 3 MW klystrons which are available above 300 MHz. Such a cavity is denoted as a coupled CH-cavity CCH. Three possible arrangements of those internal triplet lenses are discussed and are compared to each other. The operating modes as well as higher modes are then compared with a lens-free CH cavity, where the lens position was filled by ordinary drift tubes. As a result, it is shown that the rf behavior and resonance frequency for the higher harmonics of the frequency band are very similar for all four investigated arrays. This means, that the tuning behavior of the CCH cavity can be simply deduced from the lens-free CH cavity by replacing an even number of ordinary drift tubes (nβλ) with a lens-containing drift tube with adequate length and large outer diameter. This large drift tube itself oscillates like an Alvarez-type drift tube. rf simulations on a 30-gap CH cavity show that the reduction in shunt impedance is about 10% when installing a lens with length 2 beta lambda. Published by the American Physical Society 2024

Alternating phase focusing beam dynamics for drift tube linacs

In contrast to conventional E-mode resonance accelerators, H-mode DTLs provide for compact linac sections and have been established as highly efficient resonators during the last decades. Thus, H-mode structures are widely applied for heavy-ion acceleration with medium beam energies because of their outstanding capability to provide high acceleration gradients with relatively low energy consumption. To build upon those advantages, an alternating phase focusing beam dynamics layout has been applied to provide for a resonance accelerator design without internal lenses, which allows for eased commissioning, routine operation, maintenance, and potential future upgrades. The features of such a channel are going to be demonstrated on the example of two interdigital H-mode cavities, separated by an external quadrupole triplet. This setup provides for heavy ion (mass-to-charge ratio A/z≤6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$A/z\\le 6$\\end{document}) acceleration from 300 keV/u to 1400 keV/u and is used as an injector part of the superconducting continuous wave accelerator HELIAC. Hence, this promising approach generally enables effective and compact routine operation for various applications, such as super heavy ion research, material science, and radio biological applications such as heavy-ion tumor therapy.

Characterisation of plastic scintillator paddles and lightweight MWPCs for the MID subsystem of ALICE 3

The ALICE collaboration is proposing a completely new detector, ALICE 3, for operation during the LHC Runs 5 and 6. One of the ALICE 3 subsystems is the Muon IDentifier detector (MID), which has to be optimised to be efficient for the reconstruction of J/ψ at rest (muons down to p T ≈ 1.5 GeV/c) for |η| < 1.3. Given the modest particle flux expected in the MID of a few Hz/cm2, technologies like plastic scintillator bars (≈ 1 m length) equipped with wavelength-shifting fibers and silicon photomultiplier readout, and lightweight Multi-Wire Proportional Chambers (MWPCs) are under investigation. To this end, different plastic scintillator paddles and MWPCs were studied at the CERN T10 test beam facility. This paper reports on the performance of the scintillator prototypes tested at different beam momenta (from 0.5 GeV/c up to 6 GeV/c) and positions (horizontal, vertical, and angular scans). The MWPCs were tested at different momenta (from 0.5 GeV/c to 10 GeV/c) and beam intensities, their efficiency and position resolutions were verified beyond the particle rates expected with the MID in ALICE 3.

Beam Dynamics Studies for a Proposed H – type DTL Using in Eye Therapy

Abstract: In this study, we explore the KONUS (Kombinierte Null Grad Struktur) beam dynamic studies using a 3D–PIC LORASR simulation code for a specialized medical drift tube linac designed for eye therapy. A total acceleration voltage of 70.89 MV is applied through 6 CH–DTL (3 coupled and 3 non-coupled) cavities within a total of 140 gaps, spanning a length of 20 m. This setup is designed to accelerate protons from an initial energy of 3 MeV to 70 MeV, tailored for application in eye therapy. Each cavity operates at a frequency of 325.244 MHz. To maintain transverse matching of the beam, 11 triplet quadrupole lenses are distributed along the linac structure, including one in the transport section. The beam dynamics analysis provides actual values for the lengths of drift tubes and gaps. To ensure linac stability, simulations are conducted to assess machine errors. The obtained lengths of drift tubes, gaps, and periods serve as the foundation for constructing the RF model for each cavity using the CST Studio Suite. The overall results are quite promising, indicating the viability of proceeding to the next phase, which includes RF simulations and mechanical modeling. Keywords: LORASR code, KONUS, Beam dynamics, DTL, CST, Eye therapy.

Characteristics of Volatile Organic Compounds Distribution in Downtown Ansan Near Industrial Complexes

There are four industrial complexes located around Ansan City, which is one of the areas with the highest VOCs emissions in Gyeonggi region based on the emissions provided by the clean policy support system (CAPSS), Korea. In this study, proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) was used to determine the distribution of volatile organic compounds (VOCs) in urban areas near industrial complexes in Ansan City in 2023 (May to June). The PTR-TOF-MS was operated over the mass range of 10-400amu at a drift tube pressure of 2.3mbar and temperature 80&lt;sup&gt;o&lt;/sup&gt;C (E/N ~ 130Td) that enabled the collection of VOC data at 0.1Hz resolution. The mixing ratio calculations for methanol, acetaldehyde, acetonitrile, acetone, acetic acid, dimethyl sulfide, isoprene, methyl vinyl ketone (MVK), methyl ethyl ketone (MEK), benzene, toluene, styrene, xylene, trimethylbenzene and pinene reported in this study were done using the sensitivity factors obtained from the PTR-TOF-MS calibrations. As a result of the intensive measurement in springtime, among the substances constituting VOCs, methanol was the most abundant with 16.27±7.13 ppb, followed by acetone, acetaldehyde, acetic acid, methyl ethyl ketone (MEK), toluene, and xylene. VOCs compositions were dominated by oxidized VOCs, with CxHyO1 at 74%, CxHyO2 at 11%, aromatic CxHy at 10.5%, and CxHyN at 3.1%, respectively. As a result of the diurnal variations and conditional probability function (CPF) analysis, it was found that toluene and MEK were locally greatly influenced by industrial complexes distributed around Ansan City. Related with the ozone creating contribution, the ratio of VOCs to nitrogen oxide (NOx) was 6.5 (1.4 to 18.2), which appeared in the NOx-limited (4:1) and the VOCs-limited (15:1). Therefore it is suggested that the management of emission source NOx and VOCs are very important for the reduction of ozone in Ansan.

Interplatform comparison between three ion mobility techniques for human plasma lipid collision cross sections

The implementation of ion mobility spectrometry (IMS) in liquid chromatography-high-resolution mass spectrometry (LC-HRMS) workflows has become a valuable tool for improving compound annotation in metabolomics analyses by increasing peak capacity and by adding a new molecular descriptor, the collision cross section (CCS). Although some studies reported high repeatability and reproducibility of CCS determination and only few studies reported good interplatform agreement for small molecules, standardized protocols are still missing due to the lack of reference CCS values and reference materials.We present a comparison of CCS values of approximatively one hundred lipid species either commercially available or extracted from human plasma. We used three different commercial ion mobility technologies from different laboratories, drift tube IMS (DTIMS), travelling wave IMS (TWIMS) and trapped IMS (TIMS), to evaluate both instrument repeatability and interlaboratory reproducibility. We showed that CCS discrepancies of 0.3% (average) could occur depending on the data processing software tools. Moreover, eleven CCS calibrants were evaluated yielding mean RSD below 2% for eight calibrants, ESI Low concentration tuning mix (Tune Mix) showing the lowest RSD (< 0.5%) in both ion modes. Tune Mix calibrated CCS from the three different IMS instruments proved to be well correlated and highly reproducible (R2 > 0.995 and mean RSD ≤ 1%). More than 90% of the lipid CCS had deviations of less than 1%, demonstrating high comparability between techniques, and the possibility to use the CCS as molecular descriptor. We highlighted the need of standardized procedures for calibration, data acquisition, and data processing. This work demonstrates that using harmonized analytical conditions are required for interplatform reproducibility for CCS determination of human plasma lipids.

Hit efficiency study of the BESIII drift chamber

The Beijing Spectrometer III (BESIII) on the Beijing Electron Positron Collider II (BEPCII) is a unique facility operating in the τ-charm region. The multilayer drift chamber (MDC), which plays a crucial role in the measurements of momentum and dE/dx for charged particles generated during electron-positron collisions, has been operating for around 15 years. Hit efficiency is a fundamental performance criterion of the MDC. To analyze the spatial distribution of the hit efficiency and the stability during the operation over the past decade, a track-based analysis was performed using Bhabha events collected from 2012 to 2023. Decreasing in hit efficiency due to the aging effect was observed in the first three layers. A position-dependent behavior was studied, which may be related to beam-induced background.

Development of a Modular, Open-Source, Reduced-Pressure, Drift Tube Ion Mobility Spectrometer.

Toward the goal of minimizing construction costs while maintaining high performance, a new, reduced-pressure, drift tube ion mobility system is coupled with an ion trap mass analyzer through a custom ion shuttle. The availability of reduced-pressure ion mobility systems remains limited due to comparatively expensive commercial options and limited shared design features in the open literature. This report details the complete design and benchmarking characteristics of a reduced-pressure ion mobility system. The system is constructed from FR4 PCB electrodes and encased in a PTFE vacuum enclosure with custom torque-tightened couplers to utilize standard KF40 bulkheads. The PTFE enclosure directly minimizes the overall system expenses, and the implementation of threaded brass inserts allows for facile attachments to the vacuum enclosure without damaging the thermoplastic housing. Front and rear ion funnels maximize ion transmission and help mitigate the effects of radial ion diffusion. A custom planar ion shuttle transports ions from the exit of the rear ion funnel into the ion optics of an ion trap mass analyzer. The planar ion shuttle can couple the IM system to any contemporary Thermo Scientific ion trap mass analyzer. Signal stability and ion intensity remain unchanging following the implementation of the planar ion shuttle when compared to the original stacked ring ion guide. The constructed IM system showed resolving powers up to 85 for various small molecules and proteins using the Fourier transform from a ∼1 m drift tube. Recorded mobilities derived from first principles agree with published literature results with an average error of 1.1% and an average error toward literature values using single field calibration of <1.3%.

Real-Time Graph Building on FPGAs for Machine Learning Trigger Applications in Particle Physics

We present a design methodology that enables the semi-automatic generation of a hardware-accelerated graph building architectures for locally constrained graphs based on formally described detector definitions. In addition, we define a similarity measure in order to compare our locally constrained graph building approaches with commonly used k-nearest neighbour building approaches. To demonstrate the feasibility of our solution for particle physics applications, we implemented a real-time graph building approach in a case study for the Belle II central drift chamber using Field-Programmable Gate Arrays (FPGAs). Our presented solution adheres to all throughput and latency constraints currently present in the hardware-based trigger of the Belle II experiment. We achieve constant time complexity at the expense of linear space complexity and thus prove that our automated methodology generates online graph building designs suitable for a wide range of particle physics applications. By enabling an hardware-accelerated preprocessing of graphs, we enable the deployment of novel Graph Neural Networks (GNNs) in first-level triggers of particle physics experiments.

Design and characterization of an antiproton deceleration beamline for the PUMA experiment

We report on the design and characterization of an antiproton deceleration beamline, based on a pulsed drift tube, for the PUMA experiment at the Antimatter Factory at CERN. The design has been tailored to high-voltage (100kV) and ultra-high vacuum (below 10−10mbar) conditions. A first operation achieved decelerating antiprotons from an initial energy of 100keV down to (3898±3)eV, marking the initial stage in trapping antiprotons for the PUMA experiment. Employing a high-voltage ramping scheme, the pressure remains below 2×10−10mbar upstream of the pulsed drift tube for 75% of the cycle time. The beamline reached a transmission of (55±3)% for antiprotons decelerated to 4keV. The beam is focused on a position sensitive detector to a spot with horizontal and vertical standard deviations of σhoriz=(3.0±0.1)mm and σvert=(3.8±0.2)mm, respectively. This spot size is within the acceptance of the PUMA Penning trap.

The OBDT-theta board: time digitization for the theta view of Drift Tubes chambers.

We present the design and performance of the On-Board electronics for the Drift Tubes (OBDT) for the superlayer theta along the direction parallel to the beam-line, the new board built to substitute part of the CMS DT Muon on-detector electronics. The OBDT-theta is responsible for the time digitization of the DT chamber signals for the theta view, allowing further tracking and triggering of the barrel muons. It is also in charge of part of the slow-control of the DT chamber inner electronics in the theta view. Prototypes of the OBDT-theta board are under validation in different laboratories in CERN, as well as in demonstrator chambers installed in the CMS experiment. This allows evaluation of the full functionality of the boards in real conditions, showing very satisfactory results.

Tuning methods for multigap drift tube linacs.

Multigap cavities are used extensively in linear accelerators to achieve velocities up to a few percent of the speed of light, driving nuclear physics research around the world. Unlike for single-gap structures, there is no closed-form expression to calculate the output beam parameters from the cavity voltage and phase. To overcome this, we propose to use a method based on the integration of the first and second moments of the beam distribution through the axially symmetric time-dependent fields of the cavity. A beam-based calibration between the model's electric field scaling and the machine's rf amplitudes is presented, yielding a fast online energy change method, returning cavity amplitude and phase necessary for a desired output beam energy and energy spread. The method is validated with 23Na6+ beam energy measurements.

Solid phase microextraction arrow-ion mobility spectrometry for determination of selected pesticides in water

Ion mobility spectrometry with corona discharge ion source was used for the measurements of selected pesticides cybutryne, terbutryn, dichlorvos, and quinoxyfen in water. The analyses were carried out by (i) direct injection of the aqueous solution of the pesticides and (ii) extraction using solid phase microextraction by commercial SPME arrows. The instrumental and the experimental extraction parameters including the drift tube temperature, injection port temperature, and the SPME fiber type were studied and optimized to achieve the maximum signal intensity. The limit of detections obtained by the direct injection were about 0.1–1.0 mg L−1. Using the SPME arrow-ion mobility spectrometry method, the detection limits were improved 7–50 times and obtained as 0.01, 0.015, 0.05, and 0.1 mg L−1 for terbutryn, dichlorvos, cybutryne, and quinoxyfen, respectively. The recovery rate for analysis in surface water (real samples) was approximately 90–110% for both the direct injection and solid phase microextraction method. The capability of ion mobility spectrometry for the simultaneous detection of a mixture of the studied pesticides was assessed, and it was found that terbutryn, dichlorvos, and quinoxyfen can be detected simultaneously without peak overlapping.

Signal shapes in multiwire proportional chamber-based TPCs

A large-volume Time Projection Chamber (TPC) is the main tracking and particle identification (PID) detector of the ALICE experiment at the CERN LHC. PID in the TPC is performed via specific energy-loss measurements (dE/dx), which are derived from the average pulse-height distribution of ionization generated by charged-particle tracks traversing the TPC volume. During Runs 1 and 2, until 2018, the gas amplification stage was based on multiwire proportional chambers (MWPC). Signals from the MWPC show characteristic long negative tails after an initial positive peak due to the long ion drift times in the MWPC amplification region. This so-called ion tail can lead to a significant amplitude loss in subsequently measured signals, especially in the high-multiplicity environment of high-energy Pb-Pb collisions, which results in a degradation of the dE/dx resolution. A detailed study of the signal shapes measured with the ALICE TPC with the Ne-CO2 (90-10) and Ar-CO2 (90-10) gas mixtures is presented, and the results are compared with three-dimensional Garfield simulations. The impact of the ion tail on the PID performance is studied employing the ALICE simulation framework and the feasibility of an offline correction procedure to account for the ion tail is demonstrated.

New electronics for the HADES MDC drift chambers

The drift chambers of the HADES experiment at SIS-18 at GSI, Darmstadt/Germany, form the main tracking system of the spectrometer. Designed more than twenty years ago, the whole front-end electronics chain is being replaced with state-of-the-art electronics to cope with the increasing failure rate of the old electronics and with advanced requirements of the experiment, e.g. the trigger rate.The new analog signal processing is based on the PASTTREC ASIC, developed for the Straw Tube Tracker of the PANDA Experiment. The digitization of data happens in FPGA-based TDCs.The main challenges of the project are the strict spatial constraints given by the experiment setup to place the front-end boards and the noise sensitivity of the large area gas detectors. In addition, the power consumption needed to be kept low due to thermal constraints.