402 research outputs found
Direct comparison of the performance of CZT detectors contacted with various metals
Cadmium Zinc Telluride (CZT) achieves excellent spatial resolution and good
energy resolution over the broad energy range from several keV into the MeV
energy range. In this paper we present the results of a systematic study of the
performance of CZT detectors manufacturered by Orbotech (before IMARAD)
depending on surface preparation, contact materials and contact deposition. The
standard Orbotech detectors have the dimension of 2.0 x 2.0 x 0.5 cm. They have
a pixellated In anode with 8 x 8 pixels and a monolithic In cathode. Using the
same CZT substrates several times, we have made a direct comparison of the
performance of different contact materials by replacing the cathode and/or the
anode contacts with several high-workfunction metals. We present the
performance of the detectors and conclude with an overview over our ongoing
detector optimization.Comment: 8 pages, 5 figures, to appear in the proceedings of the conference
5922, "Hard X-Ray and Gamma-Ray Detector Physics VII" on the "Optics &
Photonics 2005" SPIE Symposium, July 31- August 4, 2005, San Diego, C
Thick CZT Detectors for Space-Borne X-ray Astronomy
Cadmium Zinc Telluride (CZT) detectors are having a major impact on the field
of hard X-ray astronomy. Without the need for cryogenic cooling they achieve
good spatial and energy resolutions over the broad energy range from 10 keV to
600 keV. In this paper, we briefly review the historical development of
detectors used in X-ray astronomy. Subsequently, we present an evaluation of
CZT detectors from the company Imarad. The standard 2x2x0.5 cm detectors,
contacted with 8x8 In pixels and an In cathode, exhibit FWHM energy resolutions
of 7 keV at 59 keV, and 10 keV at 662 keV. A direct measurement of the 662 keV
photopeak efficiency gives 67%. We have started a detailed study of the
performance of Imarad detectors depending on surface preparation, contact
materials, contact deposition, post-deposition detector annealing, and detector
passivation techniques. We present first results from contacting detectors with
Cr, Ag, Au, and Pt.Comment: Invited Contribution to the 49th International Symposium on Optical
Science and Technology (SPIE), August 2004, Denver, CO, SPIE, 49, 5540,
13.01. (2004
Recommended from our members
FeCrβSβ in magnetic fields: possible evidence for a multiferroic ground state.
We report on neutron diffraction, thermal expansion, magnetostriction, dielectric, and specific heat measurements on polycrystalline FeCr2S4 in external magnetic fields. The ferrimagnetic ordering temperatures TC β 170β
K and the transition at TOO β 10β
K, which has been associated with orbital ordering, are only weakly shifted in magnetic fields up to 9β
T. The cubic lattice parameter is found to decrease when entering the state below TOO. The magnetic moments of the Cr- and Fe-ions are reduced from the spin-only values throughout the magnetically ordered regime, but approach the spin-only values for fields >5.5β
T. Thermal expansion in magnetic fields and magnetostriction experiments indicate a contraction of the sample below about 60β
K. Below TOO this contraction is followed by a moderate expansion of the sample for fields larger than ~4.5β
T. The transition at TOO is accompanied by an anomaly in the dielectric constant. The dielectric constant depends on both the strength and orientation of the external magnetic field with respect to the applied electric field for T < TOO. A linear correlation of the magnetic-field-induced change of the dielectric constant and the magnetic-field dependent magnetization is observed. This behaviour is consistent with the existence of a ferroelectric polarization and a multiferroic ground state below 10β
K
Fabrication of the Ni[3]Al-based alloy formed by spark plasma sintering of VKNA powders
The material based on Ni[3]Al intermetallic has been obtained from the industrial powder of a VKNA type by the method of spark plasma sintering. Materials sintering was conducted at the temperature of 1100 Β°Π‘, compacting pressure of 20 MPa, and during soaking time equal to 5 minutes. The heating rate of samples amounted to 50 and 200 Β°Π‘/min. It has been established that the material obtained by sintering at the rate of 50 Β°Π‘/min possesses a maximum value of density (5.93 g/cm{3}) and a maximum level of bending strength (~ 400 MPa)
Isabelle/DOF: Design and Implementation
This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record17th International Conference, SEFM 2019
Oslo, Norway, September 18β20, 2019DOF is a novel framework for defining ontologies and enforcing them during document development and evolution. A major goal of DOF is the integrated development of formal certification documents (e. g., for Common Criteria or CENELEC 50128) that require consistency across both formal and informal arguments. To support a consistent development of formal and informal parts of a document, we provide Isabelle/DOF, an implementation of DOF on top of the formal methods framework Isabelle/HOL. A particular emphasis is put on a deep integration into IsabelleΓ’s IDE, which allows for smooth ontology development as well as immediate ontological feedback during the editing of a document. In this paper, we give an in-depth presentation of the design concepts of DOFΓ’s Ontology Definition Language (ODL) and key aspects of the technology of its implementation. Isabelle/DOF is the first ontology language supporting machine-checked links between the formal and informal parts in an LCF-style interactive theorem proving environment. Sufficiently annotated, large documents can easily be developed collabo- ratively, while ensuring their consistency, and the impact of changes (in the formal and the semi-formal content) is tracked automatically.IRT SystemX, Paris-Saclay, Franc
Recommended from our members
Development of High Resolution Scintillator Systems Based on Photocell Technology
Inorganic scintillator/photomultiplier-based spectrometers are the systems of choice for a multitude of X-ray and gamma radiation measurement applications. Despite widespread use, they have numerous shortcomings. The most serious shortcoming is the relatively poor energy resolution that makes isotope identification problematic, particularly in the case of trace quantities. Energy resolution in scintillator/photomultiplier tube (PMT) spectrometers is governed by a combination of the crystal intrinsic resolution that includes non-linearity effects, photomultiplier statistics, and the variability in the probability of a scintillation photon generating a photoelectron at the photocathode. It is evident that energy resolution in these systems is linked to both the physics of light generation in the scintillator and the characteristics of the PMT. PMTs also present design problems, especially in the case of handheld and portable instruments, due to their considerable weight and volume. Additionally, PMTs require well-regulated high voltage, and are vulnerable to magnetic fields. The objective of this work is to provide instrument designers of scintillation-based gamma-ray spectrometers with superior energy resolution and greatly reduced weight and volume. It is planned to achieve this advancement by optimizing the performance of a new class of inorganic scintillators by matching their emission spectra with the enhanced quantum efficiency of certain photocells
ΠΠ΅Π»ΠΊΠΎΠ²ΠΎ-Π»ΠΈΠΏΠΈΠ΄Π½ΡΠΉ ΡΠΎΡΡΠ°Π² ΠΏΡΠ»ΡΡΡ Π±Π΅ΡΠ΅Π·Ρ Π±ΠΎΡΠΎΠ΄Π°Π²ΡΠ°ΡΠΎΠΉ (Betula verrucosa) ΠΈ Π΅Π΅ Π°Π½ΡΠΈΠΎΠΊΡΠΈΠ΄Π°Π½ΡΠ½Π°Ρ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ Π² Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΠΈ ΠΎΡ ΠΌΠ΅ΡΡΠ° ΠΏΡΠΎΠΈΠ·ΡΠ°ΡΡΠ°Π½ΠΈΡ
Pollen has various effects on the human body. In order to study and compare the biological activity of the mature pollen grains of Betula verrucosa Ehrh. we investigated the protein-lipid composition and total antioxidant activity (TAA) of 10 samples from different habitats in the territory of Ukraine and the Slovak Republic. The collection sites are near highways and apartment blocks, as well as a nature reserve, forest and botanical garden. The protein content was determined by the Kjeldahl method. A chromatographic analysis of fatty acids from lipids was performed using a βCvet 500β gas chromatograph, equipped with a flame-ionization detector in the isothermal mode. The bioactivity of aqueous, ethanol and methanol extracts of pollen grains was evaluated by the DPPH free radical scavenging method (2,2-diphenyl-1-picrylhydrazyl) by means spectrophotometry in vitro. The protein content of the pollen of B. verrucosa ranged from 17.9% to 25.6%, depending on the habitat. Unsaturated fatty acids were found in higher amounts than saturated fatty acids. The profile of fatty acids indicates a higher content of palmitic (33.9%), oleic (29.5%) and linoleic (27.8%) acids and a low content of arachidonic (0.4%) and pentadecanoic (0.8%) acids. We also established that silver birch pollen is characterized by high antioxidant activity. The measured value of TAA for aqueous pollen extracts was within 74.8β85.5%. For the ethanol extracts it was quantified within 60.3β95.0% and for the methanol extracts β 46.1β92.6%. The Tukey test was used to determine the differences between the means at a level of P < 0.05. A strong correlation coefficient (0.70) was defined between the protein content and the TAA of aqueous extracts. In general, the Ukrainian and Slovak samples of pollen differ in the fatty acid composition of lipids and aqueous and ethanol TAA extracts. Pollen of B. verrucosa should be used for diagnostic, therapeutic and prophylactic purposes as close as possible to the place of origin.Β ΠΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½Ρ Π±Π΅Π»ΠΊΠΎΠ²ΡΠΉ ΠΈ Π»ΠΈΠΏΠΈΠ΄Π½ΡΠΉ ΡΠΎΡΡΠ°Π² ΠΈ Π±ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠ°Ρ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ 10 ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² ΠΏΡΠ»ΡΡΡ Betula verrucosa Ehrh. ΠΈΠ· ΡΠ°Π·Π½ΡΡ
ΠΌΠ΅ΡΡ ΠΏΡΠΎΠΈΠ·ΡΠ°ΡΡΠ°Π½ΠΈΡ Π½Π° ΡΠ΅ΡΡΠΈΡΠΎΡΠΈΠΈ Π£ΠΊΡΠ°ΠΈΠ½Ρ ΠΈ Π‘Π»ΠΎΠ²Π°ΠΊΠΈΠΈ. ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΎ ΡΠΎΠ΄Π΅ΡΠΆΠ°Π½ΠΈΠ΅ Π±Π΅Π»ΠΊΠΎΠ² (17,9β25,6%) ΠΈ 8 ΠΆΠΈΡΠ½ΡΡ
ΠΊΠΈΡΠ»ΠΎΡ (Ρ ΡΠΈΡΠ»ΠΎΠΌ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΡ
Π°ΡΠΎΠΌΠΎΠ² ΠΎΡ 14 Π΄ΠΎ 20) Π² ΡΠΎΡΡΠ°Π²Π΅ Π»ΠΈΠΏΠΈΠ΄ΠΎΠ². ΠΡΡΠ²Π»Π΅Π½ΠΎ ΠΏΡΠ΅ΠΎΠ±Π»Π°Π΄Π°Π½ΠΈΠ΅ Π½Π΅Π½Π°ΡΡΡΠ΅Π½Π½ΡΡ
ΠΆΠΈΡΠ½ΡΡ
ΠΊΠΈΡΠ»ΠΎΡ (58,6%) Ρ Π΄ΠΎΠΌΠΈΠ½ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΏΠ°Π»ΡΠΌΠΈΡΠΈΠ½ΠΎΠ²ΠΎΠΉ (33,9%), ΠΎΠ»Π΅ΠΈΠ½ΠΎΠ²ΠΎΠΉ (29,5%) ΠΈ Π»ΠΈΠ½ΠΎΠ»Π΅Π²ΠΎΠΉ (27,8%). ΠΡΠ΅Π½Π΅Π½Π° ΠΎΠ±ΡΠ°Ρ Π°Π½ΡΠΈΠΎΠΊΡΠΈΠ΄Π°Π½ΡΠ½Π°Ρ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ Π²ΠΎΠ΄Π½ΡΡ
, ΡΡΠ°Π½ΠΎΠ»ΠΎΠ²ΡΡ
ΠΈ ΠΌΠ΅ΡΠ°Π½ΠΎΠ»ΠΎΠ²ΡΡ
ΡΠΊΡΡΡΠ°ΠΊΡΠΎΠ² ΠΏΡΠ»ΡΡΡ Π±Π΅ΡΠ΅Π·Ρ Π±ΠΎΡΠΎΠ΄Π°Π²ΡΠ°ΡΠΎΠΉ Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΡΠ²ΠΎΠ±ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΡΡΠ°Π±ΠΈΠ»ΡΠ½ΠΎΠ³ΠΎ ΡΠ°Π΄ΠΈΠΊΠ°Π»Π° Π΄ΠΈΡΠ΅Π½ΠΈΠ»ΒΠΏΠΈΠΊΡΠΈΠ»Π³ΠΈΠ΄ΡΠ°Π·ΠΈΠ»Π° ΠΊΠΎΠ»ΠΎΡΠΈΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈ Π² ΡΠ΅Π°ΠΊΡΠΈΠΈ in vitro. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Ρ ΡΡΠ°ΡΠΈΡΡΠΈΡΠ΅ΡΠΊΠΈ Π΄ΠΎΡΡΠΎΠ²Π΅ΡΠ½ΡΠ΅ ΡΠ°Π·Π»ΠΈΡΠΈΡ ΠΌΠ΅ΠΆΠ΄Ρ ΠΎΠ±ΡΠ°Π·ΡΠ°ΠΌΠΈ ΠΊΠ°ΠΊ Π²Π½ΡΡΡΠΈ ΡΠΊΡΠ°ΠΈΠ½ΡΠΊΠΈΡ
ΠΈ ΡΠ»ΠΎΠ²Π°ΡΠΊΠΈΡ
Π³Π΅Π½ΠΎΡΠΈΠΏΠΎΠ², ΡΠ°ΠΊ ΠΈ ΠΌΠ΅ΠΆΠ΄Ρ Π½ΠΈΠΌΠΈ. Π Π°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΡΠ°ΠΊΡΠΎΡΡ Π²Π»ΠΈΡΠ½ΠΈΡ Π½Π° Π²Π°ΡΠΈΠ°ΡΠΈΠΈ Π±Π΅Π»ΠΊΠΎΠ²ΠΎ-Π»ΠΈΠΏΠΈΠ΄Π½ΠΎΠ³ΠΎ ΡΠΎΡΡΠ°Π²Π° ΠΏΡΠ»ΡΡΡ ΠΈ Π΅Π΅ Π±ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ.ΠΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½Ρ Π±Π΅Π»ΠΊΠΎΠ²ΡΠΉ ΠΈ Π»ΠΈΠΏΠΈΠ΄Π½ΡΠΉ ΡΠΎΡΡΠ°Π² ΠΈ Π±ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠ°Ρ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ 10 ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² ΠΏΡΠ»ΡΡΡ Betula verrucosa Ehrh. ΠΈΠ· ΡΠ°Π·Π½ΡΡ
ΠΌΠ΅ΡΡ ΠΏΡΠΎΠΈΠ·ΡΠ°ΡΡΠ°Π½ΠΈΡ Π½Π° ΡΠ΅ΡΡΠΈΡΠΎΡΠΈΠΈ Π£ΠΊΡΠ°ΠΈΠ½Ρ ΠΈ Π‘Π»ΠΎΠ²Π°ΠΊΠΈΠΈ. ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΎ ΡΠΎΠ΄Π΅ΡΠΆΠ°Π½ΠΈΠ΅ Π±Π΅Π»ΠΊΠΎΠ² (17,9β25,6%) ΠΈ 8 ΠΆΠΈΡΠ½ΡΡ
ΠΊΠΈΡΠ»ΠΎΡ (Ρ ΡΠΈΡΠ»ΠΎΠΌ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΡ
Π°ΡΠΎΠΌΠΎΠ² ΠΎΡ 14 Π΄ΠΎ 20) Π² ΡΠΎΡΡΠ°Π²Π΅ Π»ΠΈΠΏΠΈΠ΄ΠΎΠ². ΠΡΡΠ²Π»Π΅Π½ΠΎ ΠΏΡΠ΅ΠΎΠ±Π»Π°Π΄Π°Π½ΠΈΠ΅ Π½Π΅Π½Π°ΡΡΡΠ΅Π½Π½ΡΡ
ΠΆΠΈΡΠ½ΡΡ
ΠΊΠΈΡΠ»ΠΎΡ (58,6%) Ρ Π΄ΠΎΠΌΠΈΠ½ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΏΠ°Π»ΡΠΌΠΈΡΠΈΠ½ΠΎΠ²ΠΎΠΉ (33,9%), ΠΎΠ»Π΅ΠΈΠ½ΠΎΠ²ΠΎΠΉ (29,5%) ΠΈ Π»ΠΈΠ½ΠΎΠ»Π΅Π²ΠΎΠΉ (27,8%). ΠΡΠ΅Π½Π΅Π½Π° ΠΎΠ±ΡΠ°Ρ Π°Π½ΡΠΈΠΎΠΊΡΠΈΠ΄Π°Π½ΡΠ½Π°Ρ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ Π²ΠΎΠ΄Π½ΡΡ
, ΡΡΠ°Π½ΠΎΠ»ΠΎΠ²ΡΡ
ΠΈ ΠΌΠ΅ΡΠ°Π½ΠΎΠ»ΠΎΠ²ΡΡ
ΡΠΊΡΡΡΠ°ΠΊΡΠΎΠ² ΠΏΡΠ»ΡΡΡ Π±Π΅ΡΠ΅Π·Ρ Π±ΠΎΡΠΎΠ΄Π°Π²ΡΠ°ΡΠΎΠΉ Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΡΠ²ΠΎΠ±ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΡΡΠ°Π±ΠΈΠ»ΡΠ½ΠΎΠ³ΠΎ ΡΠ°Π΄ΠΈΠΊΠ°Π»Π° Π΄ΠΈΡΠ΅Π½ΠΈΠ»ΒΠΏΠΈΠΊΡΠΈΠ»Π³ΠΈΠ΄ΡΠ°Π·ΠΈΠ»Π° ΠΊΠΎΠ»ΠΎΡΠΈΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈ Π² ΡΠ΅Π°ΠΊΡΠΈΠΈ in vitro. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Ρ ΡΡΠ°ΡΠΈΡΡΠΈΡΠ΅ΡΠΊΠΈ Π΄ΠΎΡΡΠΎΠ²Π΅ΡΠ½ΡΠ΅ ΡΠ°Π·Π»ΠΈΡΠΈΡ ΠΌΠ΅ΠΆΠ΄Ρ ΠΎΠ±ΡΠ°Π·ΡΠ°ΠΌΠΈ ΠΊΠ°ΠΊ Π²Π½ΡΡΡΠΈ ΡΠΊΡΠ°ΠΈΠ½ΡΠΊΠΈΡ
ΠΈ ΡΠ»ΠΎΠ²Π°ΡΠΊΠΈΡ
Π³Π΅Π½ΠΎΡΠΈΠΏΠΎΠ², ΡΠ°ΠΊ ΠΈ ΠΌΠ΅ΠΆΠ΄Ρ Π½ΠΈΠΌΠΈ. Π Π°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΡΠ°ΠΊΡΠΎΡΡ Π²Π»ΠΈΡΠ½ΠΈΡ Π½Π° Π²Π°ΡΠΈΠ°ΡΠΈΠΈ Π±Π΅Π»ΠΊΠΎΠ²ΠΎ-Π»ΠΈΠΏΠΈΠ΄Π½ΠΎΠ³ΠΎ ΡΠΎΡΡΠ°Π²Π° ΠΏΡΠ»ΡΡΡ ΠΈ Π΅Π΅ Π±ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ
Growth of detector-grade CZT by Traveling Heater Method (THM): An advancement
In this present work we report the growth of Cd{sub 0.9}Zn{sub 0.1}Te doped with In by a modified THM technique. It has been demonstrated that by controlling the microscopically flat growth interface, the size distribution and concentration can be drastically reduced in the as-grown ingots. This results in as-grown detector-grade CZT by the THM technique. The three-dimensional size distribution and concentrations of Te inclusions/precipitations were studied. The size distributions of the Te precipitations/inclusions were observed to be below the 10-{micro}m range with the total concentration less than 10{sup 5} cm{sup -3}. The relatively low value of Te inclusions/precipitations results in excellent charge transport properties of our as-grown samples. The ({mu}{tau}){sub e} values for different as-grown samples varied between 6-20 x 10{sup -3} cm{sup 2}/V. The as-grown samples also showed fairly good detector response with resolution of {approx}1.5%, 2.7% and about 3.8% at 662 keV for quasi-hemispherical geometry for detector volumes of 0.18 cm{sup 3}, 1 cm{sup 3} and 4.2 cm{sup 3}, respectively
- β¦