Can we detect 145;liquid bombs146;

For a machine to detect explosives in liquid or solid form, it bombards an object with energy such as radio waves or neutrons and in seconds measures the reaction, a response that differs depending on the material8217;s chemical properties. Software in the machine is programmed to alert screeners if it detects chemical signatures known to match those of dangerous materials.

WHEN

Don8217;t expect the machines to be rushed into airports soon. Cost and logistical issues present challenges for these devices.

One big reason is that it is not easy to integrate the explosive-detecting machines, some of which can cost 250,000, into existing security checkpoints. Because each briefcase, purse

or other carry-on bag has to be put in a special drawer for analysis, using the detectors could significantly bog down passenger screening.

Besides, the technology in its present form produces a relatively high number of false alarms.

The 6th WHAT NEXT

For the time being, we have to rely on systems not designed to stop liquid explosives. Metal detectors figure to remain the primary method.

As the technology for detection of 8216;liquid bombs8217; evolves, we will able to move towards a more intelligent security system. For example, future screening machines could be linked so that they might let a person through with one kind of liquid but stop another traveler carrying another type of liquid that reacts explosively with what the previous person was carrying. This list of liquids to watch for would have to be constantly updated.