Homeland Security Research Articles

Thoughtlessness in the Age of Homeland Security: Race, Surveillance, and Bureaucratic Violence in Immigration Enforcement

Thoughtlessness in the Age of Homeland Security: Race, Surveillance, and Bureaucratic Violence in Immigration Enforcement

Near-complete extraction of maximum stored energy from large-core fibers using coherent pulse stacking amplification of femtosecond pulses

High field science relies on ultrashort pulse lasers with multi-joule pulse energies for studying light–matter interactions under extreme conditions and for driving particle accelerators and secondary radiation sources of x rays, gamma rays, neutrons, positrons, muons, and protons. Next-generation laser drivers will require a 103−104 times increase in pulse repetition rates, producing multi-joule energies at multi-kilowatt average powers to enable practical applications in nuclear engineering, advanced materials, medicine, biology, homeland security, and high-energy physics. Spatially coherently combined femtosecond fiber lasers are recognized as a pathway to these next-generation drivers, with significant practical advantages including high efficiency and the possibility of compact integration. However, chirped pulse amplification in fibers is capable of extracting only a small fraction (usually ∼1%) of the maximum stored energy. Here we demonstrate near-complete maximum stored energy extraction with low accumulated nonlinearity from a large-core fiber amplifier using coherent pulse stacking amplification. We have amplified a 81-pulse stacking burst in a 85 µm core chirally coupled core Yb-doped fiber, extracting up to 9.5 mJ (∼90% of stored energy) with <4.5 radians of accumulated nonlinear phase, temporally combined this burst into a single pulse, and achieved 4.2 mJ pulses of 313 fs bandwidth-limited duration after compression. This represents, to our knowledge, the highest energy extracted and compressed into a femtosecond pulse from a single fiber amplifier, enabling approximately two orders of magnitude size reduction of future high-energy coherently spatially combined fiber laser arrays.

Charge Diffusion and Repulsion in Semiconductor Detectors

Semiconductor detectors for high-energy sensing (X/γ-rays) play a critical role in fields such as astronomy, particle physics, spectroscopy, medical imaging, and homeland security. The increasing need for precise detector characterization highlights the importance of developing advanced digital twins, which help optimize the design and performance of imaging systems. Current simulation frameworks primarily focus on modeling electron–hole pair dynamics within the semiconductor bulk after the photon absorption, leading to the current signals at the nearby electrodes. However, most simulations neglect charge diffusion and Coulomb repulsion, which spatially expand the charge cloud during propagation due to the high complexity they add to the physical models. Although these effects are relatively weak, their inclusion is essential for achieving a high-fidelity replication of real detector behavior. There are some existing methods that successfully incorporate these two phenomena with minimal computational cost, including those developed by Gatti in 1987 and by Benoit and Hamel in 2009. The present work evaluates these two approaches and proposes a novel Monte Carlo technique that offers higher accuracy in exchange for increased computational time. Our new method enables more realistic performance predictions while remaining within practical computational limits.

President Biden's Proclamation on Securing the Border and DHS-DOJ Interim Final Rule- A Potential Threat to the Health of Migrants.

Immigration policy, particularly regarding migrants crossing the US-Mexico border, has been a highly debated topic for years. There is a continued debate on how to maintain national security while protecting the health and dignity of migrants. In this commentary, we argue that the Biden Administration's "Proclamation on Securing the Border" issued on June 4, 2024, alongside the Department of Homeland Security (DHS) and Department of Justice's (DOJ) Interim Final Rule, poses a significant threat to the health of migrants seeking asylum at the US-Mexico border by forcing more migrants to wait in encampments in border towns. Specifically, migrants are more likely to face increased exposure to disease, mental health effects, and violence as a result of this proclamation. We call for structural policy reform and propose several alternative policies that can be enacted at the regional and national levels to help maintain the health and dignity of migrants while still prioritizing border security.

Department of Homeland Security to award $210 million in grants for nonprofit security measures

Department of Homeland Security to award $210 million in grants for nonprofit security measures

Emerging New-Generation Semiconductor Single Crystals of Metal Halide Perovskites for Radiation Detection

Radiation detection uses semiconductor materials to convert high-energy photons into charge (direct detection) or low-energy photons (indirect detection), and it has a wide range of applications in nuclear physics, medical imaging, astronomical detection, homeland security, and other fields. Metal halide perovskites have the advantages of high frequency number, high carrier mobility, high defect tolerance, low defect density, adjustable band gap, and fast light response, and they have wide application prospects in the field of radiation detection. However, the research is still in its infancy stage, and it is far from meeting the requirements of industrial application. This paper focuses on the advantages of metal halide perovskite single-crystal materials in both semiconductors-based direct conversion detection and scintillator-based indirect detection as well as the latest progress in this promising field. This paper not only introduces the latest application of lead halide perovskite monocrystalline materials in high-energy electromagnetic radiation detection (X-ray and γ-rays), but it also introduces the latest development of α-particle/β-particle/neutron detection. Finally, this paper points out the challenges and future prospects of metal halide perovskite single-crystal materials in radiation detection.

On the legal issues of the Shiprider Program

As an essential tool for the United States to pursue its maritime interests, the Shiprider Program has become the legal basis for the United States to carry out global comprehensive maritime law enforcement cooperation. However, the United States Coast Guard (hereafter USCG) has over-expanded its maritime jurisdiction by breaking through the limitations of the United Nations Convention on the Law of the Sea (hereinafter UNCLOS) in its law enforcement activities. The USCG’ activities in the South China Sea may jeopardize other countries’ maritime rights and interests and homeland security, aggravating the maritime disputes in those regions. Therefore, this paper proposes to clarify the applicable law and improve the responsibility mechanism for the Shiprider Program to ensure that the activities of the USCG are in line with the corresponding provisions of the UNCLOS.

Intrinsic scintillation performance & europium concentration effects in RbSr2I5 and RbSr2Br5 scintillators

Scintillators play crucial roles in homeland security applications like gamma ray spectroscopy and high energy X-ray radiography. For promising new scintillators, fine-tuning the luminescent dopant concentration is one avenue to further improve their performance and tailor their properties. In this work, the effects of europium dopant concentrations on the crystal growth, luminescence and scintillation properties of RbSr2Br5 and RbSr2I5 crystals was investigated. Nine transparent 7 mm diameter single crystals were grown via the Vertical Bridgman method. The optical band gap of RbSr2Br5 was 5.9 eV and that of RbSr2I5 was 4.7 eV. High scintillation performance was achieved with a relatively low europium concentration of 1 mol%. For both RbSr2Br5:Eu and RbSr2I5:Eu crystals, light yield of 60–90,000 ph/MeV, energy resolution 2.8–4.0 % at 662 keV, and X-ray afterglow 0.79–1.5 % at 2 ms were obtained.

Influence Policing: Domestic Digital Influence Campaigns and Algorithmic Strategic Communications in UK Law Enforcement and Homeland Security

Abstract This paper conceptualizes an emerging model of algorithmic policing; ‘influence policing’. This harnesses the affordances of Internet platforms to conduct domestic digital influence campaigns for crime prevention. These campaigns use sophisticated targeted messaging to directly ‘nudge’ behaviour and shape the culture of specific groups. By targeting people using micro-level behavioural, personal-interest and location-based data, influence campaigns aim to employ insights from behavioural psychology to prevent crime at a distance. We theorize this with an analysis of a dataset of more than 12,000 adverts and in-depth fieldwork with a dedicated police strategic communications team. Influence policing provides law enforcement with new capacities to craft and manicure hidden digital encounters with targeted publics, raising questions about its democratic character and police accountability.

Chemical Sensor Technologies for Sustainable Development: Recent Advances, Classification, and Environmental Monitoring

AbstractOne of the significant issues of concern in recent times is detecting, quantifying, and monitoring various chemical contaminants in the environment. Numerous inorganic and organic substances are discharged into the environment from various anthropogenic activities, thereby polluting the ecosystems' air, water, soil, and other components. These contaminants have been documented to have deleterious effects on humans, animals, and the environment. Therefore, the need for monitoring and continual quantification of the contents of these contaminants in various environmental matrices becomes paramount. Many diverse sensors are fabricated for multiple utilizations, including liquids and gas sensors, wireless sensors, electronic tongues, and noses for detecting volatile airborne substances, pollutants, and effluents. This review focuses on cutting‐edge technology used in chemical sensors for environmental protection and sustainable development. It also discusses the fabrication and development of chemical sensors and their working principles. In addition, highlights about the applications of chemical sensors in environmental monitoring are also elaborated. This review article discusses emerging sensor technologies and their application in ecological monitoring. Further, the recognition of chemical warfare agents and homeland security applications with the help of bioelectronic nose and tongue is discussed. Finally, some challenges associated with chemical sensors and future trends are also attempted.

Selective Detection of Picric Acid by Benzodiazepine Containing Enaminone Core as Receptor and Its Application to Real Water Sample Analysis.

Nitroaromatic compounds are highly explosive and illegitimate substances. Over a decade, chemists have been affianced in extensive research on the selective and sensitive detection of these nitroaromatic explosives for homeland security and environmental protection. The benzodiazepine-based enaminone (BDE) receptor has been synthesized by aqueous extract of onion catalyzed three-component reaction between o-phenylenediamine, dimedone with an aldehyde. The BDE probe is well analyzed and applied to a sensor that selectively detects picric acid (PA). UV-Vis and fluorescence spectroscopy were used to investigate the photophysical responses of the receptor (BDE). From the observed results BDE found turn-off fluorescence with the addition of picric acid and the lowest limit of detection and limit of quantification was achieved about 24.6 nM and 73.8 nM. The fluorescence quantum yield was attained about 0.28. The BDE-PA adduct formation was confirmed by 1H NMR titration analysis. The Job's plot analysis was performed through 1H NMR titrations and established the binding stoichiometry ratio of the BDE-PA adduct as 1:1 ratio. Further, DFT calculations supported the observed photophysical responses of BDE-PA adduct to confirm the molecular level interactions. The receptor was effectively applied to approximate level of picric acid in real water sample analysis.

Raising data availability and quality for improved disruption and carbon footprint management through a novel approach to primary data sharing: Virtual Watch Tower / VWT

Abstract The global supply chain and logistics industry is a self-organizing ecosystem consisting of numerous actors that work together to move goods from end to end. The different stakeholders involved are usually interdependent organizations, like freight forwarders, carriers, terminals, and homeland security agencies and information exchange between them is required to coordinate the activities along the individual transport chains. However, the exchange of information has often been analog, flawed, late, and incomplete. New circumstances, like unprecedented supply chain disruptions, new regulatory requirements around greenhouse gas (GHG) emissions, and generally growing shipper expectations create an urgent need for improved data sharing between actors. New technologies, like digital platforms, networks, and architectures as well as social media, mobile, analytics, cloud, and internet of things (SMACT) have brought some improvements, but not the required holistic digital perspective required or expected. Averages and approximations are usually insufficient to close data gaps, e.g., only primary data allows for accurate GHG emission calculations. Primary data sharing is widely seen as the missing piece of the puzzle. Primary data is data from the source providing an accurate state and picture of a situation. Primary data sharing at scale requires a new form of digital collaboration. We propose a rethink of digital collaboration as a means for broader primary private data sharing for complete end-to-end datasets and data quality, particularly focusing on the sharing of data associated with both transport plans and progress made in the respective movements of goods for more better disruption and carbon footprint management through more accurate calculations of estimated times of arrival (ETA) and GHG emissions. We introduce an example for digital collaboration in end-to-end supply chains that is focusing specifically on primary data sharing. The new thinking around digital collaboration manifests itself in the Virtual Watch Tower / VWT initiative (www.virtualwatchtower.org). In 2022, RISE and Singapore Maritime Institute signed a collaboration agreement focused on innovation in shipping. The VWT initiative is the first collaborative project under the umbrella of this partnership. The VWT is led by RISE, A*STAR, and VTT. VWT is a community-driven, digitally empowered initiative, a cargo owner-driven, and terminal-centric approach for improved supply chain management. It is the users themselves who co-create and co-evolve the solution that they need. The initiative aims to create a community that shapes the digital tool (VWTnet) they need to reach the required higher levels of visibility. This, through primary data sharing across the supply chain ecosystem and between actors (VWT Users) participating in individual end-to-end transports (VWT Shipments). The VWT serves as an object of research to hone the new thinking and understand the implications of its implementation.

Parent-child border separation and the road to repair: addressing a global refugee phenomenon

ABSTRACT As a result of the Department of Homeland Security’s zero-tolerance policy (ZTP), over 5,000 children were separated from their parents at the U.S. southern border from 2017-2021, with over 1,000 still lacking confirmed reunifications. Separations also occur daily due to immigration raids, chaotic processing, and changing immigration policies. This article addresses the most fundamental question faced by families enduring such separations; how to mend attachment bonds that have been suddenly severed, especially within a population likely already traumatized. The paper begins by updating readers about separation in the United States and offers a concise summary of the consequences of child-parent separation. The paper then introduces Child-Parent Psychotherapy (CPP) as an intervention for affected families. This paper also uniquely applies CPP to older children and provides three case examples of its use in treating separated families. Finally, the paper offers general suggestions for supporting these families.

From Securing the Border to Securing Nature: Homeland Security as an Emerging Environmental Actor in the U.S.–Mexico Borderlands

Hundreds of miles of barriers span the U.S.–Mexico border, not only blocking the migration of people, but also crisscrossing National Parks and Wildlife Refuges and bifurcating important wildlife corridors in the process. Despite their location within federally protected places, the past and present construction of these barriers has progressed unencumbered by federal oversight given the waiver of dozens of environmental regulations. This shift in regulation amid increased border militarization has not been fully evaluated for its environmental effects, as federal conservation agencies tasked with managing public borderlands are increasingly prohibited from studying how barriers will affect the landscape in the long term. This research examines how the state is shaping environmental governance and knowledge politics in the U.S.–Mexico borderlands, an environmentally significant and hyperpoliticized region integral to the maintenance of the United States as an imperial border-making institution. Bringing together theories on political ecologies of the settler colonial state with the racialization of nature, this article demonstrates how (1) the Department of Homeland Security has emerged as an environmental actor produced through a reconfiguration of settler state power; (2) knowledge claims about the environment are produced in ways that elide the ecological consequences of border barriers; and (3) racialized discourses of migrants are codified in environmental governing documents that support increased border militarization. I conclude with a discussion of how settler colonial technologies of environmental governance create new geographies of militarization and conservation in federally protected places along the U.S.–Mexico border.

Fear and Loathing in the Homeland Security State: A Bourdieusian Account for the Expansion of ICE

Fear and Loathing in the Homeland Security State: A Bourdieusian Account for the Expansion of ICE

The Book Review Column

Graph Theory in America: The First Hundred Years (Princeton University Press, 2023) by Robin Wilson, John J. Watkins, and David J. Parks chronicles the first hundred years of graph theory in North America, starting with the arrival of James Joseph Sylvester at Johns Hopkins University in 1876 and ending with the proof of the four color theorem by Kenneth Appel and Wolfgang Haken in 1976. Computability and Complexity: Foundations and Tools for Pursuing Scientific Applications (Springer, 2024) by decorated author Rod Downey is a new undergraduate textbook that covers advanced topics such as parameterized complexity, generic case complexity, and smoothed analysis. How to Think about Algorithms, 2nd ed. (Cambridge University Press, 2024) by Jeff Edmonds aims to teach students to think like a designer of algorithms. This new edition includes a short chapter on machine learning algorithms and more than 150 new exercises. A review of the first edition of this book appeared in this column in 2009. Differential Privacy (The MIT Press, 2025) by Simson L. Garfinkel, a senior data scientist at the US Department of Homeland Security, explains the algorithmic technology used by Google, Apple, and the US Census Bureau to protect the privacy of individuals in large datasets.

Excessive Use of Force and Migrant Death and Disappearance in Southern Arizona

Executive Summary In this article, we present a qualitative analysis of the events surrounding death or disappearance in autopsy and missing person reports from the Pima County Office of the Medical Examiner (PCOME) in Arizona to highlight how interactions between border enforcement personnel and migrants can be deadly. We reviewed PCOME records of undocumented border crosser deaths between 2000 and 2023 and observed three main types of deadly U.S. Border Patrol (USBP) practices: reckless motor vehicle pursuits, aggressive strategies used to detain individuals who are on foot, and the use of lethal force. Our findings reveal that these tactics, which we argue constitute forms of “excessive use of force,” represent significant yet overlooked factors contributing to migrant death and disappearance in southern Arizona. We make the following policy recommendations: 1. Immediate measures to prevent the loss of life (A). The Department of Homeland Security (DHS) should mandate a ban on border enforcement methods that provoke fear, panic, or confusion. (B). DHS should take measures to substantially reduce the use of high-speed motor vehicle pursuits by USBP and other immigration enforcement officials. (C). DHS should ensure that USBP officers are compliant with Department of Justice (DOJ) standards on use of deadly force, in particular the policy that “Deadly force may not be used solely to prevent the escape of a fleeing suspect.” 2. Investigate Border Fatalities Involving Border Enforcement Officers (A). We call on the Government Accountability Office (GAO) to conduct an official review of all medical examiner and coroner records along the U.S.-Mexico border for fatality cases in which border enforcement personnel were involved in any way in the circumstances surrounding death. (B). We encourage the formation of civilian review boards in border regions to review medical examiner and coroner records of migrant fatalities involving immigration officials as well as immigration officials’ apprehension strategies immediately preceding fatal encounters with migrants.

Forced Migration, Deterrence, and Solutions to the Non-Natural Disaster of Migrant Deaths Along the US-Mexico Border and Beyond

Executive Summary The International Organization of Migration has characterized the US-Mexico border as the world’s deadliest land migration route. By August 2024, a minimum of 5,405 persons had died or gone missing along this border since 2014, with record high numbers since 2021. Migrant deaths occur despite decades of: US Border Patrol search and rescue initiatives; public education campaigns targeting potential migrants on the dangers of irregular migration; dozens of academic publications and reports highlighting the root causes of these deaths; efforts by consular officials, local communities, and humanitarian agencies to locate, identify, and repatriate human remains; and desperate attempts by families to learn the fate of their missing loved ones. This paper introduces a special edition of the Journal on Migration and Human Security (JMHS), which draws on original research and the expertise of medical examiners, forensic anthropologists, social scientists, and humanitarian organizations to examine this persistent human tragedy. Many of the authors investigate migrant deaths in their professional capacities. They identify the dead, return remains to family members, and champion reforms to prevent deaths and better account for the dead and missing. This JMHS special edition represents a collaboration between the University of Arizona’s Binational Migration Institute, the Center for Migration Studies of New York (CMSNY), and the Working Group on Mapping Migrant Deaths along the US Southwest Border. The Working Group includes scholars and practitioners from California, Arizona, New Mexico, Texas, and New York who have met monthly since October of 2021. The special edition examines in granular detail the causes of migrant deaths, US border enforcement strategies and tactics, migrant death statistics, and the resource and capacity challenges faced by US counties along and leading from the US-Mexico border in investigating these deaths. The US Department of Homeland Security (DHS) and many public officials attribute the deaths to the predations of human smugglers, the victims’ ignorance or assumption of risk, and the harsh “natural” conditions to which migrants finally succumb. This special issue also documents the underlying non-natural causes of this enduring tragedy, and offers both overarching and more targeted solutions to preventing and minimizing migrant deaths. The issue builds upon and extends seminal research on migrant deaths first featured in CMSNY publications more than two decades ago. Section I introduces the issue of migrant deaths by posing the question: Why should we care? Section II describes the genesis of “prevention through deterrence”—a border enforcement theory and strategy—and its evolution through subsequent Customs and Border Protection (CBP) and US Border Patrol strategic plans. It describes the immense enforcement infrastructure built around this idea by successive administrations and Congresses, and it explains why it has failed to stem irregular migration and how it has contributed to migrant deaths. Section III reviews the main causes of migrant deaths—forced migration, the combined effects of prevention through deterrence and border enforcement tactics, the denial of access to asylum, the border wall, the “naturalization” of migrant deaths, and the dominant vision of the border as a site of danger and exclusion. Section IV reviews the legislative standards for identifying, investigating, and reporting on migrant decedents. It also details the deficiencies of Border Patrol and county-level sources of data on deaths, and it outlines ways to strengthen data collection. Section V discusses the burdens placed on communities along and leading from the border in investigating deaths and their need for greater resources and capacity to address this problem. Section VI outlines the anomalies and challenges related to the Border Patrol’s migrant rescue program. Section VII describes international legal standards to guide the investigation of migrant deaths and two model programs. Section VIII sets forth policy recommendations to prevent migrant deaths and to honor and account for the dead.

High repetition-rate 0.5 Hz broadband neutron source driven by the Advanced Laser Light Source

Neutron beams are an essential tool to investigate material structure and perform nondestructive analysis, as they give unique access to element composition, thus ideally complementing density analysis allowed by standard x-rays investigation. Laser-driven neutron sources, though compact and cost-effective, currently have lower average flux than conventional neutron sources, due to the limited repetition rate of the lasers used so far. However, advancements in laser technology allow nowadays to address this challenge. Here, we report results obtained at the Advanced Laser Light Source characterizing stable production of broadband (0.1–2 MeV) neutrons produced at a high repetition rate (0.5 Hz). The interaction of laser pulses of 22 fs duration and 3.2 J on-target energy with 2-μm-thick tantalum targets produced protons in the Target Normal Sheath Acceleration (TNSA) regime up to 7.3 MeV. These protons were subsequently converted into neutrons by (p,n) reactions in lithium fluoride (LiF). Activation measurements and bubble detectors were used to characterize neutron emissions, with a neutron fluence of up to ∼1.4×105 neutrons/shot/sr and energies mainly between a few hundred of kilo-electron volt and 2 MeV. The total neutron yield was ∼5×105 neutrons/shot. This paves the way for numerous applications, e.g., in homeland security, materials science, or cultural heritage.

Teaching to Fear: How Islamophobia is Perpetuated in Criminology and Adjacent Disciplines

Throughout American law enforcement history, a persistent pattern has emerged, emphasizing marginalized groups. This emphasis extends to higher education, notably seen in the proliferation of Terrorism and Homeland Security courses post-9/11 in criminology and related fields. These courses predominantly focus on the ‘Islamic threat’ to America, reflecting broader biases in counter-terrorism policies. Such biases overlook other forms of terrorism, especially right-wing extremism. We analyzed 382 syllabi from American higher education institutions to assess this bias. Our analysis reveals a concerning prevalence of misinformation in these courses. Educators hold a pivotal role in rectifying this imbalance, shaping the perceptions of future criminologists. Addressing this bias is crucial to providing a comprehensive understanding of terrorism threats and acknowledging all forms of extremism equally. It underscores the urgency for educators to present accurate and inclusive portrayals of terrorism in their curriculum.