arXiv subjects

Sébastien Philippe

Publications and source records attributed to Sébastien Philippe.

5 recordsLinked to original sources

arXiv2026

Reconstruction of fallout deposition from U.S. atmospheric nuclear tests conducted in New Mexico and Nevada

Between 1945 and 1962, the United States conducted 101 atmospheric nuclear weapon tests in New Mexico and Nevada, dispersing radioactive fallout across the contiguous United States. We reconstruct the first 10 days of fission-product deposition from the 94 non-zero-yield tests using U.S. government test data, benchmarked particle-size distributions, and the HYSPLIT atmospheric transport model driven by high-resolution ERA5 reanalysis. Comparisons with county-level iodine-131 deposition estimates from the National Cancer Institute show good agreement for tower and surface tests and motivate refinement of the particle-size distribution parameters associated with airbursts. We aggregate per-test reconstructions into a cumulative deposition map that includes long-range fallout from the 1945 Trinity test. Trinity fallout alone reached 46 states within 10 days, consistent with contamination observed in Indiana and Iowa soon after the test. An ensemble analysis bounds meteorological uncertainty for Trinity, showing robust large-scale transport patterns despite relatively sparse 1945 observations.

physics.ao-ph↗

arXiv2021

Radiation Exposures and Compensation of Victims of French Atmospheric Nuclear Tests in Polynesia

Between 1966 and 1974, France conducted 41 atmospheric nuclear weapon tests in Polynesia. Radioactive fallout impacted downwind atolls and islands leading to the external and internal exposure of the local populations to ionizing radiation. By law, individuals who were exposed to radiation in the context of these tests can file compensation claims with the French government if they develop certain radiogenic cancers. A claimant who meets the basic eligibility criteria (place, time, and type of disease) automatically benefits from the presumption of a causal link between radiation exposure and the development of their illness, unless the exposure is deemed too low. Since 2017, an effective dose threshold of 1 mSv per year has been used in the claims adjudication process. Decisions as to whether claimants have met this 1 mSv threshold in a given year are often made on the basis of data from government dose reconstruction studies carried out in 2005 and 2006. Using new information available from recently declassified documents on the radiological impact of French atmospheric nuclear tests in Polynesia, as well as atmospheric transport modeling of radioactive fallout, this article shows that maximum doses to the public for key atmospheric tests may have been underestimated by factors of 2 to 10 and estimates that the total population exposed above the compensation threshold of 1 mSv/yr could be greater than ~110,000. This latter result corresponds to about 90% of the entire population of French Polynesia at the time of the atmospheric tests. Integrating these updated dose estimates into the claim adjudication process would enlarge the pool of eligible claimants by a factor of 10. Also discussed are the legal and policy implications of these findings.

physics.med-ph↗

arXiv2018

A Cryptographic Escrow for Treaty Declarations and Step-by-Step Verification

The verification of arms-control and disarmament agreements requires states to provide declarations, including information on sensitive military sites and assets. There are important cases, however, where negotiations of these agreements are impeded because states are reluctant to provide any such data, because of concerns about prematurely handing over militarily significant information. To address this challenge, we present a cryptographic escrow that allows a state to make a complete declaration of sites and assets at the outset and commit to its content, but only reveal the sensitive information therein sequentially. Combined with an inspection regime, our escrow allows for step-by-step verification of the correctness and completeness of the initial declaration so that the information release and inspections keep pace with parallel diplomatic and political processes. We apply this approach to the possible denuclearization of North Korea. Such approach can be applied, however, to any agreement requiring the sharing of sensitive information.

cs.CR↗

arXiv2016

A physical zero-knowledge object-comparison system for nuclear warhead verification

Zero-knowledge proofs are mathematical cryptographic methods to demonstrate the validity of a claim while providing no further information beyond the claim itself. The possibility of using such proofs to process classified and other sensitive physical data has attracted attention, especially in the field of nuclear arms control. Here we demonstrate a non-electronic fast neutron differential radiography technique using superheated emulsion detectors that can confirm that two objects are identical without revealing their geometry or composition. Such a technique could form the basis of a verification system that could confirm the authenticity of nuclear weapons without sharing any secret design information. More broadly, by demonstrating a physical zero-knowledge proof that can compare physical properties of objects, this experiment opens the door to developing other such secure proof-systems for other applications.

physics.ins-det↗

arXiv2016

Bringing Information Credibility Back Into Transparency: The Case for a Global Monitoring System Of Green House Gas Emissions

The goal of climate change governance is to stabilize greenhouse gas concentrations. This requires the reduction of anthropogenic global net emissions. In the pursuit of such a reduction, knowledge of greenhouse gas sources and sinks is critical to define baselines, and assess the effectiveness of climate governance over time. Such information and the means to independently verify its credibility continue to remain out of reach including in the recent Paris agreement. This essay argues that to make real progress in mitigating future climate change, this status quo must be challenged both intellectually and practically. First, it proposes to acknowledge and address the inconsistency between the objectives of a climate regime and the role of transparency as a mean to achieve these objectives. It does so by redefining transparency as the addition of publicity and measurability, which turns it into a credible information generating mechanism for governance. Second, it shows how in practice, a global monitoring system of greenhouse gas net emissions, based on this new definition of transparency and designed as a global public good, could provide the necessary knowledge to help frame governance solutions by providing both credibility and completeness in understanding the scope of the problem to solve.

physics.soc-ph↗