The newly designed Ludlum Model 53 Personnel Gamma Radiation Portal detects gamma radiation in or on personnel passing through the portal from either direction.  This highly sensitive portal uses eight large plastic scintillation detectors, and is shielded with either the standard 1 in (2.5 cm) or optional 2 in (5 cm) of lead.  A user-friendly interface guides personnel through the portal monitor via automated voice prompts, and is accompanied with 9 in (22.9 cm) color LCD articulating screens presenting the instrument readiness and status at the ingress and egress. Alarms are manifested both audibly and visually, and can be silenced and acknowledged via a control button located on either side of the instrument.

Three statistical counting modes are available to maximize throughput, maximize sensitivity, or fix the count time.  Several modifiable parameters adjust the alarm set point, including the false alarm probability, detection probability, background sigma coefficient (KB), and the composite sigma coefficient (KS+B).  Fast alarm and clean options provide the ability to quickly determine if personnel are contaminated or clean before the entire count cycle has ended.

Operational modes include a walk-through mode, a pause mode, and a pause-and-turn mode.  Voice prompts may be customized in any language for each of these modes.  These prompts can, for example, dictate in-house procedures to follow.  Instrument technicians have password-protected access to set up the instrument, and to  the advanced automated routines for calibrating and verifying operation.

Easily accessible USB ports facilitate connecting a keyboard to implement changes, input user ID, or upload revised software.  The system also includes an Ethernet link.  Ludlum's optional Universal network software can be used to log instrument status, user activity, and other information from one or more  instruments connected to the network. This software broadcasts emails whenever radiological alarms or instrument failures occur, and has the ability to capture images from network cameras that can be stored along with the user ID (if implemented).
 

A unique feature, not found anywhere else, is an optional weight scale that assesses the weight of the individual passing through the portal and then assigns an appropriate transmission factor for a more accurate gamma measurement.  Other options include  an additional 1 in (2.5 cm) of lead shielding, a second alarm/light stack, and the Universal network software.