July 2009 System Assessment and Validation for Emergency Responders (SAVER)

TechNote

Metal Detectors for Personnel Screening detectors provide the responder community with an essential tool to screen individuals that may be carrying or contraband that contain metallic components. Available in walk-through and handheld The U.S. Department of Homeland Security models, metal detectors are commonly used at checkpoints in , (DHS) established the System Assessment and Validation for Emergency Responders (SAVER) schools, courthouses, prisons, and military installations. Program to assist emergency responders making Walk-through metal detectors can be designed for either indoor or outdoor procurement decisions. Located within the use. Outdoor models are weatherproof and are often used at temporary Science & Technology Directorate (S&T) of DHS, the SAVER Program conducts objective venues, such as concerts or sporting events. Indoor models are typically assessments and validations on commercial installed at a fixed location. They can, however, be moved if needed. equipment and systems and provides those results along with other relevant equipment Handheld metal information to the emergency response detectors, also known as community in an operationally useful form. security wands, are often SAVER provides information on equipment that used at checkpoints in falls within the categories listed in the DHS conjunction with walk- Authorized Equipment List (AEL). through metal detectors; Information provided by the SAVER Program will the handheld model be shared nationally with the responder provides focused community, providing a life-saving and screening when the cost-saving asset to DHS, as well as federal, state, and local responders. alarm in the walk- through The SAVER Program is supported by a network has been triggered. of technical agents who perform assessment and validation activities. Further, SAVER focuses Although handheld metal primarily on two main questions for the detectors are more Personnel Screening with a emergency responder community: “What Handheld and Walk-Through Metal Detector equipment is available?” and “How does it commonly used as a perform?” secondary means of screening, they can be used as a primary screening device. For more information on this and other technologies, please see the SAVER website or Handheld metal detectors are weatherproof, easy to transport, and less contact the SAVER Program Support Office. expensive than walk-through metal detectors. Walk-through models range : 877-336-2752 in price from $2,000 to over $10,000. Handheld models range in price E-mail: [email protected] from $100 to over $400. Website: https://www.rkb.us/saver Technology Overview Opinions or points of view expressed in this document are those of the authors and do not Metal detectors use electromagnetic fields to passively or actively detect necessarily represent the view or official position the presence of metallic objects. Passive detection measures the changes of the U.S. Government. in the Earth’s caused by an object. In active detection, a This SAVER metal detector generates a time-varying magnetic field, either in the TechNote was archway of a walk-through model or in the space near a handheld model, prepared by the to determine the amount of metal present in an object. Space and Naval Warfare Systems such as , nickel and cobalt are detected by passive and active Center Atlantic, metal detectors. Other metals, such as , brass and aluminum, are for the SAVER detected only by active means. Program.

Walk-through metal detectors are categorized as To accommodate for existing background single-zone or multiple-zone. Multiple-zone electromagnetic fields, the majority of metal detectors technology is replacing single-zone technology, which calibrate automatically when powered-up. In addition, has been in use for more than 30 years. the sensitivity of most metal detectors is adjustable to In multiple-zone metal detectors, the archway is minimize the number of false and nuisance alarms. As divided into horizontal zones. The sensitivity of each the number of false or nuisance alarms increases, zone can be adjusted, increasing the ability of the throughput, defined as the number of people scanned metal detector to in a given period of time, decreases. False alarms may differentiate between be caused by objects in the environment that can emit weapons and metal or reflect electromagnetic fields. Fluorescent lights, items that do not pose a computer monitors, and structural steel are some examples of objects that can cause interference. danger, such as keys and Manufacturers have incorporated filtering hardware . The horizontal and software that suppress or compensate for zones can be further electromagnetic interference. If necessary, shifting the divided into vertical location of a checkpoint can reduce the effects of sectors. This makes it interference from certain sources such as structural possible to identify the steel in the floors and walls. approximate location of a or other Personnel should be properly trained in the operation contraband. and testing of metal detectors and the metal detectors should be tested daily before use. Walk-through metal There are several design detector testing is done by carrying a test object, trends for walk-through ranging in size from a microprocessor chip to a large metal detectors. One is , through the metal detector several times. If the integration of walk- a test object is not detected, the operator should adjust through metal detectors the sensitivity level of the metal detector. Using the as a component in lowest sensitivity setting that consistently detects a security systems. This Multi-Zone Metal Detector test object will decrease false and nuisance alarms. integration allows operators to remotely monitor metal detectors and lock The process for testing a handheld model is similar. access doors if an alarm is triggered. Another design Instead of carrying a test object through an archway, trend is the inclusion of a digital camera feature that however, the test object is scanned at a certain captures images of the individuals that walk through distance from the handheld metal detector to ensure the metal detector. This feature can aid law consistent detection. enforcement by assisting in the identification of people who flee a security checkpoint. Concerns Electromagnetic emissions from active metal detectors Considerations may cause interference with medical devices such as Some factors to consider when purchasing or pacemakers or defibrillators. Although this is rare, implementing a metal detector include power responders should be aware of the medical conditions requirements, sensitivity settings, and daily testing. that interference may cause. A standard 110 volt or 220 volt outlet provides power Resources to indoor and outdoor walk-through metal detectors. • A rechargeable battery pack is typically included with Handheld Metal Detectors for Use in Concealed an outdoor walk-through metal detector in the event Weapon and Contraband Detection (NIJ Standard that a standard outlet is not available at the checkpoint 0602.02) location. Battery packs typically provide power for up http://www.ncjrs.gov/pdffiles1/nij/200330.pdf to three days of continuous operation. Handheld metal • Walk-Through Metal Detectors for Use in detectors can provide up to 80 hours of continuous Concealed Weapon and Contraband Detection operation and can be powered by either 9-volt (V) (NIJ Standard 0601.02) batteries or rechargeable battery packs. http://www.ncjrs.gov/pdffiles1/nij/193510.pdf

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