arXiv subjects

Christopher Chambers

Publications and source records attributed to Christopher Chambers.

4 recordsLinked to original sources

arXiv2025

Elicitability

An analyst is tasked with producing a statistical study. The analyst is not monitored and is able to manipulate the study. He can receive payments contingent on his report and trusted data collected from an independent source, modeled as a statistical experiment. We describe the information that can be elicited with appropriately shaped incentives, and apply our framework to a variety of common statistical models. We then compare experiments based on the information they enable us to elicit. This order is connected to, but different from, the Blackwell order. Data preferred for estimation are also preferred for elicitation, but not conversely. Our results shed light on how using data as incentive generator in payment schemes differs from using data for statistical inference.

econ.TH↗

arXiv2024

Max- and min-stability under first-order stochastic dominance

Max-stability is the property that taking a maximum between two inputs results in a maximum between two outputs. We study max-stability with respect to first-order stochastic dominance, the most fundamental notion of stochastic dominance in decision theory. Under two additional standard axioms of nondegeneracy and lower semicontinuity, we establish a representation theorem for functionals satisfying max-stability, which turns out to be represented by the supremum of a bivariate function. A parallel characterization result for min-stability, that is, with the maximum replaced by the minimum in max-stability, is also established. By combining both max-stability and min-stability, we obtain a new characterization for a class of functionals, called the Lambda-quantiles, that appear in finance and political science.

q-fin.MF↗

arXiv2023

Simulation Study of Photon-to-Digital Converter (PDC) Timing Specifications for LoLX Experiment

The Light only Liquid Xenon (LoLX) experiment is a prototype detector aimed to study liquid xenon (LXe) light properties and various photodetection technologies. LoLX is also aimed to quantify LXe's time resolution as a potential scintillator for 10~ps time-of-flight (TOF) PET. Another key goal of LoLX is to perform a time-based separation of Cerenkov and scintillation photons for new background rejection methods in LXe experiments. To achieve this separation, LoLX is set to be equipped with photon-to-digital converters (PDCs), a photosensor type that provides a timestamp for each observed photon. To guide the PDC design, we explore requirements for time-based Cerenkov separation. We use a PDC simulator, whose input is the light information from the Geant4-based LoLX simulation model, and evaluate the separation quality against time-to-digital converter (TDC) parameters. Simulation results with TDC parameters offer possible configurations supporting a good separation. Compared with the current filter-based approach, simulations show Cerenkov separation level increases from 54% to 71% when using PDC and time-based separation. With the current photon time profile of LoLX simulation, the results also show 71% separation is achievable with just 4 TDCs per PDC. These simulation results will lead to a specification guide for the PDC as well as expected results to compare against future PDC-based experimental measurements. In the longer term, the overall LoLX results will assist large LXe-based experiments and motivate the assembly of a LXe-based TOF-PET demonstrator system.

physics.ins-det↗

arXiv2014

An RF-only ion-funnel for extraction from high-pressure gases

An RF ion-funnel technique has been developed to extract ions from a high-pressure (10 bar) noble-gas environment into vacuum ($10^{-6}$ mbar). Detailed simulations have been performed and a prototype has been developed for the purpose of extracting $^{136}$Ba ions from Xe gas with high efficiency. With this prototype, ions have been extracted for the first time from high-pressure xenon gas and argon gas. Systematic studies have been carried out and compared to the simulations. This demonstration of extraction of ions with mass comparable to that of the gas generating the high-pressure into vacuum has applications to Ba tagging from a Xe-gas time-projection chamber (TPC) for double beta decay as well as to the general problem of recovering trace amounts of an ionized element in a heavy (m$>40$ u) carrier gas.

physics.ins-det↗