Ion Back Flow (IBF) suppression is essential to avoid a space-charge distortion of the electric field under a high rate condition for the Time Projection Chamber (TPC). We developed Thick COBRA GEMs ...to investigate a capability of IBF suppression. It was found that the COBRA GEM can suppress IBF more effectively compared to a standard GEM. IBF reaches about 0.1-0.5% and energy resolution (σ) is ~ 20% with a stack configuration consisting of one standard GEM facing to the drift field and two COBRA GEMs.
We have developed a monolithic pixel detector with the silicon-on-insulator (SOI) pixel CMOS technology to use as radiation monitor, called RADPIX. The RADPIX intends to identify the type of ...radiation (α, β, γ, muon, etc.) by differences in hit pattern. The sensor is DC-coupled to the input of the pixel circuit so the leakage current I leak of a few pA for 40 μm × 40 μm at room temperature must be sunk by the pixel circuit for long time exposure. The RADPIX has the individual leakage compensation circuit. In addition to a digital output, the analog signal also can be read by using the comparator output as a store signal to latch the analog signal for the tracking accuracy enhancement. The prototype chip consists of 32 × 32 pixels with the pixel size of 40 μm × 40 μm (~1 mm square sensitive area). We report the design and the result of the basic evaluation test.
We developed a prototype time projection chamber using gas electron multipliers (GEM–TPC) for high energy heavy ion collision experiments. To investigate its performance, we conducted a beam test ...with three kinds of gases (Ar(90%)–CH
4(10%), Ar(70%)–C
2H
6(30%) and CF
4). Detection efficiency of 99%, and spatial resolution of
79
μ
m
in the pad-row direction and
313
μ
m
in the drift direction were achieved. The test results show that the GEM–TPC meets the requirements for high energy heavy ion collision experiments. The configuration and performance of the GEM–TPC are described.
The polyhedral homotopy continuation method is known to be a successful method for finding all isolated solutions of a system of polynomial equations. PHoM, an implementation of the method in C++, ...finds all isolated solutions of a polynomial system by constructing a family of modified polyhedral homotopy functions, tracing the solution curves of the homotopy equations, and verifying the obtained solutions. A software package PHoMpara parallelizes PHoM to solve a polynomial system of large size. Many characteristics of the polyhedral homotopy continuation method make parallel implementation efficient and provide excellent scalability. Numerical results include some large polynomial systems that had not been solved. PUBLICATION ABSTRACT
The sol-gel reactions of methyl- and vinyltrimethoxysilane under controlled conditions provided the corresponding polysilsesquioxanes and flexible thin films on further condensation of the ...precursors. Silicon oxycarbides containing a large amount of free carbon 58 mol% and 90 mol% were obtained in high yields 90 wt% on pyrolyzing the precursors of polymethyl-and polyvinylsilsesquioxane at 1400°C under N2 atmosphere, respectively. Moreover, pyrolytic polycondensation of polyvinylsilsesquioxane was found to give the silicon oxycarbide ceramic films without deformations and cracks. The composition and properties of films were investigated.
Summary
Objective: In general, drugs are used in accordance with an approved dosage regimen in expectation of an appropriate balance between efficacy and toxicity. However, dose control of drugs ...with a narrow therapeutic range and marked intersubject variability in pharmacokinetics should be established through individualization of dosing based on therapeutic drug monitoring (TDM). The purpose of this study was to examine differences between the approved dosage regimen and the doses of antiarrhythmic drugs and digoxin used in clinical practice and to examine the influence of TDM on dosing.
Methods: Prescription research of antiarrhythmic drugs was performed at five national hospitals in Japan. Prescriptions for antiarrhythmic drugs (cibenzoline, disopyramide, pirmenol, mexiletine, aprindine, flecainide, pilsicainide, amiodarone and digoxin) were counted for the study period. The mean dose and dose distribution of the drugs were determined in each hospital. Comparisons were made of mean dose obtained in the study with the dosage approved by the authority. In addition, the percentage of patients that received TDM was determined.
Results: A difference was seen between the approved dosage and the actual dose. For all drugs except flecainide, the mean dose was smaller than the approved dosage. For all drugs except digoxin, remarkable variations were seen in the dose distribution among the hospitals. Digoxin showed a similar dose distribution among the five hospitals. Overall, the percentage of patients that received TDM was low except for Hospital A. However, TDM of digoxin was relatively common at four of the hospitals.
Conclusions: It is concluded that, with the exception of digoxin, the appropriate dosing regimen for antiarrhythmic drugs is not yet established. The establishment of appropriate dosing regimens for antiarrhythmic drugs requires the more widespread adoption of TDM.
A future heavy-ion program at J-PARC has been discussed. The QCD phase structure in high baryon density regime will be explored with heavy ions at the beam momenta of around 10 A GeV/c at the beam ...rate of 1010–1011 Hz. For this quest, a large acceptance spectrometer is designed to measure electrons and muons, and rare probes such as multi-strangeness and charmed hadrons/nuclei. A heavy-ion acceleration scheme is under study with a new heavy-ion linac and a new booster ring, which accelerate and inject beams into the existing Rapid-Cycling Synchrotron and Main Ring synchrotron. An overview of the heavy-ion program and an accelerator design, as well as physics goals and a conceptual design of the heavy-ion experiment are discussed.
Signal shapes in multiwire proportional chamber-based TPCs Windelband, J. Alme T. Alt H. Appelshäuser M. Arslandok R. Averbeck E. Bartsch P. Becht L. Bratrud P. Braun-Munzinger H. Buesching H. Caines P. Christiansen F. Costa U. Frankenfeld J. J. Gaardhøje C. Garabatos P. Glässel T. Gunji H. Hamagaki J. W. Harris E. Hellbär H. Helstrup M. Ivanov J. Jung M. Jung A. Junique A. Kalweit R. Keidel S. Kirsch M. Kleiner M. Kowalski M. Krüger C. Lippmann M. Mager S. Masciocchi A. Matyja D. Miśkowiec R. H. Munzer L. Musa B. S. Nielsen J. Otwinowski M. Pikna A. Rehman R. Renfordt D. Röhrich H. S. Scheid C. Schmidt H. R. Schmidt K. Schweda Y. Sekiguchi D. Silvermyr B. Sitar J. Stachel K. Ullaland R. Veenhof V. Vislavicius J. Wiechula B
arXiv.org,
12/2023
Paper, Journal Article
Odprti dostop
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.
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