RuPAC2014 - List of Keywords (neutron)

Paper	Title	Other Keywords	Page
TUPSA36	Measurement of the Dose Rate and the Radiation Spectrum of the Interaction of 2 MeV Proton Beam with a Variety of Structural Materials	proton, target, radiation, vacuum	113
	D.A. Kasatov, A.N. Makarov, I.M. Shchudlo, S.Yu. Taskaev BINP SB RAS, Novosibirsk, Russia
	The paper presents the results of measurements of the spectrum and the radiation dose during irradiation of different construction materials with 2 MeV proton beam. There are shown the spectra of the induced activity of a number of materials and signals from the neutron detector. Based on the obtained results it is made the optimal choice of the target material, on which it is deposited a thin layer of lithium to generate epithermal neutrons used for boron neutron capture therapy of malignant tumors. Recommendations are given for materials desirable to use inside the high-energy beam transporting channel to reduce the dose of concomitant radiation.

TUPSA38	Estimation of the Efficiency of Biological Shielding for the Circular Hall of U-70 Accelerator at IHEP	shielding, detector, photon, target	118
	O.V. Sumaneev, G.I. Britvich, M.Y. Kostin, V.A. Pikalov IHEP, Moscow Region, Russia
	Report presents estimation of biological shielding efficiency for annular hall of U-70 accelerator. Distribution of neutron flux in concrete shielding of proton accelerator measurements carried out by method of long-lived isotopes specific activity determination. The experimental data may be compared with Monte-Carlo simulation.

WEPSB11	Test Results of 433 MHz Deuteron Linac (RFQ)	rfq, target, detector, ion	177
	Y.A. Svistunov, S.V. Grigorenko, A.N. Kuzhlev, A.K. Liverovskij, I.I. Mezhov, A.A. Ryaskov, A.P. Strokach, V.F. Tsvetkov, O.L. Veresov, Yu. Zuev NIIEFA, St. Petersburg, Russia
	The results of bench tests of the high frequency deuteron accelerator (RFQ) with output energy of 1 MeV and operating frequency of 433 MHz are presented. There are briefly discussed RFQ construction and assembling, rf system, issues of tuning and measuring of electrodynamical characteristics of RFQ. Output data obtained under accelerated beam operation with foil monitor and Beryllium target are given.

WEPSB16	Studying of the Accompanying Charged Particles in the Tandem Accelerator with Vacuum Insulation	detector, vacuum, proton, target	189
	A.N. Makarov, D.A. Kasatov, I.M. Shchudlo, S.Yu. Taskaev BINP SB RAS, Novosibirsk, Russia
	On the tandem accelerator with vacuum insulation in a steady long mode it was obtained 1.6 mA current of protons with 2 MeV energy. It was studied the one of the possible reasons of current limitation – the appearance of accompanying charged particles during acceleration of the ion beam. The paper presents and discusses the results of the accompanying beam measurement using a special detector. The detector registered an opposite positive current in the range of 80-170 mkA, which is directly dependent on vacuum conditions in the accelerator. Also it was measured the dependence of the dose rate on the total current in the accelerating gap. These measurements confirmed that injected H⁻ beam ionizes residual and stripping gas mainly in the area before the first electrode and two proposals were made to minimize the accompanying current.

WEPSB17	Development of the Injector for Vacuum Insulated Tandem Accelerator	ion, vacuum, ion-source, acceleration	191
	A.S. Kuznetsov, A.A. Alexander, M.A. Tiunov BINP SB RAS, Novosibirsk, Russia D.A. Kasatov, A.M. Koshkarev NSU, Novosibirsk, Russia
	The Vacuum Insulated Tandem Accelerator is built at the Budker Institute of Nuclear Physics.* The accelerator is designed for development of the concept of accelerator-based boron neutron capture therapy of malignant tumors in the clinic.** In the accelerator the negative hydrogen ions are accelerated by the high voltage electrode potential to the half of required energy, and after conversion of the ions into protons by means of a gas stripping target the protons are accelerated again by the same potential to the full beam energy. A number of innovative ideas posited in the design make it possible to accelerate intense beams in a compact accelerator. Number of investigations revealed weak points of the accelerator injector: unnecessary beam stripping by the residual gas and complexity to improve the vacuum conditions, the influence of the stripping gas to the ion source operation stability. To ensure the beam parameters and reliability of the facility operation required for clinical applications, the new injector is designed based on the ion source with a current up to 15 mA, providing the possibility of preliminary beam acceleration upto 120-200 keV. The paper presents the design of the injector and the results of calculations performed. Aleynik V., Bashkirtsev A., et al. Applied Radiation and Isotopes 88 (2014) 177-179. *Bayanov B., Belov V., et al. Nuclear Instr. and Methods in Physics Research A 413/2-3 (1998) 397-426.

WEPSB20	Experimental Study of the Time Dependence of the Activity of Delayed Neutrons in the Fission of 235U by Neutrons from the Reaction 7Li(p, n) on the Electrostatic Accelerator EG-1	experiment, detector, proton, target	200
	K.V. Mitrofanov, A.S. Egorov, D.E. Gremyachkin, V.F. Mitrofanov, V.M. Piksaikin, B.F. Samylin IPPE, Obninsk, Russia
	In the present work the installation created on the basis of the accelerator EG-1 (IPPE) for the experimental studies of the time dependence of delayed neutron activity from neutron induced fission of 235U is described. Measurements were carried out with neutron beam generated with the help of the 7Li(p, n) reaction. The lower limit of the investigated time range was governed by the proton beam switching system that was 20 ms. It was shown that the temporary characteristics of delayed neutrons from the fission of 235U by epithermal neutrons is consistent with the time dependence which at present is recommended as a standard. In case of the fast neutron induced fission of 235U the measured decay curve of delayed neutrons shows excess of counting rate in the time interval 0.01-0.2 s as compared with the decay curve corresponding to the recommended data.

WEPSB21	Registration of Gamma Rays from the Reaction 16O(n, p)16N on the Direct Neutron Beam of Cascade Generator KG-2.5	target, background, detector, experiment	203
	K.V. Mitrofanov, A.S. Egorov, V.M. Piksaikin, B.F. Samylin IPPE, Obninsk, Russia
	In the present work the results of analysis of the oxygen content in the water with the help of gamma-rays registration from the reaction 16O(n, p)16N is described. The samples were installed permanently on the direct beam of neutrons generated by the reaction 7Li(d, n) in the cascade generator KG-2.5 (IPPE). A comparison was carried out with experimental data obtained by the activation method in similar experimental conditions.

WEPSB23	Set-up for Measurements of Delayed Neutron Characteristics in Interaction of Heavy Nuclei with Relativistic Protons of the Synchrocyclotron PINP Gatchina	proton, detector, synchro-cyclotron, experiment	209
	A.S. Egorov, V.F. Mitrofanov, V.M. Piksaikin, B.F. Samylin IPPE, Obninsk, Russia
	In the present paper the method and set-up for measurements of delayed neutron characteristics in interaction of heavy nuclei with relativistic protons are described. On the basis of this method the time dependence of delayed neutron activity has been measured from interaction of 238U sample with 1 GeV pulsed proton beam of the synchrocyclotron of the Petersburg Institute of Nuclear Physics, Gatchina. The measured data was analyzed in frame of 8-group precursor's model with a unified set of half-lives. Obtained results on the fractional yields of delayed neutrons are compared with the appropriate data from the fast neutron induced fission of 238U.

WEPSB44	Neutron Radiation Monitoring of the Therapeutic Proton Beam Transportation	radiation, proton, monitoring, beam-transport	262
	V.M. Skorkin RAS/INR, Moscow, Russia
	A monitoring system online controls a therapeutic proton beam by measuring a secondary neutron radiation from the beam losses. The system consists of neutron detectors in the transport path passage from Linac to the facility of proton therapy and terminal controller connected to the computer. The neutron detectors measure a level of the secondary neutron radiation in real time along of the transport channel, near the formative elements. The system of the neutron detectors registers temporal variations of the beam intensity in local areas transport medical channel. These changes arise are due to changes in operating mode of the channels or instability of the elements forming the beam. The monitoring system allows to determine a intensity and temporal structure of the therapeutic beam and to detect mode and instability of the formative elements.

WEPSB49	Method of Measuring Fast Neutron Fluence Using the Planar Silicon Detectors	detector, radiation, experiment, lattice	272
	A.I. Shafronovskaia JINR, Dubna, Moscow Region, Russia
	Funding: Joint Institute for Nuclear Research, Dubna The technique reported of fast neutron fluence measurements using silicon detectors. One of the main macroscopic effects at radiation damage of silicon detectors by fast neutrons is increase of the reverse current. The increment of the reverse current detector is a linear dependence on fast neutron fluence and is determined by the formula: DI=aIxFxV, where: DI=(I1-I0), (А) – the measured increment of the reverse dark current after irradiation of the detector normalized to temperature of +20 C, aI=(5±0.5)'10^-17, (А/сm) – current constant radiation damage of silicon for neutrons with energy 1 MeV, F, (сm-2) - equivalent fluence of fast neutrons with energy 1 MeV, V=d'S, (сm3) – the volume of the detector at the full depletion voltage. The experimental results of measurements of fast neutron fluence with silicon detectors are obtained on the pulsed fast neutrons reactor (IBR-2, channel #3) and on the experimental facility KVINTA JINR, Dubna.

THPSC50	Neutron Accelerating Tubes with Microwave Deuterons Source Using Electron-cyclotron Resonance Effect	ion, plasma, cavity, ECR	441
	A.N. Didenko, B.Y. Bogdanovich, K.I. Kozlovskiy, A. Nesterovich, A.V. Prokopenko, V.L. Shatokhin, A.E. Shikanov MEPhI, Moscow, Russia
	The physical principles of increased efficiency neutron accelerating tubes based on the microwave sources of heavy hydrogen nuclides, using the electron-cyclotron resonance effect (ECR) are considered. The authors' theoretical results are given on electromagnetic oscillations generation in the working volume of the ion source of the accelerating tube with the boundary excitation of a microwave discharge. Resonator and waveguide modes for ECR-plasma excitation are thus examined. Features of neutron generation in these accelerator neutron tubes based on microwave source of heavy hydrogen nuclides are analyzed. The algorithm is developed and numerical simulation of neutron pulse formation in neutron generators based on microwave source is done taking into account target shape and the possible deuterons resonant recharge. Frequency dependences of the energy flux density transmitted from an alternating electromagnetic field to the electron component of the plasma are obtained depending on the constant longitudinal magnetic field induction and pressure in the discharge chamber. The results of these studies could form the basis for the efficient domestic portable neutron generators development based on accelerating tubes with microwave hydrogen nuclides sources.

THPSC51	Ion Source Deuteron Beam Acceleration in Gas-filled Ion-optic System	target, ion, electron, space-charge	444
	V.I. Rashchikov MEPhI, Moscow, Russia
	Deuteron beam acceleration in ion-optic system of gas-filled neutron tubes was investigated. PIC code SUMA* used for computer simulation of ionization and knock on processes and there influence on deuteron beam parameters. When deuteron and ionized particles space charge self-field forces become the same order of magnitude as external one, virtual cathode may occurs. It is happens because of injected from ion source deuterons cannot overcome their own space charge potential wall and move in transverse direction. However, electrons, produced by ionization, are trapped within the deuteron beam space charge potential wall and decrease it significantly. Thus, space charge neutralization of deuteron beams by electrons, may considerably increase target current and, as a result, output neutron flow. Moreover, own longitudinal electric field rise near the target leads to reduction of accelerating electrode – target potential wall, which was made to prevent knock on emission from the target. As a result, additional knocked on electrons may appear in the region and should be taken into account. The data obtained were compared with experimental results. * A.N. Didenko, V.I. Rashchikov, V.E. Fortov, Technical Physics, Vol. 56, No. 10,pp. 1535–1538, 2011

THPSC52	Dynamics of Plasma-Beam Formations in the Acceleration Gap of the Pulse Neutron Generator-based Vacuum Neutron Tube	plasma, target, ion, vacuum	447
	S. Sergey, S. Maslennikov, E. Shkolnikov National Research Nuclear University (MEPhI), Moscow, Russia A. Agafonov LPI RAS, Moscow, Russia
	The analysis of dynamics of plasma flows containing deuterium, zirconium ions, and electrons in acceleration gap of the pulsed neutron generator vacuum neutron tube* is presented in the paper. The investigations have been undertaken with the use of code KARAT** for the two-dimensional time-dependant regime. The limiting currents of each component for the real geometry of acceleration gap have been determined. The differences between the values of these currents and those determined with the use of the Child-Langmuir equation have been demonstrated. The analysis of dynamics of plasma emitter in the gap has been performed by the example of accelerating voltage of 120 kV and pulse duration of 1.2 mks. It has been shown that the value of the current incoming in the gap from the ions source can differ strongly from the current value at the target. For increasing of this value the partitioning of acceleration gap with the use of conductive grid which is transparent for beam and has several geometric configurations has been proposed. The ring configuration of the emitter has been considered for the same purposes. The calculations have shown that the combination of these two methods described above can allow transporting deuterons current from the anode grid to the target without losses. * E.P.Bogolubov, V.I.Ryzhkov, D.I.Yurkov. Conference "PNG and Technologies on Their Basis",2013,p.14. ** V.P.Tarakanov. User's Manual for Code KARAT. Berkeley Research Associates, Inc. 1992, p.127.

THPSC53	The NG-10 Neutron Generator for Production of Neutron Fluxes in Continuous and Pulse Modes	controls, ion, target, power-supply	450
	D.A. Solnyshkov, A.V. Antonov, A.N. Kuzhlev, N.P. Mikulinas, A.V. Morozov, G.G. Voronin NIIEFA, St. Petersburg, Russia
	Designed neutron generator is designed for a neutron yield 1x10¹¹ neutrons / s in continuous mode and includes ion accelerator with an accelerating voltage, continuously adjustable in the range of 120-150 keV and a beam current of atomic deuterium ions up to 2 mA, and the target device, in which used Ti-T target different diameters. In addition to high and stable yield of neutrons in time when operating continuously generator provides pulsed mode of operation over a wide range of duration and pulse repetition rate. Pulsed neutron generator operation is performed by modulating the discharge current of the ion source. For this purpose, a unique system of power discharge, which allows for both continuous and pulse modes. In this case it is possible to produce a smooth adjustment of the pulse width of the beam current. Switch from pulse mode to DC promptly made with the remote control.

FRCB01	Problems and Prospects of the Tandem Accelerator with Vacuum Insulation	vacuum, high-voltage, ion, tandem-accelerator	465
	S.Yu. Taskaev, D.A. Kasatov, A.S. Kuznetsov, A.N. Makarov, I.M. Shchudlo, I.N. Sorokin BINP SB RAS, Novosibirsk, Russia
	Funding: Ministry of Education and Science of Russia (project RFMEFI57614X0181) At BINP for development of boron neutron capture therapy it is proposed and constructed the tandem accelerator with vacuum insulation, which is characterized by rapid acceleration of charged particles. Problems of high-voltage strength gaps due to the large stored energy and strong electrostatic lens are solved. It is obtained a stationary 1.6 mA 2 MeV proton beam having 0.1% energy monochromaticity and 0.5% current stability. It is clarified, that further increase of the proton current in the stable mode without breakdowns is limited by the accompanying current in the high-voltage gaps. It is proposed to make vacuum conditions better in the input of the accelerator using additional cryopump, to modernize argon stripping target by its tilting or shifting and to use differential pumping inside the high-voltage electrode. Obtaining of the 3 mA 2.5 MeV proton beam will allow us to conduct boron neutron capture therapy.
	Slides FRCB01 [0.815 MB]

FRCB02	Dynamics of Processes in Subcritical Reactor Driven by Linear Accelerator	controls, feedback, linac, proton	467
	A.G. Golovkina, I.V. Kudinovich, D.A. Ovsyannikov St. Petersburg State University, St. Petersburg, Russia Y.A. Svistunov Saint Petersburg State University, Saint Petersburg, Russia
	Funding: St. Petersburg State University, grant No. 9.38.673.2013 In this paper dynamics of processes in accelerator driven system (ADS) is considered. ADS reactor operates at subcritical level and the necessary neutron supply comes from the interaction of a charged particles beam with a heavy atom nucleus (spallation reaction). Mathematical model of dynamics of subcritical reactor controlled by linear accelerator is presented. Calculation results of transient processes in the reactor core taking into account fuel feedback. The reactor power level control is carried out through the regulation of linac current impulses frequency.

Paper

Title

Other Keywords

Page

Measurement of the Dose Rate and the Radiation Spectrum of the Interaction of 2 MeV Proton Beam with a Variety of Structural Materials

proton, target, radiation, vacuum

113

D.A. Kasatov, A.N. Makarov, I.M. Shchudlo, S.Yu. Taskaev
BINP SB RAS, Novosibirsk, Russia

The paper presents the results of measurements of the spectrum and the radiation dose during irradiation of different construction materials with 2 MeV proton beam. There are shown the spectra of the induced activity of a number of materials and signals from the neutron detector. Based on the obtained results it is made the optimal choice of the target material, on which it is deposited a thin layer of lithium to generate epithermal neutrons used for boron neutron capture therapy of malignant tumors. Recommendations are given for materials desirable to use inside the high-energy beam transporting channel to reduce the dose of concomitant radiation.

TUPSA38

Estimation of the Efficiency of Biological Shielding for the Circular Hall of U-70 Accelerator at IHEP

shielding, detector, photon, target

118

O.V. Sumaneev, G.I. Britvich, M.Y. Kostin, V.A. Pikalov
IHEP, Moscow Region, Russia

Report presents estimation of biological shielding efficiency for annular hall of U-70 accelerator. Distribution of neutron flux in concrete shielding of proton accelerator measurements carried out by method of long-lived isotopes specific activity determination. The experimental data may be compared with Monte-Carlo simulation.

WEPSB11

Test Results of 433 MHz Deuteron Linac (RFQ)

rfq, target, detector, ion

177

Y.A. Svistunov, S.V. Grigorenko, A.N. Kuzhlev, A.K. Liverovskij, I.I. Mezhov, A.A. Ryaskov, A.P. Strokach, V.F. Tsvetkov, O.L. Veresov, Yu. Zuev
NIIEFA, St. Petersburg, Russia

The results of bench tests of the high frequency deuteron accelerator (RFQ) with output energy of 1 MeV and operating frequency of 433 MHz are presented. There are briefly discussed RFQ construction and assembling, rf system, issues of tuning and measuring of electrodynamical characteristics of RFQ. Output data obtained under accelerated beam operation with foil monitor and Beryllium target are given.

WEPSB16

Studying of the Accompanying Charged Particles in the Tandem Accelerator with Vacuum Insulation

detector, vacuum, proton, target

189

A.N. Makarov, D.A. Kasatov, I.M. Shchudlo, S.Yu. Taskaev
BINP SB RAS, Novosibirsk, Russia

On the tandem accelerator with vacuum insulation in a steady long mode it was obtained 1.6 mA current of protons with 2 MeV energy. It was studied the one of the possible reasons of current limitation – the appearance of accompanying charged particles during acceleration of the ion beam. The paper presents and discusses the results of the accompanying beam measurement using a special detector. The detector registered an opposite positive current in the range of 80-170 mkA, which is directly dependent on vacuum conditions in the accelerator. Also it was measured the dependence of the dose rate on the total current in the accelerating gap. These measurements confirmed that injected H⁻ beam ionizes residual and stripping gas mainly in the area before the first electrode and two proposals were made to minimize the accompanying current.

WEPSB17

Development of the Injector for Vacuum Insulated Tandem Accelerator

ion, vacuum, ion-source, acceleration

191

A.S. Kuznetsov, A.A. Alexander, M.A. Tiunov
BINP SB RAS, Novosibirsk, Russia
D.A. Kasatov, A.M. Koshkarev
NSU, Novosibirsk, Russia

The Vacuum Insulated Tandem Accelerator is built at the Budker Institute of Nuclear Physics.* The accelerator is designed for development of the concept of accelerator-based boron neutron capture therapy of malignant tumors in the clinic.** In the accelerator the negative hydrogen ions are accelerated by the high voltage electrode potential to the half of required energy, and after conversion of the ions into protons by means of a gas stripping target the protons are accelerated again by the same potential to the full beam energy. A number of innovative ideas posited in the design make it possible to accelerate intense beams in a compact accelerator. Number of investigations revealed weak points of the accelerator injector: unnecessary beam stripping by the residual gas and complexity to improve the vacuum conditions, the influence of the stripping gas to the ion source operation stability. To ensure the beam parameters and reliability of the facility operation required for clinical applications, the new injector is designed based on the ion source with a current up to 15 mA, providing the possibility of preliminary beam acceleration upto 120-200 keV. The paper presents the design of the injector and the results of calculations performed.
*Aleynik V., Bashkirtsev A., et al. Applied Radiation and Isotopes 88 (2014) 177-179.
**Bayanov B., Belov V., et al. Nuclear Instr. and Methods in Physics Research A 413/2-3 (1998) 397-426.

WEPSB20

Experimental Study of the Time Dependence of the Activity of Delayed Neutrons in the Fission of 235U by Neutrons from the Reaction 7Li(p, n) on the Electrostatic Accelerator EG-1

experiment, detector, proton, target

200

K.V. Mitrofanov, A.S. Egorov, D.E. Gremyachkin, V.F. Mitrofanov, V.M. Piksaikin, B.F. Samylin
IPPE, Obninsk, Russia

In the present work the installation created on the basis of the accelerator EG-1 (IPPE) for the experimental studies of the time dependence of delayed neutron activity from neutron induced fission of 235U is described. Measurements were carried out with neutron beam generated with the help of the 7Li(p, n) reaction. The lower limit of the investigated time range was governed by the proton beam switching system that was 20 ms. It was shown that the temporary characteristics of delayed neutrons from the fission of 235U by epithermal neutrons is consistent with the time dependence which at present is recommended as a standard. In case of the fast neutron induced fission of 235U the measured decay curve of delayed neutrons shows excess of counting rate in the time interval 0.01-0.2 s as compared with the decay curve corresponding to the recommended data.

WEPSB21

Registration of Gamma Rays from the Reaction 16O(n, p)16N on the Direct Neutron Beam of Cascade Generator KG-2.5

target, background, detector, experiment

203

K.V. Mitrofanov, A.S. Egorov, V.M. Piksaikin, B.F. Samylin
IPPE, Obninsk, Russia

In the present work the results of analysis of the oxygen content in the water with the help of gamma-rays registration from the reaction 16O(n, p)16N is described. The samples were installed permanently on the direct beam of neutrons generated by the reaction 7Li(d, n) in the cascade generator KG-2.5 (IPPE). A comparison was carried out with experimental data obtained by the activation method in similar experimental conditions.

WEPSB23

Set-up for Measurements of Delayed Neutron Characteristics in Interaction of Heavy Nuclei with Relativistic Protons of the Synchrocyclotron PINP Gatchina

proton, detector, synchro-cyclotron, experiment

209

A.S. Egorov, V.F. Mitrofanov, V.M. Piksaikin, B.F. Samylin
IPPE, Obninsk, Russia

In the present paper the method and set-up for measurements of delayed neutron characteristics in interaction of heavy nuclei with relativistic protons are described. On the basis of this method the time dependence of delayed neutron activity has been measured from interaction of 238U sample with 1 GeV pulsed proton beam of the synchrocyclotron of the Petersburg Institute of Nuclear Physics, Gatchina. The measured data was analyzed in frame of 8-group precursor's model with a unified set of half-lives. Obtained results on the fractional yields of delayed neutrons are compared with the appropriate data from the fast neutron induced fission of 238U.

WEPSB44

Neutron Radiation Monitoring of the Therapeutic Proton Beam Transportation

radiation, proton, monitoring, beam-transport

262

V.M. Skorkin
RAS/INR, Moscow, Russia

A monitoring system online controls a therapeutic proton beam by measuring a secondary neutron radiation from the beam losses. The system consists of neutron detectors in the transport path passage from Linac to the facility of proton therapy and terminal controller connected to the computer. The neutron detectors measure a level of the secondary neutron radiation in real time along of the transport channel, near the formative elements. The system of the neutron detectors registers temporal variations of the beam intensity in local areas transport medical channel. These changes arise are due to changes in operating mode of the channels or instability of the elements forming the beam. The monitoring system allows to determine a intensity and temporal structure of the therapeutic beam and to detect mode and instability of the formative elements.

WEPSB49

Method of Measuring Fast Neutron Fluence Using the Planar Silicon Detectors

detector, radiation, experiment, lattice

272

A.I. Shafronovskaia
JINR, Dubna, Moscow Region, Russia

Funding: Joint Institute for Nuclear Research, Dubna
The technique reported of fast neutron fluence measurements using silicon detectors. One of the main macroscopic effects at radiation damage of silicon detectors by fast neutrons is increase of the reverse current. The increment of the reverse current detector is a linear dependence on fast neutron fluence and is determined by the formula: DI=aIxFxV, where: DI=(I1-I0), (А) – the measured increment of the reverse dark current after irradiation of the detector normalized to temperature of +20 C, aI=(5±0.5)'10^-17, (А/сm) – current constant radiation damage of silicon for neutrons with energy 1 MeV, F, (сm-2) - equivalent fluence of fast neutrons with energy 1 MeV, V=d'S, (сm3) – the volume of the detector at the full depletion voltage. The experimental results of measurements of fast neutron fluence with silicon detectors are obtained on the pulsed fast neutrons reactor (IBR-2, channel #3) and on the experimental facility KVINTA JINR, Dubna.

THPSC50

Neutron Accelerating Tubes with Microwave Deuterons Source Using Electron-cyclotron Resonance Effect

ion, plasma, cavity, ECR

441

A.N. Didenko, B.Y. Bogdanovich, K.I. Kozlovskiy, A. Nesterovich, A.V. Prokopenko, V.L. Shatokhin, A.E. Shikanov
MEPhI, Moscow, Russia

The physical principles of increased efficiency neutron accelerating tubes based on the microwave sources of heavy hydrogen nuclides, using the electron-cyclotron resonance effect (ECR) are considered. The authors' theoretical results are given on electromagnetic oscillations generation in the working volume of the ion source of the accelerating tube with the boundary excitation of a microwave discharge. Resonator and waveguide modes for ECR-plasma excitation are thus examined. Features of neutron generation in these accelerator neutron tubes based on microwave source of heavy hydrogen nuclides are analyzed. The algorithm is developed and numerical simulation of neutron pulse formation in neutron generators based on microwave source is done taking into account target shape and the possible deuterons resonant recharge. Frequency dependences of the energy flux density transmitted from an alternating electromagnetic field to the electron component of the plasma are obtained depending on the constant longitudinal magnetic field induction and pressure in the discharge chamber. The results of these studies could form the basis for the efficient domestic portable neutron generators development based on accelerating tubes with microwave hydrogen nuclides sources.

THPSC51

Ion Source Deuteron Beam Acceleration in Gas-filled Ion-optic System

target, ion, electron, space-charge

444

V.I. Rashchikov
MEPhI, Moscow, Russia

Deuteron beam acceleration in ion-optic system of gas-filled neutron tubes was investigated. PIC code SUMA* used for computer simulation of ionization and knock on processes and there influence on deuteron beam parameters. When deuteron and ionized particles space charge self-field forces become the same order of magnitude as external one, virtual cathode may occurs. It is happens because of injected from ion source deuterons cannot overcome their own space charge potential wall and move in transverse direction. However, electrons, produced by ionization, are trapped within the deuteron beam space charge potential wall and decrease it significantly. Thus, space charge neutralization of deuteron beams by electrons, may considerably increase target current and, as a result, output neutron flow. Moreover, own longitudinal electric field rise near the target leads to reduction of accelerating electrode – target potential wall, which was made to prevent knock on emission from the target. As a result, additional knocked on electrons may appear in the region and should be taken into account. The data obtained were compared with experimental results.
* A.N. Didenko, V.I. Rashchikov, V.E. Fortov, Technical Physics, Vol. 56, No. 10,pp. 1535–1538, 2011

THPSC52

Dynamics of Plasma-Beam Formations in the Acceleration Gap of the Pulse Neutron Generator-based Vacuum Neutron Tube

plasma, target, ion, vacuum

447

S. Sergey, S. Maslennikov, E. Shkolnikov
National Research Nuclear University (MEPhI), Moscow, Russia
A. Agafonov
LPI RAS, Moscow, Russia

The analysis of dynamics of plasma flows containing deuterium, zirconium ions, and electrons in acceleration gap of the pulsed neutron generator vacuum neutron tube* is presented in the paper. The investigations have been undertaken with the use of code KARAT** for the two-dimensional time-dependant regime. The limiting currents of each component for the real geometry of acceleration gap have been determined. The differences between the values of these currents and those determined with the use of the Child-Langmuir equation have been demonstrated. The analysis of dynamics of plasma emitter in the gap has been performed by the example of accelerating voltage of 120 kV and pulse duration of 1.2 mks. It has been shown that the value of the current incoming in the gap from the ions source can differ strongly from the current value at the target. For increasing of this value the partitioning of acceleration gap with the use of conductive grid which is transparent for beam and has several geometric configurations has been proposed. The ring configuration of the emitter has been considered for the same purposes. The calculations have shown that the combination of these two methods described above can allow transporting deuterons current from the anode grid to the target without losses.
* E.P.Bogolubov, V.I.Ryzhkov, D.I.Yurkov. Conference "PNG and Technologies on Their Basis",2013,p.14.
** V.P.Tarakanov. User's Manual for Code KARAT. Berkeley Research Associates, Inc. 1992, p.127.

THPSC53

The NG-10 Neutron Generator for Production of Neutron Fluxes in Continuous and Pulse Modes

controls, ion, target, power-supply

450

D.A. Solnyshkov, A.V. Antonov, A.N. Kuzhlev, N.P. Mikulinas, A.V. Morozov, G.G. Voronin
NIIEFA, St. Petersburg, Russia

Designed neutron generator is designed for a neutron yield 1x10¹¹ neutrons / s in continuous mode and includes ion accelerator with an accelerating voltage, continuously adjustable in the range of 120-150 keV and a beam current of atomic deuterium ions up to 2 mA, and the target device, in which used Ti-T target different diameters. In addition to high and stable yield of neutrons in time when operating continuously generator provides pulsed mode of operation over a wide range of duration and pulse repetition rate. Pulsed neutron generator operation is performed by modulating the discharge current of the ion source. For this purpose, a unique system of power discharge, which allows for both continuous and pulse modes. In this case it is possible to produce a smooth adjustment of the pulse width of the beam current. Switch from pulse mode to DC promptly made with the remote control.

FRCB01

Problems and Prospects of the Tandem Accelerator with Vacuum Insulation

vacuum, high-voltage, ion, tandem-accelerator

465

S.Yu. Taskaev, D.A. Kasatov, A.S. Kuznetsov, A.N. Makarov, I.M. Shchudlo, I.N. Sorokin
BINP SB RAS, Novosibirsk, Russia

Funding: Ministry of Education and Science of Russia (project RFMEFI57614X0181)
At BINP for development of boron neutron capture therapy it is proposed and constructed the tandem accelerator with vacuum insulation, which is characterized by rapid acceleration of charged particles. Problems of high-voltage strength gaps due to the large stored energy and strong electrostatic lens are solved. It is obtained a stationary 1.6 mA 2 MeV proton beam having 0.1% energy monochromaticity and 0.5% current stability. It is clarified, that further increase of the proton current in the stable mode without breakdowns is limited by the accompanying current in the high-voltage gaps. It is proposed to make vacuum conditions better in the input of the accelerator using additional cryopump, to modernize argon stripping target by its tilting or shifting and to use differential pumping inside the high-voltage electrode. Obtaining of the 3 mA 2.5 MeV proton beam will allow us to conduct boron neutron capture therapy.

Slides FRCB01 [0.815 MB]

FRCB02

Dynamics of Processes in Subcritical Reactor Driven by Linear Accelerator

controls, feedback, linac, proton

467

A.G. Golovkina, I.V. Kudinovich, D.A. Ovsyannikov
St. Petersburg State University, St. Petersburg, Russia
Y.A. Svistunov
Saint Petersburg State University, Saint Petersburg, Russia

Funding: St. Petersburg State University, grant No. 9.38.673.2013
In this paper dynamics of processes in accelerator driven system (ADS) is considered. ADS reactor operates at subcritical level and the necessary neutron supply comes from the interaction of a charged particles beam with a heavy atom nucleus (spallation reaction). Mathematical model of dynamics of subcritical reactor controlled by linear accelerator is presented. Calculation results of transient processes in the reactor core taking into account fuel feedback. The reactor power level control is carried out through the regulation of linac current impulses frequency.