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Sally Seidel

Publications and source records attributed to Sally Seidel.

18 recordsLinked to original sources
arXiv2026

Impact of Environmental Stress on Low Gain Avalanche Diode Sensors Response

Low Gain Avalanche Diodes or LGADs are silicon sensors capable of achieving excellent timing resolution due to their characteristic internal gain. Detectors based on LGAD technology play a crucial role in High Energy and Nuclear Physics experiments, among other applications. However, their performance is affected by environmental factors such as temperature, humidity, and storage conditions. A systematic evaluation of the response of LGAD sensors as a function of these environmental parameters is therefore of essential importance for any application. LGAD sensors fabricated at the Brookhaven National Laboratory are characterized and stress-tested against various operating conditions, such as rapid temperature and humidity changes. Dedicated and detailed simulations are used to interpret the experimental results.

physics.ins-det↗
arXiv2026

Active Edge Silicon Sensors Fabricated With Edge Ion Implantation and Microwave Annealing for Dopant Activation

Silicon detectors typically require an insensitive area around their periphery to accommodate guard rings, which help maintain the electric field uniformity around edge pixels and isolate the high leakage current from the physical edges of the detector. Minimization of this insensitive region is desirable for applications in high-energy physics, X-ray experiments, and medical imaging. Existing active edge technology offers a solution for reduction or total elimination of the insensitive region, via a continuation of the highly doped backside up the sidewalls of the device. However, current methods for realizing this technology are complex and expensive. We propose a new technique that simplifies the fabrication of highly doped edges using side ion implantation and microwave annealing. Tests demonstrating the feasibility of this proposed process were performed on a set of sensors, and current versus bias voltage measurements probing the edge effects were performed before and after the edge implantation and annealing. To aid in interpretation of the results, TCAD simulations of the test devices were performed. Significant improvement in the edge leakage current is observed, indicating the promise of this simplified process for fabrication of active edge sensors.

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arXiv2025

Response of AC-coupled Low Gain Avalanche Detectors to Ionizing and Non-ionizing Radiation Damage

Low gain avalanche diodes with DC- and AC-coupled readout were exposed to ionizing and non-ionizing radiation at levels relevant to future experiments in particle, nuclear, and medical physics and to astrophysics. Damage-related change in their acceptor removal constants and in the resistivity of the region between the guard ring and the active area are reported, as is change in the leakage current and depletion voltages of the active volumes.

physics.ins-det↗
arXiv2025

Gain characterization of LGAD sensors with beta particles and 28-MeV protons

Low Gain Avalanche Diodes, also known as LGADs, are widely considered for fast-timing applications in high energy physics, nuclear physics, space science, medical imaging, and precision measurements of rare processes. Such devices are silicon-based and feature an intrinsic gain due to a $p{^+}$-doped layer that allows the production of a controlled avalanche of carriers, with multiplication on the order of 10-100. This technology can provide time resolution on the order of 20-30 ps, and variants of this technology can provide precision tracking too. The characterization of LGAD performance has so far primarily been focused on the interaction of minimum ionizing particles for high energy and nuclear physics applications. This article expands the study of LGAD performance to highly-ionizing particles, such as 28-MeV protons, which are relevant for several future scientific applications, e.g. in biology and medical physics, among others. These studies were performed with a beam of 28-MeV protons from a tandem Van de Graaff accelerator at Brookhaven National Laboratory and beta particles from a $^{90}{\rm Sr}$ source; these were used to characterize the response and the gain of an LGAD as a function of bias voltage and collected charge. The experimental results are also compared to TCAD simulations.

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arXiv2024

Evidence of Charge Multiplication in Thin $25 \mathrm{\mu m} \times 25 \mathrm{\mu m}$ Pitch 3D Silicon Sensors

Characterization measurements of $25~\mathrm{\mu m} \times 25~\mathrm{\mu m}$ pitch 3D silicon sensors are performed, for devices with active thickness of $150~\mu$m. Evidence of charge multiplication caused by impact ionization below the breakdown voltage is observed in sensors operated at $-45~^\circ\mathrm{C}$. Small-pitch 3D silicon sensors have potential as high precision 4D tracking detectors that are also able to withstand radiation fluences beyond $10^{16}$~n$_{\rm eq}/$cm$^2$. This is applicable for use at future facilities such as the High-Luminosity Large Hadron Collider and the Future Circular Collider. Characteristics of these devices are compared to those of similar sensors of pitch $50~\mathrm{\mu m}\times 50~\mathrm{\mu m}$, showing comparable charge collection at low voltage, and acceptable leakage current, depletion voltage, breakdown voltage, and capacitance despite the extremely small cell size. The unirradiated $25~\mathrm{\mu m} \times 25~\mathrm{\mu m}$ sensors exhibit charge multiplication above about 90 V reverse bias, while, as predicted, no multiplication is observed in the $50~\mathrm{\mu m} \times 50~\mathrm{\mu m}$ sensors below their breakdown voltage. The maximum gain observed below breakdown is 1.33.

physics.ins-det↗
arXiv2023

Investigation of low gain avalanche detectors exposed to proton fluences beyond 10$^{15}$ n$_\mathrm{eq}$cm$^{-2}$

Low gain avalanche detectors (LGADs) deliver excellent timing resolution, which can mitigate mis-assignment of vertices associated with pileup at the High Luminosity LHC and other future hadron colliders. The most highly irradiated LGADs will be subject to $2.5 \times10^{15} \mathrm{n}_\mathrm{eq} \mathrm{cm}^{-2}$ of hadronic fluence during HL-LHC operation; their performance must tolerate this. Hamamatsu Photonics K.K. and Fondazione Bruno Kessler LGADs have been irradiated with 400 and 500 MeV protons respectively in several steps up to $1.5 \times10^{15} \mathrm{n}_\mathrm{eq} \mathrm{cm}^{-2}$. Measurements of the acceptor removal constants of the gain layers, evolution of the timing resolution and charge collection with damage, and inter-channel isolation characteristics, for a variety of design options, are presented here.

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arXiv2021

Response of Low Gain Avalanche Detector Prototypes to Gamma Radiation

Motivated by the need for fast timing detectors to withstand up to 2 MGy of ionizing dose at the High Luminosity Large Hadron Collider, prototype low gain avalanche detectors (LGADs) have been fabricated in single pad configuration, 2x2 arrays, and related p-i-n diodes, and exposed to Co- 60 sources for study. Devices were fabricated with a range of dopant layer concentrations and, for the arrays, a variety of inter-pad distances and distances from the active area to the edge. Measurements of capacitance versus voltage and leakage current versus voltage have been made to compare pre- and post-irradiation characteristics in gain layer depletion voltage, full bulk depletion voltage, and breakdown voltage. Conclusions are drawn regarding the effects of the gammas both on surface and interface states and on their contribution to acceptor removal through non-ionizing energy loss from Compton electrons or photoelectrons. Comparison of the performances of members of the set of devices can be used to optimize gain layer parameters.

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arXiv2021

Prediction of Leakage Current and Depletion Voltage in Silicon Detectors under Extra-Terrestrial Radiation Conditions

Silicon detection is a mature technology for registering the passage of charged particles. At the same time it continues to evolve toward increasing radiation tolerance as well as precision and adaptability. For these reasons it is likely to remain a critical element of detection systems associated with extra-terrestrial exploration. Silicon sensor leakage current and depletion voltage depend upon the integrated fluence received by the sensor, and upon its thermal history during and after the irradiation process. For minimal assumptions on shielding and hence on particle energy spectrum, and using published data on Martian ground temperature, we predict the leakage current density and the depletion voltage, as a function of time, of silicon sensors deployed continuously on the Mars surface for a duration of up to 28 Earth-years, for several sensor geometries and a worst-case temperature scenario.

physics.ins-det↗
arXiv2019

Production of Quarkonia and Heavy Flavor States in ATLAS

Two recent analyses of data collected with the ATLAS detector at the Large Hadron Collider are presented. In the first, a measurement of $b$ hadron pair production is presented, based on a data set corresponding to an integrated luminosity of 11.4 fb$^{-1}$ of proton-proton collisions recorded at $\sqrt{s}=8$ TeV. Events are selected in which a $b$ hadron is reconstructed in a decay channel containing a muon. Results are presented in a fiducial volume defined by kinematic requirements on three muons based on those used in the analysis. The fiducial cross section is measured to be $17.7 \pm 0.1({\rm stat})\pm 2.0({\rm syst.})$ nb. A number of normalized differential cross sections are also measured and compared to predictions from several event generators. In the second analysis, the modification of the production of $J/ψ$, $ψ(2S)$, and $Υ(nS)~(n=1,2,3)$ in $p+$Pb collisions with respect to their production in $pp$ collisions has been studied. The $p+$Pb and $pp$ data sets correspond to integrated luminosities of 28 nb$^{-1}$ and 25 pb$^{-1}$ respectively, collected at a center-of-mass energy per nucleon pair of 5.02 TeV. The quarkonium states are reconstructed in the dimuon decay channel. The yields of $J/ψ$ and $ψ(2S)$ are separated into prompt and non-prompt sources. The measured quarkonium differential cross sections are presented as a function of rapidity and transverse momentum, as is the nuclear modification factor $R_{p{\rm Pb}}$ for the $J/ψ$ and $Υ(nS)$. No significant modification of the $J/ψ$ production is observed, while $Υ(nS)$ production is found to be suppressed at low transverse momentum in $p+$Pb collisions relative to $pp$ collisions. The production of excited charmonium and bottomonium states is found to be suppressed relative to that of the ground states in central $p+$Pb collisions.

hep-ex↗
arXiv2013

Effect of Temperature and Charged Particle Fluence on the Resistivity of Polycrystalline CVD Diamond Sensors

The resistivity of polycrystalline chemical vapor deposition diamond sensors is studied in samples exposed to fluences relevant to the environment of the High Luminosity Large Hadron Collider. We measure the leakage current for a range of bias voltages on samples irradiated with 800 MeV protons up to 1.6\times 10^{16} p/cm^2. The proton beam at LANSCE, Los Alamos National Laboratory, was applied to irradiate the samples. The devices' resistivity is extracted for temperatures in the -10^\circC to +20^\circC range.

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arXiv2013

A Method for Real Time Monitoring of Charged Particle Beam Profile and Fluence

Detectors planned for use at the Large Hadron Collider will operate in a radiation field produced by beam collisions. To predict the radiation damage to the components of the detectors, prototype devices are irradiated at test beam facilities that reproduce the radiation conditions expected. The profile of the test beam and the fluence applied per unit time must be known. Techniques such as thin metal foil activation and radiographic image analysis have been used to measure these; however, some of these techniques do not operate in real time, have low sensitivity, or have large uncertainties. We have developed a technique to monitor in real time the beam profile and fluence using an array of $p-i-n$ semiconductor diodes whose forward voltage is linear with fluence over the fluence regime relevant to, for example, tracking in the LHC Upgrade era. We have demonstrated this technique in the 800 MeV proton beam at the LANSCE facility of Los Alamos National Laboratory.

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arXiv2009

ATLAS Pixel Radiation Monitoring with HVPP4 System

In this talk we present the basis for the protocol for radiation monitoring of the ATLAS Pixel Sensors. The monitoring is based on a current measurement system, HVPP4. The status on the ATLAS HVPP4 system development is also presented.

physics.ins-det↗
arXiv2008

Heavy Quark Production at the Tevatron

Results are presented from four CDF analyses involving heavy quark production in proton-antiproton collisions at center of mass energy 1.96 TeV. The shapes of b-jets are found to be broader than inclusive predictions and broader than both PYTHIA and HERWIG defaults. A measurement of the production cross section for psi(2S) is consistent with Run 1 results and with theoretical predictions associated with parton distribution function energy dependence. The inclusive b-jet production cross section is also consistent with theoretical predictions over six orders of magnitude. The b-bbar differential production cross section is compared to several theoretical models and found to be best described by MC@NLO + JIMMY.

hep-ex↗
arXiv2004

Comparison of Three-jet Events in Proton-Antiproton Collisions at sqrt{s}=1.8 TeV to Predictions from a Next-to-leading Order QCD Calculation

The properties of three-jet events with total transverse energy greater than 320 GeV and individual jet energy greater than 20 GeV have been analyzed and compared to absolute predictions from a next-to-leading order (NLO) perturbative QCD calculation. These data, of integrated luminosity 86 pb^-1, were recorded by the CDF Experiment for proton-antiproton collisions at sqrt{s}=1.8 TeV. This study tests a model of higher order QCD processes that result in gluon emission and can be used to estimate the magnitude of the contribution of processes higher than NLO. The total cross section is measured to be 466 \pm 3(stat.)^{+207}_{-70}(syst.) pb. The differential cross section is furthermore measured for all kinematically accessible regions of the Dalitz plane, including those for which the theoretical prediction is unreliable. While the measured cross section is consistent with the theoretical prediction in magnitude, the two differ somewhat in shape in the Dalitz plane.

hep-ex↗
arXiv2002

Jet Physics at the Tevatron

Recent analyses by the CDF and D0 Collaborations of jet data produced in proton-antiproton collisions at the Fermilab Tevatron Collider are presented. These include new studies of the inclusive jet production cross section, a measurement of the strong coupling constant, the first measurement of subjet multiplicity of quark and gluon jets, examination of ratios of multijet cross sections and their implications for choice of renormalization scale, and a study of charged jet evolution and energy flow in the underlying event. The results are compared to theoretical predictions.

hep-ex↗
arXiv2000

Capacitance of Silicon Pixels

Capacitance measurements have been made on silicon pixel sensors of types n+ on n, p+ on n, and n+ on p. The arrays test a variety of implant and gap widths, and the n+ on n devices test several p-stop designs. The measurements examine inter-pixel and backplane contributions and include studies of temperature dependence. Measurements were made before and after irradiation with fluences relevant to LHC experiments and Fermilab Tevatron Run 2.

hep-ex↗
arXiv1999

Inclusive Jets at the Tevatron

Results are presented for the inclusive jet cross section versus jet transverse energy in proton-antiproton collisions at center of mass energy 1.8 TeV as measured by the CDF and D0 detectors at Fermilab's Tevatron collider. The data are compared to next-to-leading order QCD predictions using different input parton distribution functions. The ratio of inclusive jet cross sections at center of mass energy 0.63 TeV and center of mass energy 1.8 TeV, versus jet x_T, is also presented and compared to QCD predictions.

hep-ex↗