Alpha Decay Research Articles

Alpha decay properties of superheavy nuclei based on optimized alpha decay energies

Abstract The accuracy of the Finite-Range Droplet Model 2012 (FRDM) in describing the $\alpha$ decay energies of the 947 known heavy and superheavy nuclei is studied. It is clearly found that there are obvious discrepancies between the $\alpha$ decay energies obtained by FRDM and those reported by the evaluated atomic mass table AME 2020 (AME), in particular that FRDM underestimates the experimental $\alpha$ decay energies of the superheavy nuclei. The $\alpha$ decay energies of known nuclei obtained by FRDM are optimized, i.e. FRDM-NN, using a neural network approach and the accuracy is significantly improved. The $\alpha$ decay energy systematics obtained by both FRDM and FRDM-NN show the obvious shell effect at neutron number $N=184$, implying that the $N=184$ may be the magic number of the superheavy nucleus region. The $\alpha$ decay half-lives of known superheavy nuclei are calculated using the Generalized Liquid Drop Model (GLDM) and the Royer formula with the input of the optimized $\alpha$ decay energies obtained by FRDM-NN, and the calculations can reproduce the experimental data well. The $\alpha$ decay half-lives of unknown superheavy nuclei, in particular superheavy nuclei with $Z=119$ and 120, are predicted by using the GLDM and the Royer formula with the input of the $\alpha$ decay energy obtained by FRDM-NN. The relative error of two types of predicted $\alpha$ decay half-lives and superposition are analysed, and the average predictions are given. The $\alpha$ decay energies predicted by FRDM-NN and the $\alpha$ decay half-lives calculated by the GLDM and the Royer formula can provide a reference for the experimental synthesis of new superheavy elements with $Z=119$ and 120.

Discrimination of alpha decay from neutron interaction detection events in centrifugally tensioned metastable fluid detectors via machine learning analyses of cavitation-generated acoustic shock spectra

Discrimination of alpha decay from neutron interaction detection events in centrifugally tensioned metastable fluid detectors via machine learning analyses of cavitation-generated acoustic shock spectra

Delving into uncharted isotones demonstrating neutron shell closure at N=126

In our research, we have extensively investigated various decay modes including alpha, beta, proton, and spontaneous fission decay modes, focusing particularly on isotones characterized by [Formula: see text] and Z spanning from 53 to 100. Alpha-decay, one and two proton-decay half-lives were evaluated using an effective liquid drop model. Beta-decay and spontaneous fission half-lives have been evaluated using semi-empirical formulae. We observed notably shorter [Formula: see text] half-lives within the Z range of 53 to 81 and [Formula: see text]Pb is observed to be more stable. The prevalence of [Formula: see text]-decay half-lives was prominent for Z values ranging from 83 to 98, with the exception of [Formula: see text]At nuclei. Moreover, we identified two spontaneous fission emitters exhibiting half-lives ranging from microseconds to nanoseconds. Our analysis revealed significant neutron shell gaps at [Formula: see text], 66, 82 and 98 for [Formula: see text], pronounced shell structure indicative of relatively stable nuclei. Additionally, certain nuclei such as [Formula: see text]I, [Formula: see text]Au and [Formula: see text]U were found to exhibit lower stability compared to their neighboring nuclei. Our investigation led to the identification of 29 new isotones, comprising 22 [Formula: see text] emitters, five [Formula: see text] emitters and two spontaneous emitters. These newly identified isotones, synthesizable through fusion reactions, significantly contribute to advancing our comprehension of nuclear decay processes and isotonic behavior with [Formula: see text].

Theoretical Study of the Quadruple Gamma Transitions of Radioactive Radon and Radium Isotopes Based on Half-Life

Background: This study investigated multiple aspects of radon and radium’s nuclear properties since they are heavy, radioactive elements that may emit alpha, beta, and gamma radiation, which is connected to cancer and poses a risk to the environment. The purpose of this study is to investigate the significance of quadruple gamma transitions with |M(E2)|2w.u↓ as a valuable probe of the internal structure, deformations, and energy levels of atomic nuclei. Objective: By studying these gamma transitions, we hope to get more insight into the behavior of protons and neutrons within the nucleus as well as the fundamental forces governing their interactions. Methods: We applied MATLAB software to compute the probability of quadruple gamma transitions while accounting for the isotope energy characteristics and nuclei half-lives. Results: Our study’s important results about the transition forces for particular isotopes are as follows: Ra-226 was reported to have the lowest transition force value, measuring 9.6623×10−17, with a half-life of 1600 years. Furthermore, several transition force values were observed for Rn-214, the greatest values being 1.0248×104 and 1.5666×10−15. On the other hand, Rn-216 has the highest recorded transition force value (1.70305×10−4). Conclusions: The widths of Weisskopf transitions, gamma-gamma transitions, and gamma transitions were found by gathering and evaluating previously studied globally publicly available information. In the end, we successfully determined a relationship between the decay constant and the half-life of a decay event, which let us determine the probability that such events will occur within a certain time frame. Our study provides important insights into the transition probability within the examined nuclides and is in excellent agreement with global results and experimental data.

Measurement of Uranium Concentrations in the Soil Samples of Nineveh Province, Iraq Using CR-39 Detector

The physiological influence of radiation, which may induce cancer, makes the radioactive field vital to human health. Radon, which is hazardous to both humans and the environment, is deposited in soil via uranium decay. Extended exposure to elevated levels of alpha radiation, primarily radon, causes lung cancer. Thus, research is necessary to observe how the levels of human exposure vary. In evaluating natural exposure radiation, it is essential to control the quantity of radionuclides in the soil by determining the radioactivity level from these sources. Twenty samples of soil from different places in the Nineveh province in northern Iraq were analyzed for uranium content by the CR-39 nuclear track detector. These samples had radon concentrations ranging from 27.221 to 59.407 Bq.m-3, and the mean is 38.917 Bq.m-3. This mean value is below the level of reference limits 100 Bq.m-3 of the World Health Organization (WHO). Uranium levels ranged values from 0.129 to 0.281 ppm, with a mean of 0.182 ppm. Findings demonstrate that the natural radiations in the region are within the permissible range, as shown when comparing the results to global averages, the uranium concentration levels fell below the average of global value 2.8 ppm, and below the acceptable limit of 11.7 ppm.

Effect of Am-241 Irradiation on ZnO Crystallinity with Different Annealing Temperature

Am-241 is an alpha emitting isotope which can be used to fuel a nuclear battery via alphavoltaic effect by using a semiconductor to convert alpha radiation to electricity. The main issue of alphavoltaic battery is the radiation damage due to high energy alpha particle, resulted in a rapid decline in performance. Zinc oxide (ZnO) is known as a semiconductor with high radiation tolerance. In this study, the effect of annealing temperature to ZnO crystal was studied along with its alteration due to Am-241 irradiation overtime. The annealing temperatures were set at 450°C and 650°C. The irradiation process was carried out using Am-241 isotope for 12 days with an activity of 44.85 mCi and approximately 0.0866 MGy of absorbed dose. The crystal structure of fabricated and irradiated ZnO were investigated through X-ray Diffraction (XRD). The XRD diffraction pattern indicates that the crystal structure of ZnO is hexagonal wurtzite and still maintained after irradiation process. Raising the annealing temperature from 450°C to 650°C leads to a reduction in peak intensity. This change correlates with an increase in grain size post-irradiation. After exposure to alpha particle radiation, changes occurred in the diffraction peaks of ZnO. At 450°C annealing temperature, the intensity decreased by 94.822%, while at 650°C annealing temperature, the intensity decrease was 85.489%. This shows that increasing the annealing temperature can reduce the decrease in intensity after irradiation with alpha particles. The (002) plane shifted by 0.057˚ at 450°C annealing temperature and by 0.042˚ at 650°C after irradiation. In addition, the crystal lattice parameters increased after irradiation, which led to a change in the FWHM value and an increase in the crystal grain size.

Fractionated alpha and mixed beam radiation promote stronger pro-inflammatory effects compared to acute exposure and trigger phagocytosis

Introduction and methodsAiming to evaluate safety aspects of a recently proposed approach to target Alzheimer’s disease, we mimicked a complex boron neutron capture therapy field using a mixed beam consisting of high- and low-linear energy transfer (LET) radiation, 241Am alpha particles (α) and/or X-ray radiation respectively, in human microglial (HMC3) cells.ResultsAcute exposure to 2 Gy X-rays induced the strongest response in the formation of γH2AX foci 30 min post irradiation, while α- and mixed beam-induced damage (α:X-ray = 3:1) sustained longer. Fractionation of the same total dose (0.4 Gy daily) induced a similar number of γH2AX foci as after acute radiation, however, α- or mixed irradiation caused a higher expression of DNA damage response genes CDKN1A and MDM2 24 h after the last fraction, as well as a stronger decrease in cell viability and clonogenic survival compared to acute exposure. Phosphorylation of STING, followed by phosphorylation of NF-κB subunit p65, was rapidly induced (1 or 3 h, respectively) after the last fraction by all radiation qualities. This led to IL-1β secretion into the medium, strongly elevated expression of pro-inflammatory cytokine genes and enhanced phagocytosis after fractionated exposure to α- and mixed beam-irradiation compared to their acute counterparts 24 h post-irradiation. Nevertheless, all inflammatory changes were returning to basal levels or below 10–14 days post irradiation.DiscussionIn conclusion, we demonstrate strong transient pro-inflammatory induction by daily high-LET radiation in a microglia model, triggering phagocytosis which may aid in clearing amyloid beta, but importantly, from a safety perspective, without long-term alterations.

Exploring alpha emissions in neutron induced reactions via QMFT based dynamical cluster-decay approach

Abstract This study theoretically investigates alpha emission from compound nuclei formed in neutron-induced reactions, inspired by the experiments of Yu M. Gledenov et al. at Peking University, China. The research focuses on the decay dynamics of even-mass compound nuclei 144Nd* and 148Sm*, formed with neutron beam energies of 4 to 6 MeV. Employing the Dynamical Cluster-decay Model (DCM) based on Quantum Mechanical Fragmentation Theory (QMFT), high Q-value alpha emission channels 144Nd*→ 140Ce+α and 148Sm*→ 144Nd+α are explored. Cross-sections for alpha emissions are calculated by optimizing the neck-length parameter “∆R”, showing agreement with experimental data. Given the highly asymmetric incoming channel, the beam energy approximates the centre of mass energy (E beam≈E c.m. ). The study evaluates the impact of deformations, considering spherical and quadrupole-deformed configurations of the decaying fragments, and examines the alterations in potential energy surfaces. For deformed fragmentation, orientations are optimized for hot configurations. A comparative analysis of fragmentation structures, preformation profiles, and barrier characteristics is conducted between spherical and quadrupole-deformed fragmentation. The DCM’s collective clusterization approach treats all exit channels equally, emphasizing the formation of the preferred decay channel over competing channels such as fission. Observed changes in fragmentation profiles underscore the influence of nuclear parameters like angular momentum and deformations, providing insights into the dynamics of compound nucleus decay and the pivotal role of these parameters in shaping reaction outcomes.

First motional stark effect measurements at Wendelstein 7-X

The rotational transform plays a crucial role in magnetic confinement devices and its profile is directly related to stability and confinement properties. A popular way to assess the rotational transform profile is using a Motional Stark Effect diagnostic system, which relies on the splitting of the Balmer alpha emission, due to the interaction between a particle beam and the plasma. A prototype diagnostic was installed at the stellarator Wendelstein 7-X, in order to demonstrate that such a diagnostic can be operated in this device. This work presents the diagnostic design and preliminary measurements as well as the calibration procedures necessary to deal with the extra complexity of measuring polarisation via an aluminium mirror. Qualitative agreement with simulations is shown in the variation of the measured polarisation angle over wavelength. A small but significant change in the measured angle is seen with changes in the plasma beta. While of a similar order to that expected, insufficient sensitivity of the prototype precludes a quantitative match to the prediction. The required changes to sufficiently improve the sensitivity to achieve this in future experiments is discussed.

Millimeter-scale radioluminescent power for electronic sensors.

The storage and generation of electrical energy at the mm-scale is a core roadblock to realizing many untethered miniature systems, including industrial, environmental, and medically implanted sensors. We describe the potential to address the sensor energy requirement in a two-step process by first converting alpha radiation into light, which can then be translated into electrical power through a photovoltaic harvester circuit protected by a clear sealant. Different phosphorescent and scintillating materials were mixed with the alpha-emitter Th-227, and the conversion efficiency of europium-doped yttrium oxide was the highest at around 2%. Measurements of the light generated by this phosphor when combined with Th-227 reveal that over 100 nW of optical power can be expected at volumes around 1mm3 over more than two months. The use of a clear sealant, together with the evaporation of liquid solution following the mixture, can enable safe miniaturization for size-constrained medical and internet-of-things (IoT) sensor applications.

Impact of cell geometry, cellular uptake region, and tumour morphology on 225Ac and 177Lu dose distributions in prostate cancer

BackgroundRadiopharmaceutical therapy with 225Ac- and 177Lu-PSMA has shown promising results for the treatment of prostate cancer. However, the distinct physical properties of alpha and beta radiation elicit varying cellular responses, which could be influenced by factors such as tumour morphology. In this study, we use simulations to examine how cell geometry, region of pharmaceutical uptake within the cell to model different internalization fractions, and the presence of tumour hypoxia and necrosis impact nucleus absorbed doses and dose heterogeneity with 225Ac and 177Lu. We also develop nucleus absorbed dose kernels for application to autoradiography images.MethodsWe used the GATE Monte Carlo software to simulate three geometries of LNCaP prostate cancer cells (spherical, cubic, and ovoid) with activity of 225Ac or 177Lu internalized in the cytoplasm or bound to the extracellular membrane. Nucleus S-values were calculated for each geometry, source region, and isotope. The cell models were used to create nucleus absorbed dose kernels for each source region describing the dose to each nucleus in a cell layer, which were applied to simulated tumours composed of normoxic, hypoxic, or necrotic cancer cells to obtain dose rate maps. Absorbed doses within the tumours and dose heterogeneity were analyzed for each tumour morphology and isotope. Cell geometry made a minimal impact on S-values to the nucleus, however internalization resulted in higher nucleus doses. Applying the kernels to the simulated tumour maps showed that doses to each cell type varied between 225Ac and 177Lu depending on tumour morphology. Dose heterogeneity within tumours was slightly higher with 225Ac, however the tumour morphology made a larger impact on dose heterogeneity compared to the choice of isotope, with hypoxic and necrotic tumours having very heterogeneous dose distributions.ConclusionsCell geometry simplifications may still allow robust results in simulation studies. Furthermore, the morphology of the tumour itself may make a larger impact on treatment response compared to other variables such as ratio of internalization. Finally, nucleus absorbed dose kernels were created that could enable microdosimetric studies with autoradiography.

Clinical Best Practices for Radiation Safety During an Alpha DaRT Treatment.

Alpha DaRT is a new alpha radiation treatment for treating solid tumors and is currently being evaluated through clinical trials worldwide. Being a novel radiation treatment, it is important to discuss the safety considerations and procedures that are needed to ensure safe use of this unique approach. The objective of this article is to provide a set of recommendations-radiation safety best practices that were developed based on operational and clinical experience.

Melanoma Cells from Different Patients Differ in Their Sensitivity to Alpha Radiation-Mediated Killing, Sensitivity Which Correlates with Cell Nuclei Area and Double Strand Breaks.

Background/Objective: In this study, for the first time, we examined and compared the sensitivity of four patient-derived cutaneous melanoma cell lines to alpha radiation in vitro and analyzed it in view of cell nucleus area and the formation of double-strand breaks (DSB). Melanoma cells sensitivity to alpha radiation was compared to photon radiation effects. Furthermore, we compared the sensitivity of the melanoma cells to squamous cell carcinoma. Methods: Human melanoma cell lines YDFR.C, DP.C, M12.C, and M16.C, and the squamous cell carcinoma cell line, CAL 27, were irradiated in vitro using Americium-241 as alpha-particle source. Cells were irradiated with doses of 0 to 2.8 gray (Gy). Cell viability, DNA DSB, and nuclear size were measured. Results: 1. Alpha radiation caused death and proliferation arrest of all four melanoma cell lines, but inter-tumor heterogeneity was observed. 2. The most sensitive cell line (DP.C) had a significantly larger nucleus area (408 µm2) and the highest mean number of DSB per cell (9.61) compared to more resistant cells. 3. The most resistant cell, M16.C, had a much lower nucleus area (236.99 µm2) and DSB per cell (6.9). 4. Alpha radiation was more lethal than photon radiation for all melanoma cells. 5. The SCC cell, CAL 27, was more sensitive to alpha radiation than all melanoma cells but had a similar number of DSB (6.67) and nucleus size (175.49 µm2) as the more resistant cells. 6. The cytotoxic effect of alpha radiation was not affected by proliferation arrest after serum starvation. 7. Killing of cells by alpha radiation was marginally elevated by ATR or topoisomerase 1 inhibition. Conclusions: This study demonstrates that various human melanoma cells can be killed by alpha radiation but exhibit variance in sensitivity to alpha radiation. Alpha radiation applied using the Intra-tumoral Diffusing alpha-emitters Radiation Therapy (Alpha DaRT) methodology may serve as an efficient treatment for human melanoma.

Chronic bronchitis and bronchial asthma: the impact of chronic occupational radiation exposure on incidence and mortality of Mayak nuclear workers.

The information about the radiation risk of non-cancer respiratory diseases is inconsistent and mainly corresponds to mortality. Previously, an increased risk of chronic bronchitis incidence was demonstrated in the cohort of workers employed at the first Russian nuclear facility Mayak Production Association who had been chronically exposed to gamma rays (externally) and to alpha-active plutonium aerosols (internally). Within this retrospective study, we performed analyses of incidence of and mortality from chronic bronchitis and bronchial asthma using improved estimates of radiation doses provided by the "Mayak Worker Dosimetry System (MWDS) - 2013". The cohort included 22,377 individuals hired in 1948-1982, and its follow-up was extended by 10 years (to the end of 2018). The excess relative risk of chronic bronchitis incidence per unit radiation dose (ERR/Gy) and the 95% confidence interval (95% CI) were: with the 0-year lag ERR/Gy=0.07 (95% CI -0.01, 0.17) for gamma exposure and ERR/Gy=0.36 (95% CI 0.13, 0.68) for alpha exposure; with the 10-year lag ERR/Gy=0.15 (95% CI 0.04, 0.30) for gamma exposure and ERR/Gy=0.54 (95% CI 0.19, 1.03) for alpha exposure. The chronic bronchitis mortality risk was significantly associated with internal alpha exposure only for certain worker categories: ERR/Gy=4.08 (95% CI 0.59, 14.3) in males; ERR/Gy=7.10 (95% CI 0.31, 70.44) in former smokers; ERR/Gy=7.94 (95% CI 1.71, 30.2) in workers with the smoking index above 20 pack×years. No association was observed in the chronic bronchitis mortality risk with external gamma exposure. No strong evidence was observed for the impact of gamma and alpha exposure on risk of mortality from chronic bronchitis. The study confirmed the significant positive linear association of the chronic bronchitis incidence risk with gamma and alpha radiation doses from occupational chronic external and internal exposure. However, the estimates of ERR/Gy of alpha particles from internal exposure appeared to be almost 2.4-3 times lower than those based on the MWDS-2008. The observed inconsistency requires further clarification. As for bronchial asthma in Mayak workers, no association was demonstrated in the incidence and mortality risks with occupational gamma and alpha radiation exposure.

Study of Cluster Decays Including Those Leading to Doubly Magic Nucleus 298114 and Branching Ratios Relative to Alpha Decay

The study of superheavy nuclei (SHN) and their decay properties is one of the rapidly growing fields in nuclear physics. Using the CYE model, we have already studied the decay properties of the alpha decay, cluster decay, and spontaneous fission of the heavy and superheavy nuclei. In the present work, we will examine the effects by incorporating hexacontatetrapole (β6) parameter in the parent nucleus along with the quadrupole (β2), and hexadecapole (β4) deformations of the decaying parent nucleus emitting clusters 84Be and 126C. These deformations lower the half-life values, because they reduce the height and width of the potential barrier. Additionally, the creation of the doubly magic daughter 298114 from different decaying nuclei is computed. The calculated half-lives are compared with other models and are found to be in a good agreement. The branching ratios relative to the alpha-decay have also been calculated.

Gan Photonic Crystals: Spectral Dynamics in UV, X‐Ray, and Alpha Radiation

In this work, a comparative analysis of gallium nitride (GaN) thin films is conducted, both with and without photonic crystal (PhC) structures, focusing on their scintillation and photoluminescence properties. GaN's suitability for diverse optoelectronic and radiation detection applications is analyzed, and this study examines how PhC implementation can enhance these properties. Methodologically, the emission spectra is analyzed from 5.9 keV X‐ray sources, decay curves, pulse height spectra in response to 241Am 5.5 MeV alpha‐rays, and photoluminescence spectra induced by UV excitation. The findings demonstrate a substantial increase in quantum efficiency for PhC GaN, nearly tripling the light yield that of conventional plain GaN thin films under the UV excitation. The enhancement is predominantly attributed to the PhC GaN's proficiency in guiding light at 550 nm, a feature indicative of its spectral filtering capabilities, as detailed in the study. Furthermore, side‐band scintillations, stemming from inherent materials like Chromium that generate scintillations at diverse wavelengths, are effectively mitigated. A key finding of this study is the effective detection of light not only at the rear but also along the lateral sides of the films, offering new possibilities for radiation detector design and architecture.

Repair effect of He+ ions in borosilicate glass by sequential irradiation

The structural variations from alpha decay in borosilicate glasses attract much attention. The glass samples were irradiated with single and sequential beams in Xe20+ and He+ ions. Sequential irradiation means the glasses, which were pre-irradiated with Xe20+ ions, were irradiated with He+ions. The variations in macroscopic properties and microstructure were analyzed by nanoindentation, Raman spectra, infrared spectra and XPS spectra, respectively. After He+ ion irradiation, the hardness of glasses decreases, and the BO4 units increase in the glasses, attributed to the migration of Na on the sample surface. The hardness recovery was observed in sequential irradiation. Combined with the results of single ion irradiation, a reason for hardness recovery is that the migration of Na in deep layer causes the BO3 structure to transform into BO4 structure after He+ions irradiation. The variation of boron structures in sequential irradiation could be considered as the superposition of two single irradiation effects.

Pathomorphological Features of Lung Fibrosis in Individuals Occupationally Exposed to Alpha Radiation

The aim of this study was to search for the specific morphological features of radiation-induced lung fibrosis compared to pulmonary fibrosis of another origin, using biological specimens of lung tissue collected from workers internally exposed to alpha radiation. The morphological features of lung fibrosis were defined using biological specimens of lung tissue that had been collected during autopsy examinations from 56 workers diagnosed with plutonium-induced lung fibrosis during life, from 34 workers with lung fibrosis of another origin (due to chronic inflammatory lung diseases) and from 35 workers without clinical pulmonary pathology (controls). The total lung-absorbed dose of gamma radiation from external exposure did not significantly differ among the studied groups, and the total lung-absorbed dose of alpha radiation from internal exposure was significantly higher in workers with plutonium-induced lung fibrosis. To investigate the extracellular matrix components, mono- and polyclonal labeled antibodies against type I, IV, and V collagens were used. In addition, to evaluate the system of extracellular matrix metabolism regulation, the antibodies against matrix metalloproteinases MMP-2, MMP-9, tissue inhibitors of matrix metalloproteinases TIMP-1 and TIMP-2 were used. The study revealed qualitative and quantitative morphological peculiarities of plutonium-induced lung fibrosis compared to lung fibrosis of another origin. This allows us to conclude that plutonium-induced lung fibrosis is a specific type of lung fibrosis, which is characterized with specific location and architectonics of fibrosis foci within the lung, and with changes in levels of collagen, elastic and reticular fibers in the pulmonary stroma. The analysis demonstrated that hyperproduction of type V collagen plays a key role in the development of plutonium-induced lung fibrosis. In addition, the imbalance between the expression of MMPs and their inhibitors plays an important role in the development of lung fibrosis.

Quasi-stationary alpha-states from non-Hermitian Hamiltonians of even-even heavy isotones

Three isotone groups (N=128,130,132) with alpha-decaying, short-lifetime even-even nuclei of large mass number are studied in order to show that the tunneling phase of the alpha decay process is appropriately describable by a specific non-hermitian mean-field model. In this model the mean-field lifetime of the alpha cluster is extracted directly by the complex diagonalization of the non-hermitian Hamiltonian of the system. In this paper, we demonstrate that by calculating the mean-field width of the alpha clusters, in each isotone groups, by non-perturbative complex spectral calculations, then, due to the distinct patterns the isotones are naturally organized into with respect to the half-life and proton number, the total width of the alpha-decay can be approximated by matching the calculated results to experimental data.

Measuring very low radiation doses in PTFE for nuclear forensic enrichment reconstruction

Every country that has made nuclear weapons has used uranium enrichment to do so. Despite the centrality of this technology to international security, there is still no reliable physical marker of past enrichment in the open literature that can be used to perform forensic verification of historically produced weapons on gas centrifuges. We show that the extremely low radioactivity from uranium alpha emissions during enrichment leaves detectable and irreversible calorimetric signatures in the common enrichment gasket material PTFE, allowing for historical reconstruction of past enrichment activities at a sensitivity better than one weapon's quantity of highly enriched uranium. Fast scanning calorimetry also enables the measurement of recrystallization enthalpies of sequentially microtomed slices, confirming the magnitude and the type of radiation exposure while also providing detection of tampering and a method for analyzing field samples useful for treaty verification. This work opens the door for common items to be turned into precise dosimeters to detect the past presence of radioactivity, nuclear materials, and related activities with high confidence.