The Alpha Hand and clothing monitor shall comprise a set of detectors and an electronic unit.
b) Clothing probe:
a) Hand probes:
Number of monitoring channels: 4 (Right hand 1 & 2, Left hand 1 & 2).
Detector Type: 220x140mm Zns(Ag) scintillator based detection unit.
Detection Efficiency: >20 % overall for Am-241.
Probe Construction: Each channel shall have a 220x140mm Zns(Ag) scintillation detectors. They are fitted in the instrument so that they can be detached easily formaintenance.
Sensitive Area. > 300 sq. cm.
Protection Grill: The whole detector assembly shall be protected by a suitable thin metallic grill.
Detector dimensions and performance shall conform to IEC 61098 specifications.
Number of monitoring channels: one
Detector Type: 160x80mm Zns (Ag) scintillator.
Detection Efficiency: > 25% overall for plastic scintillation detector assembly with Am-241.
Probe Construction: Hand-held type. It shall be placed on a holder with micro-switch assembly on the side of the monitor. On lifting the detector, the monitoring shall be started.
The electronic unit consisting of the following :
a. Signal processing and display unit.
b. Mother board.
c. Switched mode LV supplies unit.
d. 5 channel pre-amplifier unit.
e. High voltage power supplies unit.
Signal processing and display unit: The signal processing & display unit comprising of an SBC & large TFT display perform data acquisition & control. It carries out the following functions of
User interface during configuration& measurement through the TFT display & optical sensors.
Counting of pulses from 5 individual detectors.
Storage of last 100 acquired data and last 100 contamination data.
Configuration of various parameters like PM time, BG time, BG dwell time, Low BG set point, High BG set point, Alarm set point, Baud rate, Device ID, IP address, Voice & visual guidance languages, fault diagnostic configuration, detector efficiency, detector status etc.
Generation of voice guidance messages through stereo O/P sound device during measurement cycle.
Initiates / terminates measurement cycle by sensing optical sensors status.
Communicates to remote PC through Ethernet ports using MODBUS protocol for fault diagnostics.
High Voltage, Pulse Amplifier and Data Acquisition Unit:
This unit essentially comprises of High Voltage module, 5 channel Pulse Amplifier section, FPGA based Data acquisition board and State of Art Single Board Computer unit. DC Voltages required to bias the Electronics are generated by DC-DC convertors located on this board. Signals to/from all PMTs are routed to this unit.
Switch Mode power Supplies unit:
An AC-DC converter along with switching regulators generates the necessary LV voltages of +24V, +12V & +5V respectively to power the electronic sub-systems. It is also provided with a line filter & other EMC suppression components.
5 Channel Pre-amplifier unit:
This unit comprises of 5 individual pre- amplifier modules used for connecting the ve tail pulses to TTL coming from each of the scintillation detectors. HV bias to the scintillation detectors is fed through the preamplifier unit.
Counting Range : 0 to 9999 counts
0 to 9999 cps
0 to 999.9 Bq/cm2
0 to 99999 cpm
On Overflow the display shall indicate OR
Timing range : Pre-settable from 1 to 99 seconds in 1 sec steps for COUNTS, Bq/cm2, CPS or CPM modes for Hand and Foot monitoring. Time constant for checking the Clothing monitoring is 5 seconds with display being refreshed every second.
HUMAN MACHINE INTERFACE:
Indications & controls:
Mains switch : The mains switch is provided inside the cabinet of the monitor.
Mains indication : Red LED to indicate mains power ON is provided on the display panel.
Optical sensor: The monitor shall be provided with optical sensors inside the detector cavities for sensing personnel and initializing the counting automatically.
Test switch : Through detachable keypad, provision to check the background is given.
Visual alarm : Each channel color visual mimic indication is provided on the colour LCD TFT display.
Audio Alarm : Loud audio tone.
Audio Instructions : Audio instructions shall be generated for clear, contaminated, instrument fault, monitoring in progress and incomplete operation. Voice messages shall be played back in English/Marathi/Hindi/Tamil.
Operational Guidance : Operational guidance messages shall be displayed Before monitoring, On Clear, On Contamination and On Incomplete operations shall be generated in English.
Incomplete operation : Multi-lingual textual indication accompanied by audio alert are generated when counting is interrupted.
Clear Indication : LCD mimic indicator will be ON when all the channels are clear.
Counting in progress Indication : Busy indication will be shown while Counting is ON and Time left is displayed.
Visual display : 10 colour TFT display. Given below is a partial list of the functions being carried out by the visual display.
Display normal status messages.
Visual display of monitoring in progress (including countdown of time in seconds).
Display of individual channel readings.
Background checking and display
Instructions for use.
Self explanatory, language independent symbols / user instructions.
Computer interface: The monitor has a USB port for data transfer of Acquired Data / Alarm data to a connected Pen Drive.
Power supplies: The monitor shall have a High voltage power supply unit for the detectors and a low voltage power supply unit which supplies the DC power supplies required for the Electronic unit. It shall have a very good line voltage and load regulation for all the supplies. It shall be fitted with Mains line filters to avoid line interferences. The High voltage output shall be adjustable by handheld configurator or host PC and EHT should be displayed on the display on demand. The EHT shall adjustable from 300 V to 1500 V DC.
Instrument fault indication: Fault diagnostics are carried out periodically and any failures are reported on the display like LV, HV and detector failures. Fault indications shall be cleared automatically if normal status is resumed.
Self diagnostics : The monitor has built-in self diagnostics. On being powered it shall perform tests to ensure that all components and sub systems are functioning properly. It shall check for the Power supply, High Voltage Supply, Detector, Counting and measuring circuits, Alarm Systems, Display Systems and communication port. Test points shall be provided for checking the EHT voltage and for connecting external input pulse signals.
Most of the modules of the Electronic unit and detectors shall be integrated into a column shaped cabinet with castor wheels.
The hand probes shall be fitted so that both the hands can be inserted and the optical sensors inside the cavities are activated when hands are placed to start monitoring.
The modules shall be plug in type with all the controls and display on the front panel.
The cabinet shall be rat- proof, rugged & elegant.
Dimensions and Weight: Overall Dimensions: 1500H x 600W x 800D mm Weight: <145kg.
Environment: The instrument shall be able to withstand temperature upto 50°C and relative humidity upto 90% in radiation areas.