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Détecteurs germanium hyper purs

Produits dans cette famille

Standard Electrode Coaxial Ge Detectors (SEGe)

Standard Electrode Coaxial Ge Detectors (SEGe)

Description

The conventional coaxial germanium detector is often referred to as Pure Ge, HPGe, Intrinsic Ge, or Hyperpure Ge. Regardless of the superlative used, the detector is basically a cylinder of germanium with an n-type contact on the outer surface, and a p-type contact on the surface of an axial well. The germanium has a net impurity level of around 1010 atoms/cc so that with moderate reverse bias, the entire volume between the electrodes is depleted, and an electric field extends across this active region. Photon interaction within this region produces charge carriers which are swept by the electric field to their collecting electrodes, where a charge sensitive preamplifier converts this charge into a voltage pulse proportional to the energy deposited in the detector.

The n and p contacts, or electrodes, are typically diffused lithium and implanted boron respectively. The outer n-type diffused lithium contact is about 0.5 mm thick. The inner contact is about 0.3 µm thick. A surface barrier may be substituted for the implanted boron with equal results.

The CANBERRA Coaxial Ge detector can be shipped and stored without cooling. However, long term stability is best preserved by keeping the detector cold. Like all germanium detectors, it must be cooled when it is used to avoid excessive thermally-generated leakage current. The non-perishable nature of this detector widens the application of Ge spectrometers to include field use of portable spectrometers.

The useful energy range of the Coaxial Ge detector is 40 keV to more than 10 MeV. The resolution and peak shapes are excellent and are available over a wide range of efficiencies. A list of available models is given in the accompanying table.

Features

  • Energy range from 40 keV to >10 MeV
  • High resolution - good peak shape
  • Excellent timing resolution
  • High energy rate capability
  • Equipped with Intelligent Preamplifier
  • Diode FET protection
  • Warm-up/HV shutdown
  • USB 2.0 Serial Interface

Standard Electrode Coaxial Ge Detectors (SEGe)
Coaxial Ge Detector Configuration

Broad Energy Germanium Detectors (BEGe)

Broad Energy Germanium Detectors (BEGe)

Description

Le détecteur germanium BEGe de CANBERRA couvre mieux que n’importe quel autre détecteur la gamme d’énergie de 3 keV à 3 MeV. La résolution à faible énergie est équivalente à celle d’un détecteur germanium faible énergie et la résolution à haute énergie est comparable à celle des détecteurs coaxiaux de bonne qualité.

Plus important encore, l’aspect en «galette» du BEGe améliore grandement son efficacité en dessous de 1 MeV pour les échantillons de géométrie classique. Cette forme a été choisie pour son efficacité optimale dans la gamme d’énergie la plus importante pour les analyses gamma de routine, ce qui est en totale opposition avec les mesures d’efficacité relative traditionnelles – une source ponctuelle de 60Co à 25 cm qui présente difficilement des conditions d’essais appropriées pour les échantillons réels. Voir la figure ci-dessous représentant la comparaison de détecteurs GEGe de 5000 mm² et 6500 mm² avec COAX type P de 60 % et un COAX type N de 60% (en efficacité absolu).

Outre la plus grande efficacité sur les échantillons classiques, le BEGe présente un bruit de fond plus faible que les détecteurs coaxiaux classiques car il est plus transparent vis-à-vis du bruit de fond cosmique à haute énergie qui pénètre les laboratoires de surface et vis-à-vis des rayonnements gamma haute énergie issus des radioisotopes naturels tels que le 40K et le 208TI (thorium). Cette performance du détecteur mince a longtemps été reconnue dans des applications telles que l’analyse pulmonaire des actinides.

La plupart des détecteurs basses énergies sont justement appelés ainsi car ils n’ont pas une bonne résolution à haute énergie. En fait, la résolution n’est généralement pas spécifiée au-dessus de 122 keV. Le BEGe représente à cet égard une découverte capitale. Il est équipé d’une structure à électrode qui améliore la résolution à basse énergie et il est fabriqué à partir de germanium spécifique dont le profil d’impureté améliore la collecte de charges (et ainsi la résolution et la forme des pics) à haute énergie. En effet, cela garantit une bonne résolution des pics sur toute la gamme intermédiaire qui est particulièrement importante dans l’analyse du spectre complexe de l’uranium et du plutonium.

Le détecteur BEGe et le préamplificateur associé sont normalement optimisés pour des taux de comptage inférieurs à 60 000 coups/sec. Les temps de collecte des charges interdit l’utilisation de constantes de temps courtes. La résolution est spécifiée avec un réglage optimisé de la constante de temps ou de son équivalent si une électronique numérique type Lynx® est utilisée.

L’autre avantage pour le BEGe est que les dimensions du cristal sont toujours sensiblement les mêmes que

Une fenêtre d’entrée en Béryllium ou en en aluminium est aussi disponibles. La fenêtre en Aluminium est préférable lorsqu’il n’y a pas d’intérêt pour les énergies inférieures à 30 keV et que l’on désire améliorer la solidité du capot. La fenêtre en Béryllium pourra être utilisée pour exploiter au maximum les basses énergies jusqu’à 3keV.

Features & Benefits

  • La gamme d’énergie de 3 keV à 3 MeV combine les avantages d’un détecteur (LEGe) dédié à la mesure basse énergie avec celui d’un détecteur (Coax) dédié à la mesure haute énergie
  • L’efficacité de détection et la résolution des pics ont été optimisées pour la gamme d’énergie de 3 keV à 662 keV, zone ou la localisation du rayonnement gamma est la plus concentrée
  • Cristaux à angle droit « non-bulletized » afin d’offrir une efficacité optimale pour les échantillons mesurés au contact du détecteur
  • Fenêtre d’entrée fine et stable qui permet au détecteur d’être stocké à chaud sans crainte de perte de rendement en basse énergie au fil du temps

Broad Energy Germanium Detectors (BEGe)
Broad Energy Germanium Detectors (BEGe)
Absolute Efficiency vs. Energy comparison for BE6530, BE5030, GC6020 (p-type coaxial) and GR6022 (n-type coaxial) detectors
Broad Energy Germanium Detectors (BEGe)
Absolute Efficiency vs. Energy Comparison for BE6530, GR6022 (n-type coaxial) and GC6020 (p-type coaxial) detectors – all with 60% Relative Efficiency @ 1332 keV

Reverse Electrode Coaxial Ge Detectors (REGe)

Reverse Electrode Coaxial Ge Detectors (REGe)

Description

The reverse-electrode detector (REGe) is similar in geometry to other coaxial germanium detectors with one important difference. The electrodes of the REGe are opposite from the conventional coaxial detector in that the p-type electrode, (ion-implanted boron) is on the outside, and the n-type contact (diffused lithium) is on the inside. There are two advantages to this electrode arrangement – window thickness and radiation damage resistance.

The ion-implanted outside contact is extremely thin (0.3 μm) compared to a lithium-diffused contact, enabling the REGe detector to cover a broad energy range from 3 keV up to several MeV. REGe detectors are normally equipped with a carbon composite window which is robust and provides excellent transmission to below 10 keV. Beryllium or aluminum windows are also available. Aluminum is preferred when there is no interest in energies below 20 keV and improved ruggedness is desired. Beryllium should be selected to take full advantage of the low energy capability (down to 3 keV) of the REGe detector.

It has been found that radiation damage, principally due to neutrons or charged particles, causes hole trapping in germanium. Unlike the case of the conventional coaxial detector, holes are collected by the outside electrode of the REGe detector. Since a much greater amount of the active detector volume is situated within a given distance, ∆ R, of the outside contact, than of the inside contact (Volume ≈ R2) it follows that, on average, holes have less distance to travel if they are attracted to the outside contact than if they are attracted to the inside contact. With less distance to travel, they are less likely to be trapped in radiation damaged material. The extent of the improved resistance to radiation damage depends on other facts, of course, but experimental evidence suggests that the REGe detector may be 10 times as resistant to damage as conventional coaxial germanium detectors.

Features

  • Spectroscopy from 3 keV to >10 MeV
  • Ultra-thin ion implanted contacts
  • Radiation damage resistant
  • Excellent timing resolution
  • High energy rate capability
  • Equipped with Intelligent Preamplifier
  • Diode FET protection
  • Warm-up / HV shutdown
  • USB 2.0 Serial Interface

Reverse Electrode Coaxial Ge Detectors (REGe)
REGe Detector Configuration

Extended Range Coaxial Ge Detectors (XtRa)

Extended Range Coaxial Ge Detectors (XtRa)

Description

The CANBERRA XtRa is a coaxial germanium detector having a unique thin-window contact on the front surface which extends the useful energy range down to 3 keV. Conventional coaxial detectors have a lithium-diffused contact typically between 0.5 and 1.5 mm thick. This dead layer stops most photons below 40 keV or so rendering the detector virtually worthless at low energies. The XtRa detector, with its exclusive thin entrance window and with a Carbon Composite cryostat window, offers all the advantages of conventional standard coaxial detectors such as high efficiency, good resolution, and moderate cost along with the energy response of the more expensive Reverse Electrode Ge (REGe) detector.

The response curves (below) illustrate the efficiency of the XtRa detector compared to a conventional Ge detector. The effective window thickness can be determined experimentally by comparing the intensities of the 22 keV and 88 keV peaks from 109Cd. With the standard 0.6 mm Carbon Composite window, the XtRa detector is guaranteed to give a 22 to 88 keV intensity ratio of greater than 18:1. Beryllium and aluminum windows are also available.

Features

  • Spectroscopy from 3 keV to >10 MeV
  • Wide range of efficiencies
  • High resolution - good peak shape
  • Excellent timing resolution
  • High energy rate capability
  • Equipped with Intelligent Preamplifier
  • Diode FET protection
  • Warm-up/HV shutdown
  • USB 2.0 Serial Interface

Extended Range Coaxial Ge Detectors (XtRa)
XtRa Coaxial Ge Detector

Small Anode Germanium Well Detectors (SAGe Well)

Small Anode Germanium Well Detectors (SAGe Well)

Description

The CANBERRA SAGe™ Well Detector combines excellent energy resolution at low and high energies with maximum efficiency for small samples. Like Traditional Well Detectors, the SAGe Well is fabricated with a blind hole, leaving at least 20 mm of active detector thickness at the bottom of the well. The counting geometry therefore approaches 4π.

The low detector capacitance associated with the small anode technology (similar to what is used on CANBERRA's BEGe detectors) gives the SAGe Well superior low and medium-energy resolution performance compared to Traditional Well or Coaxial Detectors, as well as excellent resolution for higher energy gamma rays.

Furthermore, the detector is manufactured with an aspect ratio of a coaxial detector to allow excellent efficiency performance for standard laboratory geometries such as Marinelli beakers or other large sample containers. The result is a versatile detector that can deliver reductions in count time, through improvements in Minimum Detectable Concentration/Activity (MDC/MDA), for a range of sample sizes and geometries counted inside the well, on the end cap or in Marinelli beakers.

The thin lithium (approximately 50 µm) diffused contact inside the well, combined with a thin-walled aluminum insert in the detector end cap (0.5 mm on the sides and a 1 mm thick bottom) provide a good low-energy response, allowing spectroscopy down to 20 keV. The contact on the outer surface of the detector is approximately 0.5 mm thick, similar to what is used on Standard Electrode Germanium (SEGe) coaxial detectors. Therefore, the useful energy range for sources outside of the well is limited to 40 keV and up.

Small Anode Germanium Well Detectors (SAGe Well)

Features / Benefits

  • Blind well approaches 4π counting geometry yielding high absolute efficiency
  • Superior resolution compared to Traditional Well Detectors at both low and high energies
  • Larger well diameter (28 mm) available with the same excellent resolution as the standard (16 mm) well sizes
  • Thin lithium diffused contact inside well allows spectroscopy from 20 keV up to 10 MeV
  • Full LabSOCS™ characterization available, allowing True Coincidence Summing correction
  • Equipped with Intelligent Preamplifier
  • USB 2.0 Serial Interface

Applications

  • Environmental samples
  • Radiobioassay
  • Geology
  • Oceanography
Traditional Germanium Well Detectors

Traditional Germanium Well Detectors

Description

The CANBERRA High-Purity Germanium (HPGe) Well Detector provides maximum efficiency for small samples because the sample is virtually surrounded by active detector material. The CANBERRA Well detector is fabricated with a blind hole rather than a through hole, leaving at least 15 mm of active detector thickness at the bottom of the well. The counting geometry therefore approaches 4π.

The Well insert in the endcap is made of aluminum with a side-wall thickness of 0.5 mm and a 1 mm thick bottom. The ion implanted contact on the detector element is negligibly thin compared to 0.5 mm of aluminum so these detectors have intrinsically good low energy response, allowing spectroscopy down to 20 keV.

Applications

  • Environmental samples
  • Geology
  • Oceanography
  • Life sciences

Features / Benefits

  • Blind well approaches 4π counting geometry yielding high absolute efficiency
  • Large variety of models available allowing to select the optimum Well detector for your application
  • Thin, ion-implanted contact inside Well allows spectroscopy from 20 keV up to 10 MeV
  • Equipped with Intelligent Preamplifier
  • USB 2.0 Serial Interface

Germanium Well Detectors (WELL)

Low Energy Germanium Detectors (LEGe)

Low Energy Germanium Detectors (LEGe)

Description

The Low Energy Germanium Detector (LEGe) is in all aspects optimized for performance at low and moderate energies and has specific advantages over conventional planar or coaxial detectors. The LEGe detector is fabricated with a thin front and side contact. The rear contact is of less than full area which gives a lower detector capacitance compared to a planar device of similar size. Since preamplifier noise increases with detector capacitance, the LEGe affords lower noise and consequently better resolution at low and moderate energies than any other detector geometry. Unlike grooved planar detectors, there is little dead germanium beyond the active region. This, and the fact that the side surface is charge collecting rather than insulating, results in fewer long-rise time pulses with improved count rate performance and peak-to-background ratios.

The LEGe detector is available with active areas from 50 mm2 to 2000 mm2 and with thicknesses ranging from 5 to 20 mm. For applications involving moderate gamma-ray energies, the LEGe may well outperform a more expensive large volume coaxial detector. The efficiency curve given below illustrates the performance of a typical LEGe detector.

To take full advantage of the low energy response of this intrinsically thin window detector, LEGe cryostats are usually equipped with a thin (1 to 20 mil) beryllium window. A LEGe cryostat can also be equipped with a 0.6 mm carbon epoxy window which improves ruggedness over the Be window, but still has a good low energy transmission. For applications at energies above 30 keV, the LEGe can be provided with a conventional 0.5 mm Aluminum window. In any case, a wide range of available CANBERRA cryostats allows optimizing the detector configuration for your application.

Features & Benefits

  • Thin front and side contact, allowing spectroscopy from 3 keV up
  • Wide range of sizes allows selecting the best detector for your application
  • Low noise and consequently high resolution at low and moderate energies
  • Equipped with Intelligent Preamplifier
  • USB 2.0 Serial Interface

Low Energy Germanium Detectors (GL)

Applications

  • Low energy gamma spectroscopy
  • X-ray absorption spectroscopy
  • Nuclear safeguards
  • XRD, XRF
Ultra-LEGe Detectors (GUL)

Ultra-LEGe Detectors (GUL)

Description

The CANBERRA Ultra-LEGe detector extends the performance range of Ge detectors down to a few hundred electron volts, providing resolution and peak-to-background ratios once thought to be unattainable with semiconductor detectors. The Ultra-LEGe retains the high-energy efficiency intrinsic to germanium detectors because of the high atomic number (Z), combined with a relatively high thickness (5-10 mm), and thus covers an extremely wide range of energies. The graph in Figure 2 below compares the efficiency on the high-energy side of the X-ray spectrum of a 5 mm thick germanium detector to typical silicon based detectors.

Conventional Ge detectors, including those made especially for low energies, suffer from poor peak shape and efficiency below 3 keV. This characteristic, once thought to be fundamental to Ge, prohibited use of Ge detectors in most analytical x-ray applications. CANBERRA has developed detector fabrication techniques which have eliminated these problems. The resulting detector, the Ultra-LEGe, delivers the intrinsic efficiency and resolution advantages of germanium without the disadvantages of the conventional germanium detector.

Features & Benefits

  • Spectroscopy from 300 eV to 300 keV
  • High efficiency compared to Si(Li) and SDD
  • Excellent resolution up to very high count rates
  • High peak/background ratio

Ultra-LEGe Detector (GUL)

Applications

  • XRF
  • XAS (XAFS, EXAFS, XANES)
  • X-ray spectroscopy
ACT-II Actinide Ge Detectors

ACT-II Actinide Ge Detectors

Description

The CANBERRA ACT-II Ge Detector was designed specifically for the detection of internally deposited actinides, particularly uranium, plutonium and americium. Because of the low gamma-ray abundance from uranium, and the low energy of the x rays from plutonium, which emits few gammas, this application demands a very specialized detector system. To achieve desired sensitivities, four detectors are placed in virtual contact with the subject in close proximity to the lungs. The measurement must be carried out in a shielded room. For optimum results, the detectors must be closely spaced, the detector background must be low, the resolution must be good, and the sensitivity of the detector must be high over the energy range of interest (13-20 keV for Pu, 60 keV for Am, and 140-190 keV for U). The ACT-II Ge Detector from CANBERRA provides all this performance and more.

Features

  • Specialized detector system for difficult-to-detect internally deposited actinides
  • Closely-spaced detectors with low background
  • Excellent resolution and high-sensitivity at low to moderate energies
  • Operates in all attitudes from vertical upright to vertical downlooking

ACT-II Actinide Ge Detectors

Germanium Array Detectors

Germanium Array Detectors

Description

The broad-band x-ray flux from synchrotron radiation sources has revitalized the relatively old experimental technique known as x-ray absorption spectrometry. X-ray absorption spectroscopy measures the attenuation of an x-ray beam passing through a sample, just as do the more familiar infrared or UV-visible techniques. Typical x-ray energies are on the order of 300 eV to 30 keV or more, compared to visible light of 2–3 eV and infrared energies of about 0.05–0.5 eV. High energy x-ray absorption transitions involve core electrons which are only slightly perturbed by chemical changes in the valence electrons, hence each element has characteristic absorption edges at which the x-ray energy is just sufficient to liberate a particular type of core electron. Since edges are generally well separated in energy, x-ray absorption is a technique which can uniquely probe the environment of any element from carbon through the transuranics. A generalized x-ray absorption spectrum is illustrated at right.

CANBERRA has been the leader in the development and production of Germanium Array Detectors for this application. Herein you will find a brief summary of our capabilities and products.

Discrete or Monolithic – Both from CANBERRA

Germanium Array Detectors

Discrete Array Detectors

Most of the x-ray array detectors manufactured by CANBERRA have been made with discrete LEGe or Ultra-LEGe detector elements coupled to reset preamplifiers. Because of the high count rates involved, the Integrated- Transistor Reset Preamp (I-TRP) is used exclusively in this application. The discrete element detectors take full advantage of the performance characteristics of LEGe and Ultra-LEGe detectors, notably the energy resolution with short pulse processing (shaping) times. These detectors operate well with shaping time constants of 1/8 μs and up. The Ultra-LEGe detector extends the usable energy range down to 300 eV or so, depending on the cryostat window. Because of the difficulty in handling large numbers of detector elements, discrete array detectors are limited to about 36 channels.

Monolithic Array Detectors

CANBERRA now has the capability to make segmented planar Ge detectors using advanced photolithographic techniques. This technology lends itself to the production of pixel detectors wherein multiple elements are formed in a single slice of germanium. Monolithic array detectors offer improved packing density compared to discrete array detectors. The packing density is defined as the active detector area divided by the total area circumscribed by the array. Monolithic detectors, which have no dead space between elements, have virtually 100% packing density. The packing density of discrete array detectors ranges from about 35 to 55%. Packing density is an important factor in applications requiring an optimized solid angle and best fit to detection area.

SAGe™ Well Detector

The iPA, CANBERRA’s standard RC-feedback preamplifier, provides intelligence for the vast majority of the HPGe product range, including all detector types that do not require a Transistor Reset Preamplifier.

The iPA’s delivery of operational and maintenance parameters to users provides ease of set up and an early warning on performance issues. This data, which may be trended over time, allows for preventative measures to be taken if a key parameter starts to shift, and ultimately improves equipment availability and productivity. Up to a year’s worth of data is logged into on-board memory and can be downloaded to a computer at any time via USB interface for in depth analysis.

Click here to learn more about CANBERRA's iPA Intelligent Preamplifier -->

Description

Germanium detectors are semiconductor diodes having a p-i-n structure in which the intrinsic (I) region is sensitive to ionizing radiation, particularly x rays and gamma rays. Under reverse bias, an electric field extends across the intrinsic or depleted region. When photons interact with the material within the depleted volume of a detector, charge carriers (holes and electrons) are produced and are swept by the electric field to the P and N electrodes. This charge, which is in proportion to the energy deposited in the detector by the incoming photon, is converted into a voltage pulse by an integral charge sensitive preamplifier.

Because germanium has relatively low band gap, these detectors must be cooled in order to reduce the thermal generation of charge carriers (thus reverse leakage current) to an acceptable level. Otherwise, leakage current induced noise destroys the energy resolution of the germanium detector. Liquid nitrogen, which has a temperature of 77 °K is the common cooling medium for such detectors. The germanium detector is mounted in a vacuum chamber which is attached to or inserted into an LN2 Dewar. The sensitive detector surfaces are thus protected from moisture and condensible contaminants.