arXiv subjects

David Flores

Publications and source records attributed to David Flores.

4 recordsLinked to original sources

arXiv2022

First Results for the pLGAD Sensor for Low-Penetrating Particles

Silicon sensors are the go-to technology for high-precision sensors in particle physics. But only recently low-noise silicon sensors with internal amplification became available. The so-called Low Gain Avalanche Detector (LGAD) sensors have been developed for applications in High Energy Physics, but lack two characteristics needed for the measurement of low-energy protons (<60 keV): a thin entrance window (in the order of tens of nm) and the efficient amplification of signals created near the sensor's surface (in a depth below 1 um). In this paper we present the so-called proton Low Gain Avalanche Detector (pLGAD) sensor concept and some results from characterization of the first prototypes of the sensor. The pLGAD is specifically designed to detect low-energy protons, and other low-penetrating particles. It will have a higher detection efficiency than non-silicon technologies, and promises to be a lot cheaper and easier to operate than competing silicon technologies.

physics.ins-det↗

arXiv2021

Undecidability of Underfitting in Learning Algorithms

Using recent machine learning results that present an information-theoretic perspective on underfitting and overfitting, we prove that deciding whether an encodable learning algorithm will always underfit a dataset, even if given unlimited training time, is undecidable. We discuss the importance of this result and potential topics for further research, including information-theoretic and probabilistic strategies for bounding learning algorithm fit.

cs.LG↗

arXiv2015

Rad-hard vertical JFET switch for the HV-MUX system of the ATLAS upgrade Inner Tracker

This work presents a new silicon vertical JFET (V-JFET) device, based on the trenched 3D-detector technology developed at IMB-CNM, to be used as switches for the High-Voltage powering scheme of the ATLAS upgrade Inner Tracker. The optimization of the device characteristics is performed by 2D and 3D TCAD simulations. Special attention has been paid to the on-resistance and the switch-off and breakdown voltages to meet the specific requirements of the system. In addition, a set of parameter values has been extracted from the simulated curves to implement a SPICE model of the proposed V-JFET transistor. As these devices are expected to operate under very high radiation conditions during the whole experiment life-time, a study of the radiation damage effects and the expected degradation on the device performance is also presented at the end of the paper.

physics.ins-det↗

arXiv2015

Design and Fabrication of an Optimum Peripheral Region for Low Gain Avalanche Detectors

Low Gain Avalanche Detectors (LGAD) represent a remarkable advance in high energy particle detection, since they provide a moderate increase (gain ~10) of the collected charge, thus leading to a notable improvement of the signal-to-noise ratio, which largely extends the possible application of Silicon detectors beyond their present working field. The optimum detection performance requires a careful implementation of the multiplication junction, in order to obtain the desired gain on the read out signal, but also a proper design of the edge termination and the peripheral region, which prevents the LGAD detectors from premature breakdown and large leakage current. This work deals with the critical technological aspects when optimising the LGAD structure. The impact of several design strategies for the device periphery is evaluated with the aid of TCAD simulations, and compared with the experimental results obtained from the first LGAD prototypes fabricated at the IMB-CNM clean room. Solutions for the peripheral region improvement are also provided.

physics.ins-det↗