An algorithm for calculating the Lorentz angle in silicon detectors

Future experiments will use silicon sensors in the harsh radiation environment of the LHC (Large Hadron Collider) and high magnetic fields. The drift direction of the charge carriers is affected by the Lorentz force due to the high magnetic field. Also the resulting radiation damage changes the properties of the drift. In this paper measurements of the Lorentz angle of electrons and holes before and after irradiation are reviewed and compared with a simple algorithm to compute the Lorentz angle.Comment: 13 pages, 7 figures, final version accepted by NIMA. Mainly clarifications included and slightly shortene

Comparison of Simulation Codes for the Beam Dynamics of Low-Energy Ions

Results are presented of the simulation of low–energy ion dynamics with three different codes: KOBRA, IGUN and CPO. To share work between different codes one needs to be confident that they agree. For test cases, good agreement was found between the codes and analytical solutions. Where possible, results have been compared to experimental data from the CERN Laser Ion Source. These simulations are in general agreement with the data of the real beam line. c The following article has been submitted to Review of Scientific Instruments. After it is published, it will be found at http://ojps.aip.org/rsio/

Lorentz angle measurements in irradiated silicon detectors between 77 K and 300 K

Future experiments are using silicon detectors in a high radiation environment and in high magnetic fields. The radiation tolerance of silicon improves by cooling it to temperatures below 180 K. At low temperatures the mobility increases, which leads to larger deflections of the charge carriers by the Lorentz force. A good knowledge of the Lorentz angle is needed for design and operation of silicon detectors. We present measurements of the Lorentz angle between 77 K and 300 K before and after irradiation with a primary beam of 21 MeV protons.Comment: 13 pages, 9 figures, submitted to ICHEP2000, Osaka, Japa

Operationalizing fairness in medical AI adoption: Detection of early Alzheimer’s Disease with 2D CNN

Objectives: To operationalize fairness in the adoption of medical artificial intelligence (AI) algorithms in terms of access to computational resources, the proposed approach is based on a two-dimensional (2D) Convolutional Neural Networks (CNN), which provides a faster, cheaper, and accurate-enough detection of early Alzheimer’s Disease (AD) and Mild Cognitive Impairment (MCI), without the need for use of large training datasets or costly high-performance computing (HPC) infrastructures. Methods: The standardized ADNI datasets are used for the proposed model, with additional skull stripping, using the BET2 approach. The 2D CNN architecture is based on LeNet-5, the LReLU activation function and a Sigmoid function were used, and batch normalization was added after every convolutional layer to stabilize the learning process. The model was optimized by manually tuning all its hyperparameters. Results: The model was evaluated in terms of accuracy, recall, precision, and f1-score. The results demonstrate that the model predicted MCI with an accuracy of .735, passing the random guessing baseline of .521, and predicted AD with an accuracy of .837, passing the random guessing baseline of .536. Discussion: The proposed approach can assist clinicians in the early diagnosis of AD and MCI, with high-enough accuracy, based on relatively smaller datasets, and without the need of HPC infrastructures. Such an approach can alleviate disparities and operationalize fairness in the adoption of medical algorithms. Conclusion: Medical AI algorithms should not be focused solely on accuracy but should also be evaluated with respect to how they might impact disparities and operationalize fairness in their adoption

Anomalous Lattice Vibrations of Single and Few-Layer MoS2

Molybdenum disulfide (MoS2) of single and few-layer thickness was exfoliated on SiO2/Si substrate and characterized by Raman spectroscopy. The number of S-Mo-S layers of the samples was independently determined by contact-mode atomic-force microscopy. Two Raman modes, E12g and A1g, exhibited sensitive thickness dependence, with the frequency of the former decreasing and that of the latter increasing with thickness. The results provide a convenient and reliable means for determining layer thickness with atomic-level precision. The opposite direction of the frequency shifts, which cannot be explained solely by van der Waals interlayer coupling, is attributed to Coulombic interactions and possible stacking-induced changes of the intralayer bonding. This work exemplifies the evolution of structural parameters in layered materials in changing from the 3-dimensional to the 2-dimensional regime.Comment: 14 pages, 4 figure

Strahlentherapie in der Behandlung von Weichteilsarkomen

Diese retrospektive Arbeit beschreibt die Behandlung von Weichteilsarkomen im Rahmen der Primärtherapie im Zeitraum von 1986 bis 2000 in der Klinik und Poliklinik für Strahlentherapie an der Westfälischen Wilhelms-Universität Münster. Dabei ist die Wirkung der Strahlentherapie bei 83 Patienten über achtzehn Jahren anhand des Verlaufs der Tumorerkrankung untersucht worden. In dem Zeitraum bis zum 01. August 2003 ist bei 27 Patienten im Rahmen der Nachsorge ein Rezidiv diagnostiziert worden. Die 5-Jahres-Rezidivfreiheitsrate für das Patientengut betrug 69 Prozent. Die 5-Jahres-Lokalrezidivrate (lokales oder lokal-systemisches Rezidiv) betrug für das Patientengut 75 Prozent. In dem festgelegten Zeitraum dieser Studie sind 30 Patienten, bei denen ein Weichteilsarkom diagnostiziert wurde, tumorspezifisch verstorben. Die 5-Jahres-Überlebensrate für das Patientengut betrug 70 Prozent

Search for composite and exotic fermions at LEP 2

A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermio

RD39 Status Report 2009

RD39 Status Report 2009. CERN RD39 Collaboration is developing super-radiation hard cryogenic silicon detectors for applications of LHC experiments and their future upgrades. The activities of RD39 Collaboration were focused in 2009 on concept of charge injected detector (CID)