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DARPA SIGMA+ using advanced intelligence analytics to detect chemical, biological, and explosives threats

Since the invention of nuclear power, there have been numerous “accidents.” From Three Mile Island and Chernobyl to the more recent problems in Fukushima, it would seem nuclear power is not fully under our control. Recently  a Chinese scientist  has warned that the single mountain under which North Korea most likely conducted its five most recent nuclear bomb tests, including the latest and most powerful could be at risk of collapsing. Wang Naiyan, the former chairman of the China Nuclear Society and senior researcher on China’s nuclear weapons program, said that if Wen’s findings were reliable, there was a risk of a major environmental disaster. Another test might cause the whole mountain to cave in on itself, leaving only a hole from which radiation could escape and drift across the region, including China, he said. Terrorist attacks involving the use of radiological and nuclear materials also  pose a potential threat to U.S. citizens and service members.


Early detection of these materials and devices made from them is a critical part of the U.S. strategy to prevent attacks. Sensitive, compact, real-time, and low-cost detectors, along with innovative deployment and networking strategies, would significantly enhance detection
and deterrence of such an attack. One of thrust areas of DARPA is to counter CBRNE threats by developing and testing networked, mobile and cost-effective nuclear- and radiological-weapons detectors that can easily be deployed to provide real-time surveillance over city-scale areas.


Current handheld radiological detectors are expensive and lack networking capability. In addition, existing neutron detectors used for nuclear materials detection at, for example, ports of entry, are large, expensive, and rely on exotic materials, such as helium-3, a rare isotope of helium that can capture a neutron from radiating nuclear sources. These limitations have prohibited widescale and continuous deployment of radiation detection systems.  Adding further complexity to the situation, abundant sources of non-threatening radiation in hospitals, on sites, and in industry settings can trick existing detectors, causing false alarms.


The SIGMA program began in 2014 with the challenge to the technology community of transforming nuclear and radiological threat detection for city-scale monitoring. It was designed to investigate new technologies that have the potential to protect city-and metropolitan-sized areas from radiological and nuclear-based terror threats through large-scale deployment of low-cost, high-capability radiation sensors and automated detection algorithms to provide real-time alerts of potential threats.


Key components of the SIGMA system include small and large form-factor mobile and static radiation sensors intended to support agile deployment strategies; the network infrastructure to connect thousands (up to ten thousand) of these sensors; the cloud-computing infrastructure to automatically analyze streaming spectroscopic data from these sensors in real-time as well as store—in an easily retrievable manner—many billions of these spectra for spatiotemporal and forensic analyses.


SIGMA developed and networked thousands of high-capability, low-cost detectors to demonstrate large-scale, continuously streaming physical sensor networks for the RN interdiction mission. In collaboration with officials in the Washington, D.C., metropolitan area and the Port Authority of New York and New Jersey, DARPA in 2016 tested the devices and networking system at critical transportation hubs and on a city-wide scale involving 1,000 detectors. That test showed the system could fuse the data provided by all those sensors to create minute-to-minute situational awareness of nuclear threats. Working in close cooperation with the Department of Homeland Security, DARPA’s technology has been on track for deployment in multiple locations. SIGMA capabilities have been tested and operationalized with federal, state, and international partners.


Working through the Joint Program Executive Office for Chemical, Biological, Radiological, and Nuclear Defense (JPEOCBRND), 1,000 wearable SIGMA radiation detectors are being deployed to U.S. Forces in the Republic of Korea. In 2019, the Department of Homeland Security awarded a commercial contract that specifies Silverside neutron detectors, developed under the SIGMA program, as
replacements for current U.S. radiation portal monitors. These monitors provide screening at critical locations, such as border entries and ports.

The success of the SIGMA program has led to a follow-on DARPA effort called SIGMA+.

DARPA is now looking at expanding SIGMA’s capabilities to include threat detection for other harmful elements such as chemicals, explosives, and biological and radiological agents. DARPA launched  SIGMA+ program in 2018 with aim  to expand SIGMA’s advance capability to detect illicit radioactive and nuclear materials by developing new sensors and networks that would alert authorities to chemical, biological, and explosives threats as well.  The SIGMA+ program aims to expand SIGMA’s advanced capability to detect illicit radioactive and nuclear materials by developing new sensors and networks that would alert authorities to chemical, biological, and explosives threats as well.


“The goal of SIGMA+ is to develop and demonstrate a real-time, persistent CBRNE early detection system by leveraging advances in sensing, data fusion, analytics, and social and behavioral modeling to address a spectrum of threats,” said Vincent Tang, SIGMA+ program manager in DARPA’s Defense Sciences Office.


In this episode of the Voices from DARPA podcast, Mark Wrobel, a program manager since 2019 in the agency’s Defense Sciences Office (DSO), chronicles progress in the SIGMA+ program and its potential near-term relevance to monitoring the environment for SARS-CoV-2, the virus that causes COVID-19. The now-completed predecessor program, SIGMA, delivered a sensor and analysis system for detecting imminent nuclear and radiological threats in complex settings like cities, stadiums, and travel hubs.


That system has been transitioning into deployments. The charge of the SIGMA+ program is to expand the threat-detection system’s abilities to include an extensive range of chemical, explosive, and biological agents. To avoid costly false alarms and potentially lethal false negatives (missed detections), the technology must be able to reliably discern actual threats from the myriad benign nuclear, radiological, chemical and biological signals that typically are present in any given location. As Wrobel puts it, “We are trying to move detection to the left of boom.”


While the SIGMA program was initially developed to detect nuclear and radiological threats, the overall SIGMA concept (distributed networked sensors with automated threat detection) is compatible with providing early warning of many other types of WMT threats; the existing SIGMA system is flexible enough to support multiple operational concepts and deployment scenarios. DARPA is therefore interested in existing products and services, and new research and development efforts, to extend and enhance the capabilities of the SIGMA system. These enhancements may involve improvements to detection power, system robustness, alert reliability, inclusion of novel sensor types and modalities (e.g., sensors for chemical or biological threats or contextual sensors such as cameras with analytics informing threat detection events), sensor and intelligence fusion concepts, or other approaches coherent with and enabling to the existing SIGMA capability and SIGMA’s overall counter-terror mission.


SIGMA+ will develop a persistent, real-time, early detection system for the full spectrum of chemical, biological, radiological, nuclear, and explosives (CBRNE) WMD threats at the city-to-region scale. The Network and Analytics thrust will pursue developments for automated, large-scale intelligence and data analytics for the SIGMA+ system, further developments for the SIGMA network backbone that are expected to be required to perform full fusion of these data and methods, and interface and interoperability.


SIGMA+ calls for the development of highly sensitive detectors and advanced intelligence analytics to detect minute traces of various substances related to weapons of mass destruction (WMD) threats. SIGMA+ will use a common network infrastructure and mobile sensing strategy, a concept that was proven effective in the SIGMA program. The SIGMA+ chemical, biological, radiological, nuclear and high-yield explosive (CBRNE) detection network would be scalable to cover a major metropolitan city and its surrounding region. Planned execution of SIGMA+ will occur in two phases. Phase 1 will focus on developing novel sensors for chemicals, explosives, and biological agents while Phase 2 will focus on network development, analytics and integration.


As part of this study, DARPA researchers from MIT Lincoln Laboratory, Physical Sciences, and Two Six Labs, built a small network of chemical sensor packages. Using the chemical sensor network and the data collected during the events, the team was able to assess the performance of the sensors and network algorithms. DARPA Defense Sciences Office programme manager Anne Fischer said: “The algorithms were developed using a custom simulation engine that fuses multiple detector inputs. We built the algorithms based on simulant releases in a large metropolitan area – so we took existing data to build the algorithms for this network framework.


In 2018, SIGMA+ devices collected background air-sampling data at the Indianapolis 500 Motor Speedway using new chemical threat sensors. In fall 2018, DARPA conducted additional testing at the speedway to determine the sensors’ ability to precisely identify the
type and location of a chemical plume’s source. The sensors performed extremely well, proving the system’s maturity for a full-scale, all-modality deployment at the 2019 Indianapolis 500.


At present, the agency is advancing additional sensor modalities, including short-range point sensors to extend the capabilities for networked chemical detection. Fischer added: “We’re looking at how we might make this network more robust and more mature.” “For example, we implemented a network at Dugway Proving Ground as part of a DoD test for simulant releases, and have shown that the network can respond to a number of chemical simulant threats different than those used in Indianapolis, as well as built-in capabilities for mobile releases.” These systems will further be developed and integrated into the SIGMA+ continuous, real-time, and scalable network architecture to increase the capabilities of the system to monitor chemical and explosive threats.




Adapting S&T’s Existing ETD Tech to Help DARPA Detect Weapons of Mass Destruction

S&T has been working not only with TSA, but also U.S. Customs and Border Protection and the U.S. Secret Service, to develop Next-Gen Mass Spec ETD capabilities for use at aviation checkpoints, border crossings, and other security operations across the country. The program team realized that this technology could easily be modified to meet a pressing DARPA need as well. “The original intent of developing this Next-Gen Mass Spec ETD technology was to give Transportation Security Officers (TSOs) an alarm resolution tool that identifies, confirms and defeats current and emerging explosive threats,” said S&T Program Manager Michael Palamar.


Many of us may have experienced being swabbed at airport checkpoints in a procedure called alarm resolution screening. TSOs use ETDs to determine whether harmful substances are present on cargo or the passengers transporting it—they use a sampling coupon to swab a piece of carry-on or checked baggage or a passenger’s hands, place the coupon inside an ETD unit, and then analyze it for the presence of potential explosive residues. Palamar continued, “We were surprised and pleased to find out that this same technology is equally adaptable for enhancing warfighters’ capabilities to detect biological and WMD threats.”


DARPA’s SIGMA+ program is tasked with detecting illicit materials via highly-capable sensors and networks that alert authorities to chemical, biological, radiological, nuclear and explosives threats. They were looking to deploy chemical sensors that not only will provide early warning of WMDs, but that could also be scalable to cover a major metropolitan city and its surrounding region. A high-resolution and high-sensitivity mass spec technology that has been ruggedized for field operations was a logical choice for the SIGMA+ program. S&T’s years of taking ETD technology to the next level resulted in the Next-Gen Mass Spec ETD that will help DARPA meet its capability need. Key features of S&T’s system include:


Enhanced capabilities to counter emergent threats. This technology is designed to meet the most demanding requirements for explosive threat detection, including detection of homemade explosives. Upgradable threat library and shortened threat library upgrade cycles. The high spectral resolving power and sensitivity of industry partner Bruker Detection Corporation’s triple-quadrupole mass spec technology play a key role in allowing faster threat identification and confirmation of specific threats.Adaptable to operations in challenging environments, such as adverse weather and high vibration environments.


The technology underwent two rounds of developmental testing and evaluation at S&T’s Transportation Security Laboratory and one round of testing at TSA’s Systems Integration Facility. It is also undergoing ruggedization for uses in air cargo facilities. In each of these testing and evaluation events, the technology showed proven capabilities in detecting and identifying emergent explosive threats. Allowing DARPA to Communicate WMD Threats in Domestic Urban Environments. Now, with some modification, this critical, cutting-edge technology has been reconfigured for DARPA to use as an air-breathing sensor for early WMD warning.


“DARPA’s SIGMA+ program has a requirement to deploy highly-capable chemical sensors as part of a mobile sensor architecture to provide WMD early warning,” noted DARPA Program Manager Dr. Mark Wrobel. “S&T’s development of an air-sampling variant of Bruker’s compact triple-quadrupole mass spectrometer has provided a capability for SIGMA+ that would otherwise not have existed.”


Leveraging S&T’s Next-Gen Mass Spec ETD engine, DARPA integrates it with an air-breathing front end for sampling air and detecting chemical and explosive trace vapors and their pre-cursors in metropolitan environments. The high sensitivity of the detection engine is instrumental in giving DARPA a real-time detection capability against WMD, and the upgradable threat library and compressed library upgrade cycles play a key role in enabling the communications of WMD threats to responsible authorities—thus enhancing national security.


Thoi Nguyen, a contract scientist supporting S&T’s development and analysis of the Next-Gen Mass Spec ETD for the last five years, seconded Dr. Wrobel’s comment. “S&T tested and evaluated several other mass spec technologies for explosives detection. This technology came out on top both in high- probability of detection and low probability of false alarm.” The Power of Collaboration is a Winning Solution for Our Homeland’s Security. S&T’s work on Next-Gen Mass Spec ETD technology continues with TSA and other DHS agencies, but it is always a proud moment when a new use case is not only identified but put into operational practice.


Commenting on this fruitful collaboration, S&T’s Dr. Laura Parker said: “It is a credit to the progress and impact of this next-generation ETD technology that S&T was able to collaborate with DARPA and share this technology. As government program managers, we are committed to using taxpayers’ money more efficiently, and this technology transition is a win-win.” S&T looks forward to future collaborations with DARPA to keep America safe.


Kromek awarded up to $5.2m contract extension to develop device to identify pathogens by DARPA

Kromek (AIM: KMK), announced in JUne 2021 that it has been awarded an extension to its contract by the Defense Advanced Research Projects Agency (“DARPA”), an agency of the US Department of Defense, to detect and identify pathogens in an urban environment. This follows successful completion of the base period of the contract which was awarded by DARPA in December 2018 to develop a vehicle-mounted biological-threat identifier.


Under the terms of the new contract, Kromek has been awarded up to $5.2m to further work on its mobile wide-area bio-surveillance system capable of detecting airborne pathogens. The total contract period is up to June 2021. The completed system aims to extend the existing SIGMA network for biological threats as part of DARPA’s SIGMA+ initiative.


The miniaturised system will be capable of detecting viruses and bacteria and is intended to be located on vehicles to detect the presence of a pathogenic threat. The small, unmanned system that will run all day will also be capable of being used in high footfall areas, such as hospitals and airports.


SIGMA+ sensors detecting the entire spectrum of weapons of mass destruction (WMD) threats

The Defense Advanced Research Projects Agency’s (DARPA) SIGMA+ program, in collaboration with the Indianapolis Metropolitan Police Department (IMPD),  concluded a three-month-long pilot study in Oct 2021 with new sensors intended to support early detection and interdictions of weapons of mass destruction (WMD) threats. The pilot involved integrating highly sensitive chemical, biological, radiological/nuclear, and explosive (CBRNE) sensors into several IMPD vehicles and gathering real-world environmental background data over a large part of the Indianapolis metropolitan region.


The environmental data collected during the exercise are being used to map the naturally occurring chemical and biological backgrounds found in the Indianapolis urban area that result from businesses, industries, and environmental patterns. The data, in turn, are supporting the development of both sensors and algorithms that minimize false positives and maximize detections of anomalies that may be associated with threat activities. During the Indianapolis pilot study, nuisance alarms were able to be suppressed by 75%.


In addition to characterizing the urban chemical background, the research team generated controlled releases of benign chemicals such as ethanol to challenge the mobile sensors. These releases were intended to simulate production of threat materials such as home-made explosives, narcotics, or other chemical hazards. SIGMA+ has developed a unique chemical referee system that integrates a laboratory-grade instrument into a mobile platform to provide real-time, ground-truth interpretation of the local chemical background.


“The Indianapolis pilot study and field testing marked the first time we were able to demonstrate the integration of cutting-edge SIGMA+ sensor technology across the entire CBRNE threat space into a law-enforcement (LE) vehicle,” said Mark Wrobel, SIGMA+ program manager in DARPA’s Defense Sciences Office. “This included air sampling, power, and the user interface that provides the vehicle operator real-time analysis of potential threats via a tablet. The ultimate goal is to outfit a citywide fleet of LE or other public service vehicles to enable a continuously refreshed mobile network that can detect WMD threats with low false-alarm rates across a city or region.”


Next steps for the SIGMA+ program include testing in other metropolitan regions and developing operational procedures to integrate sensors into real-world use. SIGMA+ algorithm and sensor developers will continue to refine software and hardware to further drive down nuisance alarms caused by the complex chemical, biological, and radiological background signatures of urban environments.



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