SiPM MEPhI Megagrant Developments in Nuclear Medicine

AbstractThree projects has been started in our laboratory as part of megagrant “High energy physics and nuclear medicine with silicon photomultiplier detectors” in NRNU MEPHI. The goal of these projects is development of devices for nuclear medicine in which replacement of photomultiplier tubes (PMT) with solid-state silicon photomultipliers promises various advantages. The first project is full-body SPECT, where replacement of PMT's could reduce size of the detector module and improve spatial resolution while keeping other parameters. The second project is development of a TOF-PET module. Replacement of PMTs with silicon photomultipliers makes it possible to use that detector not only in high magnetic fields but also for Time-of-Flight measurements (higher signal-to-noise ratio on final image) due to very high timing resolution of a SiPM. And the last project is the SiPM-based position-sensitive Gamma-spectrometer for dose monitoring in neutron-capture therapy based on SiPM's

Results of Parametric Design Studies of MOX Lead Test Assembly

The parametric studies of MOX LTA design have been executed to choose plutonium content in assembly zones for two options of MOX LTA: 3-zones and Island. For 3-zones (100% Plutonium) MOX LTA the fissile plutonium content composition of 4.2%/3,0%/2% has been chosen. MOX LTA of the chosen compositions has been studied by using multi-assembly configuration that allows investigating of influence of MOX LTA environment: uranium assemblies of different irradiation. Plutonium Island with 54 plutonium pins in the center of MOX LTA has been considered in two modifications: uniform island; and graded island with lower plutonium content in one peripheral row of pins. It is shown that plutonium content in the uniform island cannot exceed 2.7% because of adopted power peaking limitations and therefore this design seems unreasonable for practical use. For graded island the plutonium content composition 3.8%/2.8% with uranium environment of 3.7% U-235 has been chosen. Evolution of assembly power and burnup distributions, inter-pin power and isotopic distributions while fuel irradiating have been analyzed. In addition to the base uranium environment of 3.7%, a set of calculations has been executed for 4.4%. Most of the studies have been executed by the code TVS-M that is at the final stage of licensing and it is to be used in the nearest future as a base instrument for VVER core calculations while using both uranium and MOX fuel. So the obtained results must be considered as preliminary ones and they demand additional analysis and investigations

Stability and invariant linear systems of stabilization of military facilities

Рассматривается взаимосвязь между свойством инвариантности линейной системы стабилизации к действию внешних возмущений и её устойчивостью. Предложен закон стабилизации, обеспечивающий высокий порядок астатизма системы без заметного ухудшения её запаса устойчивости.Розглядається взаємозв'язок між властивостями інваріантності лінійної системи стабілізації до дії зовнішніх збурень і її стійкістю. Запропоновано закон стабілізації, що забезпечує високий порядок астатизму системи без помітного погіршення її запасу стійкості.The relation between the properties of the invariance of the linear stabilizing system to the action of external disturbances and her resistance. Proposed stabilization law, which provides higher order astatism system without noticeable degradation of its safety factor

Formamidinium iodide: Crystal structure and phase transitions

At a temperature of 100K, CH5N2 +·I- (I), crystallizes in the monoclinic space group P21/c. The formamidinium cation adopts a planar symmetrical structure [the r.m.s. deviation is 0.002Å, and the C - N bond lengths are 1.301(7) and 1.309(8)Å]. The iodide anion does not lie within the cation plane, but deviates from it by 0.643(10)Å. The cation and anion of I form a tight ionic pair by a strong N-H⋯I hydrogen bond. In the crystal of I, the tight ionic pairs form hydrogen-bonded zigzag-like chains propagating toward [20-1] via strong N-H⋯I hydrogen bonds. The hydrogen-bonded chains are further packed in stacks along [100]. The thermal behaviour of I was studied by different physicochemical methods (thermogravimetry, differential scanning calorimetry and powder diffraction). Differential scanning calorimetry revealed three narrow endothermic peaks at 346, 387 and 525K, and one broad endothermic peak at ∼605K. The first and second peaks are related to solid-solid phase transitions, while the third and fourth peaks are attributed to the melting and decomposition of I. The enthalpies of the phase transitions at 346 and 387K are estimated as 2.60 and 2.75kJmol-1, respectively. The X-ray powder diffraction data collected at different temperatures indicate the existence of I as the monoclinic (100-346K), orthorhombic (346-387K) and cubic (387-525K) polymorphic modifications

Formamidinium iodide: Crystal structure and phase transitions

At a temperature of 100K, CH5N2 +·I- (I), crystallizes in the monoclinic space group P21/c. The formamidinium cation adopts a planar symmetrical structure [the r.m.s. deviation is 0.002Å, and the C - N bond lengths are 1.301(7) and 1.309(8)Å]. The iodide anion does not lie within the cation plane, but deviates from it by 0.643(10)Å. The cation and anion of I form a tight ionic pair by a strong N-H⋯I hydrogen bond. In the crystal of I, the tight ionic pairs form hydrogen-bonded zigzag-like chains propagating toward [20-1] via strong N-H⋯I hydrogen bonds. The hydrogen-bonded chains are further packed in stacks along [100]. The thermal behaviour of I was studied by different physicochemical methods (thermogravimetry, differential scanning calorimetry and powder diffraction). Differential scanning calorimetry revealed three narrow endothermic peaks at 346, 387 and 525K, and one broad endothermic peak at ∼605K. The first and second peaks are related to solid-solid phase transitions, while the third and fourth peaks are attributed to the melting and decomposition of I. The enthalpies of the phase transitions at 346 and 387K are estimated as 2.60 and 2.75kJmol-1, respectively. The X-ray powder diffraction data collected at different temperatures indicate the existence of I as the monoclinic (100-346K), orthorhombic (346-387K) and cubic (387-525K) polymorphic modifications

Synthesis, crystal structure and magnetic properties of copper(II) complexes with 4-methyl-N-[2-[(E)-2-pyridyl[alkyl]iminomethyl]phenyl]benzenesulfamide ligands

Two types of copper(II) complexes CuL1Cl and CuL2COOCH3 with tetradentate 4-methyl-N-[2-[(E)-2-pyridylmethyliminomethyl]phenyl]benzene-sulfamide (L1) and 4-methyl-N-[2-[(E)-2-pyridylethyliminomethyl]phenyl]-benzenesulfamide (L2) ligands were synthesized. The complexes were characterized by elemental analysis, infrared and 1H NMR spectra, magnetochemical measurements, and single crystal X-ray diffraction. The Cu atoms in the complexes CuL1Cl and CuL2COOCH3 are coordinated by tosylamine N,O, imino N and pyridine N atoms of the Schiff base ligand, and one Cl or acetate ligand at the apex, thus forming the strongly distorted square-pyramidal or octahedral environment, respectively. Complexes CuL1Cl and CuL2COOCH3 are paramagnetic. © 2019 Elsevier B.V