V. Ditlov | Alikhanov Institute for Theoretical and Experimental Physics (original) (raw)

Papers by V. Ditlov

World Journal of Nuclear Science and Technology, 2018

In the present work the dependence of the bulk etch rate of CR-39 solid state nuclear track detec... more In the present work the dependence of the bulk etch rate of CR-39 solid state nuclear track detectors (SSNTD) on the concentration C and the temperature T of the NaOH etching solution has been studied. The superposition and interaction of physical and chemical processes happening during the etching phase is tried to approximate by an Arrhenius-like law which is derived from the chemical reaction kinetics in homogeneous phases. A reasonable reproduction of different experimental data was achieved. By the goodness of the fits some conclusions were drawn on the validity of empirical and plausible functional dependence of the bulk etch rate on concentration and temperature of the etchant. If it was found that if a reasonable accordance appeared when comparing fits from one data set to another, the bulk etch rate can nevertheless not be described well for widely varying C and T ranges by means of the used formula. This leads to the conclusion that more refined models have to be developed when applied to both extreme (low and high) values of temperature and concentration.

Radiation Measurements, 2008

The formalism of the many-hit model (MHM) [

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2004

The present work studied an important part of ion tracks: the Bragg peak region. Information abou... more The present work studied an important part of ion tracks: the Bragg peak region. Information about the microscopic nature of ion-energy dissipation based on zero-approximation in frame of the many-hit model of the track structure theory was studied. The detector response, Vt, was calculated in terms of Poisson’s distribution as a function of the ion’s linear energy transfer (LET). This approach can be considered to be a zero-approximation since LET is a special case of restricted energy losses with a cut off energy wcutoff=∞: LET=REL∞. Confocal microscopic data allows the visualising and analysing of the etched tracks one by one with high precision. A three-dimensional track image was observed and the track etch rate was measured. On the basis of χ2 analysis of the experimental track etch rate (square of the least deviation), with respect to that of the theoretical value, information about the energy transfer process can be obtained. Light ions of little MeV energy were slowed down in the CR-39 detector and the detectors responses close to the Bragg peak region were studied. It was shown that in the zero-approximation no one to one relation can be found between the primary linear energy transfer (LET) and the measured specific track etch rate. The statistical analysis can be split into two separate parts; before the Bragg peak (Bethe–Bloch) and after the Bragg peak (Thin Down). The two parts analysed reflect the separated domains where the etching rate increases or decreases, due to the different role of the delta-electrons in each of these domains. The main aim of this study is to develop a method for any ion describing Vt in this very sensitive Bragg region. This would allow ion identification at low velocities on the one hand, and on the other hand to have a better understanding of the physical processes involved during high velocity ion stopping.

Instruments and Experimental Techniques

The numbers of detected ions and the beam density dispersions at different depths of plate locati... more The numbers of detected ions and the beam density dispersions at different depths of plate locations that also cover the Bragg peak region were determined by automatically searching for etched micropores in photographs of surfaces of CR-39 plastic plates exposed to 12C ions with an energy of 216 MeV/amu in a chamber for radiobiological investigations at the TWAC–ITEP accelerator–accumulator facility. A computer method for seeking etched micropores along latent ion tracks in an exposed plastic is described. Frequency distributions of detected ions over microscopic areas of each surface for eight plates have been obtained and compared using a Gaussian function.

Physics of Atomic Nuclei

It is shown that during the stopping and decaying of positively charged muon (μ+) in a nuclear em... more It is shown that during the stopping and decaying of positively charged muon (μ+) in a nuclear emulsion, there arises with a probability of about 10−2 electron with energies between 10 and 180 keV. The energy spectrum and angular distribution of these electrons are measured. A hypothesis on the possible mechanism behind the appearance of electrons corresponding to μ+ decay is put forth.

The multiple scattering of β-electrons in nuclear photographic emulsion of βspectrometer is consi... more The multiple scattering of β-electrons in nuclear photographic emulsion of βspectrometer is considered. A numerical calculation method was developed on the basis of many-hit model of emulsion response in frame of the theory of multiple scattering of electrons. The dependences of spectra sensitivity, of ratio signal-noise and other parameters on β-electron energy and thickness of emulsion layer were studied.

Solid State Nuclear Track Detectors, 1978

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Radiation Measurements, 2005

Etching rates along tracks of protons and lithium ions with energies in the Bragg peak region wer... more Etching rates along tracks of protons and lithium ions with energies in the Bragg peak region were explored. The energy losses in this region, especially for protons of low energies, are of particular interest from the physical as well as biological points of view. The microscopic track etch rate, V T , is studied using the many-hit model in its first approximation assuming that V T is a function of the restricted energy loss (REL). The ions multiple scattering and straggling effects on the average experimental V T values are corrected by shifting the calculated REL values along the track, until its maximum coincides with that of the V T. The fitting of least square differences between calculated and experimental V T values is used in order to determine the many-hit model registration parameters for the detector under investigation.

Radiation Measurements, 2015

The multiple scattering of β-electrons in nuclear photographic emulsion of βspectrometer is consi... more The multiple scattering of β-electrons in nuclear photographic emulsion of βspectrometer is considered. A numerical calculation method was developed on the basis of many-hit model of emulsion response in frame of the theory of multiple scattering of electrons. The dependences of spectra sensitivity, of ratio signal-noise and other parameters on β-electron energy and thickness of emulsion layer were studied.

The measurement of positron--nucleus collisions was used to estimate the possibility of suppressi... more The measurement of positron--nucleus collisions was used to estimate the possibility of suppressing background events that simulate betabeta\beta\betabetabeta decay in the emulsion region adjacent to molybdenum conglomerates. The range of the escape of two relativistic particles from the interaction was found to be $ = (0.60\pm 0.03) ~\mu$m, which approximately corresponds to the grain size of developed nuclear emulsion. No

The Identification of Dark Matter - Proceedings of the Fourth International Workshop, 2003

An optical model of a two-phase xenon chamber for direct calculation of light fluxes has been bui... more An optical model of a two-phase xenon chamber for direct calculation of light fluxes has been built up. A calculation method of photo multiplier tubes response at charged particle interacting in chamber was deduced. A method of 3D reconstruction of event coordinates was built and studied with use of this model.

Radiation Measurements, 1997

Here we have made an attempt to describe etching along and perpendicular to the ion track axis wi... more Here we have made an attempt to describe etching along and perpendicular to the ion track axis with the many-hit response model. From experiments where sheets of Makrofol KG film were exposed to Au and Xe ions it was found that V t/V b depends on restricted energy loss (REL). Then, for the many-hit model the registration parameters of the detectors were found and were used for the calculation of the radial distributions of the transversal etching rate and were compared with experimental data.

The Identification of Dark Matter - Proceedings of the Fourth International Workshop, 2003

The current status of a development project focused on constructing a novel two-phase xenon detec... more The current status of a development project focused on constructing a novel two-phase xenon detector to search for Dark Matter is given. The response to neutrons in terms of ionisation and scintillation has been observed. Decay times of the scintillation due to nuclear recoils have been measured.

World Journal of Nuclear Science and Technology, 2018

In the present work the dependence of the bulk etch rate of CR-39 solid state nuclear track detec... more In the present work the dependence of the bulk etch rate of CR-39 solid state nuclear track detectors (SSNTD) on the concentration C and the temperature T of the NaOH etching solution has been studied. The superposition and interaction of physical and chemical processes happening during the etching phase is tried to approximate by an Arrhenius-like law which is derived from the chemical reaction kinetics in homogeneous phases. A reasonable reproduction of different experimental data was achieved. By the goodness of the fits some conclusions were drawn on the validity of empirical and plausible functional dependence of the bulk etch rate on concentration and temperature of the etchant. If it was found that if a reasonable accordance appeared when comparing fits from one data set to another, the bulk etch rate can nevertheless not be described well for widely varying C and T ranges by means of the used formula. This leads to the conclusion that more refined models have to be developed when applied to both extreme (low and high) values of temperature and concentration.

Radiation Measurements, 2008

The formalism of the many-hit model (MHM) [

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2004

The present work studied an important part of ion tracks: the Bragg peak region. Information abou... more The present work studied an important part of ion tracks: the Bragg peak region. Information about the microscopic nature of ion-energy dissipation based on zero-approximation in frame of the many-hit model of the track structure theory was studied. The detector response, Vt, was calculated in terms of Poisson’s distribution as a function of the ion’s linear energy transfer (LET). This approach can be considered to be a zero-approximation since LET is a special case of restricted energy losses with a cut off energy wcutoff=∞: LET=REL∞. Confocal microscopic data allows the visualising and analysing of the etched tracks one by one with high precision. A three-dimensional track image was observed and the track etch rate was measured. On the basis of χ2 analysis of the experimental track etch rate (square of the least deviation), with respect to that of the theoretical value, information about the energy transfer process can be obtained. Light ions of little MeV energy were slowed down in the CR-39 detector and the detectors responses close to the Bragg peak region were studied. It was shown that in the zero-approximation no one to one relation can be found between the primary linear energy transfer (LET) and the measured specific track etch rate. The statistical analysis can be split into two separate parts; before the Bragg peak (Bethe–Bloch) and after the Bragg peak (Thin Down). The two parts analysed reflect the separated domains where the etching rate increases or decreases, due to the different role of the delta-electrons in each of these domains. The main aim of this study is to develop a method for any ion describing Vt in this very sensitive Bragg region. This would allow ion identification at low velocities on the one hand, and on the other hand to have a better understanding of the physical processes involved during high velocity ion stopping.

Instruments and Experimental Techniques

The numbers of detected ions and the beam density dispersions at different depths of plate locati... more The numbers of detected ions and the beam density dispersions at different depths of plate locations that also cover the Bragg peak region were determined by automatically searching for etched micropores in photographs of surfaces of CR-39 plastic plates exposed to 12C ions with an energy of 216 MeV/amu in a chamber for radiobiological investigations at the TWAC–ITEP accelerator–accumulator facility. A computer method for seeking etched micropores along latent ion tracks in an exposed plastic is described. Frequency distributions of detected ions over microscopic areas of each surface for eight plates have been obtained and compared using a Gaussian function.

Physics of Atomic Nuclei

It is shown that during the stopping and decaying of positively charged muon (μ+) in a nuclear em... more It is shown that during the stopping and decaying of positively charged muon (μ+) in a nuclear emulsion, there arises with a probability of about 10−2 electron with energies between 10 and 180 keV. The energy spectrum and angular distribution of these electrons are measured. A hypothesis on the possible mechanism behind the appearance of electrons corresponding to μ+ decay is put forth.

The multiple scattering of β-electrons in nuclear photographic emulsion of βspectrometer is consi... more The multiple scattering of β-electrons in nuclear photographic emulsion of βspectrometer is considered. A numerical calculation method was developed on the basis of many-hit model of emulsion response in frame of the theory of multiple scattering of electrons. The dependences of spectra sensitivity, of ratio signal-noise and other parameters on β-electron energy and thickness of emulsion layer were studied.

Solid State Nuclear Track Detectors, 1978

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Radiation Measurements, 2005

Etching rates along tracks of protons and lithium ions with energies in the Bragg peak region wer... more Etching rates along tracks of protons and lithium ions with energies in the Bragg peak region were explored. The energy losses in this region, especially for protons of low energies, are of particular interest from the physical as well as biological points of view. The microscopic track etch rate, V T , is studied using the many-hit model in its first approximation assuming that V T is a function of the restricted energy loss (REL). The ions multiple scattering and straggling effects on the average experimental V T values are corrected by shifting the calculated REL values along the track, until its maximum coincides with that of the V T. The fitting of least square differences between calculated and experimental V T values is used in order to determine the many-hit model registration parameters for the detector under investigation.

Radiation Measurements, 2015

The multiple scattering of β-electrons in nuclear photographic emulsion of βspectrometer is consi... more The multiple scattering of β-electrons in nuclear photographic emulsion of βspectrometer is considered. A numerical calculation method was developed on the basis of many-hit model of emulsion response in frame of the theory of multiple scattering of electrons. The dependences of spectra sensitivity, of ratio signal-noise and other parameters on β-electron energy and thickness of emulsion layer were studied.

The measurement of positron--nucleus collisions was used to estimate the possibility of suppressi... more The measurement of positron--nucleus collisions was used to estimate the possibility of suppressing background events that simulate betabeta\beta\betabetabeta decay in the emulsion region adjacent to molybdenum conglomerates. The range of the escape of two relativistic particles from the interaction was found to be $ = (0.60\pm 0.03) ~\mu$m, which approximately corresponds to the grain size of developed nuclear emulsion. No

The Identification of Dark Matter - Proceedings of the Fourth International Workshop, 2003

An optical model of a two-phase xenon chamber for direct calculation of light fluxes has been bui... more An optical model of a two-phase xenon chamber for direct calculation of light fluxes has been built up. A calculation method of photo multiplier tubes response at charged particle interacting in chamber was deduced. A method of 3D reconstruction of event coordinates was built and studied with use of this model.

Radiation Measurements, 1997

Here we have made an attempt to describe etching along and perpendicular to the ion track axis wi... more Here we have made an attempt to describe etching along and perpendicular to the ion track axis with the many-hit response model. From experiments where sheets of Makrofol KG film were exposed to Au and Xe ions it was found that V t/V b depends on restricted energy loss (REL). Then, for the many-hit model the registration parameters of the detectors were found and were used for the calculation of the radial distributions of the transversal etching rate and were compared with experimental data.

The Identification of Dark Matter - Proceedings of the Fourth International Workshop, 2003

The current status of a development project focused on constructing a novel two-phase xenon detec... more The current status of a development project focused on constructing a novel two-phase xenon detector to search for Dark Matter is given. The response to neutrons in terms of ionisation and scintillation has been observed. Decay times of the scintillation due to nuclear recoils have been measured.