Measurement Solutions for Nuclear Safety, Security and the Environment

Détecteurs spéciaux Ge et Si(Li)

Description

Les détecteurs germanium sont des diodes à semiconducteurs ayant une structure PIN dont la région intrinsèque (I) est sensible aux rayonnements ionisants, notamment aux rayons X et gamma. En polarisation inverse, un champ électrique traverse la région intrinsèque ou irradiée. Lorsque les photons interagissent avec le matériau dans le volume irradié d'un détecteur, des porteurs de charge (électrons et trous) sont libérés et dirigés vers les électrodes P et N sous l'action du champ électrique. Cette charge, qui est proportionnelle à l'énergie déposée dans le détecteur par le photon incident, est convertie en décharge électrique par un préamplificateur de charges sensible.

Produits dans cette famille

Clover Detectors

Clover Detectors

Array of Four Coaxial Germanium Detectors for Largest Efficiency

Description

In the CLOVER detector assembly, the crystals are held on a minimized crystal holder to reduce the quantity of material surrounding the crystals and to improve peak to background ratio. With this principle CANBERRA is offering an optimized amount of HPGe material within the cap.

Moreover, crystals are packed very closely together to improve the add-back factor. The maximum gap between two adjacent crystals is ≤ 0.7 mm without any absorbent material along the whole crystal length that will absorb more than 1% of 20 keV gamma rays.

The four crystals are mounted in a common cryostat with a tapered or regular square shaped end cap.

Distance between end cap and crystals has been reduced to a very minimum to improve the solid angle and efficiency of any veto detector (BGO) which can surround the CLOVER cap. Also so called back catcher cryostats are available for given CLOVER types where a dedicated BGO detector can be installed at the rear of the cap.

A major advantage of a CLOVER detector consists of its high absorption efficiency: results are not only four times those obtained with a single crystal but, as crystals are mounted without any additional absorbing material, the full energy of a photon Compton scattered and absorbed in a second (or even a third) crystal can be determined. The full energy peak can be obtained by summing ("add-back") the energies deposited in the N segments firing.

The "Add-back" efficiency is then superior to the sum of the four individual efficiencies.

Features

  • High photopeak efficiency in 'add-back' mode
  • High efficiency in 4π geometry (well type configuration)
  • Excellent energy resolution
  • Excellent timing response
  • Optional position information (segmentation can reduce Doppler broadening)
  • Reduced vulnerability to neutron damages
  • Good sensitivity to gamma ray polarization
  • Easy maintenance
  • Optional: low background materials, electrical cooling, extended energy range

Ge Clover Detectors

The first CLOVER detector was initially developed in France by CANBERRA in the frame of the EUROGAM collaboration. The original design consisted of a close arrangement of four n type germanium detectors like a 4-leaf clover. This configuration drastically improves the total system efficiency and compensates for the still limited relative efficiency of conventional n type crystals. Well over 200 CANBERRA CLOVER detectors are currently in operation worldwide. Although CLOVER detectors should be considered as specialty detectors or scientific instruments, they are highly reliable, allowing for routine maintenance to be performed by customers on-site. As is evidence: the first EUROBALL CLOVERS delivered in 1992 are still in operation.

Applications

  • Nuclear Physics
  • Polarization measurements
  • Health Physics (well type CLOVER)
  • Any application where the highest efficiency is required without compromises on energy or timing resolution
Encapsulated Detectors

Encapsulated Detectors

Encapsulated Germanium Detectors for Gamma Measurements

Description

ENCAPSULATION TECHNIQUES

Mounting and operation of several detectors in a common vacuum with minimum spacing between consecutive elements makes a real challenge. Encapsulation techniques have been developed to minimize such problems. Placing each encapsulated detector into the vacuum in an individual aluminium cap makes it possible to separate the vacuum of each detector from the cryogenic vacuum shared by all detectors. Encapsulation drastically enhances the germanium detector reliability. This technology is key for many applications, particularly in space, and especially if associated with Ultra High Vacuum. Encapsulated germanium detectors may be easily handled by the users. They may be stored, exchanged or rearranged and be adapted to various applications with different types of cryostats.

A capsule may be regenerated many times and can be thermally annealed in an ordinary oven from neutron or proton radiation damages, without pumping. The life time of such a detector may be estimated to a minimum of seven years without service. But in reality it is much more: The first EUROBALL capsules were delivered in 1992 and are all still in operation. Encapsulated detectors hardness enables a wide application range, such as part of the payload of nacelles, space launchers, etc...

Compact arrays may be designed. The capsules manufactured for EUROBALL offer a typical wall thickness of 0.7 mm with a distance between cap and crystal of only 0.7 mm. These encapsulated detectors may be in contact with one another offering a 3 mm distance between consecutive crystals and a 1.4 mm total aluminium wall thickness.

For better follow-up of scientific progress, some segmented crystals have been encapsulated to offer high granularity, in addition to the previous advantages.

The detector granularity qualifies the number of independent cells constituting this detector. Such detectors allow a significant reduction or gamma ray broadening due to the Doppler effect.

Moreover, the use of internal and external contacts of the crystal provides information on the interacting position:

  • Vertically and transversally, by analyzing signals induced by mirror charges.
  • Radially by making a pulse shape analysis.

Accurate localization of the interaction points allows not only reduction of the Doppler effect broadening, but also gamma ray tracking.

In addition to these benefits, the segmented detector encapsulation allows the design of complex cryostats, thus signal optimization which is of much interest for pulse shape analysis.

The feasibility of the germanium detector encapsulation was studied in the frame of a collaboration between CANBERRA, the Jülich research center and the University of Cologne in Germany.

Ge Encapsulated Detectors

Features

  • For compact construction of multi-element detectors for gamma ray applications
  • For very large efficiency and solid angle coverage for high sensitivity and low detection limit gamma ray spectroscopy even in harsh environments
  • Easy annealing in standard ovens, without pumping, in case of radiation damages
  • In situ annealing in space applications
  • Long detector life time
  • Large choice of shapes (pentagonal, hexagonal) for compact matrix assemblies
  • Essential for complex cryostat development, particularly with segmented detectors
  • Total reliability Ultra High Vacuum technology
  • Easy detector handling and exchange

Applications

Such a detector is easy-to-use, reliable and robust. So, it may be used in a large range of scientific and industrial applications such as:

  • Array of detectors for gamma spectroscopy (ex: MINIBALL, AGATA, GRETA nuclear physic experiments)
  • Research laboratory – Nuclear medicine
  • Environmental measurements
  • Industrial quality control
  • Homeland Security
  • Space experiments, thanks to its in situ re-generation capabilities after radiation damages (ex.: INTEGRAL, MARS ODYSSEY, SELENE,...)
  • Assistance to Engineers
    (ex: design of complex cryostats and /or multi elements detector electronic)
Ge Ruggedized Detectors

Ge Ruggedized Detectors

Description

Germanium detectors represent the best choice when high resolution gamma spectroscopy is required for accurate nuclide identification and quantification.

However, some potential problems can compromise the use of these technologies when the spectroscopy system is intended to be used in harsh environments such as:

  • Shock and vibration (transportation by trucks, separation of space launcher stages)
  • Industrial use in sites where liquid nitrogen is not available for detector refilling
  • Extreme climatic conditions (underwater operation, very high or low temperatures, etc.) in industrial or space environments

The combination of CANBERRA's extensive experience with the evolution of new technologies (encapsulation, ultra high vacuum, waterproof design, shock absorption devices) make us the world leader in scientific and special applications involving HPGe detectors.

CANBERRA's expertise allows our specialists to deliver outstanding and reliable detection instruments for the most demanding industries and research centers. Researchers have come to depend on these specialized instruments for their most critical experiments and studies.

Applications

  • Space
  • Environment
  • D&D
  • Industry

Ge Ruggedized Detectors
This mission consists of the equipment for a satellite in orbit around the Earth to study supernova, black holes, and other emitters of gamma bursts.

Features

  • Hardened design, shock and vibration resistant
  • Adapted cooling devices (electrical coolers)
  • Multiple references in space missions (Integral, Mars Orbiter, Selene...)
  • Encapsulation techniques allowing easy exchange of each individual detector when mounted in arrays
  • Dedicated shapes and materials for cryostats (hexagonal cutting, titanium light weight capsules, telescope mount, etc.)
  • Large choice of N-type detectors and associated annealing accessories for on-site repair after radiation damage
  • Ultra High Vacuum for the best reliability
  • Waterproof design for outdoor use
  • Easy to decontaminate
Segmented Coaxial Detectors

Segmented Coaxial Detectors

Description

CANBERRA's Segmented Coaxial HPGe Detectors employ segmentation techniques available on planar detectors since the eighties (see Gutknecht et al NIM A288 (1990) 13-18) to provide high quality information signals from each detector cell (segment), while taking advantage of the total detection volume (as available with usual coaxial detectors.

The segmented coaxial Germanium offers, in addition to the characteristics of coaxial detectors (High efficiency and excellent resolution), the potential for excellent granularity.

Granularity of segmented coaxial detectors qualifies the number of independent cells constituting this detector. Longitudinal and transversal crystal segmentation in two or four drastically increases the granularity (up to 36 output channels are possible).

Such detectors allow an important reduction of gamma ray broadening due to Doppler effect.

Moreover, the use of internal and external contacts of the crystal (in case of detector segmentation) provides interaction position information:

  • Vertically and transversally by analyzing signals induced by mirror charges
  • Radially, by performing a pulse shape analysis

Accurate location of the interaction points allows not only reduction of the Doppler broadening, but also gamma ray tracking.

The external contact of a detector can be longitudinally or transversally segmented without dead zone generation. All segmentations are possible, on the front side (like a checker-board for example) and laterally (in one or two directions).

For a given n-segment detector, n+1 preamplifiers are used: one for each external segment plus one for the central contact. This design allows a better use of the full detection volume by AC coupling.

Segment separation is such that no cross-talk effect occurs between consecutive channels.

Ge Segmented Coaxial Detectors

Features

  • For gamma tracking, polarimetry, Doppler effect correction, β decay suppression
  • Longitudinal and transversal segmentation of the outer contact by photolithography (up to 36 segments), on various N type crystal geometries
  • No dead zone or absorbing material between segments
  • Monolithic detectors
  • No measurable crosstalk effects
  • Increased granularity of multi-detector systems
  • Localization of the interaction and gamma ray
  • Tracking capability through coincidence between internal core signal and segment contact signals

Applications

  • Nuclear physics:
    • Doppler effect correction
      (see also CLOVER
      detectors, Encapsulated
      detectors and Strip
      detectors)
    • Multiple site energy deposit
      and β decay suppression
    • Polarimetry
    • Tracking (see also
      Encapsulated and Strip
      detectors)
  • Compton cameras: Gamma ray sources location
  • Compton suppression
Segmented Planar Germanium EGPS series

Segmented Planar Germanium EGPS series

Detectors for X and γ Ray Measurements

Description

CANBERRA series EGPS detectors are manufactured using a proprietary technology allowing design for the best strip germanium detectors available worldwide. CANBERRA uses photolithography techniques – usually employed in microelectronics – to germanium diodes. Thus, all kinds of segmentation patterns are possible (straight or curved strips, pixels, etc.) including double sided thin window segmentation. This reliable technology has been proven since the eighties.

Segmentation offers many benefits:

  • Suppression of dead layers between consecutive strips.
  • Thinnest pitch: down to 50 µm on single sided strips.
  • Excellent performances at high count rates (up to 1 million pulses per second).
  • 2-sided photolithography capability, with pitchs up to 200 µm.
  • Excellent FWHM resolution: typically <130 eV at 5.9 keV.
  • No measurable physical crosstalk.

The segmentation techniques fit with all crystal designs: circular, rectangular, etc. Diodes which are segmented by photolithography allow easier and more accurate 3D localization of interaction points than those obtained with segmented coaxial detectors. This is due to the electrical field characteristics within the detector. Several EGPS detectors may be associated in arrays or may be stacked in a single cryostat, thus offering smaller dead layers to increase of the angular covering (or high energy ray absorption depending on system configuration).

Various similar assemblies of that kind are used for Compton Cameras. EGPS detectors are cooled at liquid nitrogen temperature and may withstand many thermal cycles without any performance degradation. Such characteristics make CANBERRA EGPS series the best choice for X or gamma ray measurements in many applications such as Physics or Astrophysics experiments as well as non invasive detection or medical application.

Applications

  • Synchrotron (EXAFS, diffraction, medical beam lines)
  • Nuclear Physics (tracking)
  • Compton cameras (imaging)
  • Non destructive control
  • Radiography
  • Medical (BNCT, Angiography)

Ge Segmented Planar Detectors

Features

  • For high performance X and γ measurements in Physics, astrophysics, non-destructive control and medicine
  • Unique proprietary segmentation techniques developed and enhanced for over 15 years
  • Large range of shapes (pixels, strips) and segmentations (straight strips, circular, single or double sided)
  • Excellent energy resolution (<130 eV at 5.9 keV, depending on geometries
    and count rate)
  • Excellent performance at high count rates, with small as well as large detectors (up to 1 Mcps)
  • Accurate localization of the interaction points (1, 2 or 3D)
  • Thickness up to 20 mm
  • Crosstalk with physical pulses 1% maximum
  • Double sided segmentation capability, using CANBERRA thin window proprietary technology
  • Available with LN2 or electrical cooling
Telescope Detectors

Telescope Detectors

Description

The purpose of a telescope arrangement of several planar and coaxial germanium detectors is to get wide energy range measurements with the best possible efficiency and background correction, like in cosmic gamma rays spectroscopy.

Stacks of planar and coaxial, pixel or strip segmented detectors can also be mounted or associated with Si(Li), PIPS detectors to best focus on X-ray or charged particles by vetoing the main signal, and remove any unwanted background.

Such arrangement increases the detector resolving power by discriminating gamma rays from the measured background, and also by reducing Doppler broadening effects.

The absorption efficiency of such detector is very high due to the larger germanium volume crossed by photons or particles.

Moreover, special care has been taken to minimize dead areas within detector assemblies and stacks.

The thin contact technology is a main issue for charged particle detection.

Indeed, a stack of several crystals is a very interesting tool for high energy charged particles measurements.

Stacks of planar and coaxial detectors and assemblies of stack in arrays in common cryostat are possible.

CANBERRA can offer a dedicated cryostat with special high cooling power LN2 Dewars developed for array detectors (Clover detectors). LN2 free solutions are possible as well with the latest electrical cooling technology. This is now a very mature cooling solution in case LN2 has to be banned because of safety or security regulations; any room constraints (industrial applications) or accessibility (space applications).

Applications

  • Waste barrel monitoring or whole body counting systems: Both applications need highest efficiency, wide energy range and lowest MDAs
  • Space spectroscopy: background reduction by multiple site method (ß decay suppression)
  • Compton cameras: telescope of double sided strip detectors (DSSDs)
  • Nuclear physics: Doppler broadening correction by incidence angle measurements (segmented planar detector stack)
  • High energy measurements of gamma rays with best achievable efficiency
  • Background reduction by vetoing of charge particles
  • High energy proton spectroscopy

Telescope Detectors

Features

  • Multi-arrangement of planar, or planar and coaxial detectors (segmented or not), HPGe or Si(Li) or PIPS®
  • Extended gamma-ray energy range or charged particle discrimination
  • Background suppression by using coincidence timing between detectors
  • No measurable crosstalk effects between channels
  • Minimized dead areas between detector layers
  • Stable thin window proprietary technology not affected by heat cycling or neutron annealings
ESLX-S & LTS Detectors

ESLX-S & LTS Detectors

Segmented Planar Silicon-Lithium Detectors for X-ray and Charged Particle Measurements

Description

The Segmented Si(Li) detectors (ESLX-S and LTS) are manufactured using a proprietary technology allowing design of the unique segmented silicon detectors available worldwide.

CANBERRA has applied the photolithography proven techniques – usually employed in microelectronics – to Si(Li) diodes. Thus, all kinds of segmentation patterns are possible (straight or curved strips, pixels, etc.).

CANBERRA also offers a proprietary double sided thin window segmentation. This enables to build telescope systems consisting of several layers of Si(Li) detectors.

Segmentation offers many advantages:

  • High efficiency through best area coverage: Suppression of dead zones between consecutive strips.
  • Best granularity: Small pitch down to 2 mm.
  • Fastest response: Good behavior at high count rates (up to 1 million pulses per second) due to fast preamplifiers without any compromise on signal to noise ratio.
  • 2-sided photolithography capability, with pitches down to 2 mm.
  • Excellent FWHM resolution: typically 150 eV at 5.9 keV on cooled ESLX-S devices for X-ray measurements.
  • No measurable crosstalk.

Segmentation techniques fit with all crystal designs: circular, rectangular, etc.

Several Si(Li) detectors may be associated in arrays to increase angular coverage or may be stacked.

ESLX-S detectors in a unique cryostat, offer high energy X-ray absorption or imaging capabilities (gamma cameras).

ESLX-S detectors are cooled at liquid nitrogen temperature and withstand many thermal cycles.

Such characteristics make ESLX-S series the best choice for X-ray measurements in many applications such as physics experiments as well as non invasive detection.

LTS detectors are operated at room temperature or are peltier cooled for improved performances compared to those at room temperature.

ESLX-S & LTS Detectors

Features

  • ESLX-S: For high performance X-ray measurements in Physics (PIXE, synchrotrons...), Non Destructive Assay and Medicine
  • LTS: For high performance charged particles measurements in Physics (Conversion Electrons, Mini-Orange) and RMS (air monitoring)
  • CANBERRA mature proprietary segmentation technique
  • Wide range of shapes (pixels, strips) and segmentations (straight strips, circular, single or double sided)
  • Excellent energy resolution (150 eV at 5.9 keV for ESLX-S, depending on geometries)
  • Good behavior at high count rates
  • Thickness up to 10 mm
  • Minimum pitch 2 mm
  • Crosstalk ≤1%
  • Double sided segmentation capability, using CANBERRA thin window proprietary technology
  • For ESLX-S: LN2, cryogenerator or Peltier cooling
  • LTS are used at room temperature but can be cooled by Peltier effect in case improved performances are required

Applications

  • PIXE (microprobes)
  • Synchrotron (EXAFS, medical beam lines)
  • Nuclear Physics
  • Non destructive control
  • Radiography
  • Imaging (gamma cameras)
  • Typically for LTS: CAM (Continuous Air Monitoring) on beta particles