REACH (SAFELY) FOR THE STARS

Feb 1, 2002 12:00 PM, By RANDY SOUTHERLAND

In the far reaches of interstellar space, a star goes nova — its light suddenly increases as the star builds to a fiery end. Soon, the star's mass collapses, and the evidence of its violent extinction is sent hurling through the galaxy. The light waves generated may not be seen from Earth for hundreds or even thousands of years. Elusive gravitational waves are also emitted, rippling through the universe at the speed of light.

Unlike astronomers who scan the heavens for a first image of an ancient event recorded in the night sky, the scientists at LIGO, a sprawling research center in the desert of eastern Washington, are looking for evidence of the elusive gravitational waves, using the world's most precise measuring instruments.

The $350 million LIGO (Laser Interferometer Gravitational Wave Observatory) facility is guarded by an access control system designed as much to protect visitors as it is to guard the precision research instruments.

High-powered interferometers are used to measure and record the gravitational waves. The interferometers are massive lasers that bounce infrared beams of light off mirrors suspended at each corner of gigantic L-shaped vacuum tubes measuring 2.5 miles long. The precision lasers can sense even the smallest motions in the mirrors.

“Should a gravitational wave come, it will literally lengthen one arm (of the laser beam) and shorten the other by various amounts depending on where it's from and how strong it is,” explains Richard McCarthy, an electrical engineer and project technician. “If a star goes supernova very close to us, it will be bigger and the frequency we see will be faster.”

The researchers are looking for movements smaller than the width of an atom. They also have to ensure the movements are not created by other events such as an earthquake or waves crashing on the Pacific coast hundreds of miles away.

Nearly a century ago, Albert Einstein first suggested that distant stars produce gravitational waves. The LIGO scientists are trying to demonstrate they actually exist. Before doing so, however, they have to prove that the interferometers are not being moved by more earth-based forces. Among the factors they have to account for is interference from their own access control system. Considerable effort went into testing readers and access control devices to ensure that the “noise” and grounding of these electric devices were not picked up by the interferometer.

“Card readers are sources,” McCarthy explains. “If they are powerful enough, they could interfere with the (laser) tables, cabling, or data signals. We had to take measurements to make sure the transmissions (from the access control system) were not high.”

The system — powered by WAPAC access control software from Natick, Mass.-based Synergistics — serves a dual purpose for the LIGO facility. “It's a laser life safety system and access control tied into one,” says Ralph Lynch, system design consultant with Moon Security Services Inc., the system integrator.

Entrance doors to the building housing the interferometers are guarded by Irvine, Calif.-based HID Corp.'s MaxiProx reader. The cards used by employees and visiting researchers incorporate both proximity and Wiegand technologies.

“The proximity cards are read by high-powered HID readers to get into the facility, and the Wiegand part of it is used to swipe a reader and gain access into the (laser) tables,” Lynch explains.

The tables allow access to the lasers themselves for diagnostic purposes and are housed within locked cabinets. The swipe tech nology was used to limit interference with the lasers. The system protects the instruments from unauthorized intruders and protects the unwary from injury by the powerful and invisible infrared lasers.

“There is an anti-passback set up to get inside the area with the laser itself,” says Curtice Burke, director of new product development at Synergistics. “In order to access that area, the technicians and the scientists must go through the clean room, get ready, utilize the card and go in.”

Before entering the laser facility, technicians must scrub the soles of their shoes, and wear special smocks and protective eyewear. To enter the laser areas, personnel must flash their access card to the long-range proximity reader in the clean room that allows them access to the anteroom leading to the laser area.

The system uses a form of zoned anti-passback operating off a single reader. This allows several individuals to access the system at the same time, without affecting anyone else's entrance. As a card is read, its information is placed in a “zone.” Each reader has a “from” zone, and a “to” zone allowing only specified admittance to a certain area. Most anti-passback systems require two readers — one for entrance and another for exit.

“At LIGO, the doors to enter the area have a reader on each side of the door; but we developed an anti-passback using a single reader at each of the laser cabinets,” Burke says. “We accomplished this by having the reader act as an ‘in’ or an ‘out’ reader based on whether someone had used it to log into a cabinet or not.”

Presenting their card allows them access and also logs them into the area. The technology ensures if personnel enter without logging in, they cannot access laser cabinets even if their card gives them prior authority to do so.

“It logs them into this room and within that room there are a number of substations that allow you to access the laser equipment,” Burke says. “If you were to follow me into that room and you didn't let the system read your card on the way in, it won't let you into any of the laser cabinets.”

Once in the area, there are a number of stations where personnel can access the laser equipment. The stations have doors monitored by the system via magnetic contacts. To open the laser cabinet, personnel must first swipe a valid card at the station.

In the event of an unauthorized person attempting access, the system will close a shutter that disables the laser, and an alarm is triggered at the WAPAC computer in the main control center. The system ensures the lasers are protected, and visitors aren't left vulnerable to the lasers.

“It's an infrared laser, so you can't see the beam,” McCarthy says. “From a safety standpoint, people need to be aware they are entering an area where laser beams are active.”

If a valid card is presented at the station, the cardholder may open a cabinet without shutting the laser off. Once that person is logged into one laser cabinet, they are unable to enter or operate any other laser cabinets without logging out and closing the first one. In addition, they cannot leave the controlled area until they log out of that particular cabinet by closing the door and swiping the card again at the same reader.

If a person attempts to open another laser cabinet or leave the area while they are logged into a cabinet, access to the cabinet or door will be denied.

“You can only open one door at any given time,” Burke says. “Once you've gone in one, you can't go in the other until you've closed and restored that cabinet.”

In addition to the card access system, the interior facility is monitored by a CCTV system using Ultrak KD 6 Ultra Dome high-resolution PTZ color cameras. Two Ultrak JPD-101 controllers located in the main control room and in a theatre reserved for tours operate the cameras. The cameras are networked into a fiber optic system that allows video images to be viewed from remote locations.

“They're able to see who's on the main floor and they can see what's going on from the control room,” Lynch says.

The LIGO staff is pleased with the safety the access control system has brought to their facility. In addition to physical security, the system is also giving them another tool in their search for gravitational waves. Reports generated by WAPAC for alarms, along with entrances and exits can be matched with measurements from the interferometers. Along with earthquakes and other distant events, it gives them one more means of proving whether the waves actually came from a faraway galaxy.

FOR THE RECORD

ABOUT THE AUTHOR

Randy Southerland is an Atlanta-based writer and regular contributor to Access Control & Security Systems.

ABOUT THE COMPANIES

For information, please circle the appropriate Reader Service number (listed below) on one of the Reader Service cards in the issue or visit infoLINK at www.securitysolutions.com.

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