M. Chiappini, A. M. Baldini, G. Cavoto, F. Cei, G. Chiarello, M. Francesconi, L. Galli, F. Grancagnolo, M. Grassi, M. Hildebrandt, D. Nicolò, M. Panareo, A. Pap… 展开作者
M. Chiappini, A. M. Baldini, G. Cavoto, F. Cei, G. Chiarello, M. Francesconi, L. Galli, F. Grancagnolo, M. Grassi, M. Hildebrandt, D. Nicolò, M. Panareo, A. Papa, F. Raffaelli, F. Renga, G. Signorelli, G. F. Tassielli, C. Voena
备注：
2 pages, 3 figures, proceeding at PisaMeeting2018 conference, published in NIMA
发表信息：
Nuclear Inst. and Methods in Physics Research A (2019)
This article presents the MEG II Cylindrical Drift CHamber (CDCH), a key detector for the phase 2 of MEG, which aims at reaching a sensitivity level of the order of $6 \times 10^{-14}$ for the charged Lepton Flavour Violating $μ^+ \rightarrow \mbox{e}^+ γ$ decay. CDCH is designed to overcome the limitations of the MEG $\mbox{e}^+$ tracker and guarantee the proper operation at high rates with long-term detector stability. CDCH is a low-mass unique volume detector with high granularity: 9 layers of 192 drift cells, few mm wide, defined by $\approx 12000$ wires in a stereo configuration for longitudinal hit localization. The total radiation length is $1.5 \times 10^{-3}$ $\mbox{X}_0$, thus minimizing the Multiple Coulomb Scattering (MCS) contribution and allowing for a single-hit resolution of 110 $μ$m and a momentum resolution of 130 keV/c. CDCH integration into the MEG II experimental apparatus will start in this year.
The reconstruction of the positron trajectory in the MEG-II experiment searching for the $μ^+ \to e^+ γ$ decay uses a cylindrical drift chamber operated with a helium-isobutane gas mixture. A stable performance of the detector in terms of its electron drift properties, avalanche multiplication, and with a gas mixture of controlled composition and purity has to be provided and continuously monitored. In this paper we describe the strategies adopted to meet the requirements imposed by the target sensitivity of MEG-II, including the construction and commissioning of a small chamber for an online …
Drift chambers operated with helium-based gas mixtures represent a common solution for tracking charged particles keeping the material budget in the sensitive volume to a minimum. The drawback of this solution is the worsening of the spatial resolution due to primary ionisation fluctuations, which is a limiting factor for high granularity drift chambers like the MEG II tracker. We report on the measurements performed on three different prototypes of the MEG II drift chamber aimed at determining the achievable single-hit resolution. The prototypes were operated with helium/isobutane gas mixture…
The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented. Another important parameter to be monitored is the pressure inside the mu…
The ATLAS muon spectrometer uses drift-tube chambers for precision tracking. The performance of these chambers in the presence of magnetic field and high radiation fluxes is studied in this article using test-beam data recorded in the Gamma Irradiation Facility at CERN. The measurements are compared to detailed predictions provided by the Garfield drift-chamber simulation programme.
The MEG experiment at the Paul Scherrer Institut searches for the charged-Lepton-Flavor-Violating mu+ -> e+ gamma decay. MEG has already set the world best upper limit on the branching ratio: BR<4.2x10^-13 @ 90% C.l. An upgrade (MEG II) of the whole detector has been approved to obtain a substantial increase of sensitivity. Currently MEG II is completing the upgrade of the various detectors, an engineering run and a pre-commissioning run were carried out during 2018 and 2019. The new positron tracker is a unique volume, ultra-light He based cylindrical drift chamber (CDCH), with high granulari…
For the upgrade of the ATLAS muon spectrometer in March 2014 new muon tracking chambers (sMDT) with drift-tubes of 15 mm diameter, half of the value of the standard ATLAS Monitored Drift-Tubes (MDT) chambers, and 10~$μ$m positioning accuracy of the sense wires have been constructed. The new chambers are designed to be fully compatible with the present ATLAS services but, with respect to the previously installed ATLAS MDT chambers, they are assembled in a more compact geometry and they deploy two additional tube layers that provide redundant rack information. The chambers are composed of 8 laye…
ATLAS muon detector upgrades aim for increased acceptance for muon triggering and precision tracking and for improved rate capability of the muon chambers in the high-background regions of the detector with increasing LHC luminosity. The small-diameter Muon Drift Tube (sMDT) chambers have been developed for these purposes. With half of the drift-tube diameter of the MDT chambers and otherwise unchanged operating parameters, sMDT chambers share the advantages of the MDTs, but have an order of magnitude higher rate capability and can be installed in detector regions where MDT chambers do not fit…
Precision drift tube chambers with a sense wire positioning accuracy of better than 20 microns are under construction for the ATLAS muon spectrometer. 70% of the 88 large chambers for the outermost layer of the central part of the spectrometer have been assembled. Measurements during chamber construction of the positions of the sense wires and of the sensors for the optical alignment monitoring system demonstrate that the requirements for the mechanical precision of the chambers are fulfilled.
A method for the precise measurement of drift times for the high-precision drift chambers used in the TWIST detector is described. It is based on the iterative correction of the space-time relationships by the time residuals of the track fit, resulting in a measurement of the effective drift times. The corrected drift time maps are parametrised individually for each chamber using spline functions. Biases introduced by the reconstruction itself are taken into account as well, making it necessary to apply the procedure to both data and simulation. The described calibration is shown to improve th…
A thick gas electron multiplier (THGEM) chamber with an effective readout area of 10$\times$10 cm$^{2}$ and a 11.3 mm ionization gap has been tested along with two regular gas electron multiplier (GEM) chambers in a cosmic ray test system. The thick ionization gap makes the THGEM chamber a mini-drift chamber. This kind mini-drift THGEM chamber is proposed as part of a transition radiation detector (TRD) for identifying electrons at an Electron Ion Collider (EIC) experiment. Through this cosmic ray test, an efficiency larger than 94$\%$ and a spatial resolution $\sim$220 $μ$m are achieved for t…
As the main tracking detector of BESIII, the drift chamber works for accurate measurements of the tracking and the momentum of the charged particles decayed from the reaction of BEPCII e+ and e-. After operation six years, the drift chamber is suffering from aging problems due to huge beam related background. The gains of the cells in the first ten layers experience an obvious decrease, reaching a maximum of about 29% for the first layer cells. Two calculation methods for the gains change (Bhabha events and accumulated charges with 0.3% aging ratio for inner chamber cells) get almost the same …
We describe in these GLA2011 proceedings the software package LArSoft, a toolkit to perform simulation, analysis and reconstruction with the Liquid Argon (LAr) Time Projection Chambers (TPCs) within the US program of proposed detectors. We demonstrate that LArSoft is a fast-maturing, sophisticated package which has taken on important analyses already, and which stands ready to be adopted by as many as five Liquid Argon Time Projection Chambers.
The Monitored Drift Tube (MDT) chambers for the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) consist of 3-4 layers of pressurised drift tubes on either side of a space frame carrying an optical deformation monitoring system. The chambers have to provide a track position resolution of 40 microns with a single-tube resolution of at least 80 microns and a sense wire positioning accu- racy of 20 ?microns (rms). The feasibility was demonstrated with the full-scale prototype of one of the largest MDT chambers with 432 drift tubes of 3.8 m length. For the ATLAS muon spec…
Small-diameter Muon Drift Tube (sMDT) chambers have been developed for the ATLAS muon detector upgrade. They possess an improved rate capability and a more compact design with respect to the existing chambers, which allows to equip detector regions uninstrument at present. The chamber assembly methods have been optimized for mass production, while the sense wire positioning accuracy is improved to below ten microns. The chambers will be ready for installation in the winter shutdown 2016/17 of the Large Hadron Collider. The design and construction of the new sMDT chambers for ATLAS will be disc…
The MEG-II experiment searches for the lepton flavor violating decay: mu in electron and gamma. The reconstruction of the positron trajectory uses a cylindrical drift chamber operated with a mixture of He and iC4H10 gas. It is important to provide a stable performance of the detector in terms of its electron transport parameters, avalanche multiplication, composition and purity of the gas mixture. In order to have a continuous monitoring of the quality of gas, we plan to install a small drift chamber, with a simple geometry that allows to measure very precisely the electron drift velocity in a…
Due to the beam related background, the inner chamber of BESIII MDC has aging effect after 5 years running. The gains of the inner chamber cells decrease obviously, and the max gain decrease is about 26% for the first layer cells. A new inner drift chamber with eight stereo sense wire layers as a backup for MDC is under construction, which is almost the same as the current one but using stepped endplates to shorten the wire length beyond the effective solid angle. This new structure will be of benefit to reducing the counting rate of single cell. The manufacture of each component is going smoo…
The Collider Detector at Fermilab (CDF) is a general-purpose experimental apparatus with an inner tracking detector for measuring charged particles, surrounded by a calorimeter for measurements of electromagnetic and hadronic showers, and a muon detector system. We present a technique for, and results of, a precise relative alignment of the drift chamber wires of the CDF tracker. This alignment has been an important component of the track momentum calibration, which is the basis for the charged-lepton calibration for the measurement of the W boson mass at CDF.
Based on real data, a new parameterized model of the Main Drift Chamber response is proposed. In this model, we tune the ratio of good hits and the residual distribution separately. The difference between simulation and data in track reconstruction efficiency reduces from 1% to 0.5%, and the momentum resolution agreement improves significantly.
The influence of fast neutrons on the occupancy and the single tube resolution of ATLAS muon drift detectors was investigated by exposing a chamber built out of 3 layers of 3 short standard drift tubes to neutron flux-densities of up to 16 kHz/cm2 at a neutron energy of E=11 MeV. Pulse shape capable NE213 scintillaton detectors and a calibrated BF3 neutron detector provided monitoring of the neutron flux-density and energy. The sensitivity of the drift chamber to the neutrons was measured to be 4*10-4 by comparing data sets with and without neutron background. For the investigation of tracks o…
Calibration of the discriminator threshold of the Amplifier-Shaper-Discriminator Chip for the Upgrade of the ATLAS Muon Drift-Tube Chambers for the High-Luminosity LHC
The Belle II detector at the SuperKEKB accelerator has a level 1 trigger implemented in field-programmable gate arrays. Due to the high luminosity of the beam, a trigger that effectively rejects beam induced background is required. A three dimensional tracking algorithm for the level 1 trigger that uses the Belle II central drift chamber detector response is being developed to reduce the recorded beam background while having a high efficiency for physics of interest. In this paper, we describe the three dimensional track trigger that finds and fits track parameters which we developed.
The performance of a small prototype of a cylindrical drift chamber (CDC) used in the COMET Phase-I experiment was studied by using an electron beam. The prototype chamber was constructed with alternating all-stereo wire configuration and operated with the He-iC$_{4}$H$_{10}$ (90/10) gas mixture without a magnetic field. The drift space-time relation, drift velocity, d$E$/d$x$ resolution, hit efficiency, and spatial resolution as a function of distance from the wire were investigated. The average spatial resolution of 150 $μ$m with the hit efficiency of 99% was obtained at applied voltages hig…
The identification of single clusters in the electronic signals produced by ionizing particles within a drift chamber is expected to significantly improve the performances of this kind of detectors in terms of particle identification capabilities and space resolution. In order to develop refined cluster recognition algorithms, it is essential to measure the response of the chamber and its electronics to single ionization clusters. This can be done by irradiating the chamber with X-rays. We report here on the studies performed on a drift chamber prototype for the MEG-II experiment at the X-ray …
Single-cell prototype drift chambers were built at TRIUMF and tested with a $\sim\unit[210]{MeV/c}$ beam of positrons, muons, and pions. A cluster-counting technique is implemented which improves the ability to distinguish muons and pions when combined with a traditional truncated-mean charge measurement. Several cluster-counting algorithms and equipment variations are tested, all showing significant improvement when combined with the traditional method. The results show that cluster counting is a feasible option for any particle physics experiment using drift chambers for particle identificat…
With half the drift-tube diameter of the Monitored Drift Tube (MDT) chambers of the ATLAS muon spectrometer and otherwise unchanged operating parameters, small-diameter Muon Drift Tube (sMDT) chambers provide an order of magnitude higher rate capability and can be installed in detector regions where MDT chambers do not fit. The chamber assembly time has been reduced by a factor of seven to one working day and the sense wire positioning accuracy improved by a factor of two to better than ten microns. Two sMDT chambers have been installed in ATLAS in 2014 to improve the momentum resolution in th…
This paper introduces the calibration of the time-to-distance relation for the BESIII drift chamber. The parameterization of the time-to-distance relation is presented. The studies of left-right asymmetry and the variation with the entrance angle are performed. The impact of dead channels on the time-to-distance relation is given special attention in order to reduce the shifts of the measured momenta for the tracks passing near dead cells. Finally we present the spatial resolution (123 μm) for barrel Bhabha events (|cosθ|<0.8) from J/ψ data taken in 2012.
The ultra-low mass cylindrical drift chamber designed for the MEG II experiment is a challenging apparatus made of 1728 phi = 20 micron gold plated tungsten sense wires, 7680 phi = 40 micron and 2496 phi = 50 micron silver plated aluminum field wires. Because of electrostatic stability requirements all the wires have to be stretched at mechanical tensions of about 25, 19 and 29 g respectively which must be controlled at a level better than 0.5 g. This chamber is presently in acquisition, but during its construction about 100 field wires broke, because of chemical corrosion induced by the atmos…
We present a measurement of the extraction efficiency of quasi-free electrons from the liquid into the gas phase in a two-phase xenon time-projection chamber. The measurements span a range of electric fields from 2.4 to 7.1 kV/cm in the liquid xenon, corresponding to 4.5 to 13.1 kV/cm in the gaseous xenon. Extraction efficiency continues to increase at the highest extraction fields, implying that additional charge signal may be attained in two-phase xenon detectors through careful high-voltage engineering of the gate-anode region.
The resolution and efficiency of a precision drift-tube chamber for the ATLAS muon spectrometer with final read-out electronics was tested at the Gamma Irradiation Facility at CERN in a 100 GeV muon beam and at photon irradiation rates of up to 990 Hz/square cm which corresponds to twice the highest background rate expected in ATLAS. A silicon strip detector telescope was used as external reference in the beam. The pulse-height measurement of the read-out electronics was used to perform time-slewing corrections which lead to an improvement of the average drift-tube resolution from 104 microns …
We present measurements of position and angular resolution of drift chambers operated with a Xe,CO$_2$(15%) mixture. The results are compared to Monte Carlo simulations and important systematic effects, in particular the dispersive nature of the absorption of transition radiation and non-linearities, are discussed. The measurements were carried out with prototype drift chambers of the ALICE Transition Radiation Detector, but our findings can be generalized to other drift chambers with similar geometry, where the electron drift is perpendicular to the wire planes.
In the ATLAS Muon Spectrometer, Monitored Drift Tube (MDT) chambers and sMDT chambers with half of the tube diameter of the MDTs are used for precision muon track reconstruction. The sMDT chambers are designed for operation at high counting rates due to neutron and gamma background irradiation expected for the HL-LHC and future hadron colliders. The existing MDT read-out electronics uses bipolar signal shaping which causes an undershoot of opposite polarity and same charge after a signal pulse. At high counting rates and short electronics dead time used for the sMDTs, signal pulses pile up on …
The electronics of the CMS Drift Tube (DT) chambers need to be replaced during Long Shutdown 3 to tolerate the High Luminosity LHC (HL-LHC) data taking conditions. The first DT prototypes of the HL-LHC electronics, the on-detector board (OBDT), have been installed in the DT chambers of one sector, out of 60 sectors, and integrated into the central data acquisition and trigger systems. The signals from the chambers are split and reach both the legacy and Phase-2 demonstrator chains, which will allow them to operate in parallel during LHC collisions.
Pressurized drift-tube chambers are efficient detectors for high-precision tracking over large areas. The Monitored Drift-Tube (MDT) chambers of the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) reach a spatial resolution of 35 micons and almost 100% tracking efficiency with 6 layers of 30 mm diameter drift tubes operated with Ar:CO2 (93:7) gas mixture at 3 bar and a gas gain of 20000. The ATLAS MDT chambers are designed to cope with background counting rates due to neutrons and gamma-rays of up to about 300 kHz per tube which will be exceeded for LHC luminosities …
The GPU-accelerated track finding method is investigated to track electrons from neutrinoless muon decay in the COMET Phase-I experiment. Inside the cylindrical drift chamber, one third of the signal electron trajectories are composed of multiple turns where the correct hit assignments to each turn partition are significant in the track finding. Scanning all possible track seeds of position and momentum can resolve the hit-to-turn assignment problem with a high robustness, but requires a huge computational cost: The initial track seeds $(θ,z,p_x,p_y,p_z)$ have broad uncertainties, so there exi…
We present pulse height measurements in drift chambers operated with Xe,CO2 gas mixtures. We investigate the attachment of primary electrons on oxygen and SF6 contaminants in the detection gas. The measurements are compared with simulations of properties of drifting electrons. We present two methods to check the gas quality: gas chromatography and Fe55 pulse height measurements using monitor detectors.
The particle identification of charged hadrons, especially for the separation of $K$ and $π$, is crucial for the flavour physics study. Ionization measurement with the cluster counting technique, which has much less fluctuation than traditional $dE/dx$ measurement, is expected to provide better particle identification for the BESIII experiment. Simulation studies, including a Garfield++ based waveform analysis and a performance study of K/πidentification in the BESIII, offline software system have been performed. The results show that $K/π$ separation power and PID efficiency would be improved…
The IDEA detector concept for a future e$^{+}$e$^{-}$ collider adopts an ultra-low mass drift chamber as a central tracking system. The He-based ultra-low mass drift chamber is designed to provide efficient tracking, a high-precision momentum measurement, and excellent particle identification by exploiting the cluster counting technique. This paper describes the expected tracking performance, obtained with full and fast simulation, for track reconstruction on detailed simulated physics events. Moreover, the details of the construction parameters of the drift chamber, including the inspection o…
The aim of this thesis was to perform the drift chamber calibration and charged particles 3d track reconstruction for the P349 antiproton polarization experiment. A dedicated procedures were designed, implemented and tested on the experimental data for the the D1 drift chamber. The calibration consisted of the drift time offsets determination, estimation of the initial drift time - space relations by means of the homogeneous irradiation method and the iterative procedure for the time - space relations optimization. Calibration curves for all wire planes of the detector were determined. The obt…
ATLAS is a detector under construction to explore the physics at the Large Hadron Collider at CERN. It has a muon spectrometer with an excellent momentum resolution of 3-10%, provided by three layers of precision monitored-drift-tube chambers in a toroidal magnetic field. A single drift tube measures a track point with a mean resolution close to 100 micron, even at the expected high neutron and gamma background rates. The tubes are positioned within the chamber with an accuracy of 20 microns, achieved by elaborate construction and assembly monitoring procedures.
A number of liquid argon time projection chambers (LAr TPC's) are being build or are proposed for neutrino experiments on long- and short baseline beams. For these detectors a distortion in the drift field due to geometrical or physics reasons can affect the reconstruction of the events. Depending on the TPC geometry and electric drift field intensity this distortion could be of the same magnitude as the drift field itself. Recently, we presented a method to calibrate the drift field and correct for these possible distortions. While straight cosmic ray muon tracks could be used for calibration…
The goals of the ongoing and planned ATLAS muon detector upgrades are to increase the acceptance for precision muon momentum measurement and triggering and to improve the rate capability of the muon chambers in the high-background regions corresponding to the increasing LHC luminosity. Smalldiameter Muon Drift Tube (sMDT) chambers have been developed for these purposes. With half the drift-tube diameter of the current ATLAS Muon Drift Tube (MDT) chambers with 30 mm drift tube diameter and otherwise unchanged operating parameters, the sMDT chambers share all the advantages of the MDTs, but have…
The Monitored Drift Tube (MDT) chambers for the muon spectrometer of the AT- LAS detector at the Large Hadron Collider (LHC) consist of 3-4 layers of pressurized drift tubes on either side of a space frame carrying an optical monitoring system to correct for deformations. The full-scale prototype of a large MDT chamber has been constructed with methods suitable for large-scale production. X-ray measurements at CERN showed a positioning accuracy of the sense wires in the chamber of better than the required 20 ?microns (rms). The performance of the chamber was studied in a muon beam at CERN. Cha…
This paper describes the calibration procedure for the drift tubes of the CMS barrel muon system and reports the main results obtained with data collected during a high statistics cosmic ray data-taking period. The main goal of the calibration is to determine, for each drift cell, the minimum time delay for signals relative to the trigger, accounting for the drift velocity within the cell. The accuracy of the calibration procedure is influenced by the random arrival time of the cosmic muons relative to the LHC clock cycle. A more refined analysis of the drift velocity was performed during the …
To measure the muon decay parameters with high accuracy, we require an array of precision drift detector layers whose relative position is known with very high accuracy. This article describes the design, construction and performance of these detectors in the TWIST (TRIUMF Weak Interaction Symmetry Test) spectrometer.
For the muon spectrometer of the ATLAS detector at the large hadron collider (LHC), large drift chambers consisting of 6 to 8 layers of pressurized drift tubes are used for precision tracking covering an active area of 5000 m2 in the toroidal field of superconducting air core magnets. The chambers have to provide a spatial resolution of 41 microns with Ar:CO2 (93:7) gas mixture at an absolute pressure of 3 bar and gas gain of 2?104. The environment in which the chambers will be operated is characterized by high neutron and background with counting rates of up to 100 per square cm and second. T…
A possible implementation of the Micro Drift Chamber (MDC) technique as a high resolution vertex detector in the upstream part of the DIRAC spectrometer was investigated in this paper. Simulations of different MDC layout were performed with the help of GARFIELD package. Based on the results of simulation the optimal chamber geometry and the gas mixture were selected. One cell prototype was produced and its characteristics were measured at different particle fluxes, various gas pressures and thresholds of electronics. Data observed together with expected coordinate resolution of MDC allow to em…
We present measurements of the energy loss of pions and electrons in drift chambers operated with a Xe,CO2(15%) mixture. The measurements are carried out for particle momenta from 1 to 6 GeV/c using prototype drift chambers for the ALICE TRD. Microscopic calculations are performed using input parameters calculated with GEANT3. These calculations reproduce well the measured average and most probable values for pions, but a higher Fermi plateau is required in order to reproduce our electron data. The widths of the measured distributions are smaller for data compared to the calculations. The elec…
The High-Luminosity LHC will provide the unique opportunity to explore the nature of physics beyond the Standard Model of strong and electroweak interactions. Highly selective first level triggers are essential for the physics programme of the ATLAS experiment at the HL-LHC where the instantaneous luminosity will exceed the LHC Run 1 instantaneous luminosity by almost an order of magnitude. The ATLAS first level muon trigger rate is dominated by low momentum muons, selected due to the moderate momentum resolution of the resistive plate and thin gap trigger chambers. This limitation can be over…
Operating HADES at the future FAIR SIS-100 accelerator challenges the rate capability of DAQ and electronics. A new, more robust version of front-end electronics needs to be built for the HADES drift chamber system. Due to the unavailability of the previously used ASD-8 analog read-out ASIC, PASTTREC (PANDA straw tube read-out ASIC) was tested as an ASD-8 replacement in different scenarios including a beam test. PASTTREC falls 20% short of the ASD-8 time precision but performs better w.r.t. signal charge measurements and overall operation stability. The measured time precision as a function of…
Studies of the performance of the CMS drift tube barrel muon system are described, with results based on data collected during the CMS Cosmic Run at Four Tesla. For most of these data, the solenoidal magnet was operated with a central field of 3.8 T. The analysis of data from 246 out of a total of 250 chambers indicates a very good muon reconstruction capability, with a coordinate resolution for a single hit of about 260 microns, and a nearly 100% efficiency for the drift tube cells. The resolution of the track direction measured in the bending plane is about 1.8 mrad, and the efficiency to re…
Air-ionization chambers have been used in radiotherapy and particle therapy for decades. However, fundamental parameters in action in the detector responses are sparsely studied. In this work we aimed to measure the electronic attachment, electrons and ions mobilities of an ionization chamber (IC) in air. The main idea is to extract these from the actual response of the IC to a single ionizing particle in order to insure that they were measured in the same condition they are to be used while neglecting undesired phenomena: recombination and space charge effect. The non-standard signal shape an…
After the high-luminosity upgrade of the Large Hadron Collider (LHC) at CERN, the ATLAS muon spectrometer is expected to work at 10 times increased background rates of gammas and neutrons. This is challenging as the momentum resolution of the spectrometer is expected to be 10 %. This requires a single tube resolution of the muon drift tubes of 80 mum. At background rates around 1000 Hz/cm2 space charge effects will lead in the slow and non-linear AR:CO2 = 93:7 gas mixture to a degradation of the drift-tube spatial resolution. This was studied before experimentally for gammas and low energetic …
Thomas Jefferson National Accelerator Facility（托马斯·杰斐逊国家加速器实验室）
In this article we describe the development of machine learning models to assist the CLAS12 tracking algorithm by identifying tracks through inferring missing segments in the drift chambers. Auto encoders are used to reconstruct missing segments from track trajectory. Implemented neural network was able to reliably reconstruct missing segment positions with accuracy of $\approx 0.35$ wires, and lead to recovery of missing tracks with accuracy of $>99.8\%$.
