Masakazu Sugaya

High-Throughput Walkthrough Detection Portal as a Measure for Counter Terrorism: Design of a Vapor Sampler for Detecting Triacetone Triperoxide Vapor by Atmospheric-Pressure Chemical-Ionization Ion-Trap Mass Spectrometry

Aiming to prevent terrorist attacks in places where many people are coming and going, we have been developing a “high-throughput detection portal system.” The portal system consists of a vapor sampler, an atmospheric-pressure chemical-ionization ion source, and an explosives detector based on ion-trap mass spectrometry. The vapor sampler was designed to be installed in an automated ticket gate of a train station. By optimizing the shape of the nozzle that controls the air flow of the vapor sampler, triacetone triperoxide (TATP) vapor could be detected at a high throughput, i.e., 1200 persons/hour. The false-positive rate of the detection portal system for TATP was evaluated by a field test performed at a train station. A multi-marker logic to determine whether TATP existed or not was adopted, and no false-positive alarms were obtained for over 3000 passengers during the field test. However, acetone, which is an inflammable liquid, was accidentally detected from the passengers during the field test. It is concluded from this detection result that this detection portal system is useful for detecting dangerous chemicals that have high vapor pressure (such as TATP and inflammable liquids) in places where many people are coming and going.

Real‐time explosive particle detection using a cyclone particle concentrator

RATIONALE There is a need for more rapid methods for the detection of explosive particles. We have developed a novel real-time analysis technique for explosive particles that uses a cyclone particle concentrator. This technique can analyze sample surfaces for the presence of particles from explosives such as TNT and RDX within 3 s, which is much faster than is possible by conventional methods. METHODS Particles are detached from the sample surface with air jet pulses, and then introduced into a cyclone particle concentrator with a high pumping speed of about 80 L/min. A vaporizer placed at the bottom of the cyclone particle concentrator immediately converts the particles into a vapor. The vapor is then ionized in the atmospheric pressure chemical ionization (APCI) source of a linear ion trap mass spectrometer. RESULTS An online connection between the vaporizer and a mass spectrometer enables high-speed detection within a few seconds, compared with the conventional off-line heating method that takes more than 10 s to raise the temperature of a sample filter unit. Since the configuration enriched the number density of explosive particles by about 80 times compared with that without the concentrator, a sub-ng amount of TNT particles on a surface was detectable. CONCLUSIONS The detection limit of our technique is comparable with that of an explosives trace detector using ion mobility spectrometry. The technique will be beneficial for trace detection in security applications, because it detects explosive particles on the surface more speedily than conventional methods.

Inspection of all beams in multielectron beam system

A testing apparatus for inspecting the beams formed by a multisource module (MSM) was built for the feasibility study of a beam splitting array (BSA), a multielectron beam system the authors are developing. In this BSA, the MSM plays the following three key roles: splitting the beam from a single cathode into 32×32 beams, converging the 32×32 beams, and blanking them individually. Accordingly, the inspection of all beams formed by the MSM is essential for the feasibility study of the system. The testing apparatus was therefore designed for measuring all the beams formed by the MSM without demagnifying them. To maintain the accuracy during the inspection of all 32×32 beams, the measurement process was automated. This testing apparatus was used to measure the diameters and misalignments of all beams formed by a prototype MSM. As a result, the mean values of the transverse and the longitudinal diameters were found to be 0.88 and 0.92μm, respectively. A single stigmator can cancel the difference between these...