Research and Production Company ZRF “RITEC” SIA Riga, LATVIA Basic Company Information Company name: ZRF “RITEC” SIA (RITEC Ltd.) Legal status: Private limited company Date of registration: 02.04.1992. It was founded on the basis of the Room Temperature Semiconductor Detectors Laboratory of Semiconductor Detectors Department of the former Riga Research and Scientific Institute of Radioisotope Instrumentation. Country of registration: Latvia VAT Reg. No.: LV40103045390 Address: 23 Aizkraukles Str., ofice 407, Riga, LV-1006, Latvia Head of the company (contact person): Mr. Victor Ivanov (Viktors Ivanovs ) Tel. number: +371-67543304 E-mail: [email protected] Web site: www.ritec.lv www.ritec.lv 2 Current number of employees: 9 Staff professional experience: 5-35 years Business profile: Research, development and production of room temperature semiconductor detectors (mainly based on CdZnTe) for various applications and some associated electronic. Main markets: EC countries, North America, Argentina, international organizations such as IAEA, EURATOM Agenda CdZnTe detectors Detection probes Examples of applications www.ritec.lv 3 CZT material Physical properties: Typical composition Atomic numbers Density Band gap Dielectric constant Pair creation energy Specific resistance Electron mobility, μe Electron lifetime, μτe Hole mobility, μp Hole lifetime, τp (μτ)e (μτ)p www.ritec.lv Cd0.9Zn0.1Te 48,30,52 5.8 g/cm3 1.57 eV 10.9 4.64 eV >1010 Ω* cm 600-1000 cm2/Vs >10-6 s 50-80 cm2/Vs ~10-6 s >10–3 cm2/Vs >10–5 cm2/Vs 4 High atomic number, high density, wide band gap, high resistance, high value of electrons μτ product and long term stability of semiinsulating Cadmium Zinc Telluride make this material a very suitable for roomtemperature semiconductor detectors fabrication. But because of the poor hole transport special methods and detectors designs must be applied. CZT detectors Types of CdZnTe detectors and detectors array: Main advantages: Main applications: planar counting and spectrometer detectors planar detectors with p-n, p-i-n or Schottky contacts Hemispherical, quasihemispherical and cylindrical detectors co-planar grid detectors various pixilated and strip detectors various Frisch grid detectors drift detectors 3D depth sensing position sensitive devices room temperature operation high spectrometric capability high registration efficiency small dimension and weight stability in time low leakage current high count rate capability X-ray and gamma-ray spectroscopic applications industrial and laboratory homeland security safeguards various X-ray and gamma-ray imaging systems Medical www.ritec.lv 5 CZT quasi-hemispherical detectors Main advantages of hemispherical detectors: comparative simplicity of design and production good spectrometric characteristic wide range of operation temperature good stability in time less critical for selection of initial CdZnTe crystals small dimensions ability for application in strong radiation fields and in out-of-theway places commercially availability rather low fabrication costs www.ritec.lv 6 Hemispherical detectors are well known as detectors where conditions of a single polarity charge collection are realized. Progress in improvement of CZT crystals characteristics allows fabrication of high quality hemispherical detectors. The high level of electrons transport characteristic ((μτ)e ≥ 10–2 cm2/Vs) of modern CZT crystals allows fabrication hemispherical detectors with volumes from a very small of 0.5-1 mm3 to a large volume about few cubic centimetres. Single charge collection www.ritec.lv 7 Possible types of quasi-hemispherical detectors www.ritec.lv 8 CZT hemispherical and quasihemispherical detectors 2R a=2d 2r + 2r + d Insensitive area _ _ Ideal Hemispherical Detector Quasi-Hemispherical Detector For simplification of manufacturing of hemispherical detectors, in practice are made quasi-hemispherical detectors with rectangular shape of sensitive volume with dimensions of axaxd. Distribution of an electrical field in the quasihemispherical detector strongly differs from an ideal distribution in an ideal hemispherical detector. There are areas with a low electric field in a detector's corners. www.ritec.lv 9 Hemispherical detectors ()e product - as high as possible, at least not less then 10-3 cm2 / V ()p product - as low as possible, at least ratio ()e /()p must be more then 20 High level of uniformity, absence of significant composition variation and crystalline defects in the detector sensitive volume High specific resistance Optimal relation for big and small radiuses of hemispherical detector electrodes for certain sets of parameters ()e, ()p and operating voltage must be kept Geometrical shape - for best results is necessary to use ideal hemispherical shape, but for simplification of manufacturing of hemispherical detectors, are made quasi-hemispherical detectors with rectangular sensitive volume www.ritec.lv 10 Measured hemispherical gamma-ray detectors energy resolution (FWHM) at 662 keV vs. electron mobility-lifetime product www.ritec.lv 11 Registration efficiency of CZT quasi-hemispherical detectors 5 measured calculated 1 calculated 2 4 Efficiency, % Insensitive areas reduce the detector sensitive volume. It is the reason of essential disagreement of calculated and measured results for small detectors. 3 With using of experimental dates about the total absorption peak efficiency the effective sensitive volume of quasi-hemispherical detectors was calculated. For small sizes detectors it is about 80 % from the total detector volume. 2 1 0 0 1 2 3 4 5 6 7 8 Thickness, mm Measured (dots) total absorption peak efficiencies and calculated photoabsorption efficiency versus quasi-hemispherical detectors thickness, assuming that the whole (1) and only 78% (2) of detector volume is sensitive to the radiation. www.ritec.lv The exceeding of measured efficiencies for larger detectors over-calculated is connected with an unaccounted contribution of multievent Compton absorption. 12 Typical detectors manufacturing process Raw material: •Ingots •Slices •Blank samples Blank samples Testing Encapsulation Temperature test www.ritec.lv Cutting Chemical etching Selected detectors Encapsulated detectors Selected detectors Blank samples with rough dimensions Blank samples Visual and IR inspection Mounting Testing Blank samples with exact dimensions Mechanical lapping Selected samples Mounted detector Testing Selected encapsulated detectors Selected detectors High-count capability test 13 Contact deposition Mechanical polishing Contacted samples Selected mounted detectors Long-term stability test Final characterization Selected detectors Serial product Energy resolution of CZT quasi-hemispherical detectors Energy resolution, keV 20 18 Detector volume 500 mm 16 Detector volume 62 mm 3 3 Dependence of the quasi-hemispherical detectors energy resolution versus gamma-radiation energy. In the first approximation there is linear dependence between these parameters. 14 12 10 8 6 4 0 200 400 600 800 1000 1200 1400 Energy, keV The best energy resolutions at 662 keV line measured with quasi-hemispherical detectors of different volumes. www.ritec.lv Detector sizes, mm Volume, mm3 Energy resolution, keV (%) Peak-toCompton ratio 1.0x1.0x0.5 1.5x1.5x0.75 2.0x2.0x1.0 2.5x2.5x1.25 5.0x5.0x2.5 10.0x10.0x5.0 15.0x15.0x7.5 0.5 1.7 4.0 7.8 62 500 1687 7.1 (1.1) 5.1(0.8) 5.5(0.8) 7.6(1.2) 7.1(1.1) 8.2(1.2) 15 (2.2) 2.0 3.6 4.4 5.0 7.2 8.0 7.0 14 Peak-to-Compton ratio of CZT quasi-hemispherical detectors 6 Volume of detectors - 500 mm Dependencies of the peak-to-Compton ratio versus energy resolution at 662 keV line for large quantities of quasihemispherical detectors with two different volumes. 3 4 3 2 1 8 7 0 10 20 30 40 50 60 70 Energy resolution, keV There is correlation between these parameters. Peak-to-Compton ratio Peak-to-Compton ratio 5 6 3 Volume of detectors - 62 mm 5 4 3 2 1 0 10 15 20 Energy resolution, keV www.ritec.lv 15 25 Mounted detectors, detection probes, some associated electronic www.ritec.lv 16 CZT Large Volume Detectors CZT/500(S), CZT/1500 and Spectrometric Detection Probe SDP310/Z CZT/1500 CZT500(S) with preamplifier PA101 SDP310/Z/(LC)/(S) www.ritec.lv 17 Spectrometric Detection Probe Model SDP500(S) www.ritec.lv 18 Subminiature Spectrometric Detection Probe SDP313 www.ritec.lv 19 CdTe/CdZnTe Detection Probes Miniature gamma-ray spectrometric detection probe SDP310 with hemispherical detector Gamma-ray spectrometric detection unit with hemispherical detector cooled by a single stage Peltier element X-Ray spectrometric detection unit with p-i-n CdTe detector cooled by two or three stage Peltier element www.ritec.lv 20 Temperature Stabilized Detection Unit TSDP410 Temperature dependence of energy resolution (FWHM) at 662 keV line for two different quasi-hemispherical detectors and for detection probe TSDP410 with thermostabilized detector of 10 mm3 . 60 Energy resolution, keV 3 etector volume 10 mm 3 detector volume 500 mm thermostabilized detection unit TSDP410 40 20 0 -20 0 20 40 60 80 o Temperature, C Removable probe of temperature stabilized detection unit TSDP410 can operate up to +70C. Thermostabilization broad of TSDP410 supports the detector's operation temperature and for signals by sound and visual about operating troubles. www.ritec.lv 21 Spectra registered by CZT probe SDP310/Z/60S 1173.2 keV 1500 Co-60 Detector volume 60 mm3 1000 160 500 356.0 keV 140 Ba-133 120 302.7 keV 0 0 1000 100 2000 channels counts 3000 4000 80 10000 60 122 keV 276.4 keV 8000 40 383.8 keV Co-57 20 6000 0 200 400 600 channels counts counts 1332.3 keV 800 1000 1200 4.5 keV 4000 136 keV 2000 0 0 200 400 600 channels www.ritec.lv 22 800 1000 Spectra registered by CZT detector CZT/500S 8000 186 keV 7000 U-235 6000 4000 144 keV 3000 163 keV 5000 2000 205 keV 1000 186 keV 4000 352 keV 295 keV Ra-226 old wristwatch 0 0 200 400 600 242 keV channels 3000 counts counts 5000 2000 609 keV 1000 0 200 400 channels www.ritec.lv 23 600 Spectrum registered by SDP310/Z/60S 400 722 keV Am-241 619 keV Am-241 600 375 keVAm-241 Pu-239 80 413.7 keV Pu-239 15000 664.4 keV Am-241 Pu-239 counts 20000 267.5 keV U-237 148.6 keV Pu-239 25000 208 keV U-237 800 164.6 keV U-237 30000 333 keV Am-241 U-237 Spectrum of reactor grade plutonium sample 60 40 10000 200 20 5000 0 0 0 200 www.ritec.lv 400 600 0 800 1000 24 1200 1400 1600 1800 Efficiency of CZT quasi hemispherical detector 4 elements detector assembly, total volume 2 cm NaJ detector Spectra of U-235 registered by detectors assembly of 2 cm3 and by NaJ (1"x1”) detector. Time and conditions of measurements are the same for both cases. 3 100000 80000 40000 20000 100 0 0 100 200 300 400 measured calculated 500 channels 10 Measured total absorption peak efficiency and calculated photoabsorption efficiency versus gamma radiation energy for CZT detector for CZT detector with a thickness of 5 mm. www.ritec.lv 25 Efficiency, % counts 60000 1 0 200 400 600 800 Energy, keV 1000 1200 1400 1600 Input count rate depending on radiation dose rate for various detectors volumes 500 mm3 (a), 40 mm3 (b), 14 mm3 (c), 0.5 mm3 (d) 10000000 Count rate, cps 1000000 100000 10000 a b c d 1000 100 1 10 100 Absorbed dose rate, mGr/h www.ritec.lv 26 1000 10000 Spectrum of Cs-137 measured by the probe SDP310/Z/005 with CZT detector of 0.5 mm3 3000 2500 Counts 2000 1500 1000 500 0 0 200 400 600 Channels www.ritec.lv 27 800 1000 CdTe p-i-n detector Detector size – 4x4x0.6 mm3 Operation temperature - -35 °C www.ritec.lv 28 Planar detector with application of pulse selection-correction device Spectrum measured without application of pulse selectioncorrection device Spectrum measured with application of pulse correction device Spectrum measured with application of pulse correctionselection device www.ritec.lv 29 Common spectrum of Ba-133, Cs-137 and Co-60 measured with application of selection-correction device Planar CZT detector, size 10x10x2 mm3 www.ritec.lv 30 Samples of applications www.ritec.lv 31 Safeguards application.Three storage types of irradiated fuel assemblies in cooling pond. www.ritec.lv 32 Spend Fuel Attribute Tester (SFAT). Chamber for underwater measurements. www.ritec.lv 33 Nuclear power plant, spent fuel cooling pond. Places for measuring probe insertion. www.ritec.lv 34 Scheme of measurements of suspended fuel assemblies www.ritec.lv 35 Irradiated fuel assembly spectrum Burn-up 180 MWd/FA. Cooling time 21 months. 3000 Counts 2000 1000 0 0 200 400 Channels www.ritec.lv 36 600 800 Gamma spectrum of 1 year old spent fuel measured with SFAT 15000 604.7 keV, Cs-134, 2.06 y 511 keV 5000 grid1ya 200 300 Channels www.ritec.lv 37 1332.5 keV, Co-60, 5.273 y 1173.23 keV, Co-60, 5.273 y 765.8 keV, Nb-95, 35.2 d 2 Hemispheric CdZnTe 60 mm SDP310/Z60 NPS Paks, unit 4 upper layer 795.8 keV, Cs-134, 2.06 y 756.7 keV, Zr-95, 64.4 d 696.5 Pr-144, 724.2 keV, Zr-95, 64.4 d Counts/channel 10000 WWER-440; 1 year old fuel 400 Underwater measuring system of bundles of fuel elements in basket Main features and dimensions Equipped underwater measuring system Configuration of internal lead shielding and collimators for application with CZT/500S Internal lead shielding www.ritec.lv 38 Measuring scheme of spent fuel bundles in basket www.ritec.lv 39 Basket with spent fuel bundles View from above, 4 m under water www.ritec.lv 40 Spectra of spent fuel bundles stored in baskets Spectrum of fuel bundle, burn-up 1676 MWd/FA, cooling time about 8 years www.ritec.lv Spectrum of fuel bundle with shank, burn-up 1857 MWd/FA, cooling time about 13 years 41 PU/U attribute test system with CZT/500S detector and MCA-166 www.ritec.lv 42 Detector module with quasi hemispherical CZT detector CZT detector of size 10x10x5 mm3 High voltage power supply Charge sensitive preamplifier and shaping amplifier www.ritec.lv 43 Mounted planar CZT detectors for various application www.ritec.lv 44 Surgical gamma-probes Schematic drawing of the surgical probe head www.ritec.lv 45 Linear arrays of planar CZT detectors 5 elements module (with preamplifiers) 16 elements assembly www.ritec.lv 46 Personal radiation detector (PRD) γ-TRACER GT1 Used CZT detector: 85 - area 2 cm2; - volume 0.4 cm3. 46 www.ritec.lv 17 47 Geological borehole logging probe Cable head Amplifier module Detector module Probe external diameter 20 mm Used detector: -CsI(Tl) with Si PIN photodiode; -Detector dimensions Ø12 x 50 mm; -Energy resolution FWHM@662 keV about 9% CZT detector can be used too. www.ritec.lv 48 Spectra of Cs-137 measured with quasihemispherical detector of 10x10x5 mm3 under IR stimulation Cs-137 Detector size 10x10x5 mm3 3000 2500 Operating voltage – 1000V Illumination by IR LED IR 204, 940 nm Radiant power: 1 – without illumination FWHM@662 keV – 14.9 keV 2 – 200 mkW FWHM@662 keV – 8.6 keV 3 – 250 mkW 4 – 300 mkW 5 – 340 mkW 2 3000 3 2500 Counts 2000 Counts 2000 4 1 1500 5 1000 500 1500 0 700 750 800 850 900 Channels 1000 500 0 200 400 600 800 Channels www.ritec.lv 49 Spectra of Am-241 and Cs-137 measured with quasi-hemispherical detectors without and with IR illumination 2000 2 1500 1500 2 1000 4.2 keV 7.2 keV 500 2000 Counts Counts Am-241 Detector size 10x10x5 mm3 1 0 1000 3.9 keV 6.3 keV 500 1500 1600 1500 1700 1800 1 Channels 0 Counts 0 1000 100 200 300 400 500 Channels Cs-137 Detector size 5x5x1.5 mm3 1 – without IR illumination 500 2 – with IR illumination 940 nm 0 200 400 600 800 1000 1200 1400 Channels www.ritec.lv 50 1600 1800 Spectrometric characteristics of different CdZnTe quasi-hemispherical detectors measured without and with IR stimulation No. Detector Operating size, mm3 voltage, V Energy resolution Energy resolution Peak-to-Compton ratio (FWHM) at 662 keV, (FWHM) at 59.5 keV, at 662 keV keV keV Without IR illumination With IR illumination Without IR illumination With IR illumination 1 10x10x5 900 20,6 9,6 3 7,6 2 10x10x5 1400 9,8 8,1 7,1 10 3 7x7x3.5 600 27,1 16,2 2,5 4,2 4 7x7x3.5 600 6,4 5,1 9,4 12,6 5 5x5x2.5 500 24,5 10,8 1,8 5,4 6 5x5x2.5 500 7,2 4,7 7,4 10 7 3x3x1.5 300 6,9 5,5 5,4 6,3 www.ritec.lv 51 Without IR illumination With IR illumination 6,3 3,8 5,4 2,8 3,3 2,4 http://www.ritec.lv e-mail:[email protected]
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