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Contrôleur de l'environnement

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Alpha Sentry CAM System

Alpha Sentry CAM System


The Alpha Sentry Continuous Air Monitor (CAM) System resolves many of the issues facing Alpha CAM users today. A patented diffusion screen removes 95% of the unattached radon daughters from the air sample (as much as 90% of the radon daughters are unattached in typical laboratory environments).

In addition, the spectroscopic algorithm (which uses a stripping method instead of ROIs) is extremely effective at subtracting out the radon daughter interference from the transuranic region of interest.

This physical and mathematical radon reduction increases the sensitivity of the Alpha Sentry, which in turn translates into a lower false alarm rate.

The distributed architecture approach taken by the Alpha Sentry CAM system enables the user to monitor potential leak situations from a point safely outside the affected area. Multi-dropping up to eight sampling heads off a single operator interface (ASM1000), enables the location of the sampling heads in the room while the ASM1000 resides in the hallway.

Sharing the operator interface resource lowers the cost per sampling location. It also makes networking to a lab-wide computer easier - there's only one connection per eight sampling heads.

In the Alpha Sentry network, the detector and multichannel analyzer electronics in each sampling head count the activity on the filter and determine if an acute release has occurred. In addition, the ASM1000 reads the spectrum from each head at regular time intervals, applies a precise spectroscopic algorithm, and determines if a chronic release has occurred. In either case, both the sampling head and the ASM1000 signal an alarm.


  • Patented radon reduction screen
  • Patented mass flow meter for accurate air flow measurement
  • High sensitivity lowers false alarm rate
  • Optional interface to laboratory-wide computer for data transfer
  • Precise radon stripping algorithm
  • Cleanable, rugged high resolution detector
  • Patented disposable filter cartridge assembly saves time and labor
  • Distributed architecture reduces sampling location cost
  • LCD screen displays spectral data and historical trends
  • Continuous self diagnostics ensure system health
  • Full compliance with ANSI N42.17B specifications
iCAM-HD High Flow Rate Alpha/Beta Air Monitor

iCAM-HD High Flow Rate Alpha/Beta Air Monitor


CANBERRA’s iCAM™-HD alpha/beta Continuous Air Monitor provides robust and reliable monitoring of airborne alpha and beta particulate activity in applications where higher sample flow rate is required than in the standard iCAM. Typical applications might include the upgrade of high sample rate passive stack sampling ports to active monitoring. Whereas standard CAMs sample at up to 60 L/min, the iCAM-HD is capable of sampling from 30 L /min up to 120 L/min, and is capable of sampling for extended periods (>1 week typ.) at >100 L/min. The new Bayesian Time Series algorithms incorporated in the iCAM-HD permit monitoring at previously unattainable low alarm levels, with low false alarm rates yet still allow rapid response to large releases.

The iCAM-HD measures airborne alpha and beta particulate activity using the same patented radon/thoron alpha compensation as the standard iCAM, but with improvements in the beta radon compensation performance. It also provides dynamic gamma compensation of beta measurements.

Air is drawn through the instrument by means of an external pump or vacuum system, and airborne particulate material is deposited on the removable filter. The filter is normally held in an exchangeable moving filter cassette, providing over one year’s unattended operation in typical conditions, but an optional fixed filter holder can also be used in the same sampling head mechanism. A 47 mm filter diameter is used to provide low pressure drop even at high flow rate, permitting extended sampling times. The filter is monitored by a CANBERRA CAM1700 PIPS® (passivated ion-implanted planar silicon) radiation detector, which allows simultaneous measurement of both alpha and beta radioactivity in the material deposited on the filter. The air flow is measured directly and reported by the instrument. The design of the stainless steel sampling head is optimized to ensure high air sampling efficiency and high transmission of particles to the filter. A second CAM1700, mounted behind the first, provides gamma compensation of the beta measurement.


Benefits of the iCAM-HD include:

  • Larger sampling head, larger filter and larger detectors accommodate sampling flow rates up to 120 L/min (7.2 m3/hr = 4.2 cfm)
  • Incorporates Bayesian time series algorithms to achieve very low alarm levels, while maintaining good response time for rapid releases
  • Ideal for high dust load industrial environments
iCAM-HD High Flow Rate Alpha/Beta Air Monitor


iCAM-HD shares these same great features with the standard iCAM:

  • Identical Radon compensation algorithms and detector technology (dual CAM PIPS®)
  • Identical amplifiers/bias generator, display and system board/CPU (iCAM Mk3)
  • Ability to connect an external G64 detector to allow gamma dose rate monitoring and alarming
  • RS-232 port for iConfig setup and configuration
  • Dual Ethernet ports with Modbus TCP compatibility
  • RS-485 port for networking to Horizon®


  • Wheeled cart or wall mounted system
  • Full-function area gamma alarm monitor capability using the optional G64 detector
  • Moving filter cassette or fixed filter holder
  • 2 hour backup battery pack (for monitor only)
iCAM Alpha/Beta Air Monitor

iCAM Alpha/Beta Air Monitor


CANBERRA’s intelligent alpha/beta Continuous Air Monitor (iCAM) provides robust and reliable monitoring of airborne alpha and beta particulate activity in the workplace. It acts as a simple alarming monitor for operators, while measuring airborne activities in real time with the sophistication required to provide low false alarm rates and high protection levels. At the same time it provides automated facilities which assist supervisors to conduct detailed setup and operational overview.

The iCAM measures airborne alpha and beta particulate activity with dynamic radon/thoron alpha and beta background compensation. It also provides static or dynamic compensation of beta measurements for gamma background depending on the choice of detector type.

Air is drawn through the instrument by means of an external pump or vacuum system, and airborne particulate material is deposited on the removable card-mounted filter. The filter is monitored by a robust CANBERRA CAM PIPS (passivated ion-implanted planar silicon) radiation detector, which allows simultaneous measurement of both alpha and beta radioactivity in the material deposited on the filter. The air flow is measured directly and reported by the instrument. The design of the airflow system is optimized to ensure high air sampling efficiency and high transmission of particles to the filter. The iCAM has high detection efficiency for both alpha and beta particles and provides good sensitivity for low energy beta detection down to 50 keV.


  • Trolley/cart mounted system, bench stand mount or wall backplate mounting
  • Dual CAM PIPS® detector version with dynamic gamma compensation
  • Full-function area gamma alarm monitor capability using the optional G64 detector
  • I/O expansion option provides RS-422 pulse train outputs (for backwards compatibility with previous Harwell instruments), and also current loop input, optoelectronic outputs and other I/O
  • TCAM PIPS acid resistant detector and flowmeter

Key Features

  • Continuous monitoring of both alpha and beta activity in air
  • Alpha MCA spectroscopy and separate beta discrimination
  • Excellent low energy beta performance: 50 keV threshold
  • Auto-adaptive spectrometric compensation for radon/thoron
  • Simple/automated checks for calibration, gain and efficiency
  • RS-485, RS-232 and Ethernet communication interfaces
  • 3 – 6 months data archive with detailed event log


  • A light and compact integrated unit, which is robust, simple to use and easy to maintain
  • All the required facilities for alpha and beta monitoring, alarms, data logging, communications and setup
  • Sensitive detection of alpha and beta particles plus intelligent adaptive algorithms, for fast, accurate alarms, resulting in high levels of protection and low false alarm rates
  • Adaptive spectrometry algorithms and automated checks for high tolerance to variations in background conditions and extended time between filter changes
iCAM Filter Options

iCAM Filter Options


CANBERRA now offers several new Filter options for the iCAM™ alpha/beta air monitor. These include:

  • ICAM/FCF – Millipore® Fluoropore FSLW 3 micron membrane filters – for improved alpha spectrum resolution with consequent reductions in Minimum Detectable Activity (MDA) and false alarm rate.
  • ICAM/FCC – For simultaneous beta particulate and molecular iodine monitoring.
  • ICAM/FCI – For simultaneous alpha particulate, beta particulate and molecular iodine monitoring.

This new filter card can dramatically improve the iCAMs performance at a low cost. In particular, false alarm rates (already low in iCAM due to the adaptive radon compensation) can be reduced by a factor of up to ten for the same alarm levels and background conditions. This improvement is achieved by replacing the standard GFA filter card with the ICAM/FCF filter, which uses a Millipore Fluoropore FSLW 3 micron membrane filter (as used in the iCAM/MF). This gives far superior alpha spectrum resolution compared to the GFA filter, and so reduces the size of the tails of the Radon and Thoron daughter peaks, thus reducing the background in the U/Pu region and reducing the MDA and false alarm rate. In good operating conditions the standard deviation of the compensated alpha reading (and thus the MDA) is reduced by a factor of >2, and in poor/high background conditions, the improvements are even more dramatic. The table below shows the reduction in MDA using the ICAM/FCF, compared to the GFA filter in good conditions:


  • > x 2 reduction in MDA, so 4–10 x reduction in false alarm rate
  • No changes in setup of iCAM required
  • Better results when counted in iSolo®/iMatic™
  • A low cost method for beta particulate and molecular 131I monitoring (non-discriminating)
  • A low cost method for alpha and beta particulate and molecular 131I monitoring (non-discriminating)
iCAM: Minimum Detectable Alpha Activity
Interfering Background: Radon and Thoron daughters: 218Po, 214Po, 212Bi and 212Po
(Radon Equilibrium Factor F = 0.5)
222Rn gas (Bq/m3) Uncompensated Alpha Background (Bq.h/m3) Minimum Detectable Alpha Activity (Bq.h/m3)
Whatman GF/A Fluoropore FSWL (3 μm)
5 min. Response 20 min. Response 5 min. Response 20 min. Response
10 7 0.3 0.2 0.2 0.12
20 14 0.4 0.3 0.25 0.17
40 28 0.6 0.4 0.35 0.25
60 42 0.7 0.5 0.45 0.30
80 56 0.8 0.55 0.50 0.35
100 70 0.9 0.65 0.55 0.37
120 84 1.0 0.70 0.60 0.40
140 98 1.1 0.75 0.65 0.45
The total radon daughters concentration in air is 2.3 times the stated 222Rn gas concentration.

As noted above, the improvement under poor conditions is even greater. The better filter spectral resolution will also give better results if the filters are counted off-line after sampling in an iSolo or iMatic.


In this version of the filter card the GFA filter medium is replaced by a charcoal-loaded filter (Whatman type 72). This filter absorbs molecular iodine with very high efficiency, in addition to collecting particulate. 131I, the most common iodine isotope of interest, has several high intensity betas and so will be detected with very high efficiency (~24%) by the iCAM's beta channel.

Detectable High-Intensity Beta Energies
Isotope I-131
Half Life 8.0207 days
Mean Beta Energy keV 181.92
Intensity % 100.50

Iodine occurs in two distinct forms: molecular iodine, i.e. I2, is normally encountered as fission product from fuel or reprocessing. This form is readily collected by a charcoal-loaded filter paper such as ICAM/FCI. The second form is organic iodine, e.g. methyl iodide, more frequently encountered in nuclear medicine. This form is not readily absorbed by a thin filter, so a bulk iodine absorption cartridge must be used (as in the CAM110PIFF). Iodine in the environment is also likely to have exchanged with organic molecules so a cartridge-type system such as the CAM110PIFF should be used for wide area environmental monitoring systems. The ICAM/FCC is not suitable for alpha particulate measurement due to the poor spectrum shape produced, but it is suitable for beta particulate in air monitoring. If simultaneous alpha, beta and iodine monitoring is required then use the ICAM/FCI filter.

The ICAM/FCI filter has both a GFA filter (for alpha and beta particulate) and a type 72 charcoal-loaded filter below it. Using the ICAM/FCI allows an iCAM to monitor for alpha and beta particulates and for molecular iodine simultaneously, with the comments above for the ICAM/FCC filter applying to the iodine monitoring. The only disadvantage of using this filter is the greater pressure drop caused by the two layers, with consequent reduction in the filter life (typically 1–2 days) compared to the lifetime of a standard GFA filter of 5–7 days.

Note, 129I and 125I do not have a detectable beta emission and so will not be detected by an iCAM fitted with the ICAM/FCI or ICAM/FCC filters.


iCAM/MF Moving Filter Head for iCAM

iCAM/MF Moving Filter Head for iCAM


The iCAM/MF moving filter detector head provides iCAM users with an option in filter handling. In place of the fixed, card mounted filter, which must be changed manually at regular intervals, the mechanism passes a continuous belt of filter material under the detector. Hence, when a filter change is required, instead of manual intervention being necessary, the iCAM firmware commands the mechanism to step the filter on, presenting a clean piece of filter material to the detector. The length of the filter roll, combined with the ability of the iCAM compensation algorithms to adapt to filter spectrum shape changes, allows up to twelve months operation with no manual intervention in typical applications. This renders the iCAM/MF ideal for use in hazardous or inaccessible areas where frequent personnel access is undesirable, e.g., long term unattended environmental monitoring. It also allows the iCAM to operate in high dust-loading environments, where otherwise frequent manual filter changes would be required.

The sampling head can draw an air sample either directly from the ambient air or remotely via a 1 in. bore hose or pipe connected via the standard iCAM air inlet adaptor.

The mechanism incorporates measurement of the pressure drop across the filter, to assist in determining when a filter change is necessary. The iCAM firmware (V200 or greater) can change the filter on any or all of the following conditions:

  • Preset time interval
  • Preset air volume
  • High filter pressure drop
  • Low flow
  • High activity
  • High radon/thoron background



  • Automatic filter change mechanism
  • Twelve months autonomous operation
  • Fluoropore™ FSLW filter roll
  • Filter ΔP measurement
  • Retro-fittable to existing iCAMs
  • For ambient sampling or remote connection via standard air inlet adaptor
  • Dual PIPS® detector for ambient gamma compensation


  • Long term unattended operation in inaccessible or unfrequented locations
  • Reduced operating costs
  • Improved performance – through use of higher resolution filter