N. Goutev

Bulgarian Academy of Sciences | BAS · Institute for Nuclear Research and Nuclear Energy (INRNE)

Excited states in the mirror nuclei ³¹P and ³¹S were populated in the 1p and 1n exit channels of the reaction ²⁰Ne + ¹²C, at a beam energy of 33 MeV. The ²⁰Ne beam was delivered for the first time by the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. Angular correlations of coincident γ-rays and Doppler-shift attenuation lifetime me...

The activity of naturally occurring radionuclides in mineral waters from certain most frequently used sources in Rhodope Mountains region, Southern Bulgaria has been measured with high precision by means of nuclear and radiochemical methods. The survey is pointed at radium-226 (226Ra), lead-210 (210Pb) and natural uranium (nat. U), which are most i...

A complex investigation on Bulgarian mineral waters from certain frequently used sources have been carried out. Specific activities of ²²⁶ Ra and concentration levels of natural uranium in mineral waters samples were analyzed using nuclear and analytical methods. ²²⁶ Ra is a naturally occurring radioisotope with a period of half live 1 600 years, w...

The Institute for Nuclear Research and Nuclear Energy at the Bulgarian Academy of Sciences is building an accelerator laboratory to operate a TR-24 cyclotron. Thus, a preliminary radiation shielding analysis of the accelerator bunker is required. For this purpose Monte-Carlo simulations have been performed and dosimetric (Dose equivalent) quantitie...

We present the cyclotron project of the Institute for Nuclear Research and Nuclear Energy which aims to centralize national the production of radioisotopes and radiopharmaceuticals and to provide opportunities for interdisciplinary research and education in the fields of Physics, Chemistry, Biology and Nuclear Energy. The human resources needed for...

The Institute for Nuclear Research and Nuclear Energy at the Bulgarian Academy of Sciences is preparing to operate a high-power cyclotron for production of isotopes for nuclear medicine. 67,68Ga are some of the target isotopes as studies have shown that both of them can be produced via direct proton irradiation with a cyclotron. The aim of this stu...

The Institute for Nuclear Research and Nuclear Energy at the Bulgarian Academy of Sciences is building a cyclotron facility dedicated to production, and research and development of radiopharmaceuticals. ¹⁸F is of primary interest and the radiological characterization of the cyclotron and it’s vault with an ¹⁸O-target has shown that local shielding...

Nuclear and analytical methods can help to determine the year of production – vintage and the geographical provenance of high quality wines. A complex analytical investigation of Melnik fine wines from "Artarkata" vineyards, Vinogradi village near Melnik in Southwest Bulgaria using different methods and equipment were performed. Nuclear methods, ba...

The Institute for Nuclear Research and Nuclear Energy is preparing to operate a high-power cyclotron for production of radioisotopes for nuclear medicine, research in radiochemistry, radiobiology, nuclear physics, solid state physics. The cyclotron is a TR24 produced by ASCI, Canada, capable to deliver proton beams in the energy range of 15 to 24 M...

Chiral symmetry is dichotomic and its spontaneous breaking by the axial angular momentum vector leads to a pair of degenerate ΔI = 1 rotational bands, called chiral doublet bands. In many cases the energy degeneracy of the chiral candidate bands has almost been observed but the transition probabilities of the analogue states have been found to be d...

An accelerator laboratory is presently under construction in Sofia at the Institute for Nuclear Research and Nuclear Energy. The laboratory will use a TR24 type of cyclotron, which provides a possibility to accelerate a proton beam with an energy of 15 to 24 MeV and current of up to 0.4 mA. An accelerator with such parameters allows to produce a la...

The development and the optimisation of negative hydrogen/deuterium ion sources goes hand in hand with modelling. In this paper a brief introduction on the physics and types of different sources, and on the Kinetic and Fluid theories for plasma description is made. Examples of some recent models are considered whereas the main emphasis is on the mo...

Excited states in mirror nuclei 31S and 31P were populated in the 1n and 1p exit channels, respectively, of the reaction 20Ne + 12C. The beam of 20Ne, with an energy of 33 MeV, was delivered for the first time by the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. Angular correlations of coincident pairs and Doppler-shift attenuation...

A review and update on the status of the Cyclotron Physics Laboratory at the Institute for Nuclear Research and Nuclear Energy as well as related research activity is presented. The main part of the research activities at the Cyclotron Physics Laboratory is directed to simulations for design considerations, for the cyclotron vault for some of the t...

In many cases the chirality was almost observed but the transition probabilities are different. This fact is clearly seen in the cases of 134Pr and 102Rh. In the case of chirality, the yrast and the side bands should be nearly degenerate. In the angular momentum region where chirality sets, the B(E2) values of the electromagnetic transitions deexci...

The structure of the S33 nucleus was investigated in the Mg24(N14,αp) fusion-evaporation reaction using a 40-MeV N14 beam. The level scheme was extended up to an excitation energy of 11.7 MeV and spin 19/2+. Lifetimes of the intermediate- and high-spin states have been investigated by the Doppler shift attenuation method. Data were compared with di...

The Department of Nuclear Medicine, “St. Marina” University Hospital in Varna, is equipped with a self-shielded BG-75 cyclotron and synthesis unit for production of single doses of 18F-FDG. The cyclotron is capable to deliver 7.5 MeV proton beam with maximal current of 5 µA. During irradiation, a small target volume of ¹⁸O-enriched water is bombard...

The efficiency of activated carbon filters used in the off gas cleaning system in Nuclear Power Plant “Kozloduy” is investigated. For the first time, high resolution gamma ray spectroscopy is applied to measure precisely the dynamic adsorption coefficient and the hold-up time of the system for radioactive noble gases using the method of frontal rad...

The lifetimes of eight lower spin levels of the yrast band in ¹⁶⁸Yb, populated via the ¹⁵⁴Sm(¹⁸O,4n) and ¹²⁴Sn(⁴⁸Ca,4n) reactions, were measured, six of them for the first time, by means of the recoil-distance Doppler-shift method. Two versions of the differential decay-curve method have been applied for the data analysis resulting in a very good a...

Excited states in 102Rh were populated in the fusion-evaporation reaction 94Zr(11B, 3n)102Rh at a beam energy of 36 MeV using the INGA spectrometer at IUAC, New Delhi. The angular correlations and the electromagnetic character of some of the gamma-ray transitions observed were investigated in details. A new chiral candidate sister band was found. L...

Systematic off-line fluorination studies on all the stable lanthanide isotopes have been performed. The results are presented as a function of various parameters such as the target temperature, the type of ion source used (hot plasma or surface ionization) and the quantity of CF4 introduced. The first on-line measurements allowed us to determine th...

An accelerator laboratory is presently under construction in Sofia at the Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences. The laboratory will use a TR24 type of cyclotron, which provides a possibility to accelerate a proton beam with an energy of 15 to 24 MeV and current of up to 0.4 mA. An accelerator with such pa...

Radiological and chemical fingerprinting can help to determine the year of production - vintage and the geographical provenance or designation of origin of high quality wines. Radiological and chemical investigations are performed on Bulgarian Melnik fine wine, as well as, on vineyard soil, grape stems and grape leaves. The gamma-ray activity of th...

Two odd-odd nuclei from the A ~ 100 and A ~ 130 regions, namely 102Rh and 134Pr have been studied in search for chiral doublet bands via 94Zr(11B,3n)102Rh and 119Sn(19F,4n)134Pr reactions, respectively. Two nearly degenerate bands built on the πg9/2 ⊗ vh11/2 configuration have been identified in 102Rh and on the πg11/2 ⊗ vh11/2 configuration for 13...

Nuclear methods and chemical fingerprinting can help in the process of determination of the year of production (vintage) and the geographical provenance or designation of origin of high quality wines. For the first time we report results obtained for fine Bulgarian wines from Melnik region, as well as, vineyard soil, vine stems and grape leaves. Th...

The response of a scintillation detector with a cylindrical 1.5-inch LaBr3:Ce crystal to incident neutrons has been measured in the energy range En = 2-12 MeV. Neutrons were produced by proton irradiation of a Li target at Ep = 5-14.6 MeV with pulsed proton beams. Using the time-of-flight information between target and detector, energy spectra of t...

A generalization of an earlier proposed version of the Differential decay curve method is presented for the analysis of Doppler-shift attenuation lifetime measurements. The lifetime is derived directly from the line shapes of the depopulating and feeding transitions without any assumptions about or fitting of the time dependence of the population o...

Excited states in 102Rh were populated in the fusion-evaporation reaction 94Zr(nB, 3n)102Rh at a beam energy of 36 MeV, using the INGA spectrometer at IUAC, New Delhi. The angular correlations and the electromagnetic character of some of the γ-ray transitions observed in 102Rh were investigated in detail. A new candidate for a chiral twin band was...

An angular correlation experiment was carried out for 33 S at Laboratori Nazionali di Legnaro with the gamma-ray detector array GASP. The reaction used was 24Mg(14N,α p)33S at a beam energy of 40MeV. An analysis of DCO ratios and triple gamma coincidences was performed. So far, a new level depopulated by 3 γ -ray transitions has been found and its...

An experiment using the Doppler Shift Attenuation Method was performed for33S at Laboratori Nazionali di Legnaro using the multi-detector array GASP. Excited states were populated in the fusion-evaporation reaction 24Mg(14N,? p)33S. The data were analyzed using the Differential Decay Curve Method with gates set on the shifted component of a directl...

Excited states in 102Rh were populated in the fusion-evaporation reaction 94Zr(11B, 3n)102Rh at a beam energy of 36 MeV, using the INGA spectrometer at IUAC, New Delhi. The angular correlations and the electromagnetic character of some of the 03B3-ray transitions observed in 102Rh were investigated in detail. A new candidate for achiral twin band w...

To investigate the interplay between collective and single particle degrees of freedom in odd nuclei, Recoil distance Doppler-shift and Doppler-shift attenuation lifetime measurements were carried out for levels in 155Dy in coincidence detection of gamma-rays. 26 lifetimes were determined using the Differential decay curve method. Particle plus tri...

Excited states in Rh102, populated in the fusion-evaporation reaction Zr94(B11,3n)Rh102 at a beam energy of 36 MeV, were studied using the Indian National Gamma Array spectrometer at Inter University Accelerator Center, New Delhi. The angular correlations and the electromagnetic character of some of the gamma-ray transitions observed were investiga...

Recoil distance Doppler-shift and Doppler-shift attenuation lifetime measurements were carried out for levels in ^{155}Dy through the coincident detection of γ rays. Twenty-six lifetimes, most of them for the first time, were determined using the differential decay curve method for the analysis of the data. At low and medium spins, particle-plus-tr...

A new version of the differential decay curve method is proposed for the analysis of Doppler-shift attenuation lifetime measurements. The lifetime is derived directly from the line shapes of the depopulating and feeding transitions on the basis of the Blaugrund approximation without including any assumptions or fitting of the time dependence of the...

Excited states in {sup 102}Rh, populated by the fusion-evaporation reaction {sup 94}Zr({sup 11}B,3n){sup 102}Rh at a beam energy of 36 MeV, were studied using the INGA spectrometer at IUAC, New Delhi. The angular correlations and the electromagnetic character of some of the gamma-ray transitions observed were investigated in details. A new chiral c...

Excited states in102Rh were populated in the fusion-evaporation reaction 96Zr(11B, 3n)102 Rh. The angular correlations and the electromagnetic character of some of the gamma-ray transitions observed were investigated in detail. A new chiral candidate sister band was found in the level-scheme of 102Rh.

Lifetimes of excited states in 155Dy were measured by means of the Recoil Distance Doppler-shift technique in the coincidence mode. The experiment was performed at the Laboratori Nazionali di Legnaro with the GASP array and the Cologne plunger using the reaction 124Sn(36S,5n)155Dy at a beam energy of 155 MeV. The Differential decay-curve method was...

The improvement of both the precision of the nuclear models and the Monte Carlo transport requires a comparison of the simulated productions of residues, the spallation of neutrons and their transport, obtained in different scenarios. The calculations of the residue production and corresponding neutron double differential cross sections are perform...

Using the (20)Ne + (12)C fusion-evaporation reaction at E20(Ne) = 33 MeV and the multidetector array GASP in conjuction with the EUCLIDES charged particle detector, angular correlations of coincident pairs of 7 transitions and lifetimes in mirror nuclei (31)S and (31)P have been measured at the Piave-Alpi accelerator of the Laboratori Nazionali di...

A novel methodology for the selective formation of lipid nanotubes with a cationic inner surface through the self-assembly of a novel unsymmetrical bolaamphiphile is discussed. The initial molecular packing of the complex was found to be controllable by the solvent used for reprecipitation. The tape and the nanotube turned out to form independently...

Selective construction of a supramolecular nanotube host with a cationic inner surface consisting of unsymmetrical bolaamphiphiles is reported on p. 2732 by Masuda, Shimizu, and co-workers. The nanotube, shown schematically on the inside cover, has different inner and outer surfaces covered with amino and sugar functionalities, respectively, and is...

Previous studies of OH stretching band of aqueous solutions of short poly(oxyethylene)s POEs showed similarities between ratios R of the intensities of the component around 3200 cm-1 (the collective in-phase OH stretching vibrations of hydrogen-bonded aggregates) and the component around 3400 cm-1 (the out of phase OH stretches) in dependence on ty...

Excess thermodynamic functions of D2O water have been calculated from the vibrationally decoupled O−D stretching spectra of very dilute solutions of HOD in H2O. Comparison of the results with reference calorimetric data for water showed a good correspondence for excess heat capacity above the melting point of ice. The excess enthalpy at the melting...

The hypothesis that the degree of hydration of poly(oxyethylene) (POE) in aqueous solution depends on the mole ratio of water molecules to ether oxygen atoms in the molecule has been verified by studying the isotropic Raman spectra in the O−H stretching region for four short-chain POEs (C 1E n C 1 withn=1−4). Excellent coincidence of the O−H stretc...

Previous studies of OH stretching band of aqueous solutions of short poly(oxyethylene)s POEs showed a similarities between ratios R of the intensities of the component around 3200 cm-1 (the collective in-phase OH stretching vibrations of hydrogen-bonded aggregates) and the component around 3400 cm-1 (the out of phase OH stretches) in dependence on...

A new recipe for surface-enhanced infrared absorption (SEIRA) active island Au films with improved adhesion in aqueous solution, low resistivity, and enhancement of the infrared (IR) absorption of about 300 was developed. The Au films prepared were utilized in studies of the ionization of self-assembled monolayers of 11-mercaptoundecanoic acid in N...

Excess thermodynamic parameters of H2O water, corresponding to the difference between parameters for liquid water and ice, have been determined from the infrared O - H stretching spectra of very dilute solutions of HOD in D2O. The analytical method applied considers the H-bonded O - H oscillators as a statistical ensemble. Comparison of the results...

Electrochemical reduction of p-nitrothiophenol (PNTP)-self-assembled monolayer (SAM) films on Au(111) surface was studied using attenuated total reflection-IR spectroscopy. The reduction potential was evaluated from the spectral changes, which depended on pH in electrolyte solutions, e.g. +0.05 V (pH 0.45), −0.55 V (pH 5.5) or −0.55 V (pH 13) (vs....

We used intensity-dependent prism coupling of poly [2-methoxy- 5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) waveguides to measure the nonlinear absorption coefficients and nonlinear refractive indices of these waveguides in the range 700-1200 nm, The material's strong nonlinearity combined with low linear waveguide losses (<1 dB/cm) led to...

The hydrogen bonding in concentrated aqueous solutions of 1,2-dimethoxyethane was studied by Raman spectroscopy of the O−H stretching band of water at various concentrations in the temperature range 218−315 K. The isotropic Raman spectra were analyzed by band decomposition, and two major components were identified in the spectra. They were assigned...

Chloroform solutions of 1,4-dioxane, 1,2-dimethoxyethane, and diethylene glycol dimethyl ether were studied by means of IR absorption spectroscopy. The intensity of the C−D stretching band of a small amount of deuterated chloroform added to the solutions was used as a probe of the strength of hydrogen bonding between the ethers and chloroform. A tw...

The hydrogen bonding in water and 2M aqueous solutions of NaCH3COO, (CH3)4NCl, NaCl and NaCSN was studied by Raman spectroscopy of the vibrationally decoupled O-D stretching band of water. The isotropic O-D stretching spectra were modeled by means of Gibbs' statistical ensembles of hydrogen bonded oscillators. The thermodynamical parameters of the...

The conformation of 1,2-dimethoxyethane in the liquid phase and in aqueous solutions was studied by Raman spectroscopy. The conformation-sensitive Raman bands of 1,2-dimethoxyethane, located in the wavenumber region 300−600 cm-1, were analyzed by means of the band decomposition based on normal coordinate analysis. The populations of the conformers...

The DOH system in H2O and 2 M aqueous salt solutions of NaSCN and (CH3)4NCl has been studied by the fluctuation model of hydrogen bonding. A number of quantitative parameters, characterizing the hydrogen bond network of the DOH system has been derived. The salts have an influence on the structure of the solutions in accordance with their positions...

The propagation of light in a symmetrical optical waveguide structure comprising two identical ion-exchanged or sol-gel waveguides with a thin water film between them has been analysed using numerical modelling. The results show that in the case of ion-exchanged waveguides there is an increase of times in the field intensity at the surface of the w...

We present a study of the hydration of the short chain poly(oxyethylene) CH3OCH2CH2OCH3 (C1E1C1) in the range of concentrations up to 0.25 mole fraction (m.f.) by analyzing the parameters of the main components of the water OH stretching band at about 3200 and 3400 cm−1. Two regions of enhancement of the hydrogen bond network in the solution were...

The hydration of the short chain poly(oxyethylene) CH 3 (OCH 2 CH 2 ) 2 O CH 3 (C 1 E 2 C 1 ) has been studied in the range of concentrations up to 0.3 mole fraction (m.f.) by analysing the parameters of the main components of the water O–H stretching band at ca. 3200 and 3400 cm -1 . Two interesting regions of enhancement of the hydrogen bond netw...

Good-quality Raman spectra of thin Si(Ti)O2planar optical waveguides are reported. The exciting light was coupled into the waveguides via a grating coupler. The Raman signal from the films could be successfully discriminated from that of the glass substrate on which the waveguiding films were deposited. Sol–gel waveguides pyrolysed at 500°C and spu...

The structure of the thin liquid films in a stable three-dimensional foam (shaving cream) has been studied by Raman scattering. Two phases existing in the foam films are identified-lamellar and isotropic. The lamellar phase is an ordered multilayer structure (gel) of stearic acid molecules in all-trans conformation. This is proved by the shape of t...

A multidimensional generalization of the Fresnel-Kirchhoff theory for analyzing the far-field pattern of a probe beam/pulse, passing trough a thin nonlinear medium is developed. The experimental results obtained agree qualitatively with the theoretical predictions. It is shown that the asymmetric induced-phase modulation offers the possibility for...