Antimicrobial and antifungal polymers are gaining the attention of pharmaceutical makers and industrial design. Nanospheres-Polymers attached Platinum(II) / (IV) complexes have been synthesized to ...investigate antimicrobial activities. Firstly, nanospheres involving Schiff bases were synthesized from (aminomethyl) polystyrene and four substitute salicylaldehyde (2-hydroxy benzaldehyde, 5-fluoro-2-hydroxy benzaldehyde, 5-kloro-2-hydroxy benzaldehyde, 5-bromo-2-hydroxy benzaldehyde). Secondly, polymers attached Platinum(II) / (IV) complexes have been prepared by means of template method. The IR spectra show that the ligands act in a monovalent bidentate fashion all nanospheres involving Schiff bases. Square-planar and octahedral structures are proposed for Pt(II) and Pt(IV), respectively. All these substances have been examined for antibacterial activity against pathogenic strains, and antifungal activity. In particular, Pt(IV) complexes were more potent bactericides than all of the synthesized substances.
A Compton camera system consisting of a silicon drift detector (SDD) and an Anger camera has been constructed to study coincidence events and the possibility of tracking a recoil electron. An event ...is considered as a coincidence when a photon emitted from a radioactive source is first Compton scattered in the SDD where the recoil electron deposits its energy and the scattered photon undergoes a photoelectric absorption in the NaI(Tl) crystal of the Anger camera. The SDD is composed of a monolithic array of 19 hexagonal cells each having an on-chip transistor which provides the first stage amplification. /sup 137/Cs source has been finely collimated in order to study events occuring at different locations within a single cell. The equipment is designed such that the measurements can be done in all detector orientations and kinematical conditions. The angular and energy distribution of coincidence events have been studied with high statistics. Energy resolution and angle measurements performed with this detector system will be presented in this paper.
The Compton camera, in principle, can improve spatial resolution and efficiency with respect to today's PET and SPECT techniques. The optimization of a Compton camera system in terms of efficiency ...and resolution is a complex multiparameter problem. The efficiency depends on various detector parameters (material, thickness, positioning, etc.). The influence of these parameters on the image reconstruction is investigated for a conventional reconstruction technique in order to find optimum detector parameters. The case studies are based on a model for a system consisting of a silicon drift detector (electron detector) and a scintillator detector (photon detector). Effects of secondary and background processes were not included in this model. It was found that high-energy gamma sources (300 keV and more) are preferable over lower-energy sources (e.g., 140 keV) commonly used for SPECT. A Si detector as an electron detector and an angular range between 30/spl deg/ and 80/spl deg/ is most useful considering the various physical and experimental constraints. An silicon drift detector (SDD) with integrated front-end electronics offers a very good energy resolution due to its low electronics noise. The intrinsic resolution of both detectors influence the overall resolution considerably. A relatively large pixel size of the SDD considered here reduces the number of readout channels, but also limits the intrinsic resolution. The thickness of the electron detector should be chosen in such a way that its effects on efficiency and spatial resolution are balanced. An interdetector distance of at least 15 cm was found to be appropriate for the detector setup considered in this paper.
FPGA-based data acquisition system for a Compton camera Nurdan, K; Çonka-Nurdan, T; Besch, H.J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2003, Letnik:
510, Številka:
1
Journal Article
Recenzirano
A data acquisition (DAQ) system with custom back-plane and custom readout boards has been developed for a Compton camera prototype. The DAQ system consists of two layers. The first layer has units ...for parallel high-speed analog-to-digital conversion and online data pre-processing. The second layer has a central board to form a general event trigger and to build the data structure for the event. This modularity and the use of field programmable gate arrays make the whole DAQ system highly flexible and adaptable to modified experimental setups. The design specifications, the general architecture of the Trigger and DAQ system and the implemented readout protocols are presented in this paper.
Silicon drift detector readout electronics for a Compton camera Çonka Nurdan, T.; Nurdan, K.; Walenta, A.H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2004, Letnik:
523, Številka:
3
Journal Article
Recenzirano
Odprti dostop
A prototype detector for Compton camera imaging is under development. A monolithic array of 19 channel silicon drift detector with on-chip electronics is going to be used as a scatter detector for ...the prototype system. Custom designed analog and digital readout electronics for this detector was first tested by using a single cell Silicon drift detector. This paper describes the readout architecture and presents the results of the measurement.
Usually the position resolution in imaging applications with gamma rays is limited due to the range of secondary reaction products to a few mm. Here a new approach will be presented using the vertex ...of the gamma interaction as the quantity for position measurement. Because the dominant interaction is the Compton effect the vertex detection method as used in particle physics needs a number of essential modifications. Therefore a detector system is investigated consisting of a stack of Si-drift detectors for the vertex detection of the first Compton interaction and a secondary absorption detector where the position of the scattered photon is detected. A number of effects and possible solutions will be discussed including depth of interaction measurement and track reconstruction of the Compton electron which yields useful information. Another very promising approach of measuring the track projection as in a TPC (Time Projection Chamber) will be presented including first successful measurements in a gas detector. Because the expected rate in the first and second detector is of the order of 1 MHz and 10 MHz respectively the concept of read out electronics and data processing based on VLSI custom chips for signal shaping and first buffering and digital pipe-line processors based on FPGAs is presented. Finally a full system for small animal imaging based on the principle of a Compton Camera will be discussed in terms of achievable resolution and sensitivity.
Silicon drift detectors (SDD) with on-chip electronics have found many applications in different fields. A detector system has recently been designed and built to study the electrons from Compton ...scatter events in such a detector. The reconstruction of the Compton electrons is a crucial issue for Compton imaging. The equipment consists of a monolithic array of 19 channel SDDs and an Anger camera. Photons emitted from a finely collimated source undergo Compton scattering within the SDD where the recoil electron is absorbed. The scattered photon is subsequently observed by photoelectric absorption in the second detector. The coincidence events are used to get the energy, position, and direction of the Compton electrons. Because the on-chip transistors provide the first stage amplification, the SDDs provide outstanding noise performance and fast shaping, so that very good energy resolution can be obtained even at room temperature. The drift detectors require a relatively low number of readout channels for large detector areas. Custom-designed analog and digital electronics provide fast readout of the SDDs. The equipment is designed such that the measurements can be done in all detector orientations and kinematical conditions. The first results obtained with this detector system will be presented in this paper.
Silicon drift detectors (SDD) with on-chip electronics have found many applications in different fields. A detector system has recently been designed and built to study the electrons from Compton ...scatter events in such a detector. The reconstruction of the Compton electrons is a crucial issue for Compton imaging. The equipment consists of a monolithic array of 19 channel SDDs and an Anger camera. Photons emitted from a finely-collimated source undergo Compton scattering within the SDD where the recoil electron is absorbed. The scattered photon is subsequently observed by photoelectric absorption in the second detector. The coincidence events are used to get the energy, position, and direction of the Compton electrons. Because the on-chip transistors provide the first stage amplification, the SDDs provide outstanding noise performance and fast shaping, so that very good energy resolution can be obtained even at room temperature. The drift detectors require a relatively low number of readout channels for large detector areas. Custom-designed analog and digital electronics provide fast readout of the SDDs. The equipment is designed such that the measurements can be done in all detector orientations and kinematical conditions. The first results obtained with this detector system will be presented in this paper.
A Compton camera system consisting of a silicon drift detector (SDD) and an Anger camera has been constructed to study coincidence events and the possibility of tracking a recoil electron. An event ...is considered as a coincidence when a photon emitted from a radioactive source is first Compton scattered in the SDD where the recoil electron deposits its energy and the scattered photon undergoes a photoelectric absorption in the NaI(Tl) crystal of the Anger camera. SDD is composed of a monolithic array of 19 cells each having an on-chip transistor which provides the first stage amplification. /sup 137/Cs source has been finely collimated in order to study events occurring at different locations within a single cell. Electron tracks depositing energy in multiple cells have also been studied by considering time coincidences between SDD cells and the Anger camera. The equipment is designed such that the measurements can be done in all detector orientations and kinematical conditions. The angular and energy distribution of coincidence events have been studied with high statistics. Energy resolution and angle measurements performed with this detector system will be presented in this paper.
Window discriminator for multiwires chamber Zhang, Z.; Venanzi, C.; Nurdan, K. ...
IEEE Symposium Conference Record Nuclear Science 2004,
2004, Letnik:
3
Conference Proceeding
Multiwire drift chambers are well known devices, widely used with good energy resolution and building principles that are relatively simple. The detection of fluorescence radiation with such detector ...is subordinated to capacities to discriminate the signal of interest from the background. This operation can be performed introducing a window discriminator stage in the read-out electronics (after the preamplification and filtering stages). A high-speed window discriminator implemented with ECL logic level is designed to trigger the data acquisition system of a position-sensitive multiwire chamber. The discriminator consists of an analogous part and a digital part. The main idea is processing with two different comparators the input signal of the discriminator - one for the low and one for the high threshold - and then using a logic circuit to decide if the original input signal is or not in the window requested. The analogous components of the discriminator have variable thresholds and output pulse widths as well as some options for high rates in the chamber. The digital components produce standard logic signals and keep real time information in the meanwhile. Measurements are performed to test such device. In particular, linearity, efficiency measurements (up to 10 MHz) and test results to evaluate the resolution in terms of amplitude of the input signal, will be presented in this work.
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