Drift Tube Research Articles

BESIII track reconstruction algorithm based on machine learning

Track reconstruction is one of the most important and challenging tasks in the offline data processing of collider experiments. For the BESIII detector working in the tau-charm energy region, plenty of efforts were made previously to improve the tracking performance with traditional methods, such as template matching and Hough transform etc. However, for difficult tracking tasks, such as the tracking of low momentum tracks, tracks from secondary vertices and tracks with high noise level, there is still large room for improvement. In this contribution, we demonstrate a novel tracking algorithm based on machine learning method. In this method, a hit pattern map representing the connectivity between drift cells is established using an enormous MC sample, based on which we design an optimal method of graph construction, then an edgeclassifying Graph Neural Network is trained to distinguish the hit-on-track from noise hits. Finally, a clustering method based on DBSCAN and RANSAC is developed to cluster hits from multiple tracks. Track fitting algorithm based on GENFIT2 is also studied to obtain the track parameters, where deterministic annealing filter are implemented to deal with ambiguities and potential noises. The preliminary results on BESIII MC sample presents promising performance, showing potential to apply this method to other trackers based on drift chamber as well, such as the CEPC and STCF detectors under pre-study.

RF-Acceleration Studies for the HBS-Linac Applying Alternating Phase Focusing Concepts

The recent layout of the Jülich High Brilliance Neutron Source (HBS) driver linac is based on short crossbar H-mode (CH) cavities operated at a fixed synchronous phase. In the last decades the computing power for the development of linacs, available to physicists and engineers, has been increased drastically. This also enabled the accelerator community to finally carry out the required R&D to generate further the idea of drift tube linacs with alternating phase focusing (APF) beam dynamics, originally proposed in the 1950s. This focusing method uses the electric fields in between the drift tubes (i.e., gaps) to provide subsequent transverse and longitudinal focusing to the beam along multiple gaps. The beam focusing properties within each gap are adjusted individually by means of the synchronous phase. As a result of the alternating phase focusing method, these linacs can operate completely without internal magnetic lenses. The R&D-program for the high brilliance neutron source HBS offered the opportunity to investigate the APF concept further in order to open this advanced concept for high duty-factor, high intensity hadron beam acceleration. Besides, a prototype APF-interdigital H-mode (IH)-cavity has been designed and is going to be build and tested in the next future.

Dielectronic recombination experiment of Na-like Kr<sup>25+</sup> at heavy ion storage ring CSRe

The experimental study of precision spectroscopy of dielectronic recombination (DR) of highly charged ions is not only important for astronomical plasma and fusion plasma, but also can be used as a new precision spectroscopy to test the strong-field quantum electrodynamic effect, measure isotope shift, and extract the radius of atomic nuclei. An specially designed electron beam energy detuning system for electron-ion recombination precision spectroscopy experiments has been installed on the heavy ion storage ring CSRe in Lanzhou, China, where the electron-ion collision energy in the center-of-mass system can be detuned to 1 keV, and an independently-developed plastic scintillator detector and multiwire proportional chamber detector have been installed downstream of the electron cooler of the CSRe for detecting recombined ions. The multiwire proportional chamber detector has the ability to non-destructively monitor the profile of the ion beam in real-time while acquiring the recombined ion counts, providing guidance for optimizing the ion beam. On this basis, the first test experiment on dielectronic recombination of Kr<sup>25+</sup> ions is carried out at the CSRe, and the dielectronic recombination rate coefficients in a range of 0–70 eV in the frame of center-of-mass are measured. In order to fully understand the experimental results, we calculate the dielectronic recombination rate coefficient of the Kr<sup>25+</sup> ion by using the flexible atomic code (FAC) and make a detailed comparison with the experimental result, showing that they are in good agreement with each other, and only the resonance energy values of the two resonance peaks at 1.695 eV and 2.573 eV are significantly different. In addition, the DR resonance energy values and intensities are obtained by fitting the experimental results in a range of 0–35 eV, and we find that the transition 3s→4l (∆<i>n</i> = 1) contributes significantly to the experimental spectral lines. Furthermore, we compare the plasma rate coefficients derived from the DR rate coefficients with those derived from the AUTOSTRUCTURE and FAC theories, which differ by 20 percent in a temperature range less than 10<sup>6</sup> K. The experimental results show that the DR experimental platform of the CSRe has very good stability and reproducibility, and can provide support for the future DR experiments of highly charged ion, i.e. for testing strong-field quantum electrodynamics effect and measuring the properties of atomic nuclei.

A custom discrete amplifier-shaper-discriminator circuit for the drift chambers of the R3B experiment at GSI

This contribution presents a pragmatic approach to read-out electronics for drift chambers used in particle physics experiments, specifically for the R3B experiment at GSI. The design uses discrete miniature SMD components and LVDS inputs of a low-cost FPGA to achieve a performance similar to classic ASIC solutions to the problem. The circuit comprises a high gain, low noise amplifier, a custom signal shaper, tailored to the specifics of proportional counter signals, and a leading-edge discriminator with programmable threshold. The presented approach offers an attractive solution for small to medium sized detector systems that require specialized read-out electronics but cannot afford the high cost and development effort associated with ASICs.

Refined drift chamber simulation in the CEPC experiment

The Circular Electron Positron Collider (CEPC) is a future experiment aimed at studying the properties of the Higgs boson with high precision. This requires excellent track reconstruction and particle identification (PID) performance, which is achieved in the 4th conceptual detector design of the CEPC experiments by combining a silicon tracker and a drift chamber. The drift chamber not only improves track reconstruction but also provides excellent PID with the cluster counting method. To evaluate the performance of this design accurately, a detailed simulation is necessary. In this paper, we present a refined drift chamber simulation by combining Geant4 and Garfield++. However, traditional waveform simulation using Garfield++ is extremely time-consuming, which motivates us to develop a fast waveform simulation method using a neural network. We validate the method using real data from the BESIII experiment. The results demonstrate the effectiveness of our approach and provide valuable insights for future experiments.

Comparison of 352 MHz linac structures for injection into an ion therapy accelerator

In the frame of ongoing initiatives for the design of a new generation of synchrotron-based accelerators for cancer therapy with ion beams, an analysis of linac designs has been started, to address a critical element with a strong impact on the performance and cost of the accelerator. The goal is to identify alternatives at lower cost and a similar or possibly smaller footprint than the standard 217 MHz injector presently used in all carbon therapy facilities in Europe. As an additional feature, a new linac design can be tailored to produce radioisotopes for treatment and diagnostics in parallel with operation as a synchrotron injector. In this paper, the attractive option of moving to 352 MHz frequency is analyzed, to a profit of reliable mechanical designs already developed for protons and of the cost savings that can be obtained using Radiofrequency (RF) power sources klystrons with a much lower cost per Watt than tubes or solid-state units. The paper is presenting a Quasi-Alvarez Drift Tube Linac (QA-DTL) version of an injector linac for carbon ions at q/A=1/3 and compare it with Inter-Digital H-Mode DTL (IH-DTL) designs. The option of a Separated-tank IH-DTL structure (S-IH-DTL) is also discussed, along with a standard IH-DTL, both at 352 MHz. Finally, a DTL design at 352 MHz for the injection of fully stripped helium ions into the synchrotron is presented.

Alvarez Drift Tube Linac for Medical Applications in the Framework of Hitriplus Project

A first beam dynamics and RF design of an Alvarez-type drift tube linac (DTL) has been defined in the framework of the EU project, HITRIplus. It is meant primarily as a carbon (12C4+) and helium (4He2+) ion injector of a compact synchrotron for patient treatment. As a second implementation, helium particle acceleration with a higher duty cycle (10%) enables radioisotope production. The 352.2 MHz structure efficiently accelerates ion species with A/q=3 and 2, in the energy range from 1 to 5 MeV/u and for a beam current up to ∼0.5 mA. The design extends to a full length of ∼6.4 meters. Permanent magnet quadrupoles are utilized all along the DTL for focusing both ion beams. This paper presents a first-phase analysis towards a realistic DTL design capable of providing full beam transmission and minimum overall emittance increase for both A/q values.

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New neutrino–nucleus interaction cross-section measurements are required to improve nuclear models sufficiently for future long baseline neutrino experiments to meet their sensitivity goals. A time projection chamber (TPC) filled with a high-pressure gas is a promising detector to characterise the neutrino sources used for such experiments. A gas-filled TPC is ideal for measuring low-energy particles, which travel further in gas than in solid or liquid detectors and using high-pressure increases the target density, resulting in more neutrino interactions. We examine the suitability of multiwire proportional chambers (MWPCs) from the ALICE TPC for use as the readout chambers of a high-pressure gas TPC. These chambers were previously operated at atmospheric pressure. 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We extrapolate that at 10 barA, an interesting pressure for future neutrino experiments, a gain of 5000 in Ar-CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext {Ar-CO}}_2$$\\end{document} with 10% CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {CO}_{2}$$\\end{document} (10,000 in Ar-CH4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {Ar-CH}_4$$\\end{document} with ∼4%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim \\!{4}{\\%}$$\\end{document}CH4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {CH}_{4}$$\\end{document}) may be achieved with anode voltage of 4.6kV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${4.6}\\,\\hbox {kV}$$\\end{document} (∼3.6kV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim \\!{3.6}\\,\\hbox {kV}$$\\end{document}).

Application of Ion Mobility Spectrometry and the Derived Collision Cross Section in the Analysis of Environmental Organic Micropollutants.

Ion mobility spectrometry (IMS) is a rapid gas-phase separation technique, which can distinguish ions on the basis of their size, shape, and charge. The IMS-derived collision cross section (CCS) can serve as additional identification evidence for the screening of environmental organic micropollutants (OMPs). In this work, we summarize the published experimental CCS values of environmental OMPs, introduce the current CCS prediction tools, summarize the use of IMS and CCS in the analysis of environmental OMPs, and finally discussed the benefits of IMS and CCS in environmental analysis. An up-to-date CCS compendium for environmental contaminants was produced by combining CCS databases and data sets of particular types of environmental OMPs, including pesticides, drugs, mycotoxins, steroids, plastic additives, per- and polyfluoroalkyl substances (PFAS), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), as well as their well-known transformation products. A total of 9407 experimental CCS values from 4170 OMPs were retrieved from 23 publications, which contain both drift tube CCS in nitrogen (DTCCSN2) and traveling wave CCS in nitrogen (TWCCSN2). A selection of publicly accessible and in-house CCS prediction tools were also investigated; the chemical space covered by the training set and the quality of CCS measurements seem to be vital factors affecting the CCS prediction accuracy. Then, the applications of IMS and the derived CCS in the screening of various OMPs were summarized, and the benefits of IMS and CCS, including increased peak capacity, the elimination of interfering ions, the separation of isomers, and the reduction of false positives and false negatives, were discussed in detail. With the improvement of the resolving power of IMS and enhancements of experimental CCS databases, the practicability of IMS in the analysis of environmental OMPs will continue to improve.

Nanoscale Reconfigurable Si Transistors: From Wires to Sheets and Unto Multi‐Wire Channels

AbstractIn this work, bottom‐up Al–Si–Al nanowire (NW) heterostructures are presented, which act as a prototype vehicle toward top‐down fabricated nanosheet (NS) and multi‐wire (MW) reconfigurable field‐effect transistors (RFETs). Evaluating the key parameters of these transistors regarding the on‐ and off‐currents as well as threshold voltages for n‐ and p‐type operation exhibit a high degree of symmetry. Most notably also a low device‐to‐device variability is achieved. In this respect, the investigated Al–Si material system reveals its relevance for reconfigurable logic cells obtained from Si NSs. To show the versatility of the proposed devices, this work reports on a combinational wired‐AND gate obtained from a multi‐gate RFET. Additionally, up‐scaling the current is achieved by realizing a MW RFET without compromising reconfigurability. The Al–Si–Al platform has substantial potential to enable complex adaptive and self‐learning combinational and sequential circuits with energy efficient and small footprint computing paradigms as well as for native components for hardware security circuits.

Evaluation of Fourier deconvolution ion mobility spectrometer as high-performance gas chromatography detector for the analysis of plant extract flavors

The Fourier deconvolution ion mobility spectrometer (FDIMS) offers multiplexing and improves the resolving power and signal-to-noise ratio. To evaluate the FDIMS as a detector for gas chromatography for the analysis of complex samples, we connected a drift tube ion mobility spectrometer to a commercial gas chromatograph and compared the performance including resolving power, sensitivity, and linear range using 2,6-di‑tert-butylpyridine. Mixed standards were also injected into the tandem system to evaluate the performance under optimized conditions. A complex plant extract sample used as natural flavoring was investigated using the resulting system. The results show that the instrument implemented with the Fourier deconvolution multiplexing method demonstrated higher performance over the traditional signal averaging method including higher resolving power, better limit of detection, and wider linear range for a variety of compounds and natural plant extract flavorings.

Design, fabrication, and characterization of a drift tube linac type double gap re-buncher cavity.

The Low Energy High Intensity Proton Accelerator (LEHIPA) at Bhabha Atomic Research Centre, India, has recently been commissioned to the target energy of 20MeV by beam acceleration through a 352MHz radio frequency quadrupole (RFQ) and drift tube linac (DTL). The medium energy beam transport (MEBT) line of LEHIPA matches the 3MeV beam from RFQ to the DTL using four electromagnetic quadrupoles and a re-buncher cavity. In the beam transport lines of high frequency linacs, TM010 mode single gap buncher cavities are conventionally used, while a double gap re-buncher cavity was chosen for the short length LEHIPA MEBT based on beam dynamics simulations. The 352MHz double gap re-buncher cavity has been designed in a DTL type geometry with a cell length of βλ. This double gap cavity is found to be more power efficient with a higher shunt impedance and transit time factor than the conventional single gap buncher cavity. Electromagnetic design simulations, fabrication details, low power and high-power RF test results, and beam test results of the re-buncher cavity are presented in this paper.

Measurement of very low-molecular weight metabolites by traveling wave ion mobility and its use in human urine samples

The collision cross-sections (CCS) measurement using ion mobility spectrometry (IMS) in combination with mass spectrometry (MS) offers a great opportunity to increase confidence in metabolite identification. However, owing to the lack of sensitivity and resolution, IMS has an analytical challenge in studying the CCS values of very low-molecular-weight metabolites (VLMs ≤ 250 Da). Here, we describe an analytical method using ultrahigh-performance liquid chromatography (UPLC) coupled to a traveling wave ion mobility-quadrupole-time-of-flight mass spectrometer optimized for the measurement of VLMs in human urine samples. The experimental CCS values, along with mass spectral properties, were reported for the 174 metabolites. The experimental data included the mass-to-charge ratio (m/z), retention time (RT), tandem MS (MS/MS) spectra, and CCS values. Among the studied metabolites, 263 traveling wave ion mobility spectrometry (TWIMS)-derived CCS values (TWCCSN2) were reported for the first time, and more than 70% of these were CCS values of VLMs. The TWCCSN2 values were highly repeatable, with inter-day variations of <1% relative standard deviation (RSD). The developed method revealed excellent TWCCSN2 accuracy with a CCS difference (ΔCCS) within ±2% of the reported drift tube IMS (DTIMS) and TWIMS CCS values. The complexity of the urine matrix did not affect the precision of the method, as evidenced by ΔCCS within ±1.92%. According to the Metabolomics Standards Initiative, 55 urinary metabolites were identified with a confidence level of 1. Among these 55 metabolites, 53 (96%) were VLMs. The larger number of confirmed compounds found in this study was a result of the addition of TWCCSN2 values, which clearly increased metabolite identification confidence.

Pedagogical review of the derivation of space-charge limiting current of an electron beam in a metal drift tube

Pedagogical review of the derivation of space-charge limiting current of an electron beam in a metal drift tube

Celastrol ameliorates energy metabolism dysfunction of hypertensive rats by dilating vessels to improve hemodynamics.

The impact of hypertension on tissue and organ damage is mediated through its influence on the structure and function of blood vessels. This study aimed to examine the potential of celastrol, a bioactive compound derived from Tripterygium wilfordii Hook F, in mitigating hypertension-induced energy metabolism disorder and enhancing blood perfusion and vasodilation. In order to investigate this phenomenon, we conducted in vivo experiments on renovascular hypertensive rats, employing indirect calorimetry to measure energy metabolism and laser speckle contrast imaging to evaluate hemodynamics. In vitro, we assessed the vasodilatory effects of celastrol on the basilar artery and superior mesenteric artery of rats using the Multi Wires Myograph System. Furthermore, we conducted preliminary investigations to elucidate the underlying mechanism. Moreover, administration of celastrol at doses of 1 and 2mg/kg yielded a notable enhancement in blood flow ranging from 6 to 31% across different cerebral and mesenteric vessels in hypertensive rats. Furthermore, celastrol demonstrated a concentration-dependent (1 × 10-7 to 1 × 10-5M) arterial dilation, independent of endothelial function. This vasodilatory effect could potentially be attributed to the inhibition of Ca2+ channels on vascular smooth muscle cells induced by celastrol. These findings imply that celastrol has the potential to ameliorate hemodynamics through vasodilation, thereby alleviating energy metabolism dysfunctions in hypertensive rats. Consequently, celastrol may hold promise as a novel therapeutic agent for the treatment of hypertension.

Ultra-Fast Ion Mobility Spectrometer for High-Throughput Chromatography.

Fast chromatography systems especially developed for high sample throughput applications require sensitive detectors with a high repetition rate. These high throughput techniques, including various chip-based microfluidic designs, often benefit from detectors providing subsequent separation in another dimension, such as mass spectrometry or ion mobility spectrometry (IMS), giving additional information about the analytes or monitoring reaction kinetics. However, subsequent separation is required at a high repetition rate. Here, we therefore present an ultra-fast drift tube IMS operating at ambient pressure. Short drift times while maintaining high resolving power are reached by several key instrumental design features: short length of the drift tube, resistor network of the drift tube, tristate ion shutter, and improved data acquisition electronics. With these design improvements, even slow ions with a reduced mobility of just 0.94 cm2/(V s) have a drift time below 1.6 ms. Such short drift times allow for a significantly increased repetition rate of 600 Hz compared with previously reported values. To further reduce drift times and thus increase the repetition rate, helium can be used as the drift gas, which allows repetition rates of up to 2 kHz. Finally, these significant improvements enable IMS to be used as a detector following ultra-fast separation including chip-based chromatographic systems or droplet microfluidic applications requiring high repetition rates.

Influence of ionization volume and sample gas flow rate on separation power in gas chromatography-ion mobility spectrometry

In this work, the influence of the sample gas flow rate and the ionization region volume of an ion mobility spectrometer (IMS) used as a detector in gas chromatography (GC) on GC-IMS peak shape has been investigated. Therefore, a drift tube IMS with a field-switching ion shutter, a defined ionization region volume and an ultra-violet radiation source was used. To identify the influence of the sample gas flow rate entering the ionization region (equals the GC carrier gas flow rate if no further make-up gas is used) and the ionization region volume on peak broadening and signal intensity, different sample volumes as they would elute from a GC were tested at a variety of sample gas flow rates at a given ionization region volume. The results clearly show that for low sample gas flow rates a depletion of sample molecules in the ionization region leads to a significant decrease in effective detector volume but also to reduced signal intensities. Therefore, for optimal performance of a GC-IMS, the optimal operating point of the GC should match the flow range, where the IMS provides the best compromise between signal-to-noise ratio and peak broadening.

Enhancing ion mobility spectrometry performance through a programmable ion swarm shaping method based on Bradbury-Nielsen gates

The ion gate is a critical element in drift tube ion mobility spectrometry (IMS) as it directly influences the resolving power and sensitivity of the system. However, the conventional Bradbury-Nielsen gate (BNG) often leads to deformation of the ion swarm shape, resulting in reduced resolving power and significant discrimination effects. To address these limitations, we propose a novel method that incorporates a cutting phase following the gate opening. This approach effectively reduces trailing edge deformation, resulting in a maximum resolving power of over 100 and increased signal intensity. Additionally, this method maintains high resolving power even during longer gate opening times. Remarkably, this method not only significantly reduces the mobility discrimination effect but also enables the achievement of reverse discrimination by adjusting the duration of the cutting phase. Consequently, it demonstrates the potential to selectively amplify the peak height of target ions. Our method offers straightforward implementation across all IMS systems utilizing the BNG, thereby significantly improving system performance.

Production of antihydrogen atoms by 6 keV antiprotons through a positronium cloud

We report on the first production of an antihydrogen beam by charge exchange of 6.1 keV antiprotons with a cloud of positronium in the GBAR experiment at CERN. The 100 keV antiproton beam delivered by the AD/ELENA facility was further decelerated with a pulsed drift tube. A 9 MeV electron beam from a linear accelerator produced a low energy positron beam. The positrons were accumulated in a set of two Penning–Malmberg traps. The positronium target cloud resulted from the conversion of the positrons extracted from the traps. The antiproton beam was steered onto this positronium cloud to produce the antiatoms. We observe an excess over background indicating antihydrogen production with a significance of 3–4 standard deviations.

Non-destructive, solvent-free quantification of wood preservatives in wood flour and wooden objects using GC-DTIMS

Qualitative and quantitative on-site detection methods for wood preservatives are of high value for the recycling industry and the occupational health and safety. Wood preservatives revealed as toxic to human and environment after decades of use. For the detection of contaminated wood and for processing of matured timber to particle boards a versatile detection method is needed. Especially historical wooden objects were treated with preservatives like pentachlorophenol, lindane or dichlorodiphenyltrichloroethane. This requires a non-destructive on-site detection method, that does not require specialized personnel. In this publication two methods are presented utilizing headspace sampling by solid-phase microextraction, subsequent separation using gas chromatography and detection by a drift tube ion mobility spectrometer (SPME–HS–GC-DTIMS). One method enables the quantitative detection of pentachlorophenol in wood flour and wood chips as they are used in wood processing industries. A limit of detection of 0.1 mg/kg was achieved using DIN 32645, which can be even more lowered. The second method enables non-destructive detection of pentachlorophenol, lindane, dichlorodiphenyltrichloroethane and other preservatives in wooden objects. Therefore, samples were prepared, which show a significantly lower concentration than typical treated objects, and used next to real samples for method validation. With the method contamination of the real samples and of the prepared samples of low concentration were proven.